draft-ietf-pim-bfd-p2mp-use-case-08.txt   draft-ietf-pim-bfd-p2mp-use-case-09.txt 
PIM Working Group G. Mirsky PIM Working Group G. Mirsky
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track J. Xiaoli Intended status: Standards Track J. Xiaoli
Expires: 28 March 2022 ZTE Corporation Expires: 10 April 2022 ZTE Corporation
24 September 2021 7 October 2021
Fast Failover in Protocol Independent Multicast - Sparse Mode (PIM-SM) Fast Failover in Protocol Independent Multicast - Sparse Mode (PIM-SM)
Using Bidirectional Forwarding Detection (BFD) for Multipoint Networks Using Bidirectional Forwarding Detection (BFD) for Multipoint Networks
draft-ietf-pim-bfd-p2mp-use-case-08 draft-ietf-pim-bfd-p2mp-use-case-09
Abstract Abstract
This document specifies how Bidirectional Forwarding Detection for This document specifies how Bidirectional Forwarding Detection for
multipoint networks can provide sub-second failover for routers that multipoint networks can provide sub-second failover for routers that
participate in Protocol Independent Multicast - Sparse Mode (PIM-SM). participate in Protocol Independent Multicast - Sparse Mode (PIM-SM).
An extension to the PIM Hello message used to bootstrap a point-to- An extension to the PIM Hello message used to bootstrap a point-to-
multipoint BFD session is also defined in this document. multipoint BFD session is also defined in this document.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 March 2022. This Internet-Draft will expire on 10 April 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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Discriminator PIM Hello option is considered malformed, and the Discriminator PIM Hello option is considered malformed, and the
receiver MUST stop processing PIM Hello options. If the value of the receiver MUST stop processing PIM Hello options. If the value of the
HeadDiscriminator field equals zero, then the BFD Discriminator PIM HeadDiscriminator field equals zero, then the BFD Discriminator PIM
Hello option MUST be considered invalid, and the receiver MUST ignore Hello option MUST be considered invalid, and the receiver MUST ignore
it. The receiver SHOULD log a notification regarding the malformed it. The receiver SHOULD log a notification regarding the malformed
or invalid BFD Discriminator Hello option under the control of a or invalid BFD Discriminator Hello option under the control of a
throttling logging mechanism. throttling logging mechanism.
2.1. Using P2MP BFD in PIM Router Monitoring 2.1. Using P2MP BFD in PIM Router Monitoring
If the head is no longer serving the function that prompted it to be
monitored, then it MUST cease including the BFD Discriminator PIM
Hello option in its PIM-Hello message, and it SHOULD shut down the
BFD session following the procedures described in Section 5.9
[RFC8562].
The head MUST create a BFD session of type MultipointHead [RFC8562]. The head MUST create a BFD session of type MultipointHead [RFC8562].
Note that any PIM-SM router, regardless of its role, MAY become a Note that any PIM-SM router, regardless of its role, MAY become a
head of a p2mp BFD session. To control the volume of BFD control head of a p2mp BFD session. To control the volume of BFD control
traffic on a shared media segment, an operator should carefully traffic on a shared media segment, an operator 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 option in its Hello The head MUST include the BFD Discriminator option in its Hello
messages, and it MUST include a 4-byte HeadDiscriminator with a value messages, and it MUST include a 4-byte HeadDiscriminator with a value
other than zero. other than zero.
If a PIM-SM router is configured to monitor the head by using p2mp If a PIM-SM router is configured to monitor the head by using p2mp
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the HeadDiscriminator in the PIM Hello message. If that is not the the HeadDiscriminator in the PIM Hello message. If that is not the
case, the tail BFD node would not be able to monitor the state of the case, 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, though the PIM-SM node, that is, the head of the p2mp BFD session, though the
regular PIM-SM mechanisms remain fully operational. regular PIM-SM mechanisms remain fully operational.
If the tail detects a MultipointHead failure [RFC8562], it MUST If the tail detects a MultipointHead failure [RFC8562], it MUST
delete the corresponding neighbor state and follow procedures defined delete the corresponding neighbor state and follow procedures defined
in [RFC7761]. in [RFC7761].
If the head ceases to include the BFD Discriminator PIM Hello option If the head ceases to include the BFD Discriminator PIM Hello option
in its PIM-Hello message, tails MUST close the corresponding in its PIM-Hello message, tails SHOULD close the corresponding
MultipointTail BFD session without affecting the PIM state in any MultipointTail BFD session without affecting the PIM state in any
way. Thus the tail stops using BFD to monitor the head and reverts way. Thus the tail stops using BFD to monitor the head and reverts
to the procedures defined in [RFC7761]. to the procedures defined in [RFC7761].
2.2. P2MP BFD in PIM DR Load Balancing 2.2. P2MP BFD in PIM DR Load Balancing
[RFC8775] specifies the PIM Designated Router Load Balancing (DRLB) [RFC8775] specifies the PIM Designated Router Load Balancing (DRLB)
functionality. Any PIM router that advertises the DRLB-Cap Hello functionality. Any PIM router that advertises the DRLB-Cap Hello
Option can become the head of a p2mp BFD session, as specified in Option can become the head of a p2mp BFD session, as specified in
Section 2.1. The head router administratively sets the Section 2.1. The head router administratively sets the
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+=======+========+==========================+===============+ +=======+========+==========================+===============+
| Value | Length | Name | Reference | | Value | Length | Name | Reference |
+=======+========+==========================+===============+ +=======+========+==========================+===============+
| TBA | 4 | BFD Discriminator Option | This document | | TBA | 4 | BFD Discriminator Option | This document |
+-------+--------+--------------------------+---------------+ +-------+--------+--------------------------+---------------+
Table 1: BFD Discriminator option type Table 1: BFD Discriminator option type
4. Security Considerations 4. Security Considerations
This document defines a way to accelerate detecting a failure that
affects PIM functionality by using BFD. The operation of either
protocol is not changed.
The security considerations discussed in [RFC7761], [RFC5880], The security considerations discussed in [RFC7761], [RFC5880],
[RFC8562], and [RFC8775] apply to this document. [RFC8562], and [RFC8775] apply to this document.
5. Acknowledgments 5. Acknowledgments
The authors cannot say enough to express their appreciation of the The authors cannot say enough to express their appreciation of the
comments and suggestions we received from Stig Venaas. The authors comments and suggestions we received from Stig Venaas. The authors
greatly appreciate the comments and suggestions by Alvaro Retana that greatly appreciate the comments and suggestions by Alvaro Retana that
improved the clarity of the document. improved the clarity of the document.
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