rfc9186xml2.original.xml   rfc9186.xml 
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<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc category="std" ipr="trust200902" docName="draft-ietf-pim-bfd-p2mp-use-case-
10">
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<front> <!DOCTYPE rfc [
<title abbrev="BFD P2MP Use in PIM-SM">Fast Failover in Protocol Independ <!ENTITY nbsp "&#160;">
ent Multicast - Sparse Mode (PIM-SM) Using Bidirectional Forwarding Detection (B <!ENTITY zwsp "&#8203;">
FD) for Multipoint Networks</title> <!ENTITY nbhy "&#8209;">
<!ENTITY wj "&#8288;">
]>
<author initials="G." surname="Mirsky" fullname="Greg Mirsky"> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" docName="draft
<organization>Ericsson</organization> -ietf-pim-bfd-p2mp-use-case-10" number="9186" obsoletes="" updates="" submission
<address> Type="IETF" category="std" consensus="true" xml:lang="en" tocInclude="true" tocD
<email>gregimirsky@gmail.com</email> epth="3" symRefs="true" sortRefs="true" version="3">
</address>
</author>
<author initials="J" surname="Xiaoli" fullname="Ji Xiaoli"> <front>
<title abbrev="BFD P2MP Use in PIM-SM">Fast Failover in Protocol Independent
Multicast - Sparse Mode (PIM-SM) Using Bidirectional Forwarding Detection (BFD)
for Multipoint Networks</title>
<seriesInfo name="RFC" value="9186"/>
<author initials="G." surname="Mirsky" fullname="Greg Mirsky">
<organization>Ericsson</organization>
<address>
<email>gregimirsky@gmail.com</email>
</address>
</author>
<author initials="X." surname="Ji" fullname="Xiaoli Ji">
<organization>ZTE Corporation</organization> <organization>ZTE Corporation</organization>
<address> <address>
<postal> <postal>
<street>No.50 Software Avenue, Yuhuatai District</street> <extaddr>Yuhuatai District</extaddr>
<region>Nanjing</region> <street>No. 50 Software Avenue</street>
<country>China</country> <city>Nanjing</city>
</postal> <country>China</country>
<email>ji.xiaoli@zte.com.cn</email> </postal>
<email>ji.xiaoli@zte.com.cn</email>
</address> </address>
</author> </author>
<date year="2022" month="January" />
<date year="2021"/>
<area>Routing</area> <area>Routing</area>
<workgroup>PIM Working Group</workgroup> <workgroup>PIM Working Group</workgroup>
<keyword>PIM-SM</keyword>
<keyword>Internet-Draft</keyword> <keyword>BFD</keyword>
<abstract>
<keyword>PIM-SM</keyword> <t>
This document specifies how Bidirectional Forwarding Detection (BFD) for
<keyword>BFD </keyword> multipoint networks
<abstract>
<t>
This document specifies how Bidirectional Forwarding Detection for multip
oint networks
can provide sub-second failover for routers that participate in Protocol Independent Multicast - Sparse Mode (PIM-SM). can provide sub-second failover for routers that participate in Protocol Independent Multicast - Sparse Mode (PIM-SM).
<!--
over shared-media segment with the sub-second convergence of the Designat
ed Router and defines the extension to bootstrap point-to-multipoint BFD se
ssion.
-->
An extension to the PIM Hello message used to An extension to the PIM Hello message used to
bootstrap a point-to-multipoint BFD session is also defined in this bootstrap a point-to-multipoint BFD session is also defined in this
document. document.
</t> </t>
</abstract> </abstract>
</front> </front>
<middle>
<middle> <section anchor="intro" numbered="true" toc="default">
<section anchor="intro" title="Introduction"> <name>Introduction</name>
<t> <t>
Faster convergence in the control plane minimizes the periods of Faster convergence in the control plane minimizes the periods of
traffic blackholing, transient routing loops, and other situations traffic loss due to the use of stale routing information, transient routing loop s, and other situations
that may negatively affect service data flow. Faster convergence that may negatively affect service data flow. Faster convergence
in the control plane is beneficial to unicast and multicast routing in the control plane is beneficial to unicast and multicast routing
protocols. protocols.
