draft-ietf-idr-v4nlri-v6nh-00.txt   draft-ietf-idr-v4nlri-v6nh-01.txt 
Inter-Domain Routing F. Le Faucheur Inter-Domain Routing F. Le Faucheur
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track E. Rosen Intended status: Standards Track E. Rosen
Expires: September 24, 2007 Cisco Systems, Inc. Expires: April 18, 2008 Cisco Systems, Inc.
March 23, 2007 October 16, 2007
Advertising an IPv4 NLRI with an IPv6 Next Hop Advertising an IPv4 NLRI with an IPv6 Next Hop
draft-ietf-idr-v4nlri-v6nh-00.txt draft-ietf-idr-v4nlri-v6nh-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 24, 2007. This Internet-Draft will expire on April 18, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
MultiProtocol-BGP (MP-BGP) specifies that the set of Network Layer MultiProtocol-BGP (MP-BGP) specifies that the set of Network Layer
protocols to which the address carried in the Next Hop field may protocols to which the address carried in the Next Hop field may
belong is determined by the Address Family Identifier (AFI) and the belong is determined by the Address Family Identifier (AFI) and the
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Furthermore, a number of these existing AFI/SAFIs allow the Next Hop Furthermore, a number of these existing AFI/SAFIs allow the Next Hop
to belong to either the IPv4 Network Layer Protocol or the IPv6 to belong to either the IPv4 Network Layer Protocol or the IPv6
Network Layer Protocol, and specify the encoding of the Next Hop Network Layer Protocol, and specify the encoding of the Next Hop
information in order to determine which of the protocols the address information in order to determine which of the protocols the address
actually belongs to. For example, [RFC4684] allows the Next Hop actually belongs to. For example, [RFC4684] allows the Next Hop
address to be either IPv4 or IPv6 and states that the Next Hop field address to be either IPv4 or IPv6 and states that the Next Hop field
address shall be interpreted as an IPv4 address, whenever the length address shall be interpreted as an IPv4 address, whenever the length
of Next Hop address is 4 octets, and as a IPv6 address, whenever the of Next Hop address is 4 octets, and as a IPv6 address, whenever the
length of the Next Hop address is 16 octets. length of the Next Hop address is 16 octets.
There are situations such as those described in There are situations such as those described in [RFC4925] and in
[I-D.ietf-softwire-problem-statement] and in [I-D.ietf-softwire-mesh-framework] where carriers (or large
[I-D.wu-softwire-mesh-framework] where carriers (or large enterprise enterprise networks acting as carrier for their internal resources)
networks acting as carrier for their internal resources) may be may be required to establish connectivity between 'islands' of
required to establish connectivity between 'islands' of networks of networks of one address family type across a transit core of a
one address family type across a transit core of a differing address differing address family type. This includes both the case of IPv6
family type. This includes both the case of IPv6 islands across an islands across an IPv4 core and the case of IPv4 islands across an
IPv4 core and the case of IPv4 islands across an IPv6 core. Where IPv6 core. Where Multi-Protocol BGP (MP-BGP) is used to advertise
Multi-Protocol BGP (MP-BGP) is used to advertise the corresponding the corresponding reachability information, this translates into the
reachability information, this translates into the requirement for a requirement for a BGP speaker to advertise Network Layer Reachability
BGP speaker to advertise Network Layer Reachability Information Information (NLRI) of a given address family via a Next Hop of a
(NLRI) of a given address family via a Next Hop of a different different address family (i.e. IPv6 NLRI with IPv4 Next Hop and IPv4
address family (i.e. IPv6 NLRI with IPv4 Next Hop and IPv4 NLRI with NLRI with IPv6 Next Hop).
IPv6 Next Hop).
The current AFI/SAFI definitions for the IPv6 address family assume The current AFI/SAFI definitions for the IPv6 address family assume
that the Next Hop address belongs to the IPv6 address family type. that the Next Hop address belongs to the IPv6 address family type.
Specifically, as per [RFC2545] and [RFC3107], when the <AFI/SAFI> is Specifically, as per [RFC2545] and [RFC3107], when the <AFI/SAFI> is
<2/1>, <2/2>, or <2/4>, the Next Hop address is assumed to be of IPv6 <2/1>, <2/2>, or <2/4>, the Next Hop address is assumed to be of IPv6
type. As per [RFC4659], when the <AFI/SAFI> is <2/128>, the Next Hop type. As per [RFC4659], when the <AFI/SAFI> is <2/128>, the Next Hop
address is assumed to be of IPv6-VPN type. address is assumed to be of IPv6-VPN type.
However, [RFC4798] and [RFC4659] specify how an IPv4 address can be However, [RFC4798] and [RFC4659] specify how an IPv4 address can be
encoded inside the Next Hop IPv6 address field when an IPv6 NLRI encoded inside the Next Hop IPv6 address field when an IPv6 NLRI
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by the BGP capability advertisement), then the NLRI in question by the BGP capability advertisement), then the NