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consensus="true" docName="draft-ietf-ipsecme-iptfs-19"     submissionType="IETF"> number="9347" obsoletes="" updates="" xml:lang="en" tocInclude="true" symRefs="true" sortRefs="true" version="3">

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  <front>
    <title abbrev="IP Traffic Flow Security">IP-TFS: Aggregation Security">Aggregation and Fragmentation Mode for ESP Encapsulating Security Payload (ESP) and its Its Use for IP Traffic Flow Security</title> Security (IP-TFS)</title>
    <seriesInfo name="RFC" value="9347"/>
    <author initials='C.' surname='Hopps' fullname='Christian Hopps'><organization>LabN initials="C." surname="Hopps" fullname="Christian Hopps">
      <organization>LabN Consulting, L.L.C.</organization><address><email>chopps@chopps.org</email></address></author>  <date/><abstract><t>This L.L.C.</organization>
      <address>
        <email>chopps@chopps.org</email>
      </address>
    </author>
    <date year="2023" month="January"/>
    <area>sec</area>
    <workgroup>ipsecme</workgroup>
<abstract>
      <t>This document describes a mechanism for aggregation and
fragmentation of IP packets when they are being encapsulated in ESP
payloads. Encapsulating Security Payload (ESP). This new payload type can be used for various purposes purposes, such
as decreasing encapsulation overhead for small IP packets; however,
the focus in this document is to enhance IPsec traffic flow security IP Traffic Flow Security
(IP-TFS) by adding Traffic Flow Confidentiality (TFC) to encrypted IP
encapsulated IP-encapsulated traffic. TFC is provided by obscuring the size and
frequency of IP traffic using a fixed-sized, fixed-size, constant-send-rate IPsec
tunnel. The solution allows for congestion control control, as well as
non-constant
nonconstant send-rate usage.</t></abstract> usage.</t>
    </abstract>
  </front>
  <middle>
    <section title="Introduction" anchor="sec-introduction"> anchor="sec-introduction" numbered="true" toc="default">
      <name>Introduction</name>
      <t>Traffic Analysis (<xref target="RFC4301"/>, analysis <xref target="RFC4301" format="default"/> <xref target="AppCrypt"/>) target="AppCrypt" format="default"/> is the act of extracting
information about data being sent through a network. While directly
obscuring the data with encryption <xref target="RFC4303"/>, target="RFC4303" format="default"/>, the patterns in the
message traffic may expose information due to variations in its shape
and timing (<xref target="RFC8546"/>, <xref target="AppCrypt"/>). target="RFC8546" format="default"/> <xref target="AppCrypt" format="default"/>. Hiding the size and frequency of
traffic is referred to as Traffic Flow Confidentiality (TFC) (TFC), per
      <xref target="RFC4303"/>.</t> target="RFC4303" format="default"/>.</t>
      <t><xref target="RFC4303"/> target="RFC4303" format="default"/> provides for TFC by allowing padding to be added to encrypted
IP packets and allowing for transmission of all-pad packets
(indicated using protocol 59). This method has the major limitation
      that it can significantly under-utilize underutilize the available bandwidth.</t>
      <t>This document defines an aggregation and fragmentation (AGGFRAG) mode
for ESP, and its as well as ESP's use for IP Traffic Flow Security (IP-TFS). This
solution provides for full TFC without the aforementioned bandwidth
limitation. This is accomplished by using a constant-send-rate IPsec
<xref target="RFC4303"/> target="RFC4303" format="default"/> tunnel with fixed-sized fixed-size encapsulating packets; however, these
fixed-sized
fixed-size packets can contain partial, whole whole, or multiple IP packets
to maximize the bandwidth of the tunnel. A non-constant send-rate nonconstant send rate is
allowed, but the confidentiality properties of its use are outside
the scope of this document.</t>
<t>For a comparison of the overhead of IP-TFS with the RFC4303
prescribed TFC solution
prescribed  in <xref target="RFC4303" format="default"/>, see <xref target="sec-comparisons-of-ip-tfs"></xref>.</t> target="sec-comparisons-of-ip-tfs" format="default"/>.</t>
      <t>Additionally, IP-TFS provides for operating fairly within congested
networks <xref target="RFC2914"/>. target="RFC2914" format="default"/>. This is important for when the IP-TFS user is not
in full control of the domain through which the IP-TFS tunnel path
flows.</t>
      <t>The mechanisms, such as the AGGFRAG mode, defined in this document
are generic with the intent of allowing for non-TFS uses, but such
uses are outside the scope of this document.</t>
      <section title="Terminology numbered="true" toc="default">
        <name>Terminology &amp; Concepts">
<t>The Concepts</name>
	        <t>
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
    NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
    "<bcp14>MAY</bcp14>", and
"OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP
14 BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.</t> here.
        </t>
        <t>This document assumes familiarity with IP security concepts concepts, including
TFC
TFC, as described in <xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
      </section>
    </section>
    <section title="The numbered="true" toc="default">
      <name>The AGGFRAG Tunnel"> Tunnel</name>
      <t>As mentioned in <xref target="sec-introduction"></xref>, target="sec-introduction" format="default"/>, the AGGFRAG mode utilizes an IPsec <xref target="RFC4303"/> target="RFC4303" format="default"/> tunnel
      as its transport. For the purpose of IP-TFS, fixed-sized fixed-size encapsulating
packets are sent at a constant rate on the AGGFRAG tunnel.</t>
      <t>The primary input to the tunnel algorithm is the requested bandwidth
to be used by the tunnel. Two values are then required to provide for
this bandwidth use, use: the fixed size of the encapsulating packets, packets and
the rate at which to send them.</t>
      <t>The fixed packet size MAY <bcp14>MAY</bcp14> either be specified manually or be
determined through other methods methods, such as the Packetization Layer MTU
Discovery (PLMTUD) (<xref target="RFC4821"/>, <xref target="RFC8899"/>) target="RFC4821" format="default"/> <xref target="RFC8899" format="default"/> or Path MTU discovery Discovery (PMTUD)
(<xref target="RFC1191"/>,
<xref target="RFC8201"/>). target="RFC1191" format="default"/> <xref target="RFC8201" format="default"/>. PMTUD is known to have issues issues, so PLMTUD is
considered the more robust option. For PLMTUD, congestion control
payloads can be used as in-band probes (see <xref target="sec-congestion-control-aggfrag-payload-payload-format"></xref> target="sec-congestion-control-aggfrag-payload-payload-format" format="default"/> and <xref target="RFC8899"/>).</t> target="RFC8899" format="default"/>).</t>
      <t>Given the encapsulating packet size and the requested bandwidth to be
used, the corresponding packet send rate can be calculated. The
packet send rate is the requested bandwidth to be used used, which is then divided by the
size of the encapsulating packet.</t>
      <t>The egress (receiving) side of the AGGFRAG tunnel MUST <bcp14>MUST</bcp14> allow for and
expect the ingress (sending) side of the AGGFRAG tunnel to vary the
size and rate of sent encapsulating packets, unless constrained by
other policy.</t>
      <section title="Tunnel Content"> numbered="true" toc="default">
        <name>Tunnel Content</name>
        <t>As previously mentioned, one issue with the TFC padding solution in
<xref target="RFC4303"/> target="RFC4303" format="default"/> is the large amount of wasted bandwidth bandwidth, as only one IP
packet can be sent per encapsulating packet. In order to maximize
bandwidth, IP-TFS breaks this one-to-one association by introducing
an AGGFRAG mode for ESP.</t>

<t>AGGFRAG
        <t>The AGGFRAG mode aggregates as well as and fragments the inner IP traffic
flow into encapsulating IPsec tunnel packets. For IP-TFS, the IPsec
encapsulating tunnel packets are a fixed size. Padding is only added
to the tunnel packets if there is no data available to be sent at
the time of tunnel packet transmission, transmission or if fragmentation has been
disabled by the receiver.</t>
        <t>This is accomplished using a new Encapsulating Security Payload (ESP, (ESP)
<xref target="RFC4303"/>) target="RFC4303" format="default"/> Next Header field value AGGFRAG_PAYLOAD
(<xref target="sec-aggfrag-payload-payload"></xref>).</t> target="sec-aggfrag-payload-payload" format="default"/>).</t>
        <t>Other non-IP-TFS uses of this AGGFRAG mode have been suggested, such
as increased performance through packet aggregation, as well as
handling MTU issues using fragmentation. These uses are not defined
here,
here but are also not restricted by this document.</t>
      </section>
      <section title="Payload Content"> numbered="true" toc="default">
        <name>Payload Content</name>
        <t>The AGGFRAG_PAYLOAD payload content defined in this document
consists of a 4 4- or 24 octet header 24-octet header, followed by either a partial
datablock,
data block, a full datablock, data block, or multiple partial or full datablocks. data blocks.
The following diagram illustrates this payload within the ESP packet.
See <xref target="sec-aggfrag-payload-payload"></xref> target="sec-aggfrag-payload-payload" format="default"/> for the exact formats of the
AGGFRAG_PAYLOAD payload.</t>
        <figure title="Layout anchor="sec-layout-of-an-aggfrag-mode-ipsec-packet">
          <name>Layout of an AGGFRAG mode Mode IPsec Packet" anchor="sec-layout-of-an-aggfrag-mode-ipsec-packet"><artwork><![CDATA[ Packet</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
 . Outer Encapsulating Header ...                                .
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
 . ESP Header...                                                 .
 +---------------------------------------------------------------+
 |   [AGGFRAG sub-type/flags]   :           BlockOffset          |
 +---------------------------------------------------------------+
 :                  [Optional Congestion Info]                   :
 +---------------------------------------------------------------+
 |       DataBlocks ...                                          ~
 ~                                                               ~
 ~                                                               |
 +---------------------------------------------------------------|
 . ESP Trailer...                                                .
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
]]></artwork></figure>
]]></artwork>
        </figure>
        <t>The <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> value is either zero or some offset into or past
the end of the <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data.</t>
        <t>If the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> value is zero zero, it means that the <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt>
data begins with a new data block.</t>
        <t>Conversely, if the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> value is non-zero non-zero, it points to the
start of the new data block, and the initial <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data
belongs to the data block that is still being re-assembled.</t> reassembled.</t>
        <t>If the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> points past the end of the <spanx style='verb'>DataBlocks</spanx> data <tt>DataBlocks</tt> data,
then the next data block occurs in a subsequent encapsulating packet.</t>
        <t>Having the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> always point at the next available data
block allows for recovering the next inner packet in the
presence of outer encapsulating packet loss.</t>
        <t>An example AGGFRAG mode packet flow can be found in <xref target="sec-example-of-an-encapsulated-ip-packet-flow"></xref>.</t> target="sec-example-of-an-encapsulated-ip-packet-flow" format="default"/>.</t>
        <section title="Data Blocks"> numbered="true" toc="default">
          <name>DataBlocks</name>
          <figure title="Layout anchor="sec-layout-of-a-datablock">
            <name>Layout of a DataBlock" anchor="sec-layout-of-a-datablock"><artwork><![CDATA[ Data Block</name>
            <artwork name="" type="" align="left" alt=""><![CDATA[
 +---------------------------------------------------------------+
 | Type  | rest of IPv4, IPv6 IPv6, or pad. pad...
 +--------
]]></artwork></figure>
]]></artwork>
          </figure>
          <t>A data block is defined by a 4-bit type code code, followed by the data
block data. The type values have been carefully chosen to coincide
with the IPv4/IPv6 version field values so that no per-data block type overhead is required to encapsulate an IP packet. Likewise, the
length of the data block is extracted from the encapsulated IPv4's
<spanx style='verb'>Total Length</spanx>
<tt>Total Length</tt> or IPv6's <spanx style='verb'>Payload Length</spanx> <tt>Payload Length</tt> fields.</t>
        </section>
        <section title="End Padding"> numbered="true" toc="default">
          <name>End Padding</name>
          <t>Since a data block's type is identified in its first 4-bits, 4 bits, the only
time padding is required is when there is no data to encapsulate. For
this end padding padding, a <spanx style='verb'>Pad <tt>Pad Data Block</spanx> Block</tt> is used.</t>
        </section>
        <section title="Fragmentation, anchor="sec-fragmentation-sequence-numbers-and-all-pad-payloads" numbered="true" toc="default">
          <name>Fragmentation, Sequence Numbers Numbers, and All-Pad Payloads" anchor="sec-fragmentation-sequence-numbers-and-all-pad-payloads"> Payloads</name>
          <t>In order for a receiver to reassemble fragmented inner packets, the
sender MUST <bcp14>MUST</bcp14> send the inner packet fragments back-to-back back to back in the
logical outer packet stream (i.e., using consecutive ESP sequence
numbers). However, the sender is allowed to insert "all-pad" payloads
(i.e., payloads with a <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> of zero and a single pad
<spanx style='verb'>DataBlock</spanx>)
data block ) in between the packets carrying the inner packet
fragment payloads. This interleaving of all-pad payloads allows the
sender to always send a tunnel packet, regardless of the
encapsulation computational requirements.</t>
          <t>When a receiver is reassembling an inner packet, and it receives an
"all-pad" payload, it increments the expected sequence number that
the next inner packet fragment is expected to arrive in.</t>
          <t>Given the above, the receiver will need to handle out-of-order
arrival of outer ESP packets prior to reassembly processing. ESP
already provides for optionally detecting replay attacks. Detecting
replay attacks normally utilizes a window method. A similar sequence
number based sequence-number-based
sliding window can be used to correct re-ordering reordering of the
outer packet stream.
Receiving a larger (newer) sequence number
packet advances the window, and received if any older ESP packets whose
sequence numbers the window has passed by are received, then the packets are dropped. A good choice
for the size of this window depends on the amount of misordering the
user is experiencing; however, a value of 3 has been suggested as a
default when no more informed choice exists.</t>
          <t>As the amount of misordering that may be present is hard to predict,
the window size SHOULD <bcp14>SHOULD</bcp14> be configurable by the user. Implementations
MAY
<bcp14>MAY</bcp14> also dynamically adjust the reordering window based on actual
misordering seen in arriving packets.</t>
          <t>Please note, when IP-TFS sends a continuous stream of packets, there
is no requirement for an explicit lost packet timer; however, using a
lost packet timer is RECOMMENDED. <bcp14>RECOMMENDED</bcp14>. If an implementation does not use a
lost packet timer and only considers an outer packet lost when the
reorder window moves by it, the inner traffic can be delayed by up to
the reorder window size times the per packet per-packet send rate. This
delay could be significant for slower send rates or when larger
reorder window sizes are in use. As the lost packet timer affects
the delay of inner packet delivery, an implementation or user could choose to set it
proportionate to the tunnel rate.</t>
          <t>While ESP guarantees an increasing sequence number with subsequently
sent packets, it does not actually require the sequence numbers to be
generated consecutively (e.g., sending only even numbered even-numbered sequence
numbers would be allowed allowed, as long as they are always increasing). Gaps
in the sequence numbers will not work for this document document, so the
sequence number stream MUST <bcp14>MUST</bcp14> increase monotonically by 1 for each
subsequent packet.</t>
          <t>When using the AGGFRAG_PAYLOAD in conjunction with replay detection,
the window size for both MAY <bcp14>MAY</bcp14> be reduced to the smaller of the two
window sizes. This is because packets outside of the smaller window
but inside the larger window would still be dropped by the mechanism with
the smaller window size. However, there is also no requirement to
make these values the same. Indeed, in some cases, such as slow
tunnels where a very small or zero reorder window size is
appropriate, the user may still want a large replay detection window
to log replayed packets. Additionally, large replay windows can be
implemented with very little overhead overhead, compared to large reorder
windows.</t>
          <t>Finally, as sequence numbers are reset when switching SAs Security Associations (SAs) (e.g., when
re-keying
rekeying a child Child SA), senders MUST NOT <bcp14>MUST NOT</bcp14> send initial fragments of an
	  inner packet using one SA and subsequent fragments in a different SA.</t>
	  <aside>
          <t>A note on <spanx style='verb'>BlockOffset</spanx> values, senders MUST <tt>BlockOffset</tt> values: Senders <bcp14>MUST</bcp14> encode the <spanx style='verb'>BlockOffset</spanx>
consistent with the <tt>BlockOffset</tt>
consistently with the immediately preceding non-all-pad payload packet.
Specifically, if the immediately preceding non-all-pad payload packet
ended with a Pad Data Block, this <spanx style='verb'>BlockOffset</spanx> MUST <tt>BlockOffset</tt> <bcp14>MUST</bcp14> be zero, as Pad
Data Blocks are never fragmented. The <spanx style='verb'>BlockOffset</spanx> MUST <tt>BlockOffset</tt> <bcp14>MUST</bcp14> be
consistent with the remaining size remaining size implied by the native length
encoding of
field from the fragmented inner packet.</t>
</aside>
          <section title="Optional numbered="true" toc="default">
            <name>Optional Extra Padding"> Padding</name>
            <t>When the tunnel bandwidth is not being fully utilized, a
sender MAY pad-out <bcp14>MAY</bcp14> pad out the current encapsulating packet in order
to deliver an inner packet un-fragmented unfragmented in the following outer
packet. The benefit would be to avoid inner packet fragmentation in
the presence of a bursty offered load (non-bursty traffic will
naturally not fragment). Senders MAY <bcp14>MAY</bcp14> also choose to allow
for a minimum fragment size to be configured (e.g., as a percentage
of the AGGFRAG_PAYLOAD payload size) to avoid fragmentation at the
cost of tunnel bandwidth. The cost costs with these methods is are complexity
and an added delay of inner traffic. The main advantage to avoiding
fragmentation is to minimize inner packet loss in the presence of
outer packet loss. When this is worthwhile (e.g., how much loss and
what type of loss is required, given different inner traffic shapes
and utilization, for this to make sense), sense) and what values to use for
the allowable/added delay may be worth researching but is outside
the scope of this document.</t>
            <t>While use of padding to avoid fragmentation does not impact
interoperability, if padding is used inappropriately inappropriately, it can reduce the effective
throughput of a tunnel. Senders implementing either of the
above approaches will need to take care to not reduce the effective
capacity, and overall utility, of the tunnel through the overuse of
padding.</t>
          </section>
        </section>
        <section title="Empty Payload"> numbered="true" toc="default">
          <name>Empty Payload</name>
          <t>To support reporting of congestion control information (described
later) using a non-AGGFRAG_PAYLOAD-enabled SA, it is allowed to send
an AGGFRAG_PAYLOAD payload with no data blocks (i.e., the ESP payload
length is equal to the AGGFRAG_PAYLOAD header length). This special
payload is called an empty payload.</t>