</t> </t>
<t> <t>
<xref target="RFC7761"/> is the current specification of the Protocol Independe <xref target="RFC7761" format="default"/> is the current specification of the P
nt Multicast - Sparse Mode (PIM-SM) rotocol Independent
for IPv4 and IPv6 networks. A conforming implementation of PIM-SM elects a Desi Multicast - Sparse Mode (PIM-SM) for IPv4 and IPv6 networks. A conforming imp
gnated Router (DR) lementation of PIM-SM elects a Designated Router (DR)
on each PIM-SM interface. When a group of PIM-SM nodes is connected to a shared media segment, e.g., Ethernet, on each PIM-SM interface. When a group of PIM-SM nodes is connected to a shared media segment, e.g., Ethernet,
the node elected as DR acts on behalf of directly connected hosts in the contex t of the PIM-SM protocol. the node elected as the DR acts on behalf of directly connected hosts in the co ntext of the PIM-SM protocol.
Failure of the DR impacts the quality of the multicast services it Failure of the DR impacts the quality of the multicast services it
provides to directly connected hosts because the default failure detection inter val provides to directly connected hosts because the default failure detection inter val
for PIM-SM routers is 105 seconds. for PIM-SM routers is 105 seconds.
</t> </t>
<t> <t>
Bidirectional Forwarding Detection (BFD) <xref target="RFC5880"/> was originall Bidirectional Forwarding Detection (BFD) <xref target="RFC5880" format="default
y defined to detect "/> was originally defined to detect
a failure of a point-to-point (p2p) path, single-hop <xref target="RFC5881"/> o a failure of a point-to-point (P2P) path, single hop <xref target="RFC5881" for
r multihop <xref target="RFC5883"/>. mat="default"/>, or multihop <xref target="RFC5883" format="default"/>.
In some PIM-SM deployments, a p2p BFD can be used to detect a failure and enabl In some PIM-SM deployments, a P2P BFD can be used to detect a failure and enabl
e faster failover. e faster failover.
<xref target="RFC8562"/> extends the BFD base specification <xref target="RFC58
80"/> for multipoint and multicast <xref target="RFC8562" format="default"/> extends the BFD base specification <x
ref target="RFC5880" format="default"/> for multipoint and multicast
networks, which matches the deployment scenarios for PIM-SM over a LAN segment. networks, which matches the deployment scenarios for PIM-SM over a LAN segment.
<!-- Among specific characteristics of p2mp BFD that particularly benefit PIM-S A BFD system in a point-to-multipoint (P2MP) environment that transmits BFD Con
M over a LAN segment is trol messages using the BFD Demand mode <xref target="RFC5880" format="default"/
a faster transition to the Up state of the p2mp BFD session due to avoidance of > creates less BFD state
the three-way handshake required in p2p BFD <xref target="RFC5880"/>. --> than the Asynchronous mode. P2MP BFD can enable
A BFD system in p2mp environment that transmits BFD Control messages using the
BFD Demand mode <xref target="RFC5880"/> creates less BFD state
than the Asynchronous mode. Point-to-multipoint (p2mp) BFD can enable
faster detection of PIM-SM router failure compared to PIM-SM without BFD and faster detection of PIM-SM router failure compared to PIM-SM without BFD and
thus minimize multicast service disruption. The monitored PIM-SM router acts as thus minimizes multicast service disruption. The monitored PIM-SM router acts a
the head and other routers as tails of a p2mp BFD s the head and other routers act as tails of a P2MP BFD
session. This document defines the monitoring of a PIM-SM router using p2mp BFD. session. This document defines the monitoring of a PIM-SM router using P2MP BFD.
This document also defines the extension to PIM-SM <xref target="RFC7761"/> This document also defines the extension to PIM-SM <xref target="RFC7761" format
to bootstrap a PIM-SM router to join in p2mp BFD session over shared media segm ="default"/>
ent. to bootstrap a PIM-SM router to join in the P2MP BFD session over a shared medi
</t> a segment.
</t>
<section title="Conventions used in this document"> <section numbered="true" toc="default">
<section title="Terminology"> <name>Conventions Used in This Document</name>
<t> <section numbered="true" toc="default">
This document uses terminology defined in <xref target="RFC5880"/>, <xref target <name>Terminology</name>
="RFC8562"/>, <t>
and <xref target="RFC7761"/>. Familiarity with these specifications and the term This document uses terminology defined in <xref target="RFC5880" format="default
inology used "/>, <xref target="RFC8562" format="default"/>,
and <xref target="RFC7761" format="default"/>. Familiarity with these specificat
ions and the terminology used
is expected. is expected.
