Advertising IPv4 Network Layer Reachability Information with an IPv6 Next Hop
RFC 5549
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RFC - Proposed Standard
(May 2009; No errata)
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2015-10-14
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RFC 5549 (Proposed Standard)
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Mark Townsley
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Network Working Group F. Le Faucheur
Request for Comments: 5549 E. Rosen
Category: Standards Track Cisco Systems
May 2009
Advertising IPv4 Network Layer Reachability Information
with an IPv6 Next Hop
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2009 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 in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract
Multiprotocol BGP (MP-BGP) specifies that the set of network-layer
protocols to which the address carried in the Next Hop field may
belong is determined by the Address Family Identifier (AFI) and the
Subsequent Address Family Identifier (SAFI). The current 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 Network Layer Reachability Information (NLRI) or
VPN-IPv4 NLRI. This document 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, the
encoding of the Next Hop in order 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.
Le Faucheur & Rosen Standards Track [Page 1]
RFC 5549 v4 NLRI with v6 NH May 2009
Table of Contents
1. Introduction ....................................................2
2. Requirements Language ...........................................4
3. Extension of AFI/SAFI Definitions for the IPv4 Address Family ...4
4. Use of BGP Capability Advertisement .............................5
5. Operations ......................................................7
6. Usage Examples ..................................................7
6.1. IPv4 over IPv6 Core ........................................7
6.2. IPv4 VPN over IPv6 Core ....................................8
7. IANA Considerations .............................................8
8. Security Considerations .........................................8
9. Acknowledgments .................................................9
10. References .....................................................9
10.1. Normative References ......................................9
10.2. Informative References ....................................9
1. Introduction
Multiprotocol BGP (MP-BGP) [RFC4760] specifies that the set of
network-layer protocols to which the address carried in the Next Hop
field may belong is determined by the Address Family Identifier (AFI)
and the Subsequent Address Family Identifier (SAFI). A number of
existing AFI/SAFIs allow the Next Hop address to belong to a
different address family than the Network Layer Reachability
Information (NLRI). For example, the AFI/SAFI <25/65> used (as per
[L2VPN-SIG]) in order to perform L2VPN auto-discovery, allows
advertising NLRI that contains the identifier of a Virtual Private
LAN Service (VPLS) instance or that identifies a particular pool of
attachment circuits at a given Provider Edge (PE), while the Next Hop
field contains the loopback address of a PE. Similarly, the AFI/SAFI
<1/132> (defined in [RFC4684]) in order to advertise Route Target
(RT) membership information, allows advertising NLRI that contains
such RT membership information, while the Next Hop field contains the
address of the advertising router.
Furthermore, a number of these existing AFI/SAFIs allow the Next Hop
to belong to either the IPv4 Network Layer Protocol or the IPv6
Network Layer Protocol, and specify the encoding of the Next Hop
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