<t>Currently
          <t>Currently, this situation is only applicable in non-IKEv2 use cases.</t> cases without Internet Key Exchange Protocol Version 2 (IKEv2).</t>
        </section>
        <section title="IP numbered="true" toc="default">
          <name>IP Header Value Mapping"> Mapping</name>
          <t><xref target="RFC4301"/> target="RFC4301" format="default"/> provides some direction on when and how to map various values
from an inner IP header to the outer encapsulating header, namely the
Don't-Fragment
Don't Fragment (DF) bit (<xref target="RFC0791"/> and <xref target="RFC8200"/>), target="RFC0791" format="default"/>, the Differentiated
Services (DS) field <xref target="RFC2474"/> target="RFC2474" format="default"/>, and the Explicit Congestion Notification
(ECN) field <xref target="RFC3168"/>. target="RFC3168" format="default"/>. Unlike in <xref target="RFC4301"/>, target="RFC4301" format="default"/>, the AGGFRAG mode may may, and often will will, be
encapsulating more than one IP packet per ESP packet. To deal with
this, these mappings are restricted further.</t>
          <section title="DF bit">
<t>AGGFRAG numbered="true" toc="default">
            <name>DF Bit</name>
            <t>The AGGFRAG mode never maps the inner DF bit bit, as it is unrelated to the
AGGFRAG tunnel functionality; the AGGFRAG mode never needs to IP fragment
the inner packets packets, and the inner packets will not affect the
fragmentation of the outer encapsulation packets.</t>
          </section>
          <section title="ECN value"> numbered="true" toc="default">
            <name>ECN Value</name>
            <t>The ECN value need not be mapped mapped, as any congestion related to the
constant-send-rate IP-TFS tunnel is unrelated (by design) to the
inner traffic flow. The sender MAY <bcp14>MAY</bcp14> still set the ECN value of inner
packets based on the normal ECN specification <xref target="RFC3168"/>, target="RFC3168" format="default"/> <xref target="RFC4301"/> and target="RFC4301" format="default"/>
<xref target="RFC6040"/>.</t> target="RFC6040" format="default"/>.</t>
          </section>
          <section title="DS field"> numbered="true" toc="default">
            <name>DS Field</name>
            <t>By default, the DS field SHOULD NOT <bcp14>SHOULD NOT</bcp14> be copied, although a sender MAY <bcp14>MAY</bcp14>
choose to allow for configuration to override this behavior. A sender
SHOULD
<bcp14>SHOULD</bcp14> also allow the DS value to be set by configuration.</t>
          </section>
        </section>
        <section title="IPv4 Time-To-Live numbered="true" toc="default">
          <name>IPv4 Time To Live (TTL), IPv6 Hop Limit, and ICMP Messages">
<t><xref target="RFC4301"/> specifies how Messages</name>
          <t>How to modify the inner packet IPv4 TTL <xref target="RFC0791"/> target="RFC0791" format="default"/> or
IPv6 Hop Limit <xref target="RFC8200"/>.</t> target="RFC8200" format="default"/> is specified in <xref target="RFC4301" format="default"/>.</t>
          <t><xref target="RFC4301"/> also target="RFC4301" format="default"/> specifies how to apply policy to authenticated and
unauthenticated ICMP error packets (e.g., Destination Unreachable)
arriving at or being forwarded through the endpoint. In endpoint, in particular,
whether to process, ignore ignore, or forward said packets. With the one
exception that this document does not change the handling of these
packets, they should be handled as specified in <xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
          <t>The one way in which an AGGFRAG tunnel differs in ICMP error packet
mechanics is with PMTU. When fragmentation is enabled on the AGGFRAG
tunnel, then no ICMP "too-big" "Too Big" errors need to be generated for
arriving ingress traffic traffic, as the arriving inner packets will be
naturally fragmented by the AGGFRAG encapsultation.</t> encapsulation.</t>
          <t>Otherwise, when fragmentation has been disabled on the AGGFRAG tunnel,
then the treatment of arriving inner traffic exactly maps to that of
a non-AGGFRAG ESP tunnel. Explicitly, IPv4 with DF set and IPv6
packets which that cannot fit in it's its own outer packet payload will
generate the appropriate ICMP "too-big" error "Too Big" error, as directed by described in <xref target="RFC4301"/>, target="RFC4301" format="default"/>,
and IPv4 packets without DF set will be IP fragmented fragmented, as directed by described in
<xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
          <t>Packets egressing the tunnel continue to be handled as specified in
<xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
          <t>All other aspects of PMTU and the handling of ICMP "Too Big" messages
(i.e., with regards to the outer AGGFRAG/ESP tunnel packet size)
also remain unchanged from <xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
        </section>
        <section title="Effective numbered="true" toc="default">
          <name>Effective MTU of the Tunnel"> Tunnel</name>
          <t>Unlike in <xref target="RFC4301"/>, target="RFC4301" format="default"/>, there is normally no effective MTU (EMTU) on an
AGGFRAG tunnel tunnel, as all IP packet sizes are properly transmitted without
requiring IP fragmentation prior to tunnel ingress. That said, a
sender MAY <bcp14>MAY</bcp14> allow for explicitly configuring an MTU for the
tunnel.</t>
          <t>If fragmentation has been disabled on the AGGFRAG tunnel, then the
tunnel's EMTU and behaviors are the same as normal IPsec tunnels
<xref target="RFC4301"/>.</t> target="RFC4301" format="default"/>.</t>
        </section>
      </section>
      <section title="Exclusive numbered="true" toc="default">
        <name>Exclusive SA Use"> Use</name>
        <t>This document does not specify mixed use of an
AGGFRAG_PAYLOAD-enabled SA. A sender MUST <bcp14>MUST</bcp14> only send AGGFRAG_PAYLOAD
payloads over an SA configured for AGGFRAG mode.</t>
      </section>
      <section title="Modes numbered="true" toc="default">
        <name>Modes of Operation"> Operation</name>
        <t>Just as with normal IPsec/ESP SAs, AGGFRAG SAs are
unidirectional. Bidirectional IP-TFS functionality is achieved by
setting up 2 AGGFRAG SAs, one in either direction.</t>
        <t>An AGGFRAG tunnel used for IP-TFS can operate in 2 modes, a
non-congestion-controlled mode and congestion-controlled mode.</t>
        <section title="Non-Congestion-Controlled Mode"> numbered="true" toc="default">
          <name>Non-Congestion-Controlled Mode</name>
          <t>In the non-congestion-controlled mode, IP-TFS sends fixed-sized fixed-size
packets over an AGGFRAG tunnel at a constant rate. The packet send
rate is constant and is not automatically adjusted adjusted, regardless of any
network congestion (e.g., packet loss).</t>
          <t>For similar reasons as given in <xref target="RFC7510"/> target="RFC7510" format="default"/>, the non-congestion-controlled
mode MUST <bcp14>MUST</bcp14> only be used where the user has full administrative control
over any path the tunnel will take, take and MUST NOT <bcp14>MUST NOT</bcp14> be used if this is
not the case. This is required so the user can guarantee the
bandwidth and also be sure as to not be negatively affecting network
congestion <xref target="RFC2914"/>. target="RFC2914" format="default"/>. In this case, packet loss should be reported to
the administrator (e.g., via syslog, YANG notification, SNMP traps,
etc.) so that any failures due to a lack of bandwidth can be
corrected. The use of circuit breakers is also RECOMMENDED <bcp14>RECOMMENDED</bcp14> (<xref target="sec-circuit-breakers"></xref>).</t> target="sec-circuit-breakers" format="default"/>).</t>
          <t>Users that choose the non-congestion-controlled mode need to
understand that this mode will send packets at a constant rate rate,
utilizing a constant constant, fixed bandwidth bandwidth, and will not adjust based on
congestion. Thus, if they do not guarantee the bandwidth required by
the tunnel, the tunnel's operation, as well as the rest of their
network, may be negatively impacted.</t>
          <t>One expected use case for the non-congestion-controlled mode is to
guarantee the full tunnel bandwidth is available and preferred over
other non-tunnel traffic. In fact, a typical site-to-site use case
might have all of the user traffic utilizing the IP-TFS tunnel.</t>