</t> </t>
</section> </section>
<section numbered="true" toc="default">
<section title="Requirements Language"> <name>Requirements Language</name>
<t> <t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQU
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", IRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
"MAY", and "OPTIONAL" in this document are to be interpreted as NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>
described in BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
when, and only when, they appear in all capitals, as shown here. "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
</t> be interpreted as
</section> described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
when, and only when, they appear in all capitals, as shown here.
</t>
</section>
</section> </section>
</section> </section>
<section anchor="bfd-discriminatorpim-hello-sec" numbered="true" toc="default">
<!-- <name>BFD Discriminator PIM Hello Option</name>
<section anchor="problem-statement" title="Problem Statement"> <t>
<t> <xref target="tlv-p2mp-bfd-boot-fig" format="default"/> displays the new option
<xref target="RFC7761"/> does not provide a method for fast, e.g., sub-second, f al
ailure detection of a neighbor PIM-SM router. BFD Discriminator PIM Hello Option
BFD already has many implementations based on HW that are capable to bootstrap a tail of the P2MP BFD session:
of supporting multiple sub-second sessions concurrently. </t>
</t> <figure anchor="tlv-p2mp-bfd-boot-fig">
</section> <name>BFD Discriminator PIM Hello Option</name>
<section anchor="bfd-discriminatorpim-hello-sec" title="BFD Discriminator PIM He <artwork name="" type="" align="left" alt=""><![CDATA[
llo Option">
<t>
<xref target="tlv-p2mp-bfd-boot-fig"/> displays the new optional
BFD Discriminator PIM Hello option
to bootstrap a tail of the p2mp BFD session.
</t>
<t>
<figure align="left" anchor="tlv-p2mp-bfd-boot-fig" title="BFD Discrim
inator PIM Hello Option">
<artwork><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType | OptionLength | | OptionType | OptionLength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HeadDiscriminator | | HeadDiscriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork> ]]></artwork>
</figure> </figure>
<t>
</t>
<t>
where new fields are interpreted as: where new fields are interpreted as:
<list> </t>
<t>OptionType: TBA.</t> <dl>
<t>OptionLength: MUST be set to 4.</t> <dt>OptionType:</dt><dd>39</dd>
<t>HeadDiscriminator: the four-octet field MUST be included in the BFD Discrimin <dt>OptionLength:</dt><dd><bcp14>MUST</bcp14> be set to 4.</dd>
ator PIM-SM Hello option. <dt>HeadDiscriminator:</dt><dd> the 4-octet field <bcp14>MUST</bcp14> be
The value MUST NOT be zero. It equals the value of My Discriminator included in the BFD Discriminator PIM-SM Hello Option.
(<xref target="RFC5880"/>) allocated by the head. </t> The value <bcp14>MUST NOT</bcp14> be zero. It equals the value of My Discriminat
</list> or
If the value of the OptionLength field is not equal to 4, the BFD Discriminator <xref target="RFC5880" format="default"/> allocated by the head. </dd>
PIM Hello option </dl>
is considered malformed, and the receiver MUST stop processing PIM Hello options <t>
. If the value of the OptionLength field is not equal to 4, the BFD Discriminator
If the value of the HeadDiscriminator field equals zero, then the BFD Discrimina PIM Hello Option
tor PIM Hello option is considered malformed, and the receiver <bcp14>MUST</bcp14> stop processing PI
MUST be considered invalid, and the receiver MUST ignore it. M Hello Options.
The receiver SHOULD log a notification regarding the malformed or invalid BFD Di If the value of the HeadDiscriminator field equals zero, then the BFD Discrimina
scriminator Hello option tor PIM Hello Option
<bcp14>MUST</bcp14> be considered invalid, and the receiver <bcp14>MUST</bcp14>
ignore it.
The receiver <bcp14>SHOULD</bcp14> log a notification regarding the malformed or
invalid BFD Discriminator Hello Option
under the control of a throttling logging mechanism. under the control of a throttling logging mechanism.
