IPv4 NLRI with IPv6 Next Hop Use Cases

Document Type Active Internet-Draft (individual)
Authors Gyan Mishra  , Mankamana Mishra  , Jeff Tantsura 
Last updated 2020-08-21
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BESS Working Group                                             G. Mishra
Internet-Draft                                              Verizon Inc.
Intended status: Standards Track                               M. Mishra
Expires: February 22, 2021                                 Cisco Systems
                                                             J. Tantsura
                                                            Apstra, Inc.
                                                         August 21, 2020

                 IPv4 NLRI with IPv6 Next Hop Use Cases


   As Enterprises and Service Providers upgrade their brown field or
   green field MPLS/SR core to an IPv6 transport such as MPLS LDPv6, SR-
   MPLSv6 or SRv6, Multiprotocol BGP (MP-BGP)now plays an important role
   in the transition of the core from IPv4 to IPv6 being able to
   continue to support legacy IPv4, VPN-IPv4, and Multicast VPN IPv4

   Multiprotocol BGP (MP-BGP) specifies that the set of usable next-hop
   address families is determined by the Address Family Identifier (AFI)
   and the Subsequent Address Family Identifier (SAFI).  Historically
   the AFI/SAFI definitions for the IPv4 address family only have
   provisions for advertising a Next Hop address that belongs to the
   IPv4 protocol when advertising IPv4 or VPN-IPv4 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.  This comprises an
   extension of the AFI/SAFI definitions to allow the address of the
   Next Hop for IPv4 NLRI or VPN-IPv4 NLRI to also belong to the IPv6
   Protocol.  [RFC5549] defines the encoding of the Next Hop to
   determine which of the protocols the address actually belongs to, and
   a new BGP Capability allowing MP-BGP Peers to dynamically discover
   whether they can exchange IPv4 NLRI and VPN-IPv4 NLRI with an IPv6
   Next Hop.

   With this new MP-BGP capability exchange allows the BGP peering
   session to act as a pure transport to allow the session to carry
   Address Family Identifier (AFI) and the Subsequent Address Family
   Identifier (SAFI) for both IPv4 and IPv6.

   This document describes the critical use case and OPEX savings of
   being able to leverage the MP-BGP capability exchange usage as a pure
   transport allowing both IPv4 and IPv6 to be carried over the same BGP
   TCP session.  By doing so, allows for the elimination of Dual
   Stacking on the PE-CE connections making the peering IPv6-ONLY to now

Mishra, et al.          Expires February 22, 2021               [Page 1]
Internet-Draft      IPv4-NLRI with IPv6-NH Use Cases         August 2020

   carry both IPv4 and IPv6 Network Layer Reachability Information
   (NLRI).  This document also provides a possible solution for IXPs
   (Internet Exchange points) that are facing IPv4 address depletion at
   these peering points to use BGP-MP capability exchange defined in
   [RFC5549] to carry IPv4 (Network Layer Reachability Information) NLRI
   in an IPv6 next hop using the [RFC5565] softwire mesh framework.

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
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   This Internet-Draft will expire on February 22, 2021.

Copyright Notice

   Copyright (c) 2020 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   6
   3.  Extension of AFI/SAFI Definitions for the IPv4 Address Family   6
   4.  Use of BGP Capability Advertisement . . . . . . . . . . . . .   7
   5.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   9
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