<t>Non-congestion-controlled
          <t>The non-congestion-controlled mode is also appropriate if ESP over TCP is
in use <xref target="RFC8229"/>. target="RFC9329" format="default"/>. However, the use of TCP is considered a highly
non-preferred, and a fall-back only fallback-only solution for IPsec. IPsec; it is highly not preferred. This is also
one of the reasons that TCP was not chosen as the encapsulation for
IP-TFS instead of AGGFRAG.</t>
        </section>
        <section title="Congestion-Controlled Mode" anchor="sec-congestion-controlled-mode"> anchor="sec-congestion-controlled-mode" numbered="true" toc="default">
          <name>Congestion-Controlled Mode</name>
          <t>With the congestion-controlled mode, IP-TFS adapts to network
congestion by lowering the packet send rate to accommodate the
congestion, as well as raising the rate when congestion subsides.
Since overhead is per packet, by allowing for maximal fixed-size
packets and varying the send rate, transport overhead is minimized.</t>
          <t>The output of the congestion control algorithm will adjust the rate
at which the ingress sends packets. While this document does not
require a specific congestion control algorithm, best current
practice RECOMMENDS that the algorithm conform to <xref target="RFC5348"/>. target="RFC5348" format="default"/>. Congestion
control principles are documented in <xref target="RFC2914"/> target="RFC2914" format="default"/> as well. <xref target="RFC4342"/>
provides There is an example in <xref target="RFC4342" format="default"/>
of the <xref target="RFC5348"/> algorithm in <xref target="RFC5348" format="default"/>, which matches the
requirements of IP-TFS (i.e., designed for fixed-size packets and send
rate varied based on congestion).</t>
          <t>The required inputs for the TCP friendly TCP-friendly rate control algorithm
described in <xref target="RFC5348"/> target="RFC5348" format="default"/> are the receiver's loss event rate and the
sender's estimated round-trip time (RTT). These values are provided by
IP-TFS using the congestion information header fields described in
<xref target="sec-congestion-information"></xref>. target="sec-congestion-information" format="default"/>. In particular, these values are sufficient to
implement the algorithm described in <xref target="RFC5348"/>.</t> target="RFC5348" format="default"/>.</t>
          <t>At a minimum, the congestion information MUST <bcp14>MUST</bcp14> be sent, from the
receiver and from the sender, at least once per RTT. Prior to
establishing an RTT RTT, the information SHOULD <bcp14>SHOULD</bcp14> be sent constantly from
the sender and the receiver so that an RTT estimate can be
established. Not receiving this information over multiple
consecutive RTT intervals should be considered a congestion event
that causes the sender to adjust its sending rate lower. For
example, <xref target="RFC4342"/> calls this is called the "no feedback timeout" in <xref target="RFC4342" format="default"/>, and it is equal
to 4 RTT intervals. When a "no feedback timeout" has occurred <xref target="RFC4342"/>
halves occurred, the sending rate.</t> rate is halved, as per <xref target="RFC4342" format="default"/>.</t>
          <t>An implementation MAY <bcp14>MAY</bcp14> choose to always include the congestion
information in its AGGFRAG payload header if it is sending it on an IP-TFS-enabled
SA. Since IP-TFS normally will operate with a large packet
size, the congestion information should represent a small portion of
the available tunnel bandwidth. An implementation choosing to always
send the data MAY <bcp14>MAY</bcp14> also choose to only update the <spanx style='verb'>LossEventRate</spanx> <tt>LossEventRate</tt>
and <spanx style='verb'>RTT</spanx> <tt>RTT</tt> header field values it sends every <spanx style='verb'>RTT</spanx> though.</t> <tt>RTT</tt> through.</t>
          <t>When choosing a congestion control algorithm (or a selection of
algorithms), note that IP-TFS is not providing for reliable delivery
of IP traffic, and so per packet ACKs per-packet acknowledgements (ACKs) are not required and are not
provided.</t>
          <t>It is worth noting that the variable send-rate send rate of a
congestion-controlled AGGFRAG tunnel, tunnel is not private; however, this
send-rate
send rate is being driven by network congestion, and as long as the
encapsulated (inner) traffic flow shape and timing are not directly
affecting the (outer) network congestion, the variations in the
tunnel rate will not weaken the provided inner traffic flow
confidentiality.</t>
          <section title="Circuit Breakers" anchor="sec-circuit-breakers"> anchor="sec-circuit-breakers" numbered="true" toc="default">
            <name>Circuit Breakers</name>
            <t>In additional addition to congestion control, implementations that support
non-congestion control the
non-congestion-control mode SHOULD <bcp14>SHOULD</bcp14> implement circuit breakers <xref target="RFC8084"/> target="RFC8084" format="default"/>
as a recovery method of last resort. When circuit breakers are
enabled
enabled, an implementation SHOULD <bcp14>SHOULD</bcp14> also enable congestion control
reports so that circuit breakers have information to act on.</t>
            <t>The pseudowire congestion considerations <xref target="RFC7893"/> target="RFC7893" format="default"/> are equally
applicable to the mechanisms defined in this document, notably the
text on inellastic inelastic traffic.</t>
            <t>One example of a simple simple, slow-trip circuit breaker (CB) that an
implementation may provide would utilize 2 values, values: the amount of
persistent loss rate required to trip the CB, circuit breaker and the required length
of time this persistent loss rate must be seen to trip the CB. circuit breaker. These
2 value are required configuration configurations from the user. When the CB circuit breaker is
tripped
tripped, the tunnel traffic is disabled, disabled and an appropriate log
message or other management type alarm is triggered triggered, indicating
operate
operation intervention is required.</t>
          </section>
        </section>
      </section>
      <section title="Summary numbered="true" toc="default">
        <name>Summary of Receiver Processing"> Processing</name>
        <t>An AGGFRAG-enabled SA receiver has a few tasks to perform.</t>
        <t>The receiver MAY <bcp14>MAY</bcp14> process incoming AGGFRAG_PAYLOAD payloads as soon as
they arrive arrive, as much as it can. I.e., can, i.e., if the incoming AGGFRAG_PAYLOAD
packet contains complete inner packet(s), the receiver should extract
and transmit them immediately. For partial packets, the receiver needs
to keep the partial packets in the memory until they fall out
from the reordering window, window or until the missing parts of the packets
are received, in which case case, it will reassemble and transmit them. If
the AGGFRAG_PAYLOAD payload contains multiple packets packets, they SHOULD <bcp14>SHOULD</bcp14> be sent
out in the order they are in the AGGFRAG_PAYLOAD (i.e., keep the
original order they were received on the other end). The cost of
using this method is that an amplification of out-of-order delivery
of inner packets can occur due to inner packet aggregation.</t>
        <t>Instead of the method described in the previous paragraph, the
receiver MAY <bcp14>MAY</bcp14> reorder out-of-order AGGFRAG_PAYLOAD payloads received
into in-sequence-order AGGFRAG_PAYLOAD payloads (<xref target="sec-fragmentation-sequence-numbers-and-all-pad-payloads"></xref>), target="sec-fragmentation-sequence-numbers-and-all-pad-payloads" format="default"/>), and only after it has an
in-order AGGFRAG_PAYLOAD payload stream would the receiver transmits transmit
the inner packets. Using this method will ensure the inner packets
are sent in order. The cost of this method is that a lost packet will
cause a delay of up to the lost packet timer interval (or the full
reorder window if no lost packet timer is used). Additionally, there
can be extra burstiness in the output stream. This burstiness can
happen when a lost packet is dropped from the re-order reorder window,
and the remaining outer packets in the re-order reorder window are immediately
processed and sent out back to back.</t>
        <t>Additionally, if congestion control is enabled, the receiver sends
congestion control data (<xref target="sec-congestion-control-aggfrag-payload-payload-format"></xref>) target="sec-congestion-control-aggfrag-payload-payload-format" format="default"/>) back to the sender sender, as described in Sections <xref target="sec-congestion-controlled-mode"></xref> target="sec-congestion-controlled-mode" format="counter"/>
and <xref target="sec-congestion-information"></xref>.</t> target="sec-congestion-information" format="counter"/>.</t>
        <t>Finally, a note on receiving incorrect <spanx style='verb'>BlockOffset</spanx> values. <tt>BlockOffset</tt> values: To account
for misbehaving senders, a receiver SHOULD <bcp14>SHOULD</bcp14> gracefully handle the case
where the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> of consecutive packets, and/or the inner
packet they share, do not agree. It MAY <bcp14>MAY</bcp14> drop the inner packet, packet or one or both of the outer packets.</t>
      </section>
    </section>
    <section title="Congestion Information" anchor="sec-congestion-information"> anchor="sec-congestion-information" numbered="true" toc="default">
      <name>Congestion Information</name>
      <t>In order to support the congestion-controlled mode, the sender needs to
know the loss event rate and to approximate the RTT <xref target="RFC5348"/>. target="RFC5348" format="default"/>. In order
to obtain these values, the receiver sends congestion control
information on its SA back to the sender. Thus, to support
congestion control control, the receiver MUST <bcp14>MUST</bcp14> have a paired SA back to the
sender (this is always the case when the tunnel was created using
IKEv2). If the SA back to the sender is a non-AGGFRAG_PAYLOAD enabled
SA non-AGGFRAG_PAYLOAD-enabled
SA, then an AGGFRAG_PAYLOAD empty payload (i.e., header only) is used
to convey the information.</t>
      <t>In order to calculate a loss event rate compatible with <xref target="RFC5348"/>, target="RFC5348" format="default"/>, the
receiver needs to have a round-trip time an RTT estimate. Thus Thus, the sender
communicates this estimate in the <spanx style='verb'>RTT</spanx> <tt>RTT</tt> header field. On startup startup, this
value will be zero zero, as no RTT estimate is yet known.</t>
      <t>In order for the sender to estimate its <spanx style='verb'>RTT</spanx> <tt>RTT</tt> value, the sender
places a timestamp value in the <spanx style='verb'>TVal</spanx> <tt>TVal</tt> header field. On first receipt
of this <spanx style='verb'>TVal</spanx>, <tt>TVal</tt>, the receiver records the new <spanx style='verb'>TVal</spanx> value <tt>TVal</tt> value, along with
the time it arrived locally. Subsequent receipt of the same <spanx style='verb'>TVal</spanx>
MUST NOT <tt>TVal</tt>
<bcp14>MUST NOT</bcp14> update the recorded time.</t>
      <t>When the receiver sends its congestion control header header, it places this latest recorded
<spanx style='verb'>TVal</spanx>
<tt>TVal</tt> in the <spanx style='verb'>TEcho</spanx> <tt>TEcho</tt> header field, along with 2 delay values, <spanx style='verb'>Echo
Delay</spanx> and <spanx style='verb'>Transmit Delay</spanx>. The <spanx style='verb'>Echo Delay</spanx> values: <tt>Echo
Delay</tt> and <tt>Transmit Delay</tt>. The <tt>Echo Delay</tt> value is the time delta
from the recorded arrival time of <spanx style='verb'>TVal</spanx> <tt>TVal</tt> and the current clock in
microseconds. The second value, <spanx style='verb'>Transmit Delay</spanx>, <tt>Transmit Delay</tt>, is the receiver's
current transmission delay on the tunnel (i.e., the average time
between sending packets on its half of the AGGFRAG tunnel).</t>
      <t>When the sender receives back its <spanx style='verb'>TVal</spanx> <tt>TVal</tt> in the <spanx style='verb'>TEcho</spanx> <tt>TEcho</tt> header field field,
it calculates 2 RTT estimates. The first is the actual delay found by
subtracting the <spanx style='verb'>TEcho</spanx> <tt>TEcho</tt> value from its current clock and then
subtracting <spanx style='verb'>Echo Delay</spanx> the <tt>Echo Delay</tt> as well. The second RTT estimate is found by
adding the received <spanx style='verb'>Transmit Delay</spanx> <tt>Transmit Delay</tt> header value to the sender's own
transmission delay (i.e., the average time between sending packets on
its half of the AGGFRAG tunnel). The larger of these 2 RTT estimates
SHOULD
<bcp14>SHOULD</bcp14> be used as the <spanx style='verb'>RTT</spanx> <tt>RTT</tt> value.</t>
      <t>The two RTT estimates are required to handle different combinations of
faster or slower tunnel packet paths with faster or slower fixed
tunnel rates. Choosing the larger of the two values guarantees that
the <spanx style='verb'>RTT</spanx> <tt>RTT</tt> is never considered faster than the aggregate transmission
delay based on the IP-TFS send rate (the second estimate), as well
as never being considered faster than the actual RTT along the tunnel
packet path (the first estimate).</t>
      <t>The receiver also calculates, and communicates in the <spanx style='verb'>LossEventRate</spanx> <tt>LossEventRate</tt>
header field, the loss event rate for use by the sender. This is
slightly different from <xref target="RFC4342"/> target="RFC4342" format="default"/>, which periodically sends all the loss
interval data back to the sender so that it can do the calculation.
See <xref target="sec-a-send-and-loss-event-rate-calculation"></xref> target="sec-a-send-and-loss-event-rate-calculation" format="default"/> for a suggested way to
calculate the loss event rate value. Initially Initially, this value will be
zero (indicating no loss) until enough data has been collected by the
receiver to update it.</t>
      <section title="ECN Support" anchor="sec-ecn-support"> anchor="sec-ecn-support" numbered="true" toc="default">
        <name>ECN Support</name>
        <t>In addition to normal packet loss information, the AGGFRAG mode supports use
of the ECN bits in the encapsulating IP header <xref target="RFC3168"/> target="RFC3168" format="default"/> for
identifying congestion. If ECN use is enabled and a packet arrives at
the egress (receiving) side with the Congestion Experienced (CE) value set,
then the receiver considers that packet as being dropped, although it
does not drop it. The receiver MUST <bcp14>MUST</bcp14> set the E bit in any
AGGFRAG_PAYLOAD payload header containing a <spanx style='verb'>LossEventRate</spanx> <tt>LossEventRate</tt> value
derived from a CE value being considered.</t>

<t><xref target="RFC3168"/> and
        <t>In <xref target="RFC4301"/>, updated by target="RFC6040" format="default"/>, which updates <xref target="RFC6040"/> defines target="RFC3168" format="default"/> and <xref target="RFC4301" format="default"/>, behaviors for marking
the outer ECN field value based on the ECN field of the inner packet. packet are defined.
As the AGGFRAG mode may have multiple inner packets present in a single
outer packet, and there is no obvious correct way to map these
multiple values to the single outer packet ECN field value, the
tunnel ingress endpoint SHOULD <bcp14>SHOULD</bcp14> operate in the "compatibility" mode mode,
rather than the "default" mode from RFC6040. <xref target="RFC6040" format="default"/>. In particular particular, this means
that the ingress (sending) endpoint of the tunnel always sets the
newly constructed outer encapsulating packet header ECN field
to Not-ECT <xref target="RFC6040"/>.</t> target="RFC6040" format="default"/>.</t>
      </section>
    </section>
    <section title="Configuration numbered="true" toc="default">
      <name>Configuration of AGGFRAG Tunnels for IP-TFS"> IP-TFS</name>
      <t>IP-TFS is meant to be deployable with a minimal amount of
configuration. All IP-TFS specific IP-TFS-specific configuration should be
specified at the unidirectional tunnel ingress (sending) side. It
is intended that non-IKEv2 operation is supported, at least, with
local static configuration.</t>
      <t>YANG and MIB documents have been defined for IP-TFS in
<xref target="I-D.ietf-ipsecme-yang-iptfs"/> target="RFC9348" format="default"/> and <xref target="I-D.ietf-ipsecme-mib-iptfs"/>.</t> target="RFC9349" format="default"/>.</t>
      <section title="Bandwidth"> numbered="true" toc="default">
        <name>Bandwidth</name>
        <t>Bandwidth is a local configuration option. For the
non-congestion-controlled mode, the bandwidth SHOULD <bcp14>SHOULD</bcp14> be configured.
For the congestion-controlled mode, the bandwidth can be configured or
the congestion control algorithm discovers and uses the maximum
bandwidth available. No standardized configuration method is
required.</t>
      </section>
      <section title="Fixed numbered="true" toc="default">
        <name>Fixed Packet Size"> Size</name>
        <t>The fixed packet size to be used for the tunnel encapsulation packets
MAY
<bcp14>MAY</bcp14> be configured manually or can be automatically determined using
other methods methods, such as PLMTUD (<xref target="RFC4821"/>, <xref target="RFC8899"/>) target="RFC4821" format="default"/> <xref target="RFC8899" format="default"/> or PMTUD (<xref target="RFC1191"/>, <xref target="RFC8201"/>). target="RFC1191" format="default"/>
<xref target="RFC8201" format="default"/>. As PMTUD is known to have issues, PLMTUD is considered the
more robust option. No standardized configuration method is required.</t>
      </section>
      <section title="Congestion Control"> numbered="true" toc="default">
        <name>Congestion Control</name>
        <t>Congestion control is a local configuration option. No standardized
configuration method is required.</t>
      </section>
    </section>
    <section title="IKEv2">
<section title="USE_AGGFRAG numbered="true" toc="default">
      <name>IKEv2</name>
      <section anchor="sec-use-aggfrag-notification-message" numbered="true" toc="default">
        <name>USE_AGGFRAG Notification Message" anchor="sec-use-aggfrag-notification-message"> Message</name>
        <t>As mentioned previously previously, AGGFRAG tunnels utilize ESP payloads of type
AGGFRAG_PAYLOAD.</t>
        <t>When using IKEv2, a new "USE_AGGFRAG" Notification Message notification message enables
the AGGFRAG_PAYLOAD payload on a child Child SA pair. The
method used is similar to how USE_TRANSPORT_MODE is negotiated, as
described in <xref target="RFC7296"/>.</t> target="RFC7296" format="default"/>.</t>
        <t>To request use of the AGGFRAG_PAYLOAD payload on the Child SA pair,
the initiator includes the USE_AGGFRAG notification in an SA payload
requesting a new Child SA (either during the initial IKE_AUTH or
during CREATE_CHILD_SA exchanges). If the request is
accepted
accepted, then the response MUST <bcp14>MUST</bcp14> also include a notification of type
USE_AGGFRAG. If the responder declines the request request, the child Child SA will
be established without AGGFRAG_PAYLOAD payload use enabled. If
this is unacceptable to the initiator, the initiator MUST <bcp14>MUST</bcp14> delete the
child
Child SA.</t>
        <t>As the use of the AGGFRAG_PAYLOAD payload is currently only defined
for non-transport mode non-transport-mode tunnels, the USE_AGGFRAG notification MUST NOT <bcp14>MUST NOT</bcp14>
be combined with the USE_TRANSPORT notification.</t>
        <t>The USE_AGGFRAG notification contains a 1 octet 1-octet payload of flags that
specify requirements from the sender of the notification. If any
requirement flags are not understood or cannot be supported by the
receiver
receiver, then the receiver SHOULD NOT <bcp14>SHOULD NOT</bcp14> enable use of AGGFRAG_PAYLOAD
(either by not responding with the USE_AGGFRAG notification, or notification or, in
the case of the initiator, by deleting the child Child SA if the now
established now-established non-AGGFRAG_PAYLOAD using SA is unacceptable).</t>
        <t>The notification type and payload flag values are defined in <xref target="sec-ikev2-use-aggfrag-notification-message"></xref>.</t> target="sec-ikev2-use-aggfrag-notification-message" format="default"/>.</t>
      </section>
    </section>
    <section title="Packet numbered="true" toc="default">
      <name>Packet and Data Formats"> Formats</name>
      <t>The packet and data formats defined below are generic with the intent
of allowing for non-IP-TFS uses, but such uses are outside the scope of
this document.</t>
      <section title="AGGFRAG_PAYLOAD Payload" anchor="sec-aggfrag-payload-payload"> anchor="sec-aggfrag-payload-payload" numbered="true" toc="default">
        <name>AGGFRAG_PAYLOAD Payload</name>
        <t>ESP Next Header value: 144</t>
        <t>An AGGFRAG payload is identified by the ESP Next Header value
AGGFRAG_PAYLOAD
AGGFRAG_PAYLOAD, which has the value 144, which has been reserved in
the IP protocol numbers space. The first octet of the payload
indicates the format of the remaining payload data.</t>
        <figure title="AGGFRAG_PAYLOAD payload format" anchor="sec-aggfrag-payload-payload-format"><artwork><![CDATA[ anchor="sec-aggfrag-payload-payload-format">
          <name>AGGFRAG_PAYLOAD Payload Format</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
  0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+-+-+-
 |   Sub-type    | ...
 +-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>

<t><list style="hanging">
<t hangText="Sub-type:"><vspace/>An
]]></artwork>
        </figure>
        <dl newline="true" spacing="normal">
          <dt>Sub-type:</dt>
          <dd>An 8-bit value indicating the payload format.</t>
</list></t> format.</dd>
        </dl>
        <t>This document defines 2 payload sub-types. These payload formats
are defined in the following sections.</t>
        <section title="Non-Congestion Control numbered="true" toc="default">
          <name>Non-Congestion-Control AGGFRAG_PAYLOAD Payload Format"> Format</name>
          <t>The non-congestion control non-congestion-control AGGFRAG_PAYLOAD payload consists of a
4-octet header header, followed by a variable amount of <spanx style='verb'>DataBlocks</spanx> data <tt>DataBlocks</tt> data, as
shown below.</t>
          <figure title="Non-congestion control payload format" anchor="sec-non-congestion-control-payload-format"><artwork><![CDATA[ anchor="sec-non-congestion-control-payload-format">
            <name>Non-Congestion-Control Payload Format</name>
            <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  Sub-Type (0) |   Reserved    |          BlockOffset          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |       DataBlocks ...
 +-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>

<t><list style="hanging">
<t hangText="Sub-type:"><vspace/>An
]]></artwork>
          </figure>
          <dl newline="true" spacing="normal">
            <dt>Sub-type:</dt>
            <dd>An octet indicating the payload format. For this
non-congestion control
non-congestion-control format, the value is 0.</t>
<t hangText="Reserved:"><vspace/>An 0.</dd>
            <dt>Reserved:</dt>
            <dd>An octet set to 0 on generation and ignored on
receipt.</t>
<t hangText="BlockOffset:"><vspace/>A
receipt.</dd>
            <dt>BlockOffset:</dt>
            <dd>A 16-bit unsigned integer counting the number of
octets of <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data before the start of a
new data block. If the start of a new data block
occurs in a subsequent payload payload, the <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt>
will point past the end of the <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data.
In this case case, all the <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data belongs to
the current data block being assembled. When the
<spanx style='verb'>BlockOffset</spanx>
<tt>BlockOffset</tt> extends into subsequent payloads payloads, it
continues to only count <spanx style='verb'>DataBlocks</spanx> <tt>DataBlocks</tt> data (i.e.,
it does not count subsequent packets
non-<spanx style='verb'>DataBlocks</spanx> data of the
non-<tt>DataBlocks</tt> data, such as header octets).</t>
<t hangText="DataBlocks:"><vspace/>Variable octets).</dd>
            <dt>DataBlocks:</dt>
            <dd>Variable number of octets that begins with the start
of a data block, block or the continuation of a previous
data block, followed by zero or more additional data
blocks.</t>
</list></t>
blocks.</dd>
          </dl>
        </section>
        <section title="Congestion anchor="sec-congestion-control-aggfrag-payload-payload-format" numbered="true" toc="default">
          <name>Congestion Control AGGFRAG_PAYLOAD Payload Format" anchor="sec-congestion-control-aggfrag-payload-payload-format"> Format</name>
          <t>The congestion control AGGFRAG_PAYLOAD payload consists of a 24
octet header 24-octet
	  header, followed by a variable amount of <spanx style='verb'>DataBlocks</spanx> data <tt>DataBlocks</tt> data, as
shown below.</t>
          <figure title="Congestion control payload format" anchor="sec-congestion-control-payload-format"><artwork><![CDATA[ anchor="sec-congestion-control-payload-format">
            <name>Congestion Control Payload Format</name>
            <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  Sub-type (1) |  Reserved |P|E|          BlockOffset          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                          LossEventRate                        |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      RTT                  |   Echo Delay ...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Echo Delay   |           Transmit Delay                |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                              TVal                             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                             TEcho                             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |       DataBlocks ...
 +-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>

