rfc9259xml2.original.xml   rfc9259.xml 
<?xml version="1.0" encoding="US-ASCII"?> <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd"> <!DOCTYPE rfc [
<?rfc toc="yes"?> <!ENTITY nbsp "&#160;">
<?rfc tocompact="yes"?> <!ENTITY zwsp "&#8203;">
<?rfc tocdepth="3"?> <!ENTITY nbhy "&#8209;">
<?rfc tocindent="yes"?> <!ENTITY wj "&#8288;">
<?rfc symrefs="yes"?> ]>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" docName="draft-ietf-6man-spring-
<?rfc inline="yes"?> srv6-oam-13" number="9259" ipr="trust200902" obsoletes="" updates="" submissionT
<?rfc compact="yes"?> ype="IETF" category="std" consensus="true" xml:lang="en" tocInclude="true" tocDe
<?rfc subcompact="no"?> pth="3" symRefs="true" sortRefs="true" version="3">
<rfc category="std" docName="draft-ietf-6man-spring-srv6-oam-13"
ipr="trust200902">
<front>
<title abbrev="SRv6 OAM">Operations, Administration, and Maintenance (OAM) i
n Segment
Routing Networks with IPv6 Data plane (SRv6)</title>
<!-- xml2rfc v2v3 conversion 3.12.2 -->
<front>
<title abbrev="SRv6 OAM">Operations, Administration, and Maintenance (OAM) i
n Segment Routing over IPv6 (SRv6)</title>
<seriesInfo name="RFC" value="9259"/>
<author fullname="Zafar Ali" initials="Z" surname="Ali"> <author fullname="Zafar Ali" initials="Z" surname="Ali">
<organization>Cisco Systems</organization> <organization>Cisco Systems</organization>
<address> <address>
<postal> <postal>
<street/> <street/>
<city/> <city/>
<code/> <code/>
<country/> <country/>
</postal> </postal>
<email>zali@cisco.com</email> <email>zali@cisco.com</email>
</address> </address>
</author> </author>
<author fullname="Clarence Filsfils" initials="C." surname="Filsfils"> <author fullname="Clarence Filsfils" initials="C." surname="Filsfils">
<organization>Cisco Systems</organization> <organization>Cisco Systems</organization>
<address> <address>
<postal> <postal>
<street/> <street/>
<city/> <city/>
<code/> <code/>
<country/> <country/>
</postal> </postal>
<email>cfilsfil@cisco.com</email> <email>cfilsfil@cisco.com</email>
</address> </address>
</author> </author>
<author fullname="Satoru Matsushima" initials="S" surname="Matsushima"> <author fullname="Satoru Matsushima" initials="S" surname="Matsushima">
<organization>Softbank</organization> <organization>Softbank</organization>
<address> <address>
<postal> <postal>
<street/> <street/>
<city/> <city/>
<code/> <code/>
<country/> <country/>
</postal> </postal>
<email>satoru.matsushima@g.softbank.co.jp</email> <email>satoru.matsushima@g.softbank.co.jp</email>
</address> </address>
</author> </author>
<author fullname="Daniel Voyer" initials="D" surname="Voyer"> <author fullname="Daniel Voyer" initials="D" surname="Voyer">
<organization>Bell Canada</organization> <organization>Bell Canada</organization>
<address> <address>
<postal> <postal>
<street/> <street/>
<city/> <city/>
<code/> <code/>
<country/> <country/>
</postal> </postal>
<email>daniel.voyer@bell.ca</email> <email>daniel.voyer@bell.ca</email>
</address> </address>
</author> </author>
<author fullname="Mach(Guoyi) Chen" initials="M" surname="Chen">
<author fullname="Mach Chen" initials="M" surname="Chen">
<organization>Huawei</organization> <organization>Huawei</organization>
<address> <address>
<postal> <postal>
<street/> <street/>
<city/> <city/>
<code/> <code/>
<country/> <country/>
</postal> </postal>
<email>mach.chen@huawei.com</email> <email>mach.chen@huawei.com</email>
</address> </address>
</author> </author>
<date year="2022" month="June" />
<date year="2022"/> <area>int</area>
<area>Routing</area>
<workgroup>6man</workgroup> <workgroup>6man</workgroup>
<keyword>SRv6</keyword> <keyword>SRv6</keyword>
<keyword>Segment Routing</keyword> <keyword>Segment Routing</keyword>
<keyword>OAM</keyword> <keyword>OAM</keyword>
<abstract> <abstract>
<t>This document describes how the existing IPv6 mechanisms for ping <t>This document describes how the existing IPv6 mechanisms for ping
and traceroute can be used in an SRv6 network. and traceroute can be used in a Segment Routing over IPv6 (SRv6) network.
The document also specifies the OAM flag in the Segment Routing Header (SR The document also specifies the OAM flag (O-flag) in the Segment Routing H
H) eader (SRH)
for performing controllable and predictable flow sampling from segment end points. for performing controllable and predictable flow sampling from segment end points.
In addition, the document describes how a centralized monitoring system pe rforms a In addition, the document describes how a centralized monitoring system pe rforms a
path continuity check between any nodes within an SRv6 domain. path continuity check between any nodes within an SRv6 domain.
</t> </t>
</abstract> </abstract>
</front> </front>
<middle>
<middle> <section numbered="true" toc="default">
<name>Introduction</name>
<section title="Introduction"> <t>
As Segment Routing over IPv6 (SRv6) <xref target="RFC8402" format="default"/>
<t>
As Segment Routing with IPv6 data plane (SRv6) <xref target="RFC8402"/>
simply adds a new type simply adds a new type
of Routing Extension Header, existing IPv6 OAM mechanisms can be used of Routing Extension Header, existing IPv6 OAM mechanisms can be used
in an SRv6 network. This document describes how the existing in an SRv6 network. This document describes how the existing
IPv6 mechanisms for ping and traceroute can be used in an SRv6 network. IPv6 mechanisms for ping and traceroute can be used in an SRv6 network.
This includes illustrations of pinging an SRv6 SID to This includes illustrations of pinging an SRv6 Segment Identifier (SID) to
verify that the SID is reachable and is locally programmed at the target node . verify that the SID is reachable and is locally programmed at the target node .
This also includes illustrations for This also includes illustrations for
tracerouting to an SRv6 SID for hop-by-hop tracerouting to an SRv6 SID for hop-by-hop
fault localization as well as path tracing to a SID. fault localization as well as path tracing to a SID.
</t> </t>
<t>
<t> This document also introduces enhancements for the OAM mechanism for SRv6
The document also introduces enhancements for the OAM networks that allow controllable and predictable flow sampling from segment
mechanism for SRv6 networks for endpoints using, e.g., the IP Flow Information Export (IPFIX) protocol
performing controllable and predictable flow sampling from segment <xref target="RFC7011" format="default"/>. Specifically, the document
endpoints using, e.g., IP Flow Information Export (IPFIX) protocol specifies the OAM flag (O-flag) in the SRH as a marking bit in the user
<xref target="RFC7011"/>. Specifically, the document specifies the packets to trigger telemetry data collection and export at the segment
O-flag in SRH as a marking-bit in the user packets to
trigger the telemetry data collection and export at the segment
endpoints. endpoints.
</t> </t>
<t>
<t> This document also outlines how the centralized OAM technique in
The document also outlines how the centralized OAM technique in <xref target="RFC8403" format="default"/> can be extended for SRv6 to perform
<xref target="RFC8403"/> can be extended for SRv6 to perform a path continuit a path continuity check between
y check between
any nodes within an SRv6 domain. any nodes within an SRv6 domain.
Specifically, the document illustrates how a centralized monitoring system ca n Specifically, the document illustrates how a centralized monitoring system ca n
monitor arbitrary SRv6 paths by monitor arbitrary SRv6 paths by
creating the loopback probes that creating loopback probes that
originate and terminate at the centralized monitoring system. originate and terminate at the centralized monitoring system.
</t> </t>
<section numbered="true" toc="default">
<section title="Requirements Language"> <name>Requirements Language</name>
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", <t>
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTION The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQU
AL" IRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
in this document are to be interpreted as described in NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>
BCP 14 <xref target="RFC2119" /> <xref target="RFC8174"/> when, RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
and only when, they appear in all capitals, as shown here.</t> "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
</section> be interpreted as
described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
<section title="Abbreviations"> when, and only when, they appear in all capitals, as shown here.
</t>
<t> The following abbreviations are used in this document:
<list style="hanging">
<t> SID: Segment ID.
</t>
<t> SL: Segments Left.
</t>
<t> SR: Segment Routing.
</t>
<t> SRH: Segment Routing Header <xref target="RFC8754"/>.
</t>
<t> SRv6: Segment Routing with IPv6 Data plane.
</t>
<t> PSP: Penultimate Segment Pop of the SRH <xref target="RFC8986"/>
.
</t>
<t> USP: Ultimate Segment Pop of the SRH <xref target="RFC8986"/>.
</t>
<t> ICMPv6: ICMPv6 Specification <xref target="RFC4443"/>.
</t>
<t> IS-IS: Intermediate System to Intermediate System
</t>
<t> OSPF: Open Shortest Path First protocol <xref target="RFC2328"/>
</t>
<t> IGP: Interior Gateway Protocols (e.g., OSPF, IS-IS).
</t>
<t> BGP-LS: Border Gateway Protocol - Link State Extensions <xref tar
get="RFC8571"/>
</t>
</list></t>
</section>
<section title="Terminology and Reference Topology">
<t> Throughout the document, the following terminology and
simple topology is used for illustration. </t>
<figure> <artwork><![CDATA[
+--------------------------| N100 |---------------------------------+
| |
| ====== link1====== link3------ link5====== link9------ ====== |
||N1||------||N2||------| N3 |------||N4||------| N5 |---||N7||
|| ||------|| ||------| |------|| ||------| |---|| ||
====== link2====== link4------ link6======link10------ ======
| | | |
---+-- | ------ | --+---
|CE 1| +-------| N6 |---------+ |CE 2|
------ link7 | | link8 ------
------
Figure 1 Reference Topology
]]>
</artwork> </figure>
<t> In the reference topology:
<list style="empty">
<t> Node j has a IPv6 loopback address 2001:db8:L:j::/128.
</t>
<t> Nodes N1, N2, N4 and N7 are SRv6-capable nodes.
</t>
<t> Nodes N3, N5 and N6 are IPv6 nodes that are not SRv6-capable.
Such nodes are referred as non-SRv6 capable nodes.
</t>
<t> CE1 and CE2 are Customer Edge devices of any data pla
ne
capability (e.g., IPv4, IPv6, L2, etc.).