</t> </t>
<section anchor="pim-dr-p2mp-bfd-sec" numbered="true" toc="default">
<section anchor="pim-dr-p2mp-bfd-sec" title="Using P2MP BFD in PIM Router Monito <name>Using P2MP BFD in PIM Router Monitoring</name>
ring"> <t>
<t>
If the head is no longer serving the function that prompted it If the head is no longer serving the function that prompted it
to be monitored, then it MUST cease including the BFD Discriminator to be monitored, then it <bcp14>MUST</bcp14> cease including the BFD Discriminat
PIM Hello option in its PIM-Hello message, and it SHOULD shut down or
the BFD session following the procedures described in Section 5.9 <xref target=" PIM Hello Option in its PIM Hello message, and it <bcp14>SHOULD</bcp14> shut dow
RFC8562"/>. n
the BFD session following the procedures described in <xref target="RFC8562" sec
tionFormat="comma" section="5.9"/>.
</t> </t>
<t> <t>
The head MUST create a BFD session of type MultipointHead <xref target="RFC8562 The head <bcp14>MUST</bcp14> create a BFD session of type MultipointHead <xref
"/>. target="RFC8562" format="default"/>.
Note that any PIM-SM router, regardless of its role, MAY become a head of a p2m Note that any PIM-SM router, regardless of its role, <bcp14>MAY</bcp14> become
p BFD session. a head of a P2MP BFD session.
To control the volume of BFD control traffic on a shared media segment, an oper To control the volume of BFD Control traffic on a shared media segment, an oper
ator should carefully ator should carefully
select PIM-SM routers configured as a head of a p2mp BFD session. select PIM-SM routers configured as a head of a P2MP BFD session.
The head MUST include the BFD Discriminator PIM Hello option in its The head <bcp14>MUST</bcp14> include the BFD Discriminator PIM Hello Option in i
ts
PIM Hello messages. PIM Hello messages.
</t> </t>
<t> <t>
A PIM-SM router that is configured to monitor the head by A PIM-SM router that is configured to monitor the head by
using p2mp BFD is referred to throughout this document as a "tail". When such a using P2MP BFD is referred to throughout this document as a "tail". When such a
tail receives a PIM-Hello packet with the BFD Discriminator PIM Hello option, th tail receives a PIM Hello packet with the BFD Discriminator PIM Hello Option, th
e tail e tail
MAY create a p2mp BFD session of type MultipointTail, as defined in <xref target <bcp14>MAY</bcp14> create a P2MP BFD session of type MultipointTail, as defined
="RFC8562"/>. in <xref target="RFC8562" format="default"/>.
</t> </t>
<t> <t>
The node that includes the BFD Discriminator PIM Hello option The node that includes the BFD Discriminator PIM Hello Option
transmits BFD Control packets periodically. For the tail to correctly transmits BFD Control packets periodically. For the tail to correctly
demultiplex BFD <xref target="RFC8562"/>, the source demultiplex BFD <xref target="RFC8562" format="default"/>, the source
address and My Discriminator of the BFD packets MUST be the same address and My Discriminator of the BFD packets <bcp14>MUST</bcp14> be the same
as the source address and the HeadDiscriminator, respectively, of the PIM Hello as the source address and the HeadDiscriminator, respectively, of the PIM Hello
message. If that is not the case, message. If that is not the case,
the tail BFD node would not be able to monitor the state of the PIM-SM node, the tail BFD node would not be able to monitor the state of the PIM-SM node --
that is, the head of the p2mp BFD session, that is, the head of the P2MP BFD session -- though the regular PIM-SM mechanism
though the regular PIM-SM mechanisms remain fully operational. s remain fully operational.
</t> </t>
<t> <t>
If the tail detects a MultipointHead failure <xref target="RFC8562"/>, If the tail detects a MultipointHead failure <xref target="RFC8562" format="defa
it MUST delete the corresponding neighbor state and follow procedures defined i ult"/>,
n <xref target="RFC7761"/> it <bcp14>MUST</bcp14> delete the corresponding neighbor state and follow proce
dures defined in <xref target="RFC7761" format="default"/>
for the DR and additional neighbor state deletion after the neighbor timeout ex pires. for the DR and additional neighbor state deletion after the neighbor timeout ex pires.
</t> </t>
<t> <t>
If the head ceases to include the BFD Discriminator PIM Hello option in its PIM If the head ceases to include the BFD Discriminator PIM Hello Option in its PIM
-Hello message, Hello message,
tails SHOULD close the corresponding MultipointTail BFD session without affecti the tail <bcp14>SHOULD</bcp14> close the corresponding MultipointTail BFD sessi
ng the PIM state in any way. on without affecting the PIM state in any way.