<t><list style="hanging">
<t hangText="Sub-type:"><vspace/>An
]]></artwork>
          </figure>
          <dl newline="true" spacing="normal">
            <dt>Sub-type:</dt>
            <dd>An octet indicating the payload format. For this
congestion control format, the value is 1.</t>
<t hangText="Reserved:"><vspace/>A 1.</dd>
            <dt>Reserved:</dt>
            <dd>A 6-bit field set to 0 on generation and ignored on
receipt.</t>
<t hangText="P:"><vspace/>A
	    receipt.</dd>
            <dt>P:</dt>
            <dd>A 1-bit value that that, if set set, indicates that PLMTUD probing is in
progress. This information can be used to avoid treating
missing packets as loss events by the CC congestion control algorithm when
running the PLMTUD probe algorithm.</t>
<t hangText="E:"><vspace/>A algorithm.</dd>
            <dt>E:</dt>
            <dd>A 1-bit value that that, if set set, indicates that Congestion Experienced
(CE) ECN bits were received and used in deriving the
reported <spanx style='verb'>LossEventRate</spanx>.</t>
<t hangText="BlockOffset:"><vspace/>The <tt>LossEventRate</tt>.</dd>
            <dt>BlockOffset:</dt>
            <dd>The same value as the non-congestion-controlled
payload format value.</t>
<t hangText="LossEventRate:"><vspace/>A value.</dd>
            <dt>LossEventRate:</dt>
            <dd>A 32-bit value specifying the inverse of the
current loss event rate rate, as calculated by the
receiver. A value of zero indicates no loss.
Otherwise
Otherwise, the loss event rate is
<spanx style='verb'>1/LossEventRate</spanx>.</t>
<t hangText="RTT:"><vspace/>A
<tt>1/LossEventRate</tt>.</dd>
            <dt>RTT:</dt>
            <dd>A 22-bit value specifying the sender's current round-trip
time RTT estimate in microseconds. The value MAY <bcp14>MAY</bcp14> be zero prior
to the sender having calculated a round-trip time an RTT estimate.
The value SHOULD <bcp14>SHOULD</bcp14> be set to zero on
non-AGGFRAG_PAYLOAD-enabled SAs. If the RTT is equal to or
larger than <spanx style='verb'>0x3FFFFF</spanx> <tt>0x3FFFFF</tt>, the value MUST <bcp14>MUST</bcp14> be set to <spanx style='verb'>0x3FFFFF</spanx>.</t>
<t hangText="Echo Delay:"><vspace/>A <tt>0x3FFFFF</tt>.</dd>
            <dt>Echo Delay:</dt>
            <dd>A 21-bit value specifying the delay in microseconds
incurred between the receiver first receiving the <spanx style='verb'>TVal</spanx>
value <tt>TVal</tt>
value, which it is sending back in <spanx style='verb'>TEcho</spanx>. <tt>TEcho</tt>. If the delay
is equal to or larger than <spanx style='verb'>0x1FFFFF</spanx> <tt>0x1FFFFF</tt>, the value MUST <bcp14>MUST</bcp14> be
set to <spanx style='verb'>0x1FFFFF</spanx>.</t>
<t hangText="Transmit Delay:"><vspace/>A <tt>0x1FFFFF</tt>.</dd>
            <dt>Transmit Delay:</dt>
            <dd>A 21-bit value specifying the transmission delay in
microseconds. This is the fixed (or average) delay on the
receiver between it sending packets on the IPTFS IP-TFS tunnel.
If the delay is equal to or larger than <spanx style='verb'>0x1FFFFF</spanx> <tt>0x1FFFFF</tt>, the
value MUST <bcp14>MUST</bcp14> be set to <spanx style='verb'>0x1FFFFF</spanx>.</t>
<t hangText="TVal:"><vspace/>An opaque <tt>0x1FFFFF</tt>.</dd>
            <dt>TVal:</dt>
            <dd>An opaque, 32-bit value that will be echoed back by the
receiver in later packets in the <spanx style='verb'>TEcho</spanx> <tt>TEcho</tt> field, along with
an <spanx style='verb'>Echo Delay</spanx> <tt>Echo Delay</tt> value of how long that echo took.</t>
<t hangText="TEcho:"><vspace/>The opaque took.</dd>
            <dt>TEcho:</dt>
            <dd>The opaque, 32-bit value from a received packet's <spanx style='verb'>TVal</spanx> <tt>TVal</tt>
field. The received <spanx style='verb'>TVal</spanx> <tt>TVal</tt> is placed in <spanx style='verb'>TEcho</spanx> <tt>TEcho</tt>, along with
an <spanx style='verb'>Echo Delay</spanx> <tt>Echo Delay</tt> value indicating how long it has been since
receiving the <spanx style='verb'>TVal</spanx> value.</t>
<t hangText="DataBlocks:"><vspace/>Variable <tt>TVal</tt> value.</dd>
            <dt>DataBlocks:</dt>
            <dd>Variable number of octets that begins with the start
of a data block, block or the continuation of a previous
data block, followed by zero or more additional data
blocks. For the special case of sending congestion
control information on a non-IP-TFS enabled SA non-IP-TFS-enabled SA, this
field MUST <bcp14>MUST</bcp14> be empty (i.e., be zero octets long).</t>
</list></t> long).</dd>
          </dl>
        </section>
        <section title="Data Blocks"> numbered="true" toc="default">
          <name>Data Blocks</name>
          <figure title="Data anchor="sec-data-block-format">
            <name>Data Block format" anchor="sec-data-block-format"><artwork><![CDATA[ Format</name>
            <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Type  | IPv4, IPv6 IPv6, or pad...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>

<t><list style="hanging">
<t hangText="Type:"><vspace/>A
]]></artwork>
          </figure>
          <dl newline="true" spacing="normal">
            <dt>Type:</dt>
            <dd>A 4-bit field where 0x0 identifies a pad data block, Pad Data Block, 0x4
indicates an IPv4 data block, and 0x6 indicates an IPv6
data block.</t>
</list></t> block.</dd>
          </dl>
          <section title="IPv4 numbered="true" toc="default">
            <name>IPv4 Data Block"> Block</name>
            <figure title="IPv4 anchor="sec-ipv4-data-block-format">
              <name>IPv4 Data Block format" anchor="sec-ipv4-data-block-format"><artwork><![CDATA[ Format</name>
              <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  0x4  |  IHL  |  TypeOfService  |         TotalLength         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Rest of the inner packet ...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>
]]></artwork>
            </figure>
            <t>These values are the actual values within the encapsulated IPv4
header. In other words, the start of this data block is the start of
the encapsulated IP packet.</t>

<t><list style="hanging">
<t hangText="Type:"><vspace/>A
            <dl newline="true" spacing="normal">
              <dt>Type:</dt>
              <dd>A 4-bit value of 0x4 indicating IPv4 (i.e., first nibble of
the IPv4 packet).</t>
<t hangText="TotalLength:"><vspace/>The packet).</dd>
              <dt>TotalLength:</dt>
              <dd>The 16-bit unsigned integer "Total Length" field of
the IPv4 inner packet.</t>
</list></t> packet.</dd>
            </dl>
          </section>
          <section title="IPv6 numbered="true" toc="default">
            <name>IPv6 Data Block"> Block</name>
            <figure title="IPv6 anchor="sec-ipv6-data-block-format">
              <name>IPv6 Data Block format" anchor="sec-ipv6-data-block-format"><artwork><![CDATA[ Format</name>
              <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  0x6  | TrafficClass  |               FlowLabel               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |         PayloadLength         | Rest of the inner packet ...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>
]]></artwork>
            </figure>
            <t>These values are the actual values within the encapsulated IPv6
header. In other words, the start of this data block is the start of
the encapsulated IP packet.</t>

<t><list style="hanging">
<t hangText="Type:"><vspace/>A
            <dl newline="true" spacing="normal">
              <dt>Type:</dt>
              <dd>A 4-bit value of 0x6 indicating IPv6 (i.e., first nibble of
the IPv6 packet).</t>
<t hangText="PayloadLength:"><vspace/>The packet).</dd>
              <dt>PayloadLength:</dt>
              <dd>The 16-bit unsigned integer "Payload Length" field
of the inner IPv6 inner packet.</t>
</list></t> packet.</dd>
            </dl>
          </section>
          <section title="Pad numbered="true" toc="default">
            <name>Pad Data Block"> Block</name>
            <figure title="Pad anchor="sec-pad-data-block-format">
              <name>Pad Data Block format" anchor="sec-pad-data-block-format"><artwork><![CDATA[ Format</name>
              <artwork name="" type="" align="left" alt=""><![CDATA[
                      1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  0x0  | Padding ...
 +-+-+-+-+-+-+-+-+-+-+-
]]></artwork></figure>

<t><list style="hanging">
<t hangText="Type:"><vspace/>A
]]></artwork>
            </figure>
            <dl newline="true" spacing="normal">
              <dt>Type:</dt>
              <dd>A 4-bit value of 0x0 indicating a padding data block.</t>
<t hangText="Padding:"><vspace/>Extends block.</dd>
              <dt>Padding:</dt>
              <dd>Extends to end of the encapsulating packet.</t>
</list></t> packet.</dd>
            </dl>
          </section>
        </section>
        <section title="IKEv2 anchor="sec-ikev2-use-aggfrag-notification-message" numbered="true" toc="default">
          <name>IKEv2 USE_AGGFRAG Notification Message" anchor="sec-ikev2-use-aggfrag-notification-message"> Message</name>
          <t>As discussed in <xref target="sec-use-aggfrag-notification-message"></xref>, target="sec-use-aggfrag-notification-message" format="default"/>, a notification
message USE_AGGFRAG is used to negotiate use of the ESP AGGFRAG_PAYLOAD
Next Header value.</t>
          <t>The USE_AGGFRAG Notification Message State Type is 16442</t> 16442.</t>
          <t>The notification payload contains 1 octet of requirement flags. There
are currently 2 requirement flags defined. This may be revised by
later specifications.</t>
          <figure title="USE_AGGFRAG requirement flags" anchor="sec-use-aggfrag-requirement-flags"><artwork><![CDATA[ anchor="sec-use-aggfrag-requirement-flags">
            <name>USE_AGGFRAG Requirement Flags</name>
            <artwork name="" type="" align="left" alt=""><![CDATA[
 +-+-+-+-+-+-+-+-+
 |0|0|0|0|0|0|C|D|
 +-+-+-+-+-+-+-+-+
]]></artwork></figure>

<t><list style="hanging">
<t hangText="0:"><vspace/>6
]]></artwork>
          </figure>
          <dl newline="true" spacing="normal">
            <dt>0:</dt>
            <dd>6 bits - Reserved MUST <bcp14>MUST</bcp14> be zero on send, unless defined by
later specifications.</t>
<t hangText="C:"><vspace/>Congestion specifications.</dd>
            <dt>C:</dt>
            <dd>Congestion Control bit. If set, then the sender is requiring
that congestion control information MUST <bcp14>MUST</bcp14> be returned to it
periodically
periodically, as defined in <xref target="sec-congestion-information"></xref>.</t>
<t hangText="D:"><vspace/>Don't target="sec-congestion-information" format="default"/>.</dd>
            <dt>D:</dt>
            <dd>Don't Fragment bit. If set, it indicates the sender of the notify
message does not support receiving packet fragments (i.e., inner
packets MUST <bcp14>MUST</bcp14> be sent using a single <spanx style='verb'>Data Block</spanx>). <tt>Data Block</tt>). This value only
applies to what the sender is capable of receiving; the sender MAY <bcp14>MAY</bcp14>
still send packet fragments unless similarly restricted by the
receiver in its USE_AGGFRAG notification.</t>
</list></t> notification.</dd>
          </dl>
        </section>
      </section>
    </section>
    <section title="IANA Considerations"> numbered="true" toc="default">
      <name>IANA Considerations</name>
      <section title="ESP numbered="true" toc="default">
        <name>ESP Next Header Value">
<t>Per the INT area directors direction, this document requests IANA
allocate Value</name>
        <t>IANA has
allocated an IP protocol number from the "Protocol Numbers - Assigned
Internet Protocol Numbers" registry</t>

<t><list style="hanging">
<t hangText="Decimal:"><vspace/>144</t>
<t hangText="Keyword:"><vspace/>AGGFRAG</t>
<t hangText="Protocol:"><vspace/>AGGFRAG registry as follows.</t>
        <dl newline="false" spacing="compact">
          <dt>Decimal:</dt>
          <dd>144</dd>
          <dt>Keyword:</dt>
          <dd>AGGFRAG</dd>
          <dt>Protocol:</dt>
          <dd>AGGFRAG encapsulation payload for ESP (TEMPORARY - registered 2022-08-26, document sent to IESG Evaluation 2022-07-14)</t>
<t hangText="Reference:"><vspace/>This document</t>
</list></t> ESP</dd>
          <dt>Reference:</dt>
          <dd>RFC 9347</dd>
        </dl>
      </section>
      <section title="AGGFRAG_PAYLOAD Sub-Type Registry">
<t>This document requests IANA create numbered="true" toc="default">
        <name>AGGFRAG_PAYLOAD Sub-Types</name>
        <t>IANA has created a registry called "AGGFRAG_PAYLOAD
Sub-Type Registry"
Sub-Types" under a new category named "ESP AGGFRAG_PAYLOAD Parameters". AGGFRAG_PAYLOAD".
The registration policy for this registry is "Expert Review"
(<xref target="RFC8126"/> and
<xref target="RFC7120"/>).</t>

<t><list style="hanging">
<t hangText="Name:"><vspace/>AGGFRAG_PAYLOAD Sub-Type Registry</t>
<t hangText="Description:"><vspace/>AGGFRAG_PAYLOAD target="RFC8126" format="default"/> <xref target="RFC7120" format="default"/>.</t>
        <dl newline="false" spacing="compact">
          <dt>Name:</dt>
          <dd>AGGFRAG_PAYLOAD Sub-Types</dd>
          <dt>Description:</dt>
          <dd>AGGFRAG_PAYLOAD Payload Formats.</t>
<t hangText="Reference:"><vspace/>This document</t>
</list></t> Formats</dd>
          <dt>Reference:</dt>
          <dd>RFC 9347</dd>
        </dl>
        <t>This initial content for this registry is as follows:</t>

<figure><artwork><![CDATA[
 Sub-Type  Name                           Reference
--------------------------------------------------------
        0  Non-Congestion Control Format  This document
        1  Congestion
        <table align="center">
          <name>AGGFRAG_PAYLOAD Sub-Types</name>
	  <thead>
	    <tr>
	      <th>Sub-Type</th>
	      <th>Name</th>
              <th>Reference</th>
	      </tr>
	  </thead>
	  <tbody>
	    <tr>
	      <td>0</td>
	      <td>Non-Congestion-Control Format</td>
	      <td>RFC 9347</td>
	    </tr>
	    <tr>
	      <td>1</td>
	      <td>Congestion Control Format      This document
    3-255  Reserved
]]></artwork></figure>

</section>

<section title="USE_AGGFRAG Format</td>
	      <td>RFC 9347</td>
	    </tr>
	    <tr>
	      <td>3-255</td>
	      <td>Reserved</td>
	      <td></td>
	    </tr>
	  </tbody>
	</table>
      </section>
      <section numbered="true" toc="default">
        <name>USE_AGGFRAG Notify Message Status Type">
<t>This document requests Type</name>
        <t>IANA has allocated a status type USE_AGGFRAG be allocated from
the "IKEv2 Notify Message Types - Status Types" registry.</t>