</t>
<t> A SID at node j with locator block 2001:db8:K::/48 and function </section>
U is represented <section numbered="true" toc="default">
<name>Abbreviations</name>
<t> The following abbreviations are used in this document:
</t>
<dl newline="false" spacing="normal">
<dt>SID:</dt>
<dd>Segment Identifier
</dd>
<dt>SL:</dt>
<dd>Segments Left
</dd>
<dt>SR:</dt>
<dd>Segment Routing
</dd>
<dt>SRH:</dt>
<dd>Segment Routing Header <xref target="RFC8754" format="default"/>
</dd>
<dt>SRv6:</dt>
<dd>Segment Routing over IPv6 <xref target="RFC8402" format="default"/
>
</dd>
<dt>PSP:</dt>
<dd>Penultimate Segment Pop <xref target="RFC8986" format="default"/>
</dd>
<dt>USP:</dt>
<dd>Ultimate Segment Pop <xref target="RFC8986" format="default"/>
</dd>
<dt>ICMPv6:</dt>
<dd>Internet Control Message Protocol for the Internet Protocol versio
n 6 <xref target="RFC4443" format="default"/>
</dd>
<dt>IS-IS:</dt>
<dd>Intermediate System to Intermediate System
</dd>
<dt>OSPF:</dt>
<dd>Open Shortest Path First <xref target="RFC2328" format="default"/>
</dd>
<dt>IGP:</dt>
<dd>Interior Gateway Protocol (e.g., OSPF and IS-IS)
</dd>
<dt>BGP-LS:</dt>
<dd>Border Gateway Protocol - Link State <xref target="RFC8571" format
="default"/>
</dd>
</dl>
</section>
<section numbered="true" toc="default">
<name>Terminology and Reference Topology</name>
<t>The terminology and
simple topology in this section are used for illustration throughout the do
cument. </t>
<figure anchor="ref-top">
<name>Reference Topology</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
+--------------------------| N100 |---------------------------------+
| |
| ====== link1====== link3------ link5====== link9------ ====== |
||N1||------||N2||------| N3 |------||N4||------| N5 |---||N7||
|| ||------|| ||------| |------|| ||------| |---|| ||
====== link2====== link4------ link6======link10------ ======
| | | |
---+-- | ------ | --+---
|CE1 | +-------| N6 |---------+ |CE2 |
------ link7 | | link8 ------
------
]]></artwork>
</figure>
<t> In the reference topology:
</t>
<ul spacing="normal">
<li> Node j has an IPv6 loopback address 2001:db8:L:j::/128.
</li>
<li> Nodes N1, N2, N4, and N7 are SRv6-capable nodes.
</li>
<li> Nodes N3, N5, and N6 are IPv6 nodes that are not SRv6-capable nod
es.
Such nodes are referred to as "non-SRv6-capable nodes".
</li>
<li> CE1 and CE2 are Customer Edge devices of any data plane
capability (e.g., IPv4, IPv6, and L2).
</li>
<li> A SID at node j with locator block 2001:db8:K::/48 and function U
is represented
by 2001:db8:K:j:U::. by 2001:db8:K:j:U::.
</t> </li>
<li> Node N100 is a controller.
<t> Node N100 is a controller. </li>
</t>
<t> The IPv6 address of the nth Link between node i and j at the i si
de
is represented as 2001:db8:i:j:in::, e.g., the IPv6 address of link6
(the 2nd link between N3 and N4) at N3 in Figure 1 is
2001:db8:3:4:32::. Similarly, the IPv6 address of link5 (the 1st
link between N3 and N4) at node N3 is 2001:db8:3:4:31::.
</t>
<t> 2001:db8:K:j:Xin:: is explicitly allocated as the End.X SID <li> The IPv6 address of the nth link between nodes i and j at the i
side
is represented as 2001:db8:i:j:in::. For example, in <xref target="ref-top"
/>, the IPv6 address of link6
(the second link between nodes N3 and N4) at node N3 is
2001:db8:3:4:32::. Similarly, the IPv6 address of link5 (the first
link between nodes N3 and N4) at node N3 is 2001:db8:3:4:31::.
</li>
<li> 2001:db8:K:j:Xin:: is explicitly allocated as the End.X SID
at node j at node j
towards neighbor node i via nth Link between node i and node j. towards neighbor node i via the nth link between nodes i and j.
e.g., 2001:db8:K:2:X31:: represents End.X at N2 towards N3 via link3 (the 1 For example, 2001:db8:K:2:X31:: represents End.X at node N2 towards node N3
st via link3 (the first
link between N2 and N3). Similarly, 2001:db8:K:4:X52:: represents the End.X link between nodes N2 and N3). Similarly, 2001:db8:K:4:X52:: represents the
at End.X at
N4 towards N5 via link10 (the 2nd node N4 towards node N5 via link10 (the second
link between N4 and N5). Please refer to <xref target="RFC8986"/> for link between nodes N4 and N5). Please refer to <xref target="RFC8986" forma
description of End.X SID. t="default"/> for
</t> a description of End.X SID.
</li>
<t> A SID list is represented as &lt;S1, S2, S3&gt; where <li> A SID list is represented as &lt;S1, S2, S3&gt;, where
S1 is the first SID S1 is the first SID
to visit, S2 is the second SID to visit and S3 is the last SID to to visit, S2 is the second SID to visit, and S3 is the last SID to
visit along the SR path. visit along the SR path.
</t> </li>
<li>
<t> (SA,DA) (S3, S2, S1; SL)(payload) represents an IPv6 packet with: <t> (SA,DA) (S3, S2, S1; SL)(payload) represents an IPv6 packet with
:
<list style="symbols">
<t> IPv6 header with source address SA, destination addresses DA and
SRH as next-header
</t> </t>
<ul spacing="normal">
<li> IPv6 header with source address SA, destination address DA, a
nd
SRH as the next header
</li>
<li><t>SRH with SID list &lt;S1, S2, S3&gt; with SegmentsLeft = SL
</t>
<t> SRH with SID list &lt;S1, S2, S3&gt; with SegmentsLeft = SL <t> Note the difference between the &lt; &gt; and () symbols:
</t>
<t> Note the difference between the &lt; &gt; and () symbols:
&lt;S1, S2, S3&gt; &lt;S1, S2, S3&gt;
represents a SID list where S1 is the first SID and S3 is the last represents a SID list where S1 is the first SID and S3 is the last
SID to traverse. (S3, S2, S1; SL) represents the same SID list but SID to traverse. (S3, S2, S1; SL) represents the same SID list but
encoded in the SRH format where the rightmost SID in the SRH is the encoded in the SRH format where the rightmost SID in the SRH is the
first SID and the leftmost SID in the SRH is the last SID. When first SID and the leftmost SID in the SRH is the last SID. When
referring to an SR policy in a high-level use-case, it is simpler referring to an SR Policy in a high-level use case, it is simpler
to use the &lt;S1, S2, S3&gt; notation. When referring to an to use the &lt;S1, S2, S3&gt; notation. When referring to an
illustration of the detailed packet behavior, the (S3, S2, S1; SL) illustration of the detailed packet behavior, the (S3, S2, S1; SL)
notation is more convenient. notation is more convenient.</t>
</t> </li>
<li> (payload) represents the payload of the packet.
<t> (payload) represents the the payload of the packet. </li>
</t> </ul>
</li>
</list></t> </ul>
</section>
</list></t>
</section> </section>
<!--end: Introduction -->
</section> <!--end: Introduction --> <section numbered="true" toc="default">
<name>OAM Mechanisms</name>
<section title="OAM Mechanisms"> <t>This section defines OAM enhancements for SRv6 networks.
<t>This section defines OAM enhancement for the SRv6 networks.
</t> </t>
<section numbered="true" toc="default">
<section title="O-flag in Segment Routing Header"> <name>OAM Flag in the Segment Routing Header</name>
<t><xref target="RFC8754" format="default"/> describes the Segment
<t><xref target="RFC8754"/> describes the Segment Routing Header (SRH) and how SR-capable nodes use it. The SRH
Routing Header (SRH) and how SR capable nodes use it. The SRH contains an 8-bit Flags field. </t>
contains an 8-bit "Flags" field. </t> <t> This document defines the following bit in the
<t> This document defines the following bit in the
SRH Flags field to carry the O-flag: </t> SRH Flags field to carry the O-flag: </t>
<artwork name="" type="" align="left" alt=""><![CDATA[
<figure> <artwork><![CDATA[
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| |O| | | |O| |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
]]> ]]></artwork>
</artwork> </figure> <t> Where:
<t> Where:
<list style="hanging">
<t> O-flag: OAM flag in the SRH Flags field defined in <xref target=
"RFC8754"/>.
</t>
</list> </t>
<dl newline="false" spacing="normal">
<dt>O-flag:</dt>
<dd>OAM flag in the SRH Flags field defined in <xref target="RFC8754"
format="default"/>.
</dd>
</dl>
<section anchor="oflag-proc" numbered="true" toc="default">
<name>OAM Flag Processing</name>
<t> The O-flag in the SRH is used as a marking bit in user packets to
trigger
telemetry data collection and export at the segment endpoints.
</t> </t>
<t> An SR domain ingress edge node encapsulates packets traversing the
<section title="O-flag Processing"> SR
domain as defined in <xref target="RFC8754" format="default"/>. The SR domai
<t> The O-flag in SRH is used as a marking-bit in the user packets to tri n ingress edge node
gger <bcp14>MAY</bcp14> use the O-flag in the SRH for marking the packet to trigg
the telemetry data collection and export at the segment endpoints. er
</t>
<t> An SR domain ingress edge node encapsulates packets traversing the SR
domain as defined in <xref target="RFC8754"/>. The SR domain ingress edge no
de
MAY use the O-flag in SRH for marking the packet to trigger
the telemetry data collection and export at the segment endpoints. the telemetry data collection and export at the segment endpoints.
Based on a local configuration, the SR domain ingress edge node Based on local configuration, the SR domain ingress edge node
may implement a classification and sampling mechanism to mark a packet wi may implement a classification and sampling mechanism to mark a packet wi
th the O-flag in SRH. th the O-flag in the SRH.
Specification of the classification and sampling method is outside the sc ope of this Specification of the classification and sampling method is outside the sc ope of this
document. document.
</t> </t>
<t>
<t>
This document does not specify the data elements that need to be exported This document does not specify the data elements that need to be exported
and the associated configurations. and the associated configurations.
Similarly, this document does not define any formats for exporting the da ta Similarly, this document does not define any formats for exporting the da ta
elements. elements.
Nonetheless, without the loss of generality, this document assumes Nonetheless, without the loss of generality, this document assumes that t
IP Flow Information Export (IPFIX) protocol <xref target="RFC7011"/> is u he
sed for exporting IP Flow Information Export (IPFIX) protocol <xref target="RFC7011" format
="default"/> is used for exporting
the traffic flow information from the network devices to a controller for the traffic flow information from the network devices to a controller for
monitoring and analytics. monitoring and analytics.
Similarly, without the loss of generality, this document assumes requeste d information Similarly, without the loss of generality, this document assumes that req uested information
elements are configured elements are configured
by the management plane through data set templates (e.g., as in IPFIX by the management plane through data set templates (e.g., as in IPFIX
<xref target="RFC7012"/>). <xref target="RFC7012" format="default"/>).
</t> </t>
<t>Implementation of the O-flag is <bcp14>OPTIONAL</bcp14>. If a node
<t>Implementation of the O-flag is OPTIONAL. If a node does not support th does not support the
e O-flag, then it simply ignores it upon reception. If a node supports
O-flag, then upon reception it simply ignores it. If a node supports
the O-flag, it can optionally advertise its potential via the O-flag, it can optionally advertise its potential via
control plane protocol(s). control plane protocol(s).
</t> </t>
<t> When N receives a packet destined to S and S is a local SID,
the line S01 of the pseudo-code associated with the SID S, as defined
in section 4.3.1.1 of <xref target="RFC8754"/>,
is appended to as follows for the O-flag processing.