Thus, the tail stops using BFD to monitor Thus, the tail stops using BFD to monitor
the head and reverts to the procedures defined in <xref target="RFC7761"/>. the head and reverts to the procedures defined in <xref target="RFC7761" format
</t> ="default"/>.
</section> </t>
</section>
<section anchor="p2mp-bfd-pim-drlb-sec" title="P2MP BFD in PIM DR Load Balancin <section anchor="p2mp-bfd-pim-drlb-sec" numbered="true" toc="default">
g"> <name>P2MP BFD in PIM DR Load Balancing</name>
<t> <t>
<xref target="RFC8775"/> specifies the PIM Designated Router Load Balancing (DRL <xref target="RFC8775" format="default"/> specifies the PIM Designated Router Lo
B) functionality. ad-Balancing (DRLB) functionality.
Any PIM router that advertises the DRLB-Cap Hello Option can become the head of Any PIM router that advertises the DR Load-Balancing Capability (DRLB-Cap) Hello
a p2mp BFD session, Option can become the head of a P2MP BFD session,
as specified in <xref target="pim-dr-p2mp-bfd-sec"/>. as specified in <xref target="pim-dr-p2mp-bfd-sec" format="default"/>.
The head router administratively sets the bfd.SessionState to Up in The head router administratively sets the bfd.SessionState to Up in
the MultipointHead session <xref target="RFC8562"/> only if it is a Group Design the MultipointHead session <xref target="RFC8562" format="default"/> only if it
ated is a Group Designated
Router (GDR) Candidate, as specified in Sections 5.5 and 5.6 of Router (GDR) Candidate, as specified in Sections <xref target="RFC8775" section=
<xref target="RFC8775"/>. If the router is no longer the GDR, then it MUST shut "5.5" sectionFormat="bare" /> and
down <xref target="RFC8775" section="5.6" sectionFormat="bare" /> of
following the procedures described in Section 5.9 <xref target="RFC8562"/>. <xref target="RFC8775"/>. If the router is no longer the GDR, then it <bcp14>MUS
For each GDR Candidate that includes T</bcp14> shut down
BFD Discriminator option in its PIM Hello, the PIM DR MUST create a MultipointT following the procedures described in <xref target="RFC8562" sectionFormat="comm
ail session <xref target="RFC8562"/>. PIM DR a" section="5.9"/>.
For each GDR Candidate that includes the
BFD Discriminator Option in its PIM Hello, the PIM DR <bcp14>MUST</bcp14> creat
e a MultipointTail session <xref target="RFC8562" format="default"/>. PIM DR
demultiplexes BFD sessions based on the value of the My Discriminator field and the source IP address. demultiplexes BFD sessions based on the value of the My Discriminator field and the source IP address.
If PIM DR detects a failure of one of the sessions, it MUST remove that router from If PIM DR detects a failure of one of the sessions, it <bcp14>MUST</bcp14> remo ve that router from
the GDR Candidate list and immediately transmit a new DRLB-List option. the GDR Candidate list and immediately transmit a new DRLB-List option.
</t> </t>
</section> </section>
<section anchor="p2mp-bfd-encap" numbered="true" toc="default">
<section anchor="p2mp-bfd-encap" title="Multipoint BFD Encapsulation"> <name>Multipoint BFD Encapsulation</name>
<t> <t>
The MultipointHead of a p2mp BFD session when transmitting BFD Control packets: The MultipointHead of a P2MP BFD session when transmitting BFD Control packets:
<list>
<t>MUST set TTL or Hop Limit value to 255 (Section 5 <xref target="RFC5881"/>).
Similarly, all received BFD Control packets that are
demultiplexed to the session MUST be discarded if the received TTL or
Hop Limit is not equal to 255;</t>
<t>MUST use the group address ALL-PIM-ROUTERS ('224.0.0.13' for IPv4 and 'ff02::
d' for IPv6) as destination IP address</t>
</list>
</t> </t>
</section> <ul empty="false" spacing="normal">
<li><bcp14>MUST</bcp14> set the TTL or Hop Limit value to 255 (<xref t
</section> arget="RFC5881" sectionFormat="comma" section="5"/>). Similarly, all received BF
D Control packets that are
<section anchor="iana-consider" title="IANA Considerations"> demultiplexed to the session <bcp14>MUST</bcp14> be discarded if the received
<t> TTL or
IANA is requested to allocate a new OptionType value from PIM-Hello Options regi Hop Limit is not equal to 255, and</li>
stry according to: <li><bcp14>MUST</bcp14> use the group address ALL-PIM-ROUTERS ("224.0.
</t> 0.13" for IPv4 and "ff02::d" for IPv6) as the destination IP address.</li>
<texttable anchor="bfd-disc-pim-alloc" title="BFD Discriminator option typ </ul>
e"> </section>
<ttcol align="left">Value</ttcol>
<ttcol align="left">Length</ttcol>
<ttcol align="left">Name</ttcol>
<ttcol align="left">Reference</ttcol>
<c>TBA</c>
<c>4</c>
<c>BFD Discriminator Option</c>
<c>This&nbsp;document</c>
</texttable>
</section> </section>
<section anchor="iana-consider" numbered="true" toc="default">
<section anchor="security" title="Security Considerations"> <name>IANA Considerations</name>
<t> <t>
This document defines a way to accelerate detecting a failure that affects PIM IANA has allocated a new OptionType value in the "PIM-Hello Options" registry ac
functionality by using BFD. The operation of either protocol is not changed. cording to <xref target="bfd-disc-pim-alloc"/>:
</t> </t>
<t> <table anchor="bfd-disc-pim-alloc" align="center">
The security considerations discussed in <xref target="RFC7761"/>, <xref target <name>BFD Discriminator Option Type</name>
="RFC5880"/>, <xref target="RFC5881"/>, <thead>
<xref target="RFC8562"/>, and <xref target="RFC8775"/> apply to this document. <tr>
</t> <th align="left">Value</th>
<!-- <th align="left">Length</th>
<t> <th align="left">Name</th>
PIM-SM link-local messages can be authenticated using various mechanisms, a <th align="left">Reference</th>
s described in Section 6.3 <xref target="RFC7761"/>. </tr>
Authentication of BFD Control messages defined in Section 6.7 <xref target= </thead>
"RFC5880"/>. Each protocol may use authentication of its messages <tbody>
independently of the mode used by the other protocol. <tr>
</t> <td align="left">39</td>
--> <td align="left">4</td>
<!-- <td align="left">BFD Discriminator Option</td>
<t> <td align="left">RFC 9186</td>
An implementation that supports this specification SHOULD use a mechanism </tr>
to </tbody>
control the maximum number of BFD sessions that can be active at the </table>
same time. </section>
</t> <section anchor="security" numbered="true" toc="default">
--> <name>Security Considerations</name>
<t>
This document defines a way to accelerate detection of a failure that affects
PIM functionality by using BFD. The operation of either protocol is not changed.
</t>
<t>
The security considerations discussed in <xref target="RFC5880" format="default
"/>, <xref target="RFC5881" format="default"/>, <xref target="RFC7761" format="d
efault"/>, <xref target="RFC8562" format="default"/>, and <xref target="RFC8775"
format="default"/> apply to this document.
</t>
</section> </section>
<section title="Acknowledgments">
<t>
The authors cannot say enough to express their appreciation of the comm
ents and suggestions we received from Stig Venaas.
The authors greatly appreciate the comments and suggestions by Alvaro R
etana that improved the clarity of this document.
</t>
</section>
</middle> </middle>
<back>
<back> <references>
<name>References</name>
<references title="Normative References"> <references>
<name>Normative References</name>
<?rfc include="reference.RFC.2119"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.8174"?> FC.2119.xml"/>
<?rfc include="reference.RFC.5880"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.5881"?> FC.8174.xml"/>
<?rfc include="reference.RFC.7761"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5880.xml"/>
<?rfc include="reference.RFC.8562"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<!-- FC.5881.xml"/>
<?rfc include="reference.I-D.ietf-pim-dr-improvement"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.8775"?> FC.7761.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8562.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.87
75.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5883.xml"/>
</references> </references>
<references title="Informative References">
<?rfc include="reference.RFC.5883"?>
<!--
<?rfc include="reference.I-D.mankamana-pim-bdr"?>
-->
</references> </references>
<section numbered="false" toc="default">
</back> <name>Acknowledgments</name>
</rfc> <t>
The authors cannot say enough to express their appreciation of the comm
ents and suggestions that were received from <contact fullname="Stig Venaas"/>.
The authors also greatly appreciate the comments and suggestions by <co
ntact fullname="Alvaro Retana"/> that improved the clarity of this document.
</t>
</section>
</back>
</rfc>
 End of changes. 38 change blocks. 
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