IPv4 routes with an IPv6 next-hop in the Babel routing protocol
draft-ietf-babel-v4viav6-00

Document Type Active Internet-Draft (babel WG)
Authors Theophile Bastian  , Juliusz Chroboczek 
Last updated 2020-10-20
Replaces draft-bastian-babel-v4ov6
Stream IETF
Intended RFC status Experimental
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Document shepherd Donald Eastlake
IESG IESG state I-D Exists
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Send notices to d3e3e3@gmail.com
Network Working Group                                         T. Bastian
Internet-Draft                           Ecole Normale Superieure, Paris
Updates: 6126bis (if approved)                             J. Chroboczek
Intended status: Experimental          IRIF, University of Paris-Diderot
Expires: April 23, 2021                                 October 20, 2020

    IPv4 routes with an IPv6 next-hop in the Babel routing protocol
                      draft-ietf-babel-v4viav6-00

Abstract

   This document defines an extension to the Babel routing protocol that
   allows annoncing routes to an IPv4 prefix with an IPv6 next-hop,
   which makes it possible for IPv4 traffic to flow through interfaces
   that have not been assigned an IPv4 address.

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
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   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 April 23, 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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   (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
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   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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Specification of Requirements . . . . . . . . . . . . . .   3
   2.  Protocol operation  . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Announcing v4-over-v6 routes  . . . . . . . . . . . . . .   3
     2.2.  Receiving v4-over-v6 routes . . . . . . . . . . . . . . .   3
     2.3.  Prefix and seqno requests . . . . . . . . . . . . . . . .   4
     2.4.  Other TLVs  . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Backwards compatibility . . . . . . . . . . . . . . . . . . .   4
   4.  Protocol encoding . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Prefix encoding . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Changes for existing TLVs . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Traditionally, a routing table maps a network prefix of a given
   address family to a next-hop address in the same address family.  The
   sole purpose of this next-hop address is to serve as an input to a
   protocol that will map it to a link-layer address, Neighbour
   Discovery (ND) [RFC4861] in the case of IPv6, Address Resolution
   (ARP) [RFC0826] in the case of IPv4.  Therefore, there is no reason
   why the address family of the next hop address should match that of
   the prefix being announced: an IPv6 next-hop yields a link-layer
   address that is suitable for forwarding both IPv6 or IPv4 traffic.

   We call a route towards an IPv4 prefix that uses an IPv6 next hop a
   "v4-over-v6" route.  Since an IPv6 next-hop can use a link-local
   address that is autonomously configured, the use of v4-over-v6 routes
   enables a mode of operation where the network core has no statically
   assigned IP addresses of either family, thus significantly reducing
   the amount of manual configuration.

   This document describes an extension that allows the Babel routing
   protocol [RFC6126bis] to announce routes towards IPv6 prefixes with
   IPv4 next hops.  The extension is inspired by a previously defined
   extension to the BGP protocol [RFC5549].

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