<t><list style="hanging">
<t hangText="Decimal:"><vspace/>16442</t>
<t hangText="Name:"><vspace/>USE_AGGFRAG</t>
<t hangText="Reference:"><vspace/>This document</t>
</list></t>
        <dl newline="false" spacing="compact">
          <dt>Decimal:</dt>
          <dd>16442</dd>
          <dt>Name:</dt>
          <dd>USE_AGGFRAG</dd>
          <dt>Reference:</dt>
          <dd>RFC 9347</dd>
        </dl>
      </section>
    </section>
    <section title="Implementation Status">
<t>[ RFC Ed.: please remove this entire section as well as the reference to
RFC7942 prior to publication. ]</t>

<t>[Section added during IESG review to help with evaluation]</t>

<t>This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in <xref target="RFC7942"/>. The
description of implementations in this section is intended to assist
the IETF in its decision processes in progressing drafts to RFCs.
Please note that the listing of any individual implementation here
does not imply endorsement by the IETF. This is not intended as, and
must not be construed to be, a catalog of available implementations
or their features. Readers are advised to note that other
implementations may exist.</t>

<t>According to RFC 7942, "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature. It
is up to the individual working groups to use this information as
they see fit".</t>

<t>Currently the author and contributors are aware of 1 full and completed
implementation and 1 underway implementation of IP-TFS as defined in
this document. These 2 are described below.</t>

<section title="Reference Implementation - VPP + Strongswan">
<t>The entire IP-TFS protocol including congestion control mode has been
implemented in VPP (Vector Packet Processor), and published to github
with an Open Source (Apache 2) License. VPP is a highly efficient
forwarding plane implemented in user-space utlizing direct control
and polling of physical devices to provide high speed low-latency
forwarding in Linux. By pinning packet processing threads directly to
CPU cores for their exclusive use a high degree of control is given
to the protocol designer.</t>

<t>The IKEv2 additions were implemented in Strongswan and are licensed
using the GNU public license used by the Strongswan project.</t>

<t>Finally, an extensive automation suite was also created and is
included with the open source implementation, which tests the
functionality as well as the performance of the implementation, and
most importantly verifies, through precise timing tracing and
time-stamping, the decoupling of the users offered load from the
tunnel packets (i.e., the Traffic Flow Security).</t>

<t>The verification process utilized the <eref target="https://trex-tgn.cisco.com/">TREX</eref> packet generator for high
bandwidth testing as well as other tools such as iperf. The test
hardware included large servers with 10GE, 40GE and 100GE network
interfaces, as well as small SoC (system on a chip) network
appliances, and also cloud deployments.</t>

<t>Tested IP-TFS tunnel rates ranged from 10M all the way to 10GE on the
small network appliance, for the large servers multiple 10GE tunnel
rates were tested as well.</t>

<t>Offered loads included partial, full and oversubscribed bandwidths
from various flow types consisting of small packets, large packets,
random sized packets, sequential sized packets, and multiple IMIX
variations sized flows. Timing analysis was done with variable rate
traffic, impulse traffic and random bursty traffic.</t>

<t>The quality of the reference implementation should be considered
production level as it underwent extensive testing and verification.</t>

<t>The organization responsible for this implementation is LabN
Consulting, L.L.C.</t>

<t>URLs to the implementation follow.</t>

<t><list style="symbols">
<t><eref target="https://github.com/LabNConsulting/vpp/tree/labn-stable/2009-public">VPP+IPTFS</eref>, <eref target="https://github.com/LabNConsulting/vpp/tree/labn-stable/2009-public/src/plugins/iptfs">iptfs plugin</eref></t>
<t><eref target="https://github.com/LabNConsulting/strongswan/tree/labn-5.8-public">Strongswan IKEv2</eref></t>
</list></t>

<t>The implementation was last updated April, 2021.</t>

</section>

<section title="In Progress Linux Kernel Implementation.">
<t>A second open source implementation has begun by LabN Consulting
L.L.C., within the Linux IPsec xfrm stack. Development has also been
coordinated with the Linux IPsec community, and was being
worked by the same during the most recent IETF 114 hackathon.</t>

<t>Currently the quality is alpha level with aggregation-only complete and
fragmentation support underway with congestion control to follow.</t>

<t>This implementation is licensed under the GNU public license and can
be found at the following URLs</t>

<t><list style="symbols">
<t>development environment: <eref target="https://github.com/LabNConsulting/iptfs-dev"/></t>
<t>linux kernel source: <eref target="https://github.com/LabNConsulting/iptfs-linux"/></t>
<t>iproute2 source: <eref target="https://github.com/LabNConsulting/iptfs-iproute2"/></t>
</list></t>

</section>

</section>

<section title="Security Considerations"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>This document describes an aggregation and fragmentation mechanism to
efficiently implement TFC for IP traffic. This approach is expected to reduce
the efficacy of traffic analysis on IPsec communication. Other than
the additional security afforded by using this mechanism, IP-TFS
utilizes the security protocols <xref target="RFC4303"/> target="RFC4303" format="default"/> and <xref target="RFC7296"/> target="RFC7296" format="default"/>, and so their
security considerations apply to IP-TFS as well.</t>
      <t>As noted in <xref target="sec-ecn-support"></xref>, target="sec-ecn-support" format="default"/>, the ECN bits are not protected by IPsec and
thus may constitute a covert channel. For this reason, ECN use SHOULD
NOT <bcp14>SHOULD
NOT</bcp14> be enabled by default.</t>
      <t>As noted previously in <xref target="sec-congestion-controlled-mode"></xref>, target="sec-congestion-controlled-mode" format="default"/>, for TFC to be
maintained, the encapsulated traffic flow should not be
affecting network congestion in a predictable way, and if it would be,
then non-congestion-controlled mode use should be considered instead.</t>
    </section>
  </middle>
  <back>
<references title="Normative References">

<reference  anchor='RFC2119' target='https://www.rfc-editor.org/info/rfc2119'>
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials='S.' surname='Bradner' fullname='S. Bradner'><organization /></author>
<date year='1997' month='March' />
<abstract><t>In many standards track documents several words are used to signify the requirements in the specification.  These words are often capitalized. This document defines these words as they should be interpreted in IETF documents.  This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='2119'/>
<seriesInfo name='DOI' value='10.17487/RFC2119'/>
</reference>

<reference  anchor='RFC4303' target='https://www.rfc-editor.org/info/rfc4303'>
<front>
<title>IP Encapsulating Security Payload (ESP)</title>
<author initials='S.' surname='Kent' fullname='S. Kent'><organization /></author>
<date year='2005' month='December' />
<abstract><t>This document describes an updated version of the Encapsulating Security Payload (ESP) protocol, which is designed to provide a mix of security services in IPv4 and IPv6.  ESP is used to provide confidentiality, data origin authentication, connectionless integrity, an anti-replay service (a form of partial sequence integrity), and limited traffic flow confidentiality.  This document obsoletes RFC 2406 (November 1998).  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4303'/>
<seriesInfo name='DOI' value='10.17487/RFC4303'/>
</reference>

<reference  anchor='RFC7296' target='https://www.rfc-editor.org/info/rfc7296'>
<front>
<title>Internet Key Exchange Protocol Version 2 (IKEv2)</title>
<author initials='C.' surname='Kaufman' fullname='C. Kaufman'><organization /></author>
<author initials='P.' surname='Hoffman' fullname='P. Hoffman'><organization /></author>
<author initials='Y.' surname='Nir' fullname='Y. Nir'><organization /></author>
<author initials='P.' surname='Eronen' fullname='P. Eronen'><organization /></author>
<author initials='T.' surname='Kivinen' fullname='T. Kivinen'><organization /></author>
<date year='2014' month='October' />
<abstract><t>This document describes version 2 of the Internet Key Exchange (IKE) protocol.  IKE is a component of IPsec used for performing mutual authentication and establishing and maintaining Security Associations (SAs).  This document obsoletes RFC 5996, and includes all of the errata for it.  It advances IKEv2 to be an Internet Standard.</t></abstract>
</front>
<seriesInfo name='STD' value='79'/>
<seriesInfo name='RFC' value='7296'/>
<seriesInfo name='DOI' value='10.17487/RFC7296'/>
</reference>

<reference  anchor='RFC8174' target='https://www.rfc-editor.org/info/rfc8174'>
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></author>
<date year='2017' month='May' />
<abstract><t>RFC 2119 specifies common key words that may be used in protocol  specifications.  This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the  defined special meanings.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='8174'/>
<seriesInfo name='DOI' value='10.17487/RFC8174'/>
</reference>
    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4303.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7296.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
      </references>
<references title="Informative References">
      <references>
        <name>Informative References</name>

        <reference anchor="AppCrypt">
          <front>
            <title>Applied Cryptography: Protocols, Algorithms, and Source Code in C</title>
            <author initials='B.' surname='Schneier' fullname='Bruce Schneier'><organization/></author>
<date day="1" month="11" year="2017"/>
</front>
</reference>

<reference  anchor='RFC0791' target='https://www.rfc-editor.org/info/rfc791'>
<front>
<title>Internet Protocol</title>
<author initials='J.' surname='Postel' fullname='J. Postel'><organization /></author>
<date year='1981' month='September' />
</front>
<seriesInfo name='STD' value='5'/>
<seriesInfo name='RFC' value='791'/>
<seriesInfo name='DOI' value='10.17487/RFC0791'/>
</reference>

<reference  anchor='RFC1191' target='https://www.rfc-editor.org/info/rfc1191'>
<front>
<title>Path MTU discovery</title>
<author initials='J.' surname='Mogul' fullname='J. Mogul'><organization /></author>
<author initials='S.' surname='Deering' fullname='S. Deering'><organization /></author>
<date year='1990' month='November' />
<abstract><t>This memo describes a technique for dynamically discovering the maximum transmission unit (MTU) of an arbitrary internet path.  It specifies a small change to the way routers generate one type of ICMP message.  For a path that passes through a router that has not been so changed, this technique might not discover the correct Path MTU, but it will always choose a Path MTU as accurate as, and in many cases more accurate than, the Path MTU that would be chosen by current practice.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='1191'/>
<seriesInfo name='DOI' value='10.17487/RFC1191'/>
</reference>

<reference  anchor='RFC2474' target='https://www.rfc-editor.org/info/rfc2474'>
<front>
<title>Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers</title>
<author initials='K.' surname='Nichols' fullname='K. Nichols'><organization /></author>
<author initials='S.' surname='Blake' fullname='S. Blake'><organization /></author>
<author initials='F.' surname='Baker' fullname='F. Baker'><organization /></author>
<author initials='D.' surname='Black' fullname='D. Black'><organization /></author>
<date year='1998' month='December' />
<abstract><t>This document defines the IP header field, called the DS (for differentiated services) field.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='2474'/>
<seriesInfo name='DOI' value='10.17487/RFC2474'/>
</reference>

<reference  anchor='RFC2914' target='https://www.rfc-editor.org/info/rfc2914'>
<front>
<title>Congestion Control Principles</title>
<author initials='S.' surname='Floyd' fullname='S. Floyd'><organization /></author>
<date year='2000' month='September' />
<abstract><t>The goal of this document is to explain the need for congestion control in the Internet, and to discuss what constitutes correct congestion control.  This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='41'/>
<seriesInfo name='RFC' value='2914'/>
<seriesInfo name='DOI' value='10.17487/RFC2914'/>
</reference>

<reference  anchor='RFC3168' target='https://www.rfc-editor.org/info/rfc3168'>
<front>
<title>The Addition of Explicit Congestion Notification (ECN) to IP</title>
<author initials='K.' surname='Ramakrishnan' fullname='K. Ramakrishnan'><organization /></author>
<author initials='S.' surname='Floyd' fullname='S. Floyd'><organization /></author>
<author initials='D.' surname='Black' fullname='D. Black'><organization /></author>
<date year='2001' month='September' />
<abstract><t>This memo specifies the incorporation of ECN (Explicit Congestion Notification) to TCP and IP, including ECN's use of two bits in the IP header.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='3168'/>
<seriesInfo name='DOI' value='10.17487/RFC3168'/>
</reference>

<reference  anchor='RFC4301' target='https://www.rfc-editor.org/info/rfc4301'>
<front>
<title>Security Architecture for the Internet Protocol</title>
<author initials='S.' surname='Kent' fullname='S. Kent'><organization /></author>
<author initials='K.' surname='Seo' fullname='K. Seo'><organization /></author>
<date year='2005' month='December' />
<abstract><t>This document describes an updated version of the &quot;Security Architecture for IP&quot;, which is designed to provide security services for traffic at the IP layer.  This document obsoletes RFC 2401 (November 1998).  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4301'/>
<seriesInfo name='DOI' value='10.17487/RFC4301'/>
</reference>

<reference  anchor='RFC4342' target='https://www.rfc-editor.org/info/rfc4342'>
<front>
<title>Profile for Datagram Congestion Control Protocol (DCCP) Congestion Control ID 3: TCP-Friendly Rate Control (TFRC)</title>
<author initials='S.' surname='Floyd' fullname='S. Floyd'><organization /></author>
<author initials='E.' surname='Kohler' fullname='E. Kohler'><organization /></author>
<author initials='J.' surname='Padhye' fullname='J. Padhye'><organization /></author>
<date year='2006' month='March' />
<abstract><t>This document contains the profile for Congestion Control Identifier 3, TCP-Friendly Rate Control (TFRC), in the Datagram Congestion Control Protocol (DCCP).  CCID 3 should be used by senders that want a TCP-friendly sending rate, possibly with Explicit Congestion Notification (ECN), while minimizing abrupt rate changes.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4342'/>
<seriesInfo name='DOI' value='10.17487/RFC4342'/>
</reference>

<reference  anchor='RFC4821' target='https://www.rfc-editor.org/info/rfc4821'>
<front>
<title>Packetization Layer Path MTU Discovery</title>
<author initials='M.' surname='Mathis' fullname='M. Mathis'><organization /></author>
<author initials='J.' surname='Heffner' fullname='J. Heffner'><organization /></author>
<date year='2007' month='March' />
<abstract><t>This document describes a robust method for Path MTU Discovery (PMTUD) that relies on TCP or some other Packetization Layer to probe an Internet path with progressively larger packets.  This method is described as an extension to RFC 1191 and RFC 1981, which specify ICMP-based Path MTU Discovery for IP versions 4 and 6, respectively.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4821'/>
<seriesInfo name='DOI' value='10.17487/RFC4821'/>
</reference>

<reference  anchor='RFC5348' target='https://www.rfc-editor.org/info/rfc5348'>
<front>
<title>TCP Friendly Rate Control (TFRC): Protocol Specification</title>
<author initials='S.' surname='Floyd' fullname='S. Floyd'><organization /></author>
<author initials='M.' surname='Handley' fullname='M. Handley'><organization /></author>
<author initials='J.' surname='Padhye' fullname='J. Padhye'><organization /></author>
<author initials='J.' surname='Widmer' fullname='J. Widmer'><organization /></author>
<date year='2008' month='September' />
<abstract><t>This document specifies TCP Friendly Rate Control (TFRC).  TFRC is a congestion control mechanism for unicast flows operating in a best-effort Internet environment.  It is reasonably fair when competing for bandwidth with TCP flows, but has a much lower variation of throughput over time compared with TCP, making it more suitable for applications such as streaming media where a relatively smooth sending rate is of importance.</t><t>This document obsoletes RFC 3448 and updates RFC 4342.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='5348'/>
<seriesInfo name='DOI' value='10.17487/RFC5348'/>
</reference>

<reference  anchor='RFC6040' target='https://www.rfc-editor.org/info/rfc6040'>
<front>
<title>Tunnelling of Explicit Congestion Notification</title>
<author initials='B.' surname='Briscoe' fullname='B. Briscoe'><organization /></author>
<date year='2010' month='November' />
<abstract><t>This document redefines how the explicit congestion notification (ECN) field of the IP header should be constructed on entry to and exit from any IP-in-IP tunnel.  On encapsulation, it updates RFC 3168 to bring all IP-in-IP tunnels (v4 or v6) into line with RFC 4301 IPsec ECN processing.  On decapsulation, it updates both RFC 3168 and RFC 4301 to add new behaviours for previously unused combinations of inner and outer headers.  The new rules ensure the ECN field is correctly propagated across a tunnel whether it is used to signal one or two severity levels of congestion; whereas before, only one severity level was supported.  Tunnel endpoints can be updated in any order without affecting pre-existing uses of the ECN field, thus ensuring backward compatibility.  Nonetheless, operators wanting to support two severity levels (e.g., for pre-congestion notification -- PCN) can require compliance with this new specification.  A thorough analysis of the reasoning for these changes and the implications is included.  In the unlikely event that the new rules do not meet a specific need, RFC 4774 gives guidance on designing alternate ECN semantics, and this document extends that to include tunnelling issues.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6040'/>
<seriesInfo name='DOI' value='10.17487/RFC6040'/>
</reference>