</t>
<figure> <artwork><![CDATA[ <t>The following is appended to line S01 of the pseudocode
S01.1. IF O-flag is set and local configuration permits associated with the SID S (as defined in <xref target="RFC8754"
sectionFormat="of" section="4.3.1.1" format="default"/>) when N
receives a packet destined to S, S is a local SID, and the O-flag is
processed.
</t>
<sourcecode type="pseudocode"><![CDATA[
S01.1. IF the O-flag is set and local configuration permits
O-flag processing { O-flag processing {
a. Make a copy of the packet. a. Make a copy of the packet.
b. Send the copied packet, along with a timestamp b. Send the copied packet, along with a timestamp,
to the OAM process for telemetry data collection to the OAM process for telemetry data collection
and export. ;; Ref1 and export. ;; Ref1
} }
Ref1: To provide an accurate timestamp, an implementation should copy Ref1: To provide an accurate timestamp, an implementation should
and record the timestamp as soon as possible during packet processing. copy and record the timestamp as soon as possible during packet
Timestamp and any other metadata is not carried in the packet forwarded to th processing. Timestamp and any other metadata are not carried in
e next hop. the packet forwarded to the next hop.
]]> ]]></sourcecode>
</artwork> </figure> <t> Please note that the O-flag processing happens before execution of
regular
<t> Please note that the O-flag processing happens before execution of re processing of the local SID S. Specifically, line S01.1 of the pseudocode
gular specified in this document is inserted between lines S01
processing of the local SID S. Specifically, the line S01.1 of the pseudo and S02 of the pseudocode defined in <xref target="RFC8754" sectionFormat="o
-code f" section="4.3.1.1" format="default"/>.
specified in this document is inserted between line S01 </t>
and S02 of the pseudo-code defined in section 4.3.1.1 of <xref target="RFC87 <t>
54"/>.
</t>
<t>
Based on the Based on the
requested information elements configured requested information elements configured
by the management plane through data set templates <xref target="RFC7012"/ >, by the management plane through data set templates <xref target="RFC7012" format="default"/>,
the OAM process exports the requested information elements. the OAM process exports the requested information elements.
The information elements include parts of the packet header and/or parts of The information elements include parts of the packet header and/or parts of
the packet payload for flow identification. the packet payload for flow identification.
The OAM process uses information elements defined in The OAM process uses information elements defined in
IPFIX <xref target="RFC7011"/> and PSAMP <xref target="RFC5476"/> for exporti ng the requested sections IPFIX <xref target="RFC7011" format="default"/> and Packet Sampling (PSAMP) < xref target="RFC5476" format="default"/> for exporting the requested sections
of the mirrored packets. of the mirrored packets.
</t> </t>
<t>
<t>
If the penultimate segment of a segment-list is a Penultimate Segment Pop (P SP) SID, If the penultimate segment of a segment list is a PSP SID,
telemetry data from the ultimate segment cannot be requested. This is becaus e, telemetry data from the ultimate segment cannot be requested. This is becaus e,
when the penultimate segment is a PSP SID, when the penultimate segment is a PSP SID,
the SRH is removed at the penultimate segment and the O-flag is the SRH is removed at the penultimate segment, and the O-flag is
not processed at the ultimate segment. not processed at the ultimate segment.
</t> </t>
<t>
<t> The processing node <bcp14>MUST</bcp14>
The processing node MUST
rate-limit the number of packets punted to the OAM process rate-limit the number of packets punted to the OAM process
to a configurable rate. to a configurable rate.
This is to avoid hitting any performance impact on the OAM and This is to avoid impacting the
the telemetry collection processes. Failure in implementing the rate performance of the OAM and
limit can lead to a denial-of-service attack, as detailed in section 4. telemetry collection processes. Failure to implement the rate
limit can lead to a denial-of-service attack, as detailed in <xref target=
</t> "Security" format="default"/>.
<t> </t>
The OAM process MUST NOT process the copy of the packet or respond <t>
to any upper-layer header The OAM process <bcp14>MUST NOT</bcp14> process the copy of the packet or r
espond
to any Upper-Layer header
(like ICMP, UDP, (like ICMP, UDP,
etc.) payload to prevent multiple evaluations of the datagram. etc.) payload to prevent multiple evaluations of the datagram.
</t> </t>
<t>
<t>
The OAM process is expected to be located on the routing node processing t he packet. The OAM process is expected to be located on the routing node processing t he packet.
Although the specification of the OAM process or the external controller Although the specification of the OAM process or the external controller
operations are beyond the scope of this document, the OAM process SHOULD N OT be operations are beyond the scope of this document, the OAM process <bcp14>S HOULD NOT</bcp14> be
topologically distant from the routing node, as this is likely to create s ignificant security topologically distant from the routing node, as this is likely to create s ignificant security
and congestion issues. and congestion issues.
How to correlate the data collected from different nodes at an How to correlate the data collected from different nodes at an
external controller is also outside the scope of the document. external controller is also outside the scope of this document.
Appendix A illustrates use of the O-flag for implementing <xref target="app-illustrations" /> illustrates use of the O-flag for impl
ementing
a hybrid OAM mechanism, where the "hybrid" classification a hybrid OAM mechanism, where the "hybrid" classification
is based on RFC7799 <xref target="RFC7799"/>. is based on <xref target="RFC7799" format="default"/>.
</t>
</section> <!--end: O-flag Processing -->
</section> <!--end: O-flag -->
<section title="OAM Operations"> </t>
</section>
<!--end: O-flag Processing -->
</section>
<!--end: O-flag -->
<t> IPv6 OAM operations can be performed for any SRv6 SID whose behavior <section numbered="true" toc="default">
allows Upper Layer Header processing for an applicable OAM payload <name>OAM Operations</name>
<t> IPv6 OAM operations can be performed for any SRv6 SID whose behavior
allows Upper-Layer header processing for an applicable OAM payload
(e.g., ICMP, UDP). (e.g., ICMP, UDP).
</t> </t>
<t> Ping to an SRv6 SID is used to verify <t> Ping to an SRv6 SID is used to verify
that the SID is reachable and is locally programmed at the target node. that the SID is reachable and is locally programmed at the target node.
Traceroute to a SID is used for hop-by-hop Traceroute to a SID is used for hop-by-hop
fault localization as well as path tracing to a SID. Appendix A fault localization as well as path tracing to a SID. <xref target="app-illus
illustrates the ICMPv6 based ping and the UDP based traceroute mechanisms trations" />
illustrates the ICMPv6-based ping and UDP-based traceroute mechanisms
for ping and traceroute to an SRv6 SID. Although this document only for ping and traceroute to an SRv6 SID. Although this document only
illustrates ICMPv6 ping and UDP based traceroute to an SRv6 SID, the procedur illustrates ICMPv6-based ping and UDP-based traceroute to an SRv6 SID, the pr
es are ocedures are
equally applicable to other IPv6 OAM probing to an SRv6 SID equally applicable to other OAM mechanisms that probe an SRv6 SID
(e.g., Bidirectional Forwarding Detection (BFD) <xref target="RFC5880"/>, (e.g., Bidirectional Forwarding Detection (BFD) <xref target="RFC5880" format
Seamless BFD (SBFD) <xref target="RFC7880"/>, STAMP probe message processing ="default"/>,
[I-D.gandhi-spring-stamp-srpm], etc.). Seamless BFD (S-BFD) <xref target="RFC7880" format="default"/>, and Simple Two-w
ay Active Measurement Protocol (STAMP) probe message processing
<xref target="I-D.ietf-spring-stamp-srpm" format="default"/>).
Specifically, as Specifically, as
long as local configuration allows the Upper-layer Header processing of long as local configuration allows the Upper-Layer header processing of
the applicable OAM payload for SRv6 SIDs, the existing IPv6 OAM the applicable OAM payload for SRv6 SIDs, the existing IPv6 OAM
techniques can be used to target a probe to a (remote) SID. techniques can be used to target a probe to a (remote) SID.
</t> </t>
<t> IPv6 OAM operations can be performed with the target SID in the IPv6
<t> IPv6 OAM operations can be performed with the target SID in the IPv6 destination address without an SRH or with an SRH where the target SID is the la
destination address without SRH or with SRH where the target SID is the last seg st segment.
ment.
In general, OAM operations to a target SID may not exercise all of its In general, OAM operations to a target SID may not exercise all of its
processing depending on its behavior definition. processing depending on its behavior definition.
For example, ping to an End.X SID <xref target="RFC8986"/> For example, ping to an End.X SID <xref target="RFC8986" format="default"/>
only validates the SID is locally programmed at the target node only validates the SID is locally programmed at the target node
and does not validate switching to the and does not validate switching to the
correct outgoing interface. correct outgoing interface.
To exercise the behavior To exercise the behavior
of a target SID, the OAM operation should construct the probe in a manner of a target SID, the OAM operation should construct the probe in a manner
similar to a data packet that exercises the SID behavior, i.e. to include similar to a data packet that exercises the SID behavior, i.e. to include
that SID as a transit SID in either an SRH or IPv6 DA of an outer IPv6 header that SID as a transit SID in either an SRH or IPv6 DA of an outer IPv6 header
or as appropriate or as appropriate
based on the definition of the SID behavior. based on the definition of the SID behavior.
</t> </t>
</section>
<!--end: Ping and Traceroute -->
</section> <!--end: Ping and Traceroute --> </section>
<!--end: OAM Mechanisms -->
</section> <!--end: OAM Mechanisms -->
<section anchor="Status" title="Implementation Status">
<t> This section is to be removed prior to publishing as an RFC.
</t>
<t> See [I-D.matsushima-spring-srv6-deployment-status] for updated
deployment and interoperability reports.
</t>
</section> <!--end: Implementation Status-->
<section anchor="Security" title="Security Considerations">
<t> <xref target="RFC8754"/> defines the notion of an SR domain and <section anchor="Security" numbered="true" toc="default">
use of SRH within the SR domain. <name>Security Considerations</name>
<t> <xref target="RFC8754" format="default"/> defines the notion of an SR
domain and
use of the SRH within the SR domain.
The use of OAM procedures described in this document is restricted to an SR domain. The use of OAM procedures described in this document is restricted to an SR domain.
For example, similar to the SID manipulation, O-flag manipulation is not co For example, similar to SID manipulation, O-flag manipulation is not consid
nsidered ered
as a threat within the SR domain. a threat within the SR domain.
Procedures for securing an SR domain are defined the section 5.1 and sectio Procedures for securing an SR domain are defined in Sections <xref target="
n 7 of RFC8754" format="default" section="5.1" sectionFormat="bare"/> and <xref target=
<xref target="RFC8754"/>. "RFC8754" format="default" section="7" sectionFormat="bare"/> of
</t> <xref target="RFC8754" format="default"/>.
</t>
<t> <t>
As noted in section 7.1 of <xref target="RFC8754"/>, As noted in <xref target="RFC8754" format="default" sectionFormat="of" sect
ion="7.1"/>,
compromised nodes within the SR domain may mount attacks. The O-flag compromised nodes within the SR domain may mount attacks. The O-flag
may be set by an attacking node attempting a denial-of-service attack on th e may be set by an attacking node attempting a denial-of-service attack on th e
OAM process at the segment endpoint node. OAM process at the segment endpoint node.
