PIM Encoding and Procedures for Unicast IPv4 prefixes with IPv6 next-hop
The information below is for an old version of the document.
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|Authors||Ashutosh Gupta , Stig Venaas|
|RFC stream||Internet Engineering Task Force (IETF)|
|Stream||WG state||WG Document|
|IESG||IESG state||I-D Exists|
|Send notices to||(None)|
Network Working Group A. Gupta Internet-Draft Avi Networks Intended status: Experimental S. Venaas Expires: March 16, 2018 Cisco Systems September 12, 2017 PIM Encoding and Procedures for Unicast IPv4 prefixes with IPv6 next-hop draft-ietf-pim-ipv4-prefix-over-ipv6-nh-00.txt Abstract Multi-Protocol BGP (MP-BGP) has support for distributing next-hop information for multiple address families using one AFI/SAFI Network Layer Reachability Information (NLRI). [RFC5549] specifies the extensions necessary to allow advertising IPv4 NLRI or VPN-IPv4 NLRI with a Next Hop address that belongs to the IPv6 protocol. While the next-hop info is learnt via MP-BGP, certain procedures are needed to enable traffic forwarding. This document describes PIM extensions and the use-cases for multicast forwarding in various scenarios. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on March 16, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect Gupta & Venaas Expires March 16, 2018 [Page 1] Internet-Draft PIM procedures for IPv4 prefix with IPv6 NHSeptember 2017 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction Figure 1: Example Topology +-------------+ +-------------+ | | | | | Router1 1::1/64 1::2/64 Router2 | 10.1.1.1/32--+ +--------I1---------| +-+PIM receiver | 22.214.171.124/24 126.96.36.199/24 | | + + | | | | | +-------------+ +-------------+ While use of MP-BGP along with [RFC5549] enables one routing protocol session to exchange next-hop info for both IPv4 and IPv6 prefixes, forwarding plane needs additional procedures to enable forwarding in Gupta & Venaas Expires March 16, 2018 [Page 2] Internet-Draft PIM procedures for IPv4 prefix with IPv6 NHSeptember 2017 data-plane. For example, when a IPv4 prefix is learnt over IPv6 next-hop, forwarding plane resolves the MAC-Address (L2-Adjacency) for IPv6 next-hop and uses it as destination-mac while doing inter- subnet forwarding. While it's simple to find the required information for unicast forwarding, multicast forwarding in same scenario poses additional requirements. Multicast traffic is forwarding on a tree build by multicast routing protocols such as PIM. Multicast routing protocols are address family dependent and hence a system enabled with IPv4 and IPv6 multicast routing will have two PIM sessions one for each of the AF. Also, Multicast routing protocol uses Unicast reachability information to find unique Reverse Path Forwarding Neighbor. Further it sends control messages such as PIM Join to form the tree. Now when a PIMv4 session needs to initiate new multicast tree in event of discovering new receiver It consults Unicast control plane to find next-hop information. While this multicast tree can be Shared or Shortest Path tree, PIMv4 will need a PIMv4 neighbor to send join. However, the Unicast control plane can provide IPv6 next-hop as explained earlier and hence we need certain procedures to find corresponding PIMv4 neighbor address. This address is vital for correct prorogation of join and furthermore to build multicast tree. This document describes various approaches along with their use-cases and pros-cons. In example topology, Router1 and Router2 are PIMv4 and PIMv6 neighbors on Interface I1. Router2 leanrns prefix 10.1.1.1/32's next-hop as 1::164 on Interface I1 as advertised by Router1 using BGP IPV6 NLRI.But in order to send (10.1.1.1/32, multicast-group) PIMv4 join on Interface I1, Router1 needs to find corresponding PIMv4 neighbor. In case there are multiple PIMv4 neighbors on same Interface I1, problem is aggravated. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. 2. Solution A PIM router can advertise its locally configured IPv6 addresses on the interface in PIMv4 Hello messages as per RFC4601 section 4.3.4. Same applies for IPv4 address in PIMv6 Hello. PIM will keep this info for each neighbor in Neighbor-cache along with DR-priority, hold-time etc. Once IPv6 Next-hop is notified to PIMv4, it will look into neighbors on the notified RPF-interface and find PIMv4 neighbor advertising same IPv6 local address in secondary Neighbor-list. If Gupta & Venaas Expires March 16, 2018 [Page 3] Internet-Draft PIM procedures for IPv4 prefix with IPv6 NHSeptember 2017 such a match is found, that particular neighbor will be uses as IPv4 RPF-Neighbor for initiating upstream join. This method is valid for networks enabled with PIMv4 and PIMv6 both as well for the networks enabled with only PIMv4 with IPv6 BGP session or PIMv6 with IPv4 BGP session. This method does't required any additional config changes in the network. 3. Security Considerations There are no new security considerations. 4. IANA Considerations There are no IANA considerations. 5. References 5.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. 5.2. Informative References [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, DOI 10.17487/RFC4601, August 2006, <https://www.rfc-editor.org/info/rfc4601>. [RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network Layer Reachability Information with an IPv6 Next Hop", RFC 5549, DOI 10.17487/RFC5549, May 2009, <https://www.rfc-editor.org/info/rfc5549>. [RFC6395] Gulrajani, S. and S. Venaas, "An Interface Identifier (ID) Hello Option for PIM", RFC 6395, DOI 10.17487/RFC6395, October 2011, <https://www.rfc-editor.org/info/rfc6395>. Authors' Addresses Gupta & Venaas Expires March 16, 2018 [Page 4] Internet-Draft PIM procedures for IPv4 prefix with IPv6 NHSeptember 2017 Ashutosh Gupta Avi Networks 5155 Old Ironsides Dr. Suite 100 Santa Clara, CA 95054 USA Email: email@example.com Stig Venaas Cisco Systems 821 Alder Drive San Jose, CA 95035 USA Email: firstname.lastname@example.org Gupta & Venaas Expires March 16, 2018 [Page 5]