<reference  anchor='RFC7120' target='https://www.rfc-editor.org/info/rfc7120'>
<front>
<title>Early IANA Allocation of Standards Track Code Points</title>
<author initials='M.' surname='Cotton' fullname='M. Cotton'><organization /></author>
<date year='2014' month='January' />
<abstract><t>This memo describes the process for early allocation of code points by IANA from registries for which &quot;Specification Required&quot;, &quot;RFC                        Required&quot;, &quot;IETF Review&quot;, or &quot;Standards Action&quot; policies apply.  This process can be used to alleviate the problem where code point allocation is needed to facilitate desired or required implementation and deployment experience prior to publication of an RFC, which would normally trigger code point allocation.  The procedures in this document are intended to apply only to IETF Stream documents.</t></abstract>
</front>
<seriesInfo name='BCP' value='100'/>
<seriesInfo name='RFC' value='7120'/>
<seriesInfo name='DOI' value='10.17487/RFC7120'/>
</reference>

<reference  anchor='RFC7510' target='https://www.rfc-editor.org/info/rfc7510'>
<front>
<title>Encapsulating MPLS in UDP</title>
<author initials='X.' surname='Xu' fullname='X. Xu'><organization /></author>
<author initials='N.' surname='Sheth' fullname='N. Sheth'><organization /></author>
<author initials='L.' surname='Yong' fullname='L. Yong'><organization /></author>
<author initials='R.' surname='Callon' fullname='R. Callon'><organization /></author>
<author initials='D.' surname='Black' fullname='D. Black'><organization /></author>
<date year='2015' month='April' />
<abstract><t>This document specifies an IP-based encapsulation for MPLS, called MPLS-in-UDP for situations where UDP (User Datagram Protocol) encapsulation is preferred to direct use of MPLS, e.g., to enable UDP-based ECMP (Equal-Cost Multipath) or link aggregation.  The MPLS- in-UDP encapsulation technology must only be deployed within a single network (with a single network operator) or networks of an adjacent set of cooperating network operators where traffic is managed to avoid congestion, rather than over the Internet where congestion control is required.  Usage restrictions apply to MPLS-in-UDP usage for traffic that is not congestion controlled and to UDP zero checksum usage with IPv6.</t></abstract>
</front>
<seriesInfo name='RFC' value='7510'/>
<seriesInfo name='DOI' value='10.17487/RFC7510'/>
</reference>

<reference  anchor='RFC7893' target='https://www.rfc-editor.org/info/rfc7893'>
<front>
<title>Pseudowire Congestion Considerations</title>
<author initials='Y(J)' surname='Stein' fullname='Y(J) Stein'><organization /></author>
<author initials='D.' surname='Black' fullname='D. Black'><organization /></author>
<author initials='B.' surname='Briscoe' fullname='B. Briscoe'><organization /></author>
<date year='2016' month='June' />
<abstract><t>Pseudowires (PWs) have become a common mechanism for tunneling traffic and may be found in unmanaged scenarios competing for network resources both with other PWs and with non-PW traffic, such as TCP/IP flows.  Thus, it is worthwhile specifying under what conditions such competition is acceptable, i.e., the PW traffic does not significantly harm other traffic or contribute more than it should to congestion.  We conclude that PWs transporting responsive traffic behave as desired without the need for additional mechanisms.  For inelastic PWs (such as Time Division Multiplexing (TDM) PWs), we derive a bound under which such PWs consume no more network capacity than a TCP flow.  For TDM PWs, we find that the level of congestion at which the PW can no longer deliver acceptable TDM service is never significantly greater, and is typically much lower, than this bound. Therefore, as long as the PW is shut down when it can no longer deliver acceptable TDM service, it will never do significantly more harm than even a single TCP flow.  If the TDM service does not automatically shut down, a mechanism to block persistently unacceptable TDM pseudowires is required.</t></abstract>
</front>
<seriesInfo name='RFC' value='7893'/>
<seriesInfo name='DOI' value='10.17487/RFC7893'/>
</reference>

<reference  anchor='RFC7942' target='https://www.rfc-editor.org/info/rfc7942'>
<front>
<title>Improving Awareness of Running Code: The Implementation Status Section</title>
<author initials='Y.' surname='Sheffer' fullname='Y. Sheffer'><organization /></author>
<author initials='A.' surname='Farrel' fullname='A. Farrel'><organization /></author>
<date year='2016' month='July' />
<abstract><t>This document describes a simple process that allows authors of Internet-Drafts to record the status of known implementations by including an Implementation Status section.  This will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature.</t><t>This process is not mandatory.  Authors of Internet-Drafts are encouraged to consider using the process for their documents, and working groups are invited to think about applying the process to all of their protocol specifications.  This document obsoletes RFC 6982, advancing it to a Best Current Practice.</t></abstract>
</front>
<seriesInfo name='BCP' value='205'/>
<seriesInfo name='RFC' value='7942'/>
<seriesInfo name='DOI' value='10.17487/RFC7942'/>
</reference>

<reference  anchor='RFC8084' target='https://www.rfc-editor.org/info/rfc8084'>
<front>
<title>Network Transport Circuit Breakers</title>
<author initials='G.' surname='Fairhurst' fullname='G. Fairhurst'><organization /></author>
<date year='2017' month='March' />
<abstract><t>This document explains what is meant by the term &quot;network transport                          Circuit Breaker&quot;.  It describes the need for Circuit Breakers (CBs) for network tunnels and applications when using non-congestion- controlled traffic and explains where CBs are, and are not, needed. It also defines requirements for building a CB and the expected outcomes of using a CB within the Internet.</t></abstract>
</front>
<seriesInfo name='BCP' value='208'/>
<seriesInfo name='RFC' value='8084'/>
<seriesInfo name='DOI' value='10.17487/RFC8084'/>
</reference>

<reference  anchor='RFC8126' target='https://www.rfc-editor.org/info/rfc8126'>
<front>
<title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
<author initials='M.' surname='Cotton' fullname='M. Cotton'><organization /></author>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></author>
<author initials='T.' surname='Narten' fullname='T. Narten'><organization /></author>
<date year='2017' month='June' />
<abstract><t>Many protocols make use of points of extensibility that use constants to identify various protocol parameters.  To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper.  For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA).</t><t>To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed.  This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry.</t><t>This is the third edition of this document; it obsoletes RFC 5226.</t></abstract>
</front>
<seriesInfo name='BCP' value='26'/>
<seriesInfo name='RFC' value='8126'/>
<seriesInfo name='DOI' value='10.17487/RFC8126'/>
</reference>

<reference  anchor='RFC8200' target='https://www.rfc-editor.org/info/rfc8200'>
<front>
<title>Internet Protocol, Version 6 (IPv6) Specification</title>
<author initials='S.' surname='Deering' fullname='S. Deering'><organization /></author>
<author initials='R.' surname='Hinden' fullname='R. Hinden'><organization /></author>
<date year='2017' month='July' />
<abstract><t>This document specifies version 6 of the Internet Protocol (IPv6). It obsoletes RFC 2460.</t></abstract>
</front>
<seriesInfo name='STD' value='86'/>
<seriesInfo name='RFC' value='8200'/>
<seriesInfo name='DOI' value='10.17487/RFC8200'/>
</reference>

<reference  anchor='RFC8201' target='https://www.rfc-editor.org/info/rfc8201'>
<front>
<title>Path MTU Discovery for IP version 6</title>
<author initials='J.' surname='McCann' fullname='J. McCann'><organization /></author>
<author initials='S.' surname='Deering' fullname='S. Deering'><organization /></author>
<author initials='J.' surname='Mogul' fullname='J. Mogul'><organization /></author>
<author initials='R.' surname='Hinden' fullname='R. Hinden' role='editor'><organization /></author>
<date year='2017' month='July' />
<abstract><t>This document describes Path MTU Discovery (PMTUD) for IP version 6. It is largely derived from RFC 1191, which describes Path MTU Discovery for IP version 4.  It obsoletes RFC 1981.</t></abstract>
</front>
<seriesInfo name='STD' value='87'/>
<seriesInfo name='RFC' value='8201'/>
<seriesInfo name='DOI' value='10.17487/RFC8201'/>
</reference>

<reference  anchor='RFC8229' target='https://www.rfc-editor.org/info/rfc8229'>
<front>
<title>TCP Encapsulation of IKE and IPsec Packets</title>
<author initials='T.' surname='Pauly' fullname='T. Pauly'><organization /></author>
<author initials='S.' surname='Touati' fullname='S. Touati'><organization /></author>
<author initials='R.' surname='Mantha' fullname='R. Mantha'><organization /></author>
<date year='2017' month='August' />
<abstract><t>This document describes a method to transport Internet Key Exchange Protocol (IKE) and IPsec packets over a TCP connection for traversing network middleboxes that may block IKE negotiation over UDP.  This method, referred to as &quot;TCP encapsulation&quot;, involves sending both IKE packets for Security Association establishment and Encapsulating Security Payload (ESP) packets over a TCP connection.  This method is intended to be used as a fallback option when IKE cannot be negotiated over UDP.</t></abstract>
</front>
<seriesInfo name='RFC' value='8229'/>
<seriesInfo name='DOI' value='10.17487/RFC8229'/>
</reference>

<reference  anchor='RFC8546' target='https://www.rfc-editor.org/info/rfc8546'>
<front>
<title>The Wire Image of a Network Protocol</title>
<author initials='B.' surname='Trammell' fullname='B. Trammell'><organization /></author>
<author initials='M.' surname='Kuehlewind' fullname='M. Kuehlewind'><organization /></author>
<date year='2019' month='April' />
<abstract><t>This document defines the wire image, an abstraction of the information available to an on-path non-participant in a networking protocol.  This abstraction is intended to shed light on the implications that increased encryption has for network functions that use the wire image.</t></abstract>
</front>
<seriesInfo name='RFC' value='8546'/>
<seriesInfo name='DOI' value='10.17487/RFC8546'/>
</reference>

<reference  anchor='RFC8899' target='https://www.rfc-editor.org/info/rfc8899'>
<front>
<title>Packetization Layer Path MTU Discovery for Datagram Transports</title>
<author initials='G.' surname='Fairhurst' fullname='G. Fairhurst'><organization /></author>
<author initials='T.' surname='Jones' fullname='T. Jones'><organization /></author>
<author initials='M.' surname='Tüxen' fullname='M. Tüxen'><organization /></author>
<author initials='I.' surname='Rüngeler' fullname='I. Rüngeler'><organization /></author>
<author initials='T.' surname='Völker' fullname='T. Völker'><organization /></author> initials="B." surname="Schneier" fullname="Bruce Schneier">
              <organization/>
            </author>
            <date year='2020' month='September' />
<abstract><t>This document specifies Datagram Packetization Layer Path MTU Discovery (DPLPMTUD). This is a robust method for Path MTU Discovery (PMTUD) for datagram Packetization Layers (PLs). It allows a PL, or a datagram application that uses a PL, to discover whether a network path can support the current size of datagram.  This can be used to detect and reduce the message size when a sender encounters a packet black hole. It can also probe a network path to discover whether the maximum packet size can be increased.  This provides functionality for datagram transports that is equivalent to the PLPMTUD specification for TCP, specified in RFC 4821, which it updates. It also updates the UDP Usage Guidelines to refer to this method for use with UDP datagrams and updates SCTP.</t><t>The document provides implementation notes for incorporating Datagram PMTUD into IETF datagram transports or applications that use datagram transports.</t><t>This specification updates RFC 4960, RFC 4821, RFC 6951, RFC 8085, and RFC 8261.</t></abstract> year="1996"/>
          </front>
<seriesInfo name='RFC' value='8899'/>
<seriesInfo name='DOI' value='10.17487/RFC8899'/>
        </reference>

        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.0791.xml"/>
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<reference anchor="I-D.ietf-ipsecme-mib-iptfs" target="https://www.ietf.org/archive/id/draft-ietf-ipsecme-mib-iptfs-03.txt"> anchor='RFC9349' target='https://www.rfc-editor.org/info/rfc9349'>
<front>
<title>Definitions of Managed Objects for IP Traffic Flow Security</title>
<author initials="D." surname="Fedyk" fullname="Don Fedyk">
<organization>LabN Consulting, L.L.C.</organization>
</author>
<author initials="E." surname="Kinzie" fullname="Eric Kinzie">
<organization>LabN Consulting, L.L.C.</organization>
</author>
<date day="18" month="November" year="2021"/>
    <abstract>
      <t>This document describes managed objects for the the management of IP Traffic Flow Security additions to IKEv2 and IPsec. This document provides a read only version of the objects defined in the YANG module for the same purpose.</t>
    </abstract> month="January" year="2023"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-ipsecme-mib-iptfs-03"/> name="RFC" value="9349"/>
<seriesInfo name="DOI" value="10.17487/RFC9349"/>
</reference>

<reference anchor="I-D.ietf-ipsecme-yang-iptfs" target="https://www.ietf.org/archive/id/draft-ietf-ipsecme-yang-iptfs-10.txt"> anchor='RFC9348' target='https://www.rfc-editor.org/info/rfc9348'>
<front>
<title>A YANG Data Model for IP Traffic Flow Security</title>
<author initials="D." surname="Fedyk" fullname="Don Fedyk">
<organization>LabN Consulting, L.L.C.</organization>
</author>
<author initials="C." surname="Hopps" fullname="Christian Hopps">
<organization>LabN Consulting, L.L.C.</organization>
</author>
<date day="31" month="August" year="2022"/>
    <abstract>
      <t>This document describes a YANG module for the management of IP Traffic Flow Security additions to IKEv2 and IPsec.</t>
    </abstract> month="January" year="2023"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-ipsecme-yang-iptfs-10"/> name="RFC" value="9348"/>
<seriesInfo name="DOI" value="10.17487/RFC9348"/>
</reference>

      </references>
    </references>
    <section title="Example anchor="sec-example-of-an-encapsulated-ip-packet-flow" numbered="true" toc="default">
      <name>Example of An an Encapsulated IP Packet Flow" anchor="sec-example-of-an-encapsulated-ip-packet-flow"> Flow</name>
      <t>Below, an example inner IP packet flow within the encapsulating tunnel
packet stream is shown. Notice how encapsulated IP packets can start
and end anywhere, and more than one or less than 1 one may occur in a
single encapsulating packet.</t>
      <figure title="Inner anchor="sec-inner-and-outer-packet-flow">
        <name>Inner and outer packet flow" anchor="sec-inner-and-outer-packet-flow"><artwork><![CDATA[ Outer Packet Flow</name>
        <artwork name="" type="" align="left" alt=""><![CDATA[
  Offset: 0        Offset: 100    Offset: 2000    Offset: 600
 [ ESP1  (1404) ][ ESP2  (1404) ][ ESP3  (1404) ][ ESP4  (1404) ]
 [--750--][--750--][60][-240-][--3000----------------------][pad]
]]></artwork></figure>
]]></artwork>
      </figure>
      <t>Each outer encapsulating ESPupayload ESP space is a fixed-size fixed size of 1404
octets
      octets, the first 4 octets of which contains contain the AGGFRAG header.
The encapsulated IP packet flow (lengths include the IP header and
payload) is as follows: a 750-octet packet, a 750-octet packet, a
60-octet packet, a 240-octet packet, and a 3000-octet packet.</t>
      <t>The <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> values in the 4 AGGFRAG payload headers for this
packet flow would thus be: 0, 100, 2000, 600 and 600, respectively. The first
encapsulating packet (ESP1) has a zero <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt>, which points at the
IP data block immediately following the AGGFRAG header. The following
packet's (ESP2) <spanx style='verb'>BlockOffset</spanx> <tt>BlockOffset</tt> points inward 100 octets to the start of the
60-octet data block. The third encapsulating packet (ESP3) contains the
middle portion of the 3000-octet data block block, so the offset points past
its end and into the fourth encapsulating packet. The fourth packet's
(ESP4) offset is 600, pointing at the padding which that follows the
completion of the continued 3000-octet packet.</t>
    </section>
    <section title="A anchor="sec-a-send-and-loss-event-rate-calculation" numbered="true" toc="default">
      <name>A Send and Loss Event Rate Calculation" anchor="sec-a-send-and-loss-event-rate-calculation"> Calculation</name>
      <t>The current best practice indicates that congestion control SHOULD <bcp14>SHOULD</bcp14> be
done in a TCP-friendly way. A TCP-friendly congestion control algorithm
is described in <xref target="RFC5348"/>. target="RFC5348" format="default"/>. For this IP-TFS use case (as with <xref target="RFC4342"/>), target="RFC4342" format="default"/>), the
(fixed) packet size is used as the segment size for the algorithm. The
main formula in the algorithm for the send rate is then as follows:</t>