An implementation correctly implementing An implementation correctly implementing
the rate limiting in section 2.1.1 is not susceptible to that the rate limiting described in <xref target="oflag-proc" /> is not suscepti ble to that
denial-of-service attack. denial-of-service attack.
Additionally, SRH Flags are protected by the HMAC TLV, as Additionally, SRH flags are protected by the Hashed Message Authentication
described in section 2.1.2.1 of <xref target="RFC8754"/>. Code (HMAC) TLV, as
described in <xref target="RFC8754" format="default" sectionFormat="of" sec
tion="2.1.2.1"/>.
Once an HMAC is generated for a segment list with the O-flag set, Once an HMAC is generated for a segment list with the O-flag set,
it can be used for an arbitrary amount of traffic using that it can be used for an arbitrary amount of traffic using that
segment list with O-flag set. segment list with the O-flag set.
</t>
<t> </t>
<t>
The security properties of the channel used to send exported packets marked The security properties of the channel used to send exported packets marked
by the O-flag will depend on the specific OAM processes used. by the O-flag will depend on the specific OAM processes used.
An on-path attacker able to observe this OAM channel could conduct An on-path attacker able to observe this OAM channel could conduct
traffic analysis, or potentially eavesdropping (depending on the OAM config uration), traffic analysis, or potentially eavesdropping (depending on the OAM config uration),
of this telemetry for the entire SR domain from such a vantage point. of this telemetry for the entire SR domain from such a vantage point.
</t> </t>
<t>
<t>
This document does not This document does not
impose any additional security challenges to be considered beyond impose any additional security challenges to be considered beyond the
security threats described in <xref target="RFC4884"/>, <xref target="RFC44 security threats described in <xref target="RFC4884" format="default"/>, <x
43"/>, ref target="RFC4443" format="default"/>,
<xref target="RFC0792"/>, <xref target="RFC0792" format="default"/>,
<xref target="RFC8754"/> and <xref target="RFC8986"/>. <xref target="RFC8754" format="default"/>, and <xref target="RFC8986" format
</t> ="default"/>.
</t>
</section> <!--end: Security Considerations--> </section>
<!--end: Security Considerations-->
<section anchor="PRIVACY" title="Privacy Considerations">
<t> The per-packet marking capabilities of the O-flag provides a granular <section anchor="PRIVACY" numbered="true" toc="default">
<name>Privacy Considerations</name>
<t> The per-packet marking capabilities of the O-flag provide a granular
mechanism to collect telemetry. When this collection is deployed by an ope rator mechanism to collect telemetry. When this collection is deployed by an ope rator
with knowledge and consent of the users, it will enable a variety of diagno stics with the knowledge and consent of the users, it will enable a variety of di agnostics
and monitoring to support the OAM and security operations use cases needed for and monitoring to support the OAM and security operations use cases needed for
resilient network operations. However, this collection mechanism will also resilient network operations. However, this collection mechanism will also
provide an explicit protocol mechanism to operators for surveillance and provide an explicit protocol mechanism to operators for surveillance and
pervasive monitoring use cases done contrary to the user's consent. pervasive monitoring use cases done contrary to the user's consent.
</t> </t>
</section>
</section> <!--end: asd --> <!--end: asd -->
<section anchor="IANA" title="IANA Considerations">
<t> This document requests that IANA allocate the following
registration in the "Segment
Routing Header Flags" sub-registry for the "Internet Protocol Version
6 (IPv6) Parameters" registry maintained by IANA:
<figure> <artwork><![CDATA[
+-------+------------------------------+---------------+ <section anchor="IANA" numbered="true" toc="default">
| Bit | Description | Reference | <name>IANA Considerations</name>
+=======+==============================+===============+ <t>IANA has registered the following in the "Segment
| 2 | O-flag | This document | Routing Header Flags" subregistry in the "Internet Protocol Version
+-------+------------------------------+---------------+ 6 (IPv6) Parameters" registry:
</t>
]]> <table anchor="iana-table">
</artwork> </figure> <name></name>
</t> <thead>
<tr>
<th>Bit</th>
<th>Description</th>
<th>Reference</th>
</tr>
</thead>
<tbody>
<tr>
<td>2</td>
<td>O-flag</td>
<td>RFC 9259</td>
</tr>
</tbody>
</table>
</section> <!--end: IANA Considerations--> </section>
<!--end: IANA Considerations-->
</middle> </middle>
<back> <back>
<references title="Normative References">
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.211
9.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.875
4.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.898
6.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.817
4.xml"?>
</references> <displayreference target="I-D.ietf-spring-stamp-srpm" to="STAMP-SR"/>
<references title="Informative References">
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.079
2.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.444
3.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.488
4.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.583 <references>
7.xml"?> <name>References</name>
<references>
<name>Normative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8754.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8986.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8174.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.0792.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.4443.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.4884.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5837.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8403.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8402.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7011.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5476.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7012.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7799.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5880.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7880.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.2328.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8571.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.9197.xml"/>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.840 <!-- [I-D.gandhi-spring-stamp-srpm] Replaced by [I-D.ietf-spring-stamp-srpm] IES
3.xml"?> G state I-D Exists -->
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.840
2.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.701
1.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.547
6.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.701
2.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.779
9.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.588
0.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.788
0.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.232
8.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.857
1.xml"?>
<?rfc include="https://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference <reference anchor="I-D.ietf-spring-stamp-srpm">
.I-D.matsushima-spring-srv6-deployment-status.xml"?> <front>
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ga <title>Performance Measurement Using Simple TWAMP (STAMP) for Segment Rout
ndhi-spring-stamp-srpm.xml"?> ing Networks</title>
<?rfc include="https://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference <author fullname="Rakesh Gandhi" role="editor">
.I-D.draft-ietf-ippm-ioam-data-11.xml"?> <organization>Cisco Systems, Inc.</organization>
</author>
<author fullname="Clarence Filsfils">
<organization>Cisco Systems, Inc.</organization>
</author>
<author fullname="Daniel Voyer">
<organization>Bell Canada</organization>
</author>
<author fullname="Mach(Guoyi) Chen">
<organization>Huawei</organization>
</author>
<author fullname="Bart Janssens">
<organization>Colt</organization>
</author>
<author fullname="Richard Foote">
<organization>Nokia</organization>
</author>
<date month="February" day="1" year="2022" />
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-spring-stamp-srpm-03" />
<format type="TXT" target="https://www.ietf.org/archive/id/draft-ietf-spring-
stamp-srpm-03.txt" />
</reference>
</references>
</references> </references>
<section anchor="app-illustrations" numbered="true" toc="default">
<section title="Illustrations"> <name>Illustrations</name>
<t> This appendix shows how some of the
<t> This appendix shows how some of the
existing IPv6 OAM mechanisms can be used in an SRv6 network. It also existing IPv6 OAM mechanisms can be used in an SRv6 network. It also
illustrates an OAM mechanism for illustrates an OAM mechanism for
performing controllable and predictable flow sampling from segment performing controllable and predictable flow sampling from segment
endpoints. How centralized OAM technique in endpoints. How the centralized OAM technique in
<xref target="RFC8403"/> can be extended for SRv6 is also described in this a <xref target="RFC8403" format="default"/> can be extended for SRv6 is also de
ppendix. scribed in this appendix.
</t> </t>
<section numbered="true" toc="default">
<section title="Ping in SRv6 Networks"> <name>Ping in SRv6 Networks</name>
<t> The existing mechanism to perform the reachability checks,
<t> The existing mechanism to perform the reachability checks,
along the shortest path, continues to work without any modification. along the shortest path, continues to work without any modification.
Any IPv6 node (SRv6 capable or a non-SRv6 capable) can initiate, transit, Any IPv6 node (SRv6-capable or non-SRv6-capable) can initiate, transit,
and egress a ping packet. and egress a ping packet.
</t> </t>
<t> The following subsections outline some additional use cases of the ICM <t> The following subsections outline some additional use cases of ICMPv
Pv6 ping in 6 ping in
the SRv6 networks. SRv6 networks.
</t> </t>
<section numbered="true" toc="default">
<section title="Pinging an IPv6 Address via a Segment-list"> <name>Pinging an IPv6 Address via a Segment List</name>
<t> If an SRv6-capable ingress node wants to ping an IPv6 address via
<t> If an SRv6-capable ingress node wants to ping an IPv6 address via an an
arbitrary segment list &lt;S1, S2, S3&gt;, it needs to initiate an ICMPv6 arbitrary segment list &lt;S1, S2, S3&gt;, it needs to initiate an ICMPv6
ping with an SR header containing the SID list &lt;S1, S2, S3&gt;. This is ping with an SR header containing the SID list &lt;S1, S2, S3&gt;. This is
illustrated using the topology in Figure 1. User issues a ping from node N1 illustrated using the topology in <xref target="ref-top"/>. The user issues
to a a ping from node N1 to a
loopback of node N5, via segment list &lt;2001:db8:K:2:X31::, 2001:db8:K:4: loopback of node N5 via segment list &lt;2001:db8:K:2:X31::, 2001:db8:K:4:X
X52::&gt;. 52::&gt;.
The SID behavior used in the example is End.X SID, The SID behavior used in the example is End.X,
as described in <xref target="RFC8986"/>, but the procedure is as described in <xref target="RFC8986" format="default"/>, but the procedur
e is
equally applicable to any other (transit) SID type. equally applicable to any other (transit) SID type.
</t> </t>
<t><xref target="sample-ping"/> contains sample output for a ping requ
<t> Figure 2 contains sample output for a ping request initiated at node est initiated at node
N1 to a loopback address of node N5 via a segment list &lt;2001:db8:K:2:X31 N1 to a loopback address of node N5 via segment list &lt;2001:db8:K:2:X31::
::, ,
2001:db8:K:4:X52::&gt;. 2001:db8:K:4:X52::&gt;.
</t> </t>
<figure anchor="sample-ping">
<figure> <artwork><![CDATA[ <name>Sample Ping Output at an SRv6-Capable Node</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
> ping 2001:db8:L:5:: via segment-list 2001:db8:K:2:X31::, > ping 2001:db8:L:5:: via segment list 2001:db8:K:2:X31::,
2001:db8:K:4:X52:: 2001:db8:K:4:X52::
Sending 5, 100-byte ICMPv6 Echos to B5::, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625
/0.749/0.931 ms
Figure 2 A sample ping output at an SRv6-capable node
]]>
</artwork> </figure>
<t> All transit nodes process the echo request message like any other Sending 5, 100-byte ICMPv6 Echos to B5::, timeout is 2 seconds:
data packet carrying SR header and hence do not require any change. !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625
/0.749/0.931 ms
]]></artwork>
</figure>
<t> All transit nodes process the echo request message like any other
data packet carrying an SR header and hence do not require any change.
Similarly, the egress node does not Similarly, the egress node does not
require any change to process the ICMPv6 echo request. For example, require any change to process the ICMPv6 echo request. For example,
in the ping example of Figure 2: in the example in <xref target="sample-ping"/>:
<list style="symbols"> </t>
<t>Node N1 initiates an ICMPv6 ping packet with SRH as follows <ul spacing="normal">
<li>Node N1 initiates an ICMPv6 ping packet with the SRH as follows:
(2001:db8:L:1::, 2001:db8:K:2:X31::) (2001:db8:L:1::, 2001:db8:K:2:X31::)
(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=2, (2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=2,
NH = ICMPv6)(ICMPv6 Echo Request). NH = ICMPv6)(ICMPv6 Echo Request).
