Explicit Reverse Path Forwarding (RPF) Vector
RFC 7891
Internet Engineering Task Force (IETF) J. Asghar
Request for Comments: 7891 IJ. Wijnands, Ed.
Category: Standards Track S. Krishnaswamy
ISSN: 2070-1721 A. Karan
Cisco Systems
V. Arya
DIRECTV Inc.
June 2016
Explicit Reverse Path Forwarding (RPF) Vector
Abstract
The PIM Reverse Path Forwarding (RPF) Vector TLV defined in RFC 5496
can be included in a PIM Join Attribute such that the RPF neighbor is
selected based on the unicast reachability of the RPF Vector instead
of the source or Rendezvous Point associated with the multicast tree.
This document defines a new RPF Vector Attribute type such that an
explicit RPF neighbor list can be encoded in the PIM Join Attribute,
thus bypassing the unicast route lookup.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7891.
Asghar, et al. Standards Track [Page 1]
RFC 7891 Explicit Reverse Path Forwarding (RPF) Vector June 2016
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use of the PIM Explicit RPF Vector . . . . . . . . . . . . . 4
5. Explicit RPF Vector Attribute TLV Format . . . . . . . . . . 5
6. Mixed Vector Processing . . . . . . . . . . . . . . . . . . . 5
7. Conflicting RPF Vectors . . . . . . . . . . . . . . . . . . . 5
8. PIM Asserts . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Join Suppression . . . . . . . . . . . . . . . . . . . . . . 6
10. Unsupported Explicit Vector Handling . . . . . . . . . . . . 7
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
12. Security Considerations . . . . . . . . . . . . . . . . . . . 7
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
13.1. Normative References . . . . . . . . . . . . . . . . . . 8
13.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
Asghar, et al. Standards Track [Page 2]
RFC 7891 Explicit Reverse Path Forwarding (RPF) Vector June 2016
1. Introduction
The procedures in [RFC5496] define how an RPF Vector can be used to
influence the path selection in the absence of a route to the source.
The same procedures can be used to override a route to the source
when it exists. It is possible to include multiple RPF Vectors in
the list where each router along the path will perform a unicast
route lookup on the first Vector in the attribute list. Once the
router owning the address of the RPF Vector is reached, following the
procedures in [RFC5496], the RPF Vector will be removed from the
attribute list. This will result in a 'loosely' routed path that
still depends on unicast reachability to the RPF Vector(s).
In some scenarios, the network administrators don't want to rely on
the unicast reachability to the RPF Vector address and want to build
a path strictly based on the RPF Vectors. In that case, the RPF
Vectors represent a list of directly connected PIM neighbors along
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