<figure><artwork><![CDATA[
      <artwork name="" type="" align="left" alt=""><![CDATA[
                              1
   X = -----------------------------------------------
       R * (sqrt(2*p/3) + 12*sqrt(3*p/8)*p*(1+32*p^2))
]]></artwork></figure>

<t>Where <spanx style='verb'>X</spanx>
]]></artwork>
      <t><tt>X</tt> is the send rate in packets per second, <spanx style='verb'>R</spanx> <tt>R</tt> is the
round trip time estimate
RTT estimate, and <spanx style='verb'>p</spanx> <tt>p</tt> is the loss event rate (the inverse
of which is provided by the receiver).</t>
      <t>In addition, the algorithm in <xref target="RFC5348"/> target="RFC5348" format="default"/> also uses an <spanx style='verb'>X_recv</spanx> <tt>X_recv</tt> value (the
receiver's receive rate). For IP-TFS IP-TFS, one MAY <bcp14>MAY</bcp14> set this value according to
the sender's current tunnel send-rate (<spanx style='verb'>X</spanx>).</t> send rate (<tt>X</tt>).</t>
      <t>The IP-TFS receiver, having the RTT estimate from the sender sender, can use the
same method as described in <xref target="RFC5348"/> target="RFC5348" format="default"/> and <xref target="RFC4342"/> target="RFC4342" format="default"/> to collect the loss
intervals and calculate the loss event rate value using the weighted
average as indicated. The receiver communicates the inverse of this
value back to the sender in the AGGFRAG_PAYLOAD payload header field
<spanx style='verb'>LossEventRate</spanx>.</t>
<tt>LossEventRate</tt>.</t>
      <t>The IP-TFS sender now has both the <spanx style='verb'>R</spanx> <tt>R</tt> and <spanx style='verb'>p</spanx> <tt>p</tt> values and can calculate
the correct sending rate. If following <xref target="RFC5348"/>, target="RFC5348" format="default"/>, the sender should also
use the slow start mechanism described therein when the IP-TFS SA is
first established.</t>
    </section>
    <section title="Comparisons of IP-TFS" anchor="sec-comparisons-of-ip-tfs">

<section title="Comparing Overhead"> anchor="sec-comparisons-of-ip-tfs" numbered="true" toc="default">
      <name>Comparisons of IP-TFS</name>
      <section numbered="true" toc="default">
        <name>Comparing Overhead</name>
        <t>For comparing overhead, the overhead of ESP for both normal and AGGFRAG
tunnel packets must be calculated, and so an algorithm for encryption
and authentication must be chosen. For the data below below, AES-GCM-256 was
selected. This leads to an IP+ESP overhead of 54.</t>

<figure><artwork><![CDATA[
        <artwork name="" type="" align="left" alt=""><![CDATA[
  54 = 20 (IP) + 8 (ESPH) + 2 (ESPF) + 8 (IV) + 16 (ICV)
]]></artwork></figure>
]]></artwork>
        <t>Additionally, for IP-TFS, non-congestion control non-congestion-control AGGFRAG_PAYLOAD
headers were chosen chosen, which adds 4 octets octets, for a total overhead of 58.</t>
        <section title="IP-TFS Overhead"> numbered="true" toc="default">
          <name>IP-TFS Overhead</name>
          <t>For comparison, the overhead of an AGGFRAG payload is 58 octets per outer packet.
Therefore, the octet overhead per inner packet is 58 divided by the
number of outer packets required (fractions allowed). The overhead
as a percentage of inner packet size is a constant based on the Outer
MTU size.</t>

<figure><artwork><![CDATA[
          <artwork name="" type="" align="left" alt=""><![CDATA[
   OH = 58 / Outer Payload Size / Inner Packet Size
   OH % of Inner Packet Size = 100 * OH / Inner Packet Size
   OH % of Inner Packet Size = 5800 / Outer Payload Size
]]></artwork></figure>

<figure title="IP-TFS
]]></artwork>
          <table anchor="sec-ip-tfs-overhead-as-percentage-of-inner-packet-size" align="center">
            <name>IP-TFS Overhead as Percentage of Inner Packet Size" anchor="sec-ip-tfs-overhead-as-percentage-of-inner-packet-size"><artwork><![CDATA[
                     Type  IP-TFS  IP-TFS  IP-TFS
                      MTU     576    1500    9000
                    PSize     518    1442    8942
                   -------------------------------
                       40  11.20%   4.02%   0.65%
                      576  11.20%   4.02%   0.65%
                     1500  11.20%   4.02%   0.65%
                     9000  11.20%   4.02%   0.65%
]]></artwork></figure>

</section>

<section title="ESP Size</name>
	    <thead>
	      <tr>
		<th>Type</th>
		<th>IP-TFS</th>
		<th>IP-TFS</th>
		<th>IP-TFS</th>
	      </tr>
	      <tr>
		<th>MTU</th>
		<th>576</th>
		<th>1500</th>
		<th>9000</th>
	      </tr>
	      <tr>
		<th>PSize</th>
		<th>518</th>
		<th>1442</th>
		<th>8942</th>
	      </tr>
	    </thead>
	    <tbody>
	      <tr>
		<td>40</td>
		<td>11.20%</td>
		<td>4.02%</td>
		<td>0.65% </td>
	     </tr>
              <tr>
		<td>576</td>
		<td>11.20%</td>
		<td>4.02%</td>
		<td>0.65%</td>
	     </tr>
              <tr>
		<td>1500</td>
		<td>11.20%</td>
		<td>4.02%</td>
		<td>0.65%</td>
	      </tr>
	      <tr>
                  <td>9000</td>
		  <td>11.20%</td>
		  <td>4.02%</td>
		  <td>0.65%</td>
		</tr>
	      </tbody>
	    </table>
        </section>
        <section numbered="true" toc="default">
          <name>ESP with Padding Overhead"> Overhead</name>
          <t>The overhead per inner packet for constant-send-rate padded constant-send-rate-padded ESP
(i.e., traditional original IPsec TFC) is 36 octets plus any padding, unless
fragmentation is required.</t>
          <t>When fragmentation of the inner packet is required to fit in the
outer IPsec packet, overhead is the number of outer packets required
to carry the fragmented inner packet times both the inner IP overhead Overhead
(20) and the outer packet overhead (54) minus the initial inner IP
overhead
Overhead plus any required tail padding in the last encapsulation
packet. The required tail padding is the number of required packets
times the difference of the Outer Payload Size and the IP Overhead
minus the Inner Payload Size. So:</t>

<figure><artwork><![CDATA[
          <artwork name="" type="" align="left" alt=""><![CDATA[
  Inner Payload Size = IP Packet Size - IP Overhead
  Outer Payload Size = MTU - IPsec Overhead

                Inner Payload Size
  NF0 = ----------------------------------
         Outer Payload Size - IP Overhead

  NF = CEILING(NF0)

  OH = NF * (IP Overhead + IPsec Overhead)
       - IP Overhead
       + NF * (Outer Payload Size - IP Overhead)
       - Inner Payload Size

  OH = NF * (IPsec Overhead + Outer Payload Size)
       - (IP Overhead + Inner Payload Size)

  OH = NF * (IPsec Overhead + Outer Payload Size)
       - Inner Packet Size
]]></artwork></figure>
]]></artwork>
        </section>
      </section>
      <section title="Overhead Comparison"> numbered="true" toc="default">
        <name>Overhead Comparison</name>
        <t>The following tables collect the overhead values for some common L3
MTU sizes in order to compare them. The first table is the number of
octets of overhead for a given L3 MTU sized MTU-sized packet. The second table
is the percentage of overhead in the same MTU sized MTU-sized packet.</t>

<t></t>

<figure title="Overhead comparison in octets" anchor="sec-overhead-comparison-in-octets"><artwork><![CDATA[
        Type  ESP+Pad  ESP+Pad  ESP+Pad  IP-TFS  IP-TFS  IP-TFS
      L3 MTU      576     1500     9000     576    1500    9000
       PSize      522     1446     8946     518    1442    8942
     -----------------------------------------------------------
          40      482     1406     8906     4.5     1.6     0.3
         128      394     1318     8818    14.3     5.1     0.8
         256      266     1190     8690    28.7    10.3     1.7
         518        4      928     8428    58.0    20.8     3.4
         576      576      870     8370    64.5    23.2     3.7
        1442      286        4     7504   161.5    58.0     9.4
        1500      228     1500     7446   168.0    60.3     9.7
        8942     1426     1558        4  1001.2   359.7    58.0
        9000     1368     1500     9000  1007.7   362.0    58.4
]]></artwork></figure>

<figure title="Overhead
        <table anchor="sec-overhead-comparison-in-octets" align="center">
          <name>Overhead Comparison in Octets</name>
	  <thead>
	    <tr>
	      <th>Type</th>
	      <th>ESP+Pad</th>
	      <th>ESP+Pad</th>
	      <th>ESP+Pad</th>
	      <th>IP-TFS</th>
	      <th>IP-TFS</th>
	      <th>IP-TFS</th>
	    </tr>
	    <tr>
	      <th>L3 MTU</th>
	      <th>576</th>
	      <th>1500</th>
	      <th>9000</th>
	      <th>576</th>
	      <th>1500</th>
	      <th>9000</th>
	    </tr>
	    <tr>
	      <th>PSize</th>
	      <th>522</th>
	      <th>1446</th>
	      <th>8946</th>
	      <th>518</th>
	      <th>1442</th>
	      <th>8942 </th>
	    </tr>
	  </thead>
	  <tbody>
	    <tr>
	      <td>40</td>
	      <td>482</td>
	      <td>1406</td>
	      <td>8906</td>
	      <td>4.5</td>
	      <td>1.6</td>
	      <td>0.3</td>
	    </tr>
	    <tr>
              <td>128</td>
	      <td>394</td>
	      <td>1318</td>
	      <td>8818</td>
	      <td>14.3</td>
	      <td>5.1</td>
	      <td>0.8</td>
	   </tr>
           <tr>
	      <td>256</td>
	      <td>266</td>
	      <td>1190</td>
	      <td>8690</td>
	      <td>28.7</td>
	      <td>10.3</td>
	      <td>1.7</td>
	   </tr>
            <tr>
	      <td>518</td>
              <td>4</td>
	      <td>928</td>
	      <td>8428</td>
	      <td>58.0</td>
	      <td>20.8</td>
	      <td>3.4 </td>
	    </tr>
	    <tr>
	      <td>576</td>
	      <td>576</td>
	      <td>870</td>
	      <td>8370</td>
	      <td>64.5</td>
	      <td>23.2</td>
	      <td>3.7</td>
	   </tr>
           <tr>
              <td>1442</td>
	      <td>286</td>
              <td>4</td>
	      <td>7504</td>
	      <td>161.5</td>
	      <td>58.0</td>
	      <td>9.4</td>
	   </tr>
           <tr>
              <td>1500</td>
	      <td>228</td>
	      <td>1500</td>
	      <td>7446</td>
	      <td>168.0</td>
	      <td>60.3</td>
	      <td>9.7</td>
	   </tr>
            <tr>
              <td>8942</td>
	      <td>1426</td>
	      <td>1558</td>
              <td>4</td>
	      <td>1001.2</td>
	      <td>359.7</td>
	      <td>58.0</td>
	   </tr>
            <tr>
              <td>9000</td>
	      <td>1368</td>
	      <td>1500</td>
	      <td>9000</td>
	      <td>1007.7</td>
	      <td>362.0</td>
	      <td>58.4</td>
	    </tr>
	  </tbody>
	</table>
        <table anchor="sec-overhead-as-percentage-of-inner-packet-size" align="center">
          <name>Overhead as Percentage of Inner Packet Size" anchor="sec-overhead-as-percentage-of-inner-packet-size"><artwork><![CDATA[
       Type  ESP+Pad  ESP+Pad   ESP+Pad  IP-TFS  IP-TFS  IP-TFS
        MTU      576     1500      9000     576    1500    9000
      PSize      522     1446      8946     518    1442    8942
     -----------------------------------------------------------
         40  1205.0%  3515.0%  22265.0%  11.20%   4.02%   0.65%
        128   307.8%  1029.7%   6889.1%  11.20%   4.02%   0.65%
        256   103.9%   464.8%   3394.5%  11.20%   4.02%   0.65%
        518     0.8%   179.2%   1627.0%  11.20%   4.02%   0.65%
        576   100.0%   151.0%   1453.1%  11.20%   4.02%   0.65%
       1442    19.8%     0.3%    520.4%  11.20%   4.02%   0.65%
       1500    15.2%   100.0%    496.4%  11.20%   4.02%   0.65%
       8942    15.9%    17.4%      0.0%  11.20%   4.02%   0.65%
       9000    15.2%    16.7%    100.0%  11.20%   4.02%   0.65%
]]></artwork></figure>

</section>

<section title="Comparing Size</name>
	  <thead>
	    <tr>
	      <th>Type</th>
	      <th>ESP+Pad</th>
	      <th>ESP+Pad</th>
	      <th>ESP+Pad</th>
	      <th>IP-TFS</th>
	      <th>IP-TFS</th>
	      <th>IP-TFS</th>
	    </tr>
	    <tr>
	      <th>MTU</th>
	      <th>576</th>
	      <th>1500</th>
	      <th>9000</th>
	      <th>576</th>
	      <th>1500</th>
	      <th>9000</th>
	    </tr>
	    <tr>
	      <th>PSize</th>
	      <th>522</th>
	      <th>1446</th>
	      <th>8946</th>
	      <th>518</th>
	      <th>1442</th>
	      <th>8942</th>
	    </tr>
	  </thead>
	  <tbody>
	    <tr>
	      <td>40</td>
	      <td>1205.0%</td>
	      <td>3515.0%</td>
	      <td>22265.0%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
              <td>128</td>
	      <td>307.8%</td>
	      <td>1029.7%</td>
	      <td>6889.1%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
              <td>256</td>
	      <td>103.9%</td>
	      <td>464.8%</td>
	      <td>3394.5%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
              <td>518</td>
	      <td>0.8%</td>
	      <td>179.2%</td>
	      <td>1627.0%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
              <td>576</td>
	      <td>100.0%</td>
	      <td>151.0%</td>
	      <td>1453.1%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
	      <td>1442</td>
	      <td>19.8%</td>
	      <td>0.3%</td>
	      <td>520.4%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
	      <td>1500</td>
	      <td>15.2%</td>
	      <td>100.0%</td>
	      <td>496.4%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
	      <td>8942</td>
	      <td>15.9%</td>
	      <td>17.4%</td>
	      <td>0.0%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	    <tr>
	      <td>9000</td>
	      <td>15.2%</td>
	      <td>16.7%</td>
	      <td>100.0%</td>
	      <td>11.20%</td>
	      <td>4.02%</td>
	      <td>0.65%</td>
	    </tr>
	  </tbody>
	</table>
      </section>
      <section numbered="true" toc="default">
        <name>Comparing Available Bandwidth"> Bandwidth</name>
        <t>Another way to compare the two solutions is to look at the amount of
available bandwidth each solution provides. The following sections
consider and compare the percentage of available bandwidth. For the
sake of providing a well-understood baseline baseline, normal (unencrypted)
Ethernet as well as and normal ESP values are included.</t>
        <section title="Ethernet"> numbered="true" toc="default">
          <name>Ethernet</name>
          <t>In order to calculate the available bandwidth bandwidth, the per packet per-packet overhead
is calculated first. The total overhead of Ethernet is 14+4 octets of
header and CRC Cyclic Redundancy Check (CRC) plus an additional 20 octets of framing (preamble,
start, and inter-packet gap), for a total of 38 octets. Additionally,
	  the minimum payload is 46 octets.</t>

<figure title="L2
	  <table anchor="sec-l2-octets-per-packet" align="center">
	    <name>L2 Octets Per Packet" anchor="sec-l2-octets-per-packet"><artwork><![CDATA[
      Size  E Packet</name>
	    <thead>
	      <tr>
		<th>Size</th>
		<th>E + P  E P</th>
		<th>E + P  E P</th>
		<th>E + P  IPTFS  IPTFS  IPTFS  Enet   ESP
       MTU    590   1514   9014    590   1514   9014   any   any
        OH     92     92     92     96     96     96    38    74
     ------------------------------------------------------------
        40    614   1538   9038     47     42     40    84   114
       128    614   1538   9038    151    136    129   166   202
       256    614   1538   9038    303    273    258   294   330
       518    614   1538   9038    614    552    523   574   610
       576   1228   1538   9038    682    614    582   614   650
      1442   1842   1538   9038   1709   1538   1457  1498  1534
      1500   1842   3076   9038   1777   1599   1516  1538  1574
      8942  11052  10766   9038  10599   9537   9038  8998  9034
      9000  11052  10766  18076  10667   9599   9096  9038  9074
]]></artwork></figure>

<figure title="Packets P</th>
		<th>IPTFS</th>
		<th>IPTFS</th>
		<th>IPTFS</th>
		<th>Enet</th>
		<th>ESP</th>
	      </tr>
	      <tr>
		<th>MTU</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>any</th>
		<th>any</th>
	      </tr>
	      <tr>
		<th>OH</th>
		<th>92</th>
		<th>92</th>
		<th>92</th>
		<th>96</th>
		<th>96</th>
		<th>96</th>
		<th>38</th>
		<th>74</th>
	      </tr>
	    </thead>
	    <tbody>
	      <tr>
		<td>40</td>
		<td>614</td>
		<td>1538</td>
		<td>9038</td>
		<td>47</td>
		<td>42</td>
		<td>40</td>
		<td>84</td>
		<td>114</td>
	      </tr>
	      <tr>
		<td>128</td>
		<td>614</td>
		<td>1538</td>
		<td>9038</td>
		<td>151</td>
		<td>136</td>
		<td>129</td>
		<td>166</td>
		<td>202</td>
	      </tr>
	      <tr>
		<td>256</td>
		<td>614</td>
		<td>1538</td>
		<td>9038</td>
		<td>303</td>
		<td>273</td>
		<td>258</td>
		<td>294</td>
		<td>330</td>
	      </tr>
	      <tr>
		<td>518</td>
		<td>614</td>
		<td>1538</td>
		<td>9038</td>
		<td>614</td>
		<td>552</td>
		<td>523</td>
		<td>574</td>
		<td>610</td>
	      </tr>
	      <tr>
		<td>576</td>
		<td>1228</td>
		<td>1538</td>
		<td>9038</td>
		<td>682</td>
		<td>614</td>
		<td>582</td>
		<td>614</td>
		<td>650</td>
	      </tr>
	      <tr>
		<td>1442</td>
		<td>1842</td>
		<td>1538</td>
		<td>9038</td>
		<td>1709</td>
		<td>1538</td>
		<td>1457</td>
		<td>1498</td>
		<td>1534</td>
	      </tr>
	      <tr>
		<td>1500</td>
		<td>1842</td>
		<td>3076</td>
		<td>9038</td>
		<td>1777</td>
		<td>1599</td>
		<td>1516</td>
		<td>1538</td>
		<td>1574</td>
	      </tr>
	      <tr>
		<td>8942</td>
		<td>11052</td>
		<td>10766</td>
		<td>9038</td>
		<td>10599</td>
		<td>9537</td>
		<td>9038</td>
		<td>8998</td>
		<td>9034</td>
	      </tr>
	      <tr>
		<td>9000</td>
		<td>11052</td>
		<td>10766</td>
		<td>18076</td>
		<td>10667</td>
		<td>9599</td>
		<td>9096</td>
		<td>9038</td>
		<td>9074</td>
	      </tr>
	    </tbody>
	  </table>
	  <table anchor="sec-packets-per-second-on-10g-ethernet">
	    <name>Packets Per Second on 10G Ethernet" anchor="sec-packets-per-second-on-10g-ethernet"><artwork><![CDATA[
     Size  E Ethernet</name>
	    <thead>
	      <tr>
		<th>Size</th>
		<th>E + P  E P</th>
		<th>E + P  E P</th>
		<th>E + P  IPTFS  IPTFS  IPTFS  Enet   ESP
      MTU  590    1514   9014   590    1514   9014   any    any
       OH  92     92     92     96     96     96     38     74
    --------------------------------------------------------------
       40  2.0M   0.8M   0.1M   26.4M  29.3M  30.9M  14.9M  11.0M
      128  2.0M   0.8M   0.1M   8.2M   9.2M   9.7M   7.5M   6.2M
      256  2.0M   0.8M   0.1M   4.1M   4.6M   4.8M   4.3M   3.8M
      518  2.0M   0.8M   0.1M   2.0M   2.3M   2.4M   2.2M   2.1M
      576  1.0M   0.8M   0.1M   1.8M   2.0M   2.1M   2.0M   1.9M
     1442  678K   812K   138K   731K   812K   857K   844K   824K
     1500  678K   406K   138K   703K   781K   824K   812K   794K
     8942  113K   116K   138K   117K   131K   138K   139K   138K
     9000  113K   116K   69K    117K   130K   137K   138K   137K
]]></artwork></figure>

<figure title="Percentage P</th>
		<th>IPTFS</th>
		<th>IPTFS</th>
		<th>IPTFS</th>
		<th>Enet</th>
		<th>ESP</th>
	      </tr>
	      <tr>
		<th>MTU</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>any</th>
		<th>any</th>
	      </tr>
	      <tr>
		<th>OH</th>
		<th>92</th>
		<th>92</th>
		<th>92</th>
		<th>96</th>
		<th>96</th>
		<th>96</th>
		<th>38</th>
		<th>74</th>
	      </tr>
	    </thead>
	    <tbody>
	      <tr>
		<td>40</td>
		<td>2.0M</td>
		<td>0.8M</td>
		<td>0.1M</td>
		<td>26.4M</td>
		<td>29.3M</td>
		<td>30.9M</td>
		<td>14.9M</td>
		<td>11.0M</td>
	      </tr>
	      <tr>
		<td>128</td>
		<td>2.0M</td>
		<td>0.8M</td>
		<td>0.1M</td>
		<td>8.2M</td>
		<td>9.2M</td>
		<td>9.7M</td>
		<td>7.5M</td>
		<td>6.2M</td>
	      </tr>
	      <tr>
		<td>256</td>
		<td>2.0M</td>
		<td>0.8M</td>
		<td>0.1M</td>
		<td>4.1M</td>
		<td>4.6M</td>
		<td>4.8M</td>
		<td>4.3M</td>
		<td>3.8M</td>
	      </tr>
	      <tr>
		<td>518</td>
		<td>2.0M</td>
		<td>0.8M</td>
		<td>0.1M</td>
		<td>2.0M</td>
		<td>2.3M</td>
		<td>2.4M</td>
		<td>2.2M</td>
		<td>2.1M</td>
	      </tr>
	      <tr>
		<td>576</td>
		<td>1.0M</td>
		<td>0.8M</td>
		<td>0.1M</td>
		<td>1.8M</td>
		<td>2.0M</td>
		<td>2.1M</td>
		<td>2.0M</td>
		<td>1.9M</td>
	      </tr>
	      <tr>
		<td>1442</td>
		<td>678K</td>
		<td>812K</td>
		<td>138K</td>
		<td>731K</td>
		<td>812K</td>
		<td>857K</td>
		<td>844K</td>
		<td>824K</td>
	      </tr>
	      <tr>
		<td>1500</td>
		<td>678K</td>
		<td>406K</td>
		<td>138K</td>
		<td>703K</td>
		<td>781K</td>
		<td>824K</td>
		<td>812K</td>
		<td>794K</td>
	      </tr>
	      <tr>
		<td>8942</td>
		<td>113K</td>
		<td>116K</td>
		<td>138K</td>
		<td>117K</td>
		<td>131K</td>
		<td>138K</td>
		<td>139K</td>
		<td>138K</td>
	      </tr>
	      <tr>
		<td>9000</td>
		<td>113K</td>
		<td>116K</td>
		<td>69K</td>
		<td>117K</td>
		<td>130K</td>
		<td>137K</td>
		<td>138K</td>
		<td>137K</td>
	      </tr>
	    </tbody>
	  </table>
          <table anchor="sec-percentage-of-bandwidth-on-10g-ethernet" align="center">
            <name>Percentage of Bandwidth on 10G Ethernet" anchor="sec-percentage-of-bandwidth-on-10g-ethernet"><artwork><![CDATA[
 Size   E Ethernet</name>
	    <thead>
	      <tr>
		<th>Size</th>
		<th>E + P   E P</th>
		<th>E + P   E P</th>
		<th>E + P   IPTFS   IPTFS   IPTFS    Enet     ESP
          590    1514    9014     590    1514    9014     any     any
           92      92      92      96      96      96      38      74
----------------------------------------------------------------------
   40   6.51%   2.60%   0.44%  84.36%  93.76%  98.94%  47.62%  35.09%
  128  20.85%   8.32%   1.42%  84.36%  93.76%  98.94%  77.11%  63.37%
  256  41.69%  16.64%   2.83%  84.36%  93.76%  98.94%  87.07%  77.58%
  518  84.36%  33.68%   5.73%  84.36%  93.76%  98.94%  93.17%  87.50%
  576  46.91%  37.45%   6.37%  84.36%  93.76%  98.94%  93.81%  88.62%
 1442  78.28%  93.76%  15.95%  84.36%  93.76%  98.94%  97.43%  95.12%
 1500  81.43%  48.76%  16.60%  84.36%  93.76%  98.94%  97.53%  95.30%
 8942  80.91%  83.06%  98.94%  84.36%  93.76%  98.94%  99.58%  99.18%
 9000  81.43%  83.60%  49.79%  84.36%  93.76%  98.94%  99.58%  99.18%
]]></artwork></figure> P</th>
		<th>IP-TFS</th>
		<th>IP-TFS</th>
		<th>IP-TFS</th>
		<th>Enet</th>
		<th>ESP</th>
	      </tr>
	      <tr>
		<th>MTU</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>590</th>
		<th>1514</th>
		<th>9014</th>
		<th>any</th>
		<th>any</th>
	      </tr>
	      <tr>
		<th>OH</th>
		<th>92</th>
		<th>92</th>
		<th>92</th>
		<th>96</th>
		<th>96</th>
		<th>96</th>
		<th>38</th>
		<th>74</th>
	      </tr>
	    </thead>
	    <tbody>
	      <tr>
		<td>40</td>
		<td>6.51%</td>
		<td>2.60%</td>
		<td>0.44%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>47.62%</td>
		<td>35.09%</td>
	      </tr>
	      <tr>
		<td>128</td>
		<td>20.85%</td>
		<td>8.32%</td>
		<td>1.42%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>77.11%</td>
		<td>63.37%</td>
	      </tr>
	      <tr>
		<td>256</td>
		<td>41.69%</td>
		<td>16.64%</td>
		<td>2.83%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>87.07%</td>
		<td>77.58%</td>
	      </tr>
	      <tr>
		<td>518</td>
		<td>84.36%</td>
		<td>33.68%</td>
		<td>5.73%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>93.17%</td>
		<td>87.50%</td>
	      </tr>
	      <tr>
		<td>576</td>
		<td>46.91%</td>
		<td>37.45%</td>
		<td>6.37%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>93.81%</td>
		<td>88.62%</td>
	      </tr>
	      <tr>
		<td>1442</td>
		<td>78.28%</td>
		<td>93.76%</td>
		<td>15.95%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>97.43%</td>
		<td>95.12%</td>
	      </tr>
	      <tr>
		<td>1500</td>
		<td>81.43%</td>
		<td>48.76%</td>
		<td>16.60%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>97.53%</td>
		<td>95.30%</td>
	      </tr>
	      <tr>
		<td>8942</td>
		<td>80.91%</td>
		<td>83.06%</td>
		<td>98.94%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>99.58%</td>
		<td>99.18%</td>
	      </tr>
	      <tr>
		<td>9000</td>
		<td>81.43%</td>
		<td>83.60%</td>
		<td>49.79%</td>
		<td>84.36%</td>
		<td>93.76%</td>
		<td>98.94%</td>
		<td>99.58%</td>
		<td>99.18%</td>
	      </tr>
	    </tbody>
	  </table>
          <t>A sometimes unexpected result of using an AGGFRAG tunnel (or any packet
aggregating tunnel) is that, for small- to medium-sized packets, the
available bandwidth is actually greater than native plain Ethernet. This is
due to the reduction in Ethernet framing overhead. This increased
bandwidth is paid for with an increase in latency. This latency is
the time to send the unrelated octets in the outer tunnel frame. The
following table illustrates the latency for some common values on a
10G Ethernet link. The table also includes latency introduced by
	  padding if using ESP with padding.</t>

<figure title="Added Latency" anchor="sec-added-latency"><artwork><![CDATA[
                     ESP+Pad  ESP+Pad  IP-TFS   IP-TFS
                     1500     9000     1500     9000

              ------------------------------------------
                 40  1.12 us  7.12 us  1.17 us  7.17 us
                128  1.05 us  7.05 us  1.10 us  7.10 us
                256  0.95 us  6.95 us  1.00 us  7.00 us
                518  0.74 us  6.74 us  0.79 us  6.79 us
                576  0.70 us  6.70 us  0.74 us  6.74 us
               1442  0.00 us  6.00 us  0.05 us  6.05 us
               1500  1.20 us  5.96 us  0.00 us  6.00 us
]]></artwork></figure>
          <table anchor="sec-added-latency" align="center">
            <name>Added Latency</name>
	    <thead>
	      <tr>
		<th>Size</th>
		<th>ESP+Pad</th>
		<th>ESP+Pad</th>
		<th>IP-TFS</th>
		<th>IP-TFS</th>
	      </tr>
	      <tr>
		<th>MTU</th>
		<th>1500</th>
		<th>9000</th>
		<th>1500</th>
		<th>9000</th>
	      </tr>
	    </thead>
	    <tbody>
              <tr>
		<td>40</td>
		<td>1.12 us</td>
		<td>7.12 us</td>
		<td>1.17 us</td>
		<td>7.17 us</td>
	      </tr>
	      <tr>
		<td>128</td>
		<td>1.05 us</td>
		<td>7.05 us</td>
		<td>1.10 us</td>
		<td>7.10 us</td>
	      </tr>
	      <tr>
		<td>256</td>
		<td>0.95 us</td>
		<td>6.95 us</td>
		<td>1.00 us</td>
		<td>7.00 us</td>
	      </tr>
	      <tr>
		<td>518</td>
		<td>0.74 us</td>
		<td>6.74 us</td>
		<td>0.79 us</td>
		<td>6.79 us</td>
	      </tr>
	      <tr>
		<td>576</td>
		<td>0.70 us</td>
		<td>6.70 us</td>
		<td>0.74 us</td>
		<td>6.74 us</td>
	      </tr>
	      <tr>
		<td>1442</td>
		<td>0.00 us</td>
		<td>6.00 us</td>
		<td>0.05 us</td>
		<td>6.05 us</td>
	      </tr>
	      <tr>
		<td>1500</td>
		<td>1.20 us</td>
		<td>5.96 us</td>
		<td>0.00 us</td>
		<td>6.00 us</td>
	      </tr>
	    </tbody>
	  </table>
          <t>Notice that the latency values are very similar between the two
solutions; however, whereas IP-TFS provides for constant high
bandwidth, in some cases even exceeding native plain Ethernet, ESP with
padding often greatly reduces available bandwidth.</t>
        </section>
      </section>
    </section>
    <section title="Acknowledgements"> numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t>We would like to thank Don Fedyk <contact fullname="Don Fedyk"/> for help in reviewing and editing
this work. We would also like to thank Michael Richardson, Sean
Turner, Valery Smyslov and Tero Kivinen <contact fullname="Michael Richardson"/>, <contact fullname="Sean
Turner"/>, <contact fullname="Valery Smyslov"/>, and <contact fullname="Tero Kivinen"/> for reviews and many
suggestions for improvements, as well as Joseph Touch <contact fullname="Joseph Touch"/> for the
transport area review and suggested improvements.</t>
    </section>
    <section title="Contributors"> numbered="false" toc="default">
      <name>Contributors</name>
      <t>The following people person made significant contributions to this document.</t>

<figure><artwork><![CDATA[
   Lou Berger
   LabN
      <contact fullname="Lou Berger">
	<organization>LabN Consulting, L.L.C.

   Email: lberger@labn.net
]]></artwork></figure> L.L.C.</organization>
	<address>
	  <email>lberger@labn.net</email>
	</address>
      </contact>
    </section>
  </back>
</rfc>