</t> </li>
<li>Node N2, which is an SRv6-capable node, performs the standard
<t>Node N2, which is an SRv6-capable node, performs the standard
SRH processing. Specifically, it executes the End.X behavior SRH processing. Specifically, it executes the End.X behavior
indicated by the 2001:db8:K:2:X31:: SID and forwards the packet on lin indicated by the 2001:db8:K:2:X31:: SID and forwards the packet on lin
k3 to N3.</t> k3 to node N3.</li>
<li> Node N3, which is a non-SRv6-capable node, performs the standar
<t> Node N3, which is a non-SRv6 capable node, performs the standard d
IPv6 processing. Specifically, it forwards the echo request IPv6 processing. Specifically, it forwards the echo request
based on the DA 2001:db8:K:4:X52:: in the IPv6 header. </t> based on DA 2001:db8:K:4:X52:: in the IPv6 header. </li>
<li> Node N4, which is an SRv6-capable node, performs the standard
<t> Node N4, which is an SRv6-capable node, performs the standard
SRH processing. Specifically, it observes the End.X behavior SRH processing. Specifically, it observes the End.X behavior
(2001:db8:K:4:X52::) and forwards the packet on link10 towards N5. (2001:db8:K:4:X52::) and forwards the packet on link10 towards node N5 .
If 2001:db8:K:4:X52:: is a PSP SID, If 2001:db8:K:4:X52:: is a PSP SID,
the penultimate node (Node N4) does not, should not and cannot differe ntiate the penultimate node (node N4) does not, should not, and cannot differ entiate
between the data packets and OAM probes. between the data packets and OAM probes.
Specifically, if 2001:db8:K:4:X52:: is a PSP SID, Specifically, if 2001:db8:K:4:X52:: is a PSP SID,
node N4 executes the SID like any other data packet with DA = 2001:db8 :K:4:X52:: node N4 executes the SID like any other data packet with DA = 2001:db8 :K:4:X52::
and removes the SRH. and removes the SRH.
</t> </li>
<li> The echo request packet at node N5 arrives as an IPv6 packet wi
<t> The echo request packet at N5 arrives as an IPv6 packet with or th or
without an SRH. If N5 receives the packet with SRH, it skips SRH proce without an SRH. If node N5 receives the packet with an SRH, it skips S
ssing (SL=0). RH processing (SL=0).
In either case, Node N5 performs the In either case, node N5 performs the
standard ICMPv6 processing on the echo request and responds with the standard ICMPv6 processing on the echo request and responds with the
echo reply message to N1. The echo reply message is IP routed. echo reply message to node N1. The echo reply message is IP routed.
</t>
</list> </t>
</section> <!--end: Pinging an IPv6 address via a sid-list -->
<section title="Pinging a SID"> </li>
</ul>
</section>
<!--end: Pinging an IPv6 address via a sid-list -->
<t> <section numbered="true" toc="default">
The ping mechanism described above applies equally to perform SID <name>Pinging a SID</name>
reachability check and to validate the SID is locally programmed at the target n <t>
ode. The ping mechanism described above can also be used to perform SID
This is explained using an example in the reachability checks and to validate that the SID is locally programmed at
following. The example uses ping to an END SID, as described in <xref target= the target node.
"RFC8986"/>, This is explained in the
following example. The example uses ping to an End SID, as described in <xref
target="RFC8986" format="default"/>,
but the procedure is but the procedure is
equally applicable to ping any other SID behaviors. equally applicable to ping any other SID behaviors.
</t> </t>
<t> Consider the example where the user wants to ping a remote
<t> Consider the example where the user wants to ping a remote
SID 2001:db8:K:4::, via 2001:db8:K:2:X31::, from node N1. SID 2001:db8:K:4::, via 2001:db8:K:2:X31::, from node N1.
The ICMPv6 echo request is processed at the individual nodes The ICMPv6 echo request is processed at the individual nodes
along the path as follows: along the path as follows:
<list style="symbols"> </t>
<t>Node N1 initiates an ICMPv6 ping packet with SRH as follows <ul spacing="normal">
<li>Node N1 initiates an ICMPv6 ping packet with the SRH as follows:
(2001:db8:L:1::, 2001:db8:K:2:X31::) (2001:db8:L:1::, 2001:db8:K:2:X31::)
(2001:db8:K:4::, 2001:db8:K:2:X31::; SL=1; (2001:db8:K:4::, 2001:db8:K:2:X31::; SL=1;
NH=ICMPv6)(ICMPv6 Echo Request). </t> NH=ICMPv6)(ICMPv6 Echo Request). </li>
<li>Node N2, which is an SRv6-capable node, performs the standard
<t>Node N2, which is an SRv6-capable node, performs the standard
SRH processing. Specifically, it executes the End.X behavior SRH processing. Specifically, it executes the End.X behavior
indicated by the 2001:db8:K:2:X31:: SID on the echo request packet. If indicated by the 2001:db8:K:2:X31:: SID on the echo request packet. If
2001:db8:K:2:X31:: is a PSP SID, node N4 executes the SID like any 2001:db8:K:2:X31:: is a PSP SID, node N4 executes the SID like any
other data packet with DA = 2001:db8:K:2:X31:: and removes the other data packet with DA = 2001:db8:K:2:X31:: and removes the
SRH. SRH.
</t> </li>
<t> Node N3, which is a non-SRv6 capable node, performs <li> Node N3, which is a non-SRv6-capable node, performs
the standard IPv6 processing. Specifically, it forwards the the standard IPv6 processing. Specifically, it forwards the
echo request based on DA = 2001:db8:K:4:: in the IPv6 header.</t> echo request based on DA = 2001:db8:K:4:: in the IPv6 header.</li>
<li>When node N4 receives the packet, it
<t>When node N4 receives the packet, it processes the target SID (2001:db8:K:4::). </li>
processes the target SID (2001:db8:K:4::). </t> <li> If the target SID (2001:db8:K:4::) is not locally instantiated
<t> If the target SID (2001:db8:K:4::) is not locally instantiated
and does not represent a local interface, and does not represent a local interface,
the packet is discarded </t> the packet is discarded </li>
<li>
<t>
If the target SID (2001:db8:K:4::) is locally instantiated or If the target SID (2001:db8:K:4::) is locally instantiated or
represents a local interface, the node processes represents a local interface, the node processes
the upper layer header. the Upper-Layer header.
As part of the upper layer header processing node N4 respond As part of the Upper-Layer header processing, node N4 responds
to the ICMPv6 echo request message and responds with the to the ICMPv6 echo request message with an
echo reply message. The echo reply message is IP routed. echo reply message. The echo reply message is IP routed.
</t> </li>
</ul>
</list> </section>
<!--end: SID Ping -->
</t>
</section> <!--end: SID Ping -->
</section> <!--end: Ping-->
<section title="Traceroute"> </section>
<!--end: Ping-->
<t> The existing traceroute <section numbered="true" toc="default">
mechanisms, along the shortest path, continues to work without any modifica <name>Traceroute in SRv6 Networks</name>
tion. <t> The existing traceroute
Any IPv6 node (SRv6 capable or a non-SRv6 capable) can initiate, transit, mechanisms, along the shortest path, continue to work without any modificat
ion.
Any IPv6 node (SRv6-capable or a non-SRv6-capable) can initiate, transit,
and egress a traceroute probe. and egress a traceroute probe.
</t> </t>
<t> <t>
The following subsections outline some additional use cases of the tracerou The following subsections outline some additional use cases of traceroute
te in SRv6 networks.
in the SRv6 networks. </t>
</t> <section numbered="true" toc="default">
<name>Traceroute to an IPv6 Address via a Segment List</name>
<section title="Traceroute to an IPv6 Address via a Segment-list"> <t> If an SRv6-capable ingress node wants to traceroute to an IPv6 ad
dress
<t> If an SRv6-capable ingress node wants to traceroute to IPv6 address
via an arbitrary segment list &lt;S1, S2, S3&gt;, it needs to initiate via an arbitrary segment list &lt;S1, S2, S3&gt;, it needs to initiate
a traceroute probe with an SR header containing the SID list a traceroute probe with an SR header containing the SID list
&lt;S1, S2, S3&gt;. User issues a traceroute &lt;S1, S2, S3&gt;. The user issues a traceroute
from node N1 to a loopback of node N5, via segment list from node N1 to a loopback of node N5 via segment list
&lt;2001:db8:K:2:X31::, 2001:db8:K:4:X52::&gt;. &lt;2001:db8:K:2:X31::, 2001:db8:K:4:X52::&gt;.
The SID behavior used in the example is End.X SID, as described in The SID behavior used in the example is End.X, as described in
<xref target="RFC8986"/>, <xref target="RFC8986" format="default"/>,
but the procedure is equally applicable to any other (transit) SID but the procedure is equally applicable to any other (transit) SID
type. type.
Figure 3 contains sample output for the traceroute <xref target="sample-traceroute"/> contains sample output for the tracerout e
request. request.
</t> </t>
<figure anchor="sample-traceroute">
<figure> <artwork><![CDATA[ <name>Sample Traceroute Output at an SRv6-Capable Node</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
> traceroute 2001:db8:L:5:: via segment-list 2001:db8:K:2:X31::, > traceroute 2001:db8:L:5:: via segment list 2001:db8:K:2:X31::,
2001:db8:K:4:X52:: 2001:db8:K:4:X52::
Tracing the route to 2001:db8:L:5::
1 2001:db8:2:1:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:db8:K:2:X31::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=2)
2 2001:db8:3:2:31:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=1)
3 2001:db8:4:3::41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=1)
4 2001:db8:5:4::52:: 0.879 msec 0.916 msec 1.024 msec
DA: 2001:db8:L:5::
Figure 3 A sample traceroute output at an SRv6-capable node
]]>
</artwork> </figure>
<t> In the sample traceroute output, the information displayed at each h Tracing the route to 2001:db8:L:5::
op 1 2001:db8:2:1:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:db8:K:2:X31::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=2)
2 2001:db8:3:2:31:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=1)
3 2001:db8:4:3::41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:L:5::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::, SL=1)
4 2001:db8:5:4::52:: 0.879 msec 0.916 msec 1.024 msec
DA: 2001:db8:L:5::
]]></artwork>
</figure>
<t> In the sample traceroute output, the information displayed at eac
h hop
is obtained using the contents of the "Time Exceeded" or is obtained using the contents of the "Time Exceeded" or
"Destination Unreachable" ICMPv6 responses. These ICMPv6 responses "Destination Unreachable" ICMPv6 responses. These ICMPv6 responses
are IP routed. are IP routed.
</t> </t>
<t> In the sample traceroute output, the information for link3 is
<t> In the sample traceroute output, the information for link3 is returned by node N3, which is a
returned by N3, which is a non-SRv6-capable node. Nonetheless, the ingress node is able to display
non-SRv6 capable node. Nonetheless, the ingress node is able to display SR header contents as the packet travels through the non-SRv6-capable node.
SR header contents as the packet travels through the non-SRv6 capable node. This is because the "Time Exceeded" ICMPv6 message can
This is because the "Time Exceeded Message" ICMPv6 message can
contain as much of the invoking packet as possible without the contain as much of the invoking packet as possible without the
ICMPv6 packet exceeding the minimum IPv6 MTU <xref target="RFC4443"/>. The SR ICMPv6 packet exceeding the minimum IPv6 MTU <xref target="RFC4443" format= "default"/>. The SR
header is included in these ICMPv6 messages initiated by the header is included in these ICMPv6 messages initiated by the
non-SRv6 capable transit nodes that are not running SRv6 software. non-SRv6-capable transit nodes that are not running SRv6 software.
Specifically, a node generating ICMPv6 message containing a copy of Specifically, a node generating an ICMPv6 message containing a copy of
the invoking packet does not need to understand the extension the invoking packet does not need to understand the extension
header(s) in the invoking packet. header(s) in the invoking packet.
</t> </t>
<t> The segment list information returned for the first hop is return
<t> The segment list information returned for the first hop is returned by ed by node N2,
N2,
which is an SRv6-capable node. Just like for the second hop, the ingress no de which is an SRv6-capable node. Just like for the second hop, the ingress no de
is able to display SR header contents for the first hop. is able to display SR header contents for the first hop.
</t> </t>
<t> There is no difference in processing of the traceroute probe at a
<t> There is no difference in processing of the traceroute probe at an n
SRv6-capable and a non-SRv6 capable node. Similarly, both SRv6-capable and SRv6-capable and a non-SRv6-capable node. Similarly, both SRv6-capable and
non-SRv6 capable nodes may use the address of the interface on non-SRv6-capable nodes may use the address of the interface on
which probe was received as the source address in the ICMPv6 which probe was received as the source address in the ICMPv6
response. ICMPv6 extensions defined in <xref target="RFC5837"/> can be used to response. ICMPv6 extensions defined in <xref target="RFC5837" format="defau lt"/> can be used to
display information about the IP interface through which the display information about the IP interface through which the
datagram would have been forwarded had it been forwardable, and the datagram would have been forwarded had it been forwardable, the
IP next hop to which the datagram would have been forwarded, the IP IP next hop to which the datagram would have been forwarded, the IP
interface upon which a datagram arrived, the sub-IP component of an interface upon which the datagram arrived, and the sub-IP component of an
IP interface upon which a datagram arrived. IP interface upon which the datagram arrived.
</t> </t>
<t> The IP address of the interface on which the traceroute probe was rece ived <t> The IP address of the interface on which the traceroute probe was received
is useful. This information can also be used to verify if SIDs is useful. This information can also be used to verify if SIDs
2001:db8:K:2:X31:: and 2001:db8:K:4:X52:: are executed correctly by N2 and N4, 2001:db8:K:2:X31:: and 2001:db8:K:4:X52:: are executed correctly by nodes N 2 and N4,
respectively. Specifically, the information displayed for the second hop respectively. Specifically, the information displayed for the second hop
contains the incoming interface address 2001:db8:2:3:31:: at N3. contains the incoming interface address 2001:db8:2:3:31:: at node N3.
This matches with the expected interface bound to End.X behavior This matches the expected interface bound to End.X behavior
2001:db8:K:2:X31:: (link3). Similarly, the information displayed for the fo urth hop 2001:db8:K:2:X31:: (link3). Similarly, the information displayed for the fo urth hop
contains the incoming interface address 2001:db8:4:5::52:: at N5. contains the incoming interface address 2001:db8:4:5::52:: at node N5.
This matches with the expected interface bound to the End.X behavior This matches the expected interface bound to the End.X behavior
2001:db8:K:4:X52:: (link10). 2001:db8:K:4:X52:: (link10).
</t> </t>
</section>
</section> <!--end: Tracerouting an IPv6 Address via a Segment-list --> <!--end: Tracerouting an IPv6 Address via a Segment list -->
<section title="Traceroute to a SID">
<t> The mechanism to traceroute an IPv6 Address via a Segment-list <section numbered="true" toc="default">
described in the previous section applies <name>Traceroute to a SID</name>
equally to traceroute a remote SID behavior, as explained using an
example in the following.
The example uses traceroute to an END SID, as described in <xref target="RF
C8986"/>,
but the procedure is
equally applicable to tracerouting any other SID behaviors.
</t>
<t> Please note that traceroute to a SID is <t>The mechanism to traceroute an IPv6 address via a segment list
described in the previous section can also be used to traceroute a
remote SID behavior, as explained in the following example. The
example uses traceroute to an End SID, as described in <xref
target="RFC8986" format="default"/>, but the procedure is equally
applicable to tracerouting any other SID behaviors.
</t>
<t> Please note that traceroute to a SID is
exemplified using UDP probes. However, the procedure is equally exemplified using UDP probes. However, the procedure is equally
applicable to other implementations of traceroute mechanism. applicable to other implementations of traceroute mechanism.
The UDP encoded message to traceroute a SID would use the UDP ports The UDP encoded message to traceroute a SID would use the UDP ports
assigned by IANA for "traceroute use". assigned by IANA for "traceroute use".
</t> </t>
<t> Consider the example where the user wants to traceroute a remote S
<t> Consider the example where the user wants to traceroute a remote SID ID
2001:db8:K:4::, via 2001:db8:K:2:X31::, from node N1. The 2001:db8:K:4::, via 2001:db8:K:2:X31::, from node N1. The
traceroute probe is processed at the individual nodes along the path traceroute probe is processed at the individual nodes along the path
as follows: as follows:
<list style="symbols"> </t>
<t>Node N1 initiates a traceroute probe packet as follows <ul spacing="normal">
<li>Node N1 initiates a traceroute probe packet as follows
(2001:db8:L:1::, 2001:db8:K:2:X31::) (2001:db8:L:1::, 2001:db8:K:2:X31::)
(2001:db8:K:4::, 2001:db8:K:2:X31::; SL=1; NH=UDP)(Traceroute probe). (2001:db8:K:4::, 2001:db8:K:2:X31::; SL=1; NH=UDP)(Traceroute probe).
The first traceroute probe is sent with hop-count value set to 1. The first traceroute probe is sent with the hop-count value set to 1.
The hop-count value is incremented by 1 for each following traceroute The hop-count value is incremented by 1 for each subsequent traceroute
probes. probe.
</t>
<t>When node N2 receives the packet with hop-count = 1, it </li>
processes the hop-count expiry. Specifically, the node N2 <li>When node N2 receives the packet with hop-count = 1, it
responds with the ICMPv6 message (Type: "Time Exceeded", Code: processes the hop-count expiry. Specifically, node N2
"Hop limit exceeded in transit"). The ICMPv6 response responds with the ICMPv6 message with type "Time Exceeded" and code
"hop limit exceeded in transit". The ICMPv6 response
is IP routed. is IP routed.
</t> </li>
<t>When Node N2 receives the packet with hop-count > 1, it <li>When node N2 receives the packet with hop-count &gt; 1, it
performs the standard SRH processing. Specifically, it executes performs the standard SRH processing. Specifically, it executes
the End.X behavior indicated by the the End.X behavior indicated by the
2001:db8:K:2:X31:: SID on the traceroute probe. 2001:db8:K:2:X31:: SID on the traceroute probe.
If 2001:db8:K:2:X31:: is a PSP SID, If 2001:db8:K:2:X31:: is a PSP SID,
node N2 executes the SID like any other data packet with DA = 2001:db8:K:2 :X31:: node N2 executes the SID like any other data packet with DA = 2001:db8:K:2 :X31::
and removes the SRH. and removes the SRH.
</t> </li>
<t>When node N3, which is a non-SRv6 capable node, receives the packet <li>When node N3, which is a non-SRv6-capable node, receives the pac
ket
with hop-count = 1, it processes the with hop-count = 1, it processes the
hop-count expiry. Specifically, the node N3 responds with the hop-count expiry. Specifically, node N3 responds with the
ICMPv6 message (Type: "Time Exceeded", Code: "Hop limit ICMPv6 message with type "Time Exceeded" and code "Hop limit
exceeded in Transit"). The ICMPv6 response is IP routed. exceeded in transit". The ICMPv6 response is IP routed.
</t> </li>
<t>When node N3, which is a non-SRv6 capable node, receives the packet <li>When node N3, which is a non-SRv6-capable node, receives the pac
with hop-count > 1, it performs the standard IPv6 processing. ket
with hop-count &gt; 1, it performs the standard IPv6 processing.
Specifically, it forwards the traceroute probe based on DA Specifically, it forwards the traceroute probe based on DA
2001:db8:K:4:: in the IPv6 header. </t> 2001:db8:K:4:: in the IPv6 header. </li>
<t>When node N4 receives the packet with DA set to the local SID 2001: <li>When node N4 receives the packet with DA set to the local SID 20
db8:K:4::, it 01:db8:K:4::, it
processes the END SID. </t> processes the End SID. </li>
<li> If the target SID (2001:db8:K:4::) is not locally instantiated
<t> If the target SID (2001:db8:K:4::) is not locally instantiated and and
does not represent a local interface, the packet is discarded. does not represent a local interface, the packet is discarded.
</t> </li>
<li>
<t>
If the target SID (2001:db8:K:4::) is locally instantiated or represen ts a If the target SID (2001:db8:K:4::) is locally instantiated or represen ts a
local interface, the node processes local interface, the node processes
the upper layer header. the Upper-Layer header.
As part of the upper layer header processing node N4 responds As part of the Upper-Layer header processing, node N4 responds
with the ICMPv6 message (Type: Destination unreachable, Code: with the ICMPv6 message with type "Destination Unreachable" and code
Port Unreachable). The ICMPv6 response "Port Unreachable". The ICMPv6 response
is IP routed. is IP routed.
</t> </li>
</list> </ul>
</t> <t><xref target="sample-output"/> displays a sample traceroute output
for this example.
<t> Figure 4 displays a sample traceroute output for this example.
<figure> <artwork><![CDATA[
> traceroute 2001:db8:K:4:X52:: via segment-list 2001:db8:K:2:X31::
Tracing the route to SID 2001:db8:K:4:X52::
1 2001:db8:2:1:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:db8:K:2:X31::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1)
2 2001:db8:3:2:21:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0)
3 2001:db8:4:3:41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0)
Figure 4 A sample output for hop-by-hop traceroute to a SID
]]>
</artwork> </figure>
</t>
</section> <!--end: Traceroute to a SID behavior-->
</section> <!--end: Traceroute --> </t>
<figure anchor="sample-output">
<name>Sample Output for Hop-by-Hop Traceroute to a SID</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
> traceroute 2001:db8:K:4:X52:: via segment list 2001:db8:K:2:X31::
<section title="A Hybrid OAM Using O-flag"> Tracing the route to SID 2001:db8:K:4:X52::
1 2001:db8:2:1:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:db8:K:2:X31::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1)
2 2001:db8:3:2:21:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0)
3 2001:db8:4:3:41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:db8:K:4:X52::,
SRH:(2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0)
]]></artwork>
</figure>
</section>
<!--end: Traceroute to a SID behavior-->
<t> This section illustrates a hybrid OAM mechanism using </section>
the the O-flag. Without loss of the generality, the illustration <!--end: Traceroute -->
assumes N100 is a centralized controller.
</t>
<t> <section numbered="true" toc="default">
The illustration is different than the In-situ OAM defined in <name>Hybrid OAM Using the OAM Flag</name>
[I.D-draft-ietf-ippm-ioam-data]. This is because In-situ OAM records <t> This section illustrates a hybrid OAM mechanism using
operational and telemetry information in the packet as the packet traverses the O-flag. Without loss of the generality, the illustration
a path between two points in the network [I.D-draft-ietf- assumes node N100 is a centralized controller.
ippm-ioam-data]. The illustration in this subsection does not require the re </t>
cording of OAM <t>
data in the packet. This illustration is different from the "in situ OAM" defined in <xref
target="RFC9197" format="default"/>. This is because in situ OAM records
operational and telemetry information in the packet as the packet
traverses a path between two points in the network <xref target="RFC9197"
format="default"/>. The illustration in this subsection does not require
the recording of OAM data in the packet.
</t> </t>
<t>
<t>
The illustration does not assume any formats for exporting the data The illustration does not assume any formats for exporting the data
elements or the data elements that need to be exported. elements or the data elements that need to be exported.
The illustration assumes system clocks among all nodes in the SR domain a re synchronized. The illustration assumes system clocks among all nodes in the SR domain a re synchronized.
</t> </t>
<t> Consider the example where the user wants to monitor sampled IPv4
<t> Consider the example where the user wants to monitor sampled IPv4 VPN 999 traffic going from CE1 to CE2 via a low-latency SR Policy P installe
VPN 999 traffic going from CE1 to CE2 via a low latency SR policy P installe d
d at node N1.
at Node N1. To exercise a low-latency path, the SR Policy P forces the packet via segmen
To exercise a low latency path, the SR Policy P forces the packet via segmen ts
ts
2001:db8:K:2:X31:: and 2001:db8:K:4:X52::. 2001:db8:K:2:X31:: and 2001:db8:K:4:X52::.
The VPN SID at N7 associated with VPN 999 is 2001:db8:K:7:DT999::. The VPN SID at node N7 associated with VPN 999 is 2001:db8:K:7:DT999::.
2001:db8:K:7:DT999:: is a USP SID. 2001:db8:K:7:DT999:: is a USP SID.
N1, N4, and N7 are capable of processing O-flag but Nodes N1, N4, and N7 are capable of processing the O-flag, but
N2 is not capable of processing O-flag. node N2 is not capable of processing the O-flag.
N100 is the centralized controller capable of processing and correlating Node N100 is the centralized controller capable of processing and correlatin
g
the copy of the packets sent from nodes N1, N4, and N7. the copy of the packets sent from nodes N1, N4, and N7.
N100 is aware of O-flag processing capabilities. Node N100 is aware of O-flag processing capabilities.
Controller N100 with the help from nodes N1, N4, N7 and implements a hybrid Node N100, with help from nodes N1, N4, and N7, implements a hybrid
OAM mechanism using the O-flag as follows: OAM mechanism using the O-flag as follows:
<list style="symbols"> </t>
<t> A packet P1:(IPv4 header)(payload) is sent from CE1 to Node N1. </ <ul spacing="normal">
t> <li> <t>A packet P1 is sent from CE1 to node N1. The packet is:</t>
<t> Node N1 steers the packet P1 through the Policy P. <t>P1: (IPv4 header)(payload)</t></li>
Based on a local configuration, Node N1 also implements logic to sampl <li> <t>Node N1 steers packet P1 through the SR Policy P.
e Based on local configuration, node N1 also implements logic to sample
traffic steered through policy P for hybrid OAM purposes. traffic steered through SR Policy P for hybrid OAM purposes.
Specification for the sampling logic is beyond the scope of this docum ent. Specification for the sampling logic is beyond the scope of this docum ent.
Consider the case where packet P1 is classified as a packet to be moni tored Consider the case where packet P1 is classified as a packet to be moni tored
via the hybrid OAM. via the hybrid OAM.
Node N1 sets O-flag during the encapsulation required by policy P. Node N1 sets the O-flag during the encapsulation required by SR Policy P.
As part of setting the O-flag, node N1 also sends a timestamped copy As part of setting the O-flag, node N1 also sends a timestamped copy
of the packet P1: (2001:db8:L:1::, 2001:db8:K:2:X31::) of packet P1 to a local
(2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=2; O OAM process. The packet is:</t>
-flag=1; <t>P1: (2001:db8:L:1::, 2001:db8:K:2:X31::) (2001:db8:K:7:DT999::,
NH=IPv4)(IPv4 header)(payload) to a local 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=2; O-flag=1;
OAM process. The local OAM process sends a full or partial copy of NH=IPv4)(IPv4 header)(payload)</t>
the packet P1 to the controller N100. <t>The local OAM process sends a full or partial copy of
packet P1 to node N100.
The OAM process includes the The OAM process includes the
recorded timestamp, additional recorded timestamp, additional
OAM information like incoming and outgoing interface, etc. along OAM information (like incoming and outgoing interface), and
with any applicable metadata. any applicable metadata.
Node N1 forwards the original packet towards the next Node N1 forwards the original packet towards the next
segment 2001:db8:K:2:X31::. </t> segment 2001:db8:K:2:X31::.</t> </li>
<t> When node N2 receives the packet with O-flag set, it ignores <li> <t>When node N2 receives the packet with the O-flag set, it
the O-flag. This is because node N2 is not capable of processing ignores the O-flag. This is because node N2 is not capable of
the O-flag. Node N2 processing the O-flag. Node N2 performs the standard SRv6 SID and
performs the standard SRv6 SID and SRH processing. Specifically, it ex SRH processing. Specifically, it executes the End.X behavior <xref
ecutes target="RFC8986" format="default"/>
the End.X indicated by the 2001:db8:K:2:X31:: SID and forwards packet P1 over
behavior indicated by the link3 towards node N3. The packet is:</t>
2001:db8:K:2:X31:: SID as described in <xref target="RFC8986"/> <t>P1: (2001:db8:L:1::, 2001:db8:K:4:X52::) (2001:db8:K:7:DT999::,
and forwards the packet P1 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1; O-flag=1;
(2001:db8:L:1::, 2001:db8:K:4:X52::) NH=IPv4)(IPv4 header)(payload)
(2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1; O </t>
-flag=1; </li>
NH=IPv4)(IPv4 header)(payload) over link 3 towards Node N3. <li>When node N3, which is a non-SRv6-capable node, receives packet P1
</t> , it performs the standard IPv6 processing.
<t>When node N3, which is a non-SRv6 capable node, receives the packet Specifically, it forwards packet P1 based on DA
P1
, it performs the standard IPv6 processing.
Specifically, it forwards the packet P1 based on DA
2001:db8:K:4:X52:: in the IPv6 header. 2001:db8:K:4:X52:: in the IPv6 header.
</t> </li>
<t>When node N4 receives the packet P1 <li><t>When node N4 receives packet P1, it processes the O-flag. The p
(2001:db8:L:1::, 2001:db8:K:4:X52::) acket is:</t>
<t>P1: (2001:db8:L:1::, 2001:db8:K:4:X52::)
(2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1; O -flag=1; (2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=1; O -flag=1;
NH=IPv4)(IPv4 header)(payload), it processes the O-flag. NH=IPv4)(IPv4 header)(payload)
As part of processing the O-flag, it sends a timestamped copy of </t>
<t>As part of processing the O-flag, it sends a timestamped copy of
the packet to a local OAM process. the packet to a local OAM process.
Based on a local configuration, the local OAM process sends a full or Based on local configuration, the local OAM process sends a full or pa
partial rtial
copy of the packet copy of packet
P1 to the controller N100. The OAM process includes the P1 to node N100. The OAM process includes the
recorded timestamp, additional recorded timestamp, additional
OAM information like incoming and outgoing interface, etc. along OAM information (like incoming and outgoing interface, etc.), and
with any applicable metadata. any applicable metadata.
Node N4 performs the standard SRv6 SID and SRH processing on the origi nal packet P1. Node N4 performs the standard SRv6 SID and SRH processing on the origi nal packet P1.
Specifically, it executes Specifically, it executes
the End.X behavior indicated by the 2001:db8:K:4:X52:: SID and forward the End.X behavior indicated by the 2001:db8:K:4:X52:: SID and forward
s the packet P1 s packet P1
(2001:db8:L:1::, 2001:db8:K:7:DT999::) over link10 towards node N5. The packet is:</t>
<t>P1: (2001:db8:L:1::, 2001:db8:K:7:DT999::)
(2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0; O -flag=1; (2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0; O -flag=1;
NH=IPv4)(IPv4 header)(payload) over link 10 towards Node N5. NH=IPv4)(IPv4 header)(payload)
</t> </t>
<t>When node N5, which is a non-SRv6 capable node, receives the packet </li>
P1, <li>When node N5, which is a non-SRv6-capable node, receives packet P1
,
it performs the standard IPv6 processing. it performs the standard IPv6 processing.
Specifically, it forwards the packet based on DA Specifically, it forwards the packet based on DA
2001:db8:K:7:DT999:: in the IPv6 header. 2001:db8:K:7:DT999:: in the IPv6 header.
</t> </li>
<t>When node N7 receives the packet P1 <li><t>When node N7 receives packet P1, it processes the O-flag. The p
(2001:db8:L:1::, 2001:db8:K:7:DT999::) acket is:</t>
<t>P1: (2001:db8:L:1::, 2001:db8:K:7:DT999::)
(2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0; O -flag=1; (2001:db8:K:7:DT999::, 2001:db8:K:4:X52::, 2001:db8:K:2:X31::; SL=0; O -flag=1;
NH=IPv4)(IPv4 header)(payload), it processes the O-flag. NH=IPv4)(IPv4 header)(payload)
As part of processing the O-flag, it sends a timestamped copy of </t>
<t>As part of processing the O-flag, it sends a timestamped copy of
the packet to a local OAM process. the packet to a local OAM process.
The local OAM process sends a full or partial copy of the packet The local OAM process sends a full or partial copy of packet
P1 to the controller N100. The OAM process includes the P1 to node N100. The OAM process includes the
recorded timestamp, additional recorded timestamp, additional
OAM information like incoming and outgoing interface, etc. along OAM information (like incoming and outgoing interface, etc.), and
with any applicable metadata. any applicable metadata.
Node N7 performs the standard SRv6 SID and SRH processing on the origi nal packet P1. Node N7 performs the standard SRv6 SID and SRH processing on the origi nal packet P1.
Specifically, it executes the VPN SID indicated by the 2001:db8:K:7:DT 999:: SID Specifically, it executes the VPN SID indicated by the 2001:db8:K:7:DT 999:: SID
and based on lookup in table 100 forwards the packet P1 and, based on lookup in table 100, forwards packet P1
(IPv4 header)(payload) towards CE 2. towards CE2. The packet is:</t>
</t> <t>P1: (IPv4 header)(payload)
</t>
<t> </li>
The controller N100 processes and correlates the copy of the packets <li>
sent from nodes N1, N4 and N7 to find segment-by-segment delays and Node N100 processes and correlates the copy of the packets
sent from nodes N1, N4, and N7 to find segment-by-segment delays and
provide other hybrid OAM information related to packet P1. provide other hybrid OAM information related to packet P1.
For segment-by-segment delay computation, it is assumed that clock For segment-by-segment delay computation, it is assumed that clocks
are synchronized time across the SR domain. are synchronized across the SR domain.
</t>
<t>
The process continues for any other sampled packets. </t>
</list>
</t>
</section> <!--end: O-flag -->
<section title="Monitoring of SRv6 Paths"> </li>
<li>
The process continues for any other sampled packets. </li>
</ul>
</section>
<!--end: O-flag -->
<t> In the recent past, network operators demonstrated interest in perform <section numbered="true" toc="default">
ing <name>Monitoring of SRv6 Paths</name>
network OAM functions in a centralized manner. <xref target='RFC8403'/> <t> In the recent past, network operators demonstrated interest in perf
describes such a centralized OAM mechanism. Specifically, the document orming
network OAM functions in a centralized manner. <xref target="RFC8403" format
="default"/>
describes such a centralized OAM mechanism. Specifically, <xref target="RFC
8403" format="default"/>
describes a procedure that can be used to perform path continuity describes a procedure that can be used to perform path continuity
check between any nodes within an SR domain from a centralized checks between any nodes within an SR domain from a centralized
monitoring system. However, the document focuses on SR networks with MPLS d monitoring system. However, while <xref target="RFC8403" format="default"/>
ata focuses on SR networks with MPLS data
plane. This document describes how plane, this document describes how
the concept can be used to perform path monitoring in an SRv6 network the concept can be used to perform path monitoring in an SRv6 network
from a centralized controller. from a centralized controller.
</t> </t>
<t> In the reference topology in <xref target="ref-top"/>, node N100 us
<t> In the reference topology in Figure 1, N100 uses an IGP protocol es an IGP protocol
like OSPF or IS-IS to get the topology view within the IGP domain. like OSPF or IS-IS to get a view of the topology within the IGP domain.
N100 can also use BGP-LS to get the complete view of an inter-domain Node N100 can also use BGP-LS to get the complete view of an inter-domain
topology. The controller leverages the visibility of topology. The controller leverages the visibility of
the topology to monitor the paths between the various endpoints. the topology to monitor the paths between the various endpoints.
</t> </t>
<t>Node N100 advertises an End
<t>The controller N100 advertises an END SID <xref target="RFC8986" format="default"/> 2001:db8:K:100:1::. To monito
SID <xref target="RFC8986"/> 2001:db8:K:100:1::. To monitor any r any
arbitrary SRv6 paths, the controller can create a loopback probe that origi nates and arbitrary SRv6 paths, the controller can create a loopback probe that origi nates and
terminates on Node N100. To distinguish between a failure in the monitored path terminates on node N100. To distinguish between a failure in the monitored path
and loss of connectivity between the controller and the network, and loss of connectivity between the controller and the network,
Node N100 runs a suitable mechanism to monitor its connectivity to the moni node N100 runs a suitable mechanism to monitor its connectivity to the moni
tored network. tored network.
</t> </t>
<t>
<t> The following example illustrates loopback probes in which node N100
The loopback probes are exemplified using an example where controller N100
needs to verify a needs to verify a
segment list &lt;2001:db8:K:2:X31::, 2001:db8:K:4:X52::&gt;: segment list &lt;2001:db8:K:2:X31::, 2001:db8:K:4:X52::&gt;:
<list style="symbols"> </t>
<t>N100 generates an OAM packet (2001:db8:L:100::, <ul spacing="normal">
<li>Node N100 generates an OAM packet (2001:db8:L:100::,
2001:db8:K:2:X31::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::, 2001:db8:K:2:X31::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::,
SL=2)(OAM Payload). The controller routes the probe packet towards the fi rst SL=2)(OAM Payload). The controller routes the probe packet towards the fi rst
segment, which is 2001:db8:K:2:X31::. segment, which is 2001:db8:K:2:X31::.
</t> </li>
<li>Node N2 executes the End.X behavior indicated by the 2001:db8:K:2:
<t>Node N2 executes the End.X behavior indicated by the 2001:db8:K:2:X31: X31:: SID and
: SID and
forwards the packet forwards the packet
(2001:db8:L:100::, (2001:db8:L:100::,
2001:db8:K:4:X52::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::, 2001:db8:K:4:X52::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::,
SL=1)(OAM Payload) on link3 to N3. SL=1)(OAM Payload) on link3 to node N3.
</t> </li>
<li> Node N3, which is a non-SRv6-capable node, performs the standard
<t> Node N3, which is a non-SRv6 capable node, performs the standard
IPv6 processing. Specifically, it forwards the packet IPv6 processing. Specifically, it forwards the packet
based on the DA 2001:db8:K:4:X52:: in the IPv6 header. </t> based on DA 2001:db8:K:4:X52:: in the IPv6 header. </li>
<li>Node N4 executes the End.X behavior indicated by the 2001:db8:K:4:
<t>Node N4 executes the End.X behavior indicated by the 2001:db8:K:4:X52: X52:: SID and
: SID and
forwards the packet forwards the packet
(2001:db8:L:100::, (2001:db8:L:100::,
2001:db8:K:100:1::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::, 2001:db8:K:100:1::)(2001:db8:K:100:1::, 2001:db8:K:4:X52::, 2001:db8:K:2: X31::,
SL=0)(OAM Payload) on link10 to N5. SL=0)(OAM Payload) on link10 to node N5.
</t> </li>
<li> Node N5, which is a non-SRv6-capable node, performs the standard
<t> Node N5, which is a non-SRv6 capable node, performs the standard
IPv6 processing. Specifically, it forwards the packet IPv6 processing. Specifically, it forwards the packet
based on the DA 2001:db8:K:100:1:: in the IPv6 header. </t> based on DA 2001:db8:K:100:1:: in the IPv6 header. </li>
<li>Node N100 executes the standard SRv6 END behavior. It
<t>Node N100 executes the standard SRv6 END behavior. It decapsulates the header and consumes the probe for OAM processing. The in
decapsulates the header and consume the probe for OAM processing. The inf formation
ormation in the OAM payload is used to detect missing probes, round-trip delay, et
in the OAM payload is used to detect any missing probes, round trip delay c.
, etc. </li>
</t> </ul>
<t> The OAM payload type or
</list>
</t>
<t> The OAM payload type or
the information carried in the OAM probe is a local implementation the information carried in the OAM probe is a local implementation
decision at the controller and is outside the scope of this document. decision at the controller and is outside the scope of this document.
</t> </t>
</section>
</section> <!--end: Monitoring of SRv6 Paths --> <!--end: Monitoring of SRv6 Paths -->
</section> <!--end: Illustrations--> </section>
<!--end: Illustrations-->
<section anchor="Acknowledgements" title="Acknowledgements"> <section anchor="Acknowledgements" numbered="false" toc="default">
<t> The authors would like to thank Joel M. Halpern, Greg Mirsky, <name>Acknowledgements</name>
Bob Hinden, Loa Andersson, Gaurav Naik, Ketan Talaulikar and Haoyu Song <t> The authors would like to thank <contact fullname="Joel M. Halpern"/>,
<contact fullname="Greg Mirsky"/>,
<contact fullname="Bob Hinden"/>, <contact fullname="Loa Andersson"/>, <co
ntact fullname="Gaurav Naik"/>, <contact fullname="Ketan Talaulikar"/>, and <con
tact fullname="Haoyu Song"/>
for their review comments. </t> for their review comments. </t>
</section> </section>
<section anchor="Contributors" numbered="false" toc="default">
<name>Contributors</name>
<t>The following people contributed to this document:
</t>
<contact fullname="Robert Raszuk" >
<organization>Bloomberg LP</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region><code></code>
<country></country>
</postal>
<email>robert@raszuk.net</email>
</address>
</contact>
<section anchor="Contributors" title="Contributors"> <contact fullname="John Leddy" >
<t>The following people have contributed to this document: <organization>Individual</organization>
<figure> <address>
<artwork><![CDATA[ <postal>
Robert Raszuk <street></street>
Bloomberg LP <city></city>
Email: robert@raszuk.net <region></region><code></code>
]]> <country></country>
</artwork> </postal>
</figure> <email>john@leddy.net</email>
</address>
<figure> </contact>
<artwork><![CDATA[
John Leddy
Individual
Email: john@leddy.net
]]>
</artwork>
</figure>
<figure>
<artwork><![CDATA[
Gaurav Dawra
LinkedIn
Email: gdawra.ietf@gmail.com
]]>
</artwork>
</figure>
<figure> <contact fullname="Gaurav Dawra" >
<artwork><![CDATA[ <organization>LinkedIn</organization>
Bart Peirens <address>
Proximus <postal>
Email: bart.peirens@proximus.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</postal>
<email>gdawra.ietf@gmail.com</email>
</address>
</contact>
<figure> <contact fullname="Bart Peirens" >
<artwork><![CDATA[ <organization>Proximus</organization>
Nagendra Kumar <address>
Cisco Systems, Inc. <postal>
Email: naikumar@cisco.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</postal>
<email>bart.peirens@proximus.com</email>
</address>
</contact>
<figure> <contact fullname="Nagendra Kumar" >
<artwork><![CDATA[ <organization>Cisco Systems, Inc.</organization>
Carlos Pignataro <address>
Cisco Systems, Inc. <postal>
Email: cpignata@cisco.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</postal>
<email>naikumar@cisco.com</email>
</address>
</contact>
<figure> <contact fullname="Carlos Pignataro" >
<artwork><![CDATA[ <organization>Cisco Systems, Inc.</organization>
Rakesh Gandhi <address>
Cisco Systems, Inc. <postal>
Canada <street></street>
Email: rgandhi@cisco.com <city></city>
]]> <region></region><code></code>
</artwork> <country></country>
</figure> </postal>
<email>cpignata@cisco.com</email>
</address>
</contact>
<figure> <contact fullname="Rakesh Gandhi" >
<artwork><![CDATA[ <organization>Cisco Systems, Inc.</organization>
Frank Brockners <address>
Cisco Systems, Inc. <postal>
Germany <street></street>
Email: fbrockne@cisco.com <city></city>
]]> <region></region><code></code>
</artwork> <country></country>
</figure> </postal>
<email>rgandhi@cisco.com</email>
</address>
</contact>
<figure> <contact fullname="Frank Brockners" >
<artwork><![CDATA[ <organization>Cisco Systems, Inc.</organization>
Darren Dukes <address>
Cisco Systems, Inc. <postal>
Email: ddukes@cisco.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</postal>
<email>fbrockne@cisco.com</email>
</address>
</contact>
<figure> <contact fullname="Darren Dukes" >
<artwork><![CDATA[ <organization>Cisco Systems, Inc.</organization>
Cheng Li <address>
Huawei <postal>
Email: chengli13@huawei.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</postal>
<email>ddukes@cisco.com</email>
</address>
</contact>
<figure> <contact fullname="Cheng Li" >
<artwork><![CDATA[ <organization>Huawei</organization>
Faisal Iqbal <address>
Individual <postal>
Email: faisal.ietf@gmail.com <street></street>
]]> <city></city>
</artwork> <region></region><code></code>
</figure> <country></country>
</t> </postal>
<email>chengli13@huawei.com</email>
</address>
</contact>
<contact fullname="Faisal Iqbal" >
<organization>Individual</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region><code></code>
<country></country>
</postal>
<email>faisal.ietf@gmail.com</email>
</address>
</contact>
</section> </section>
</back> </back>
</rfc> </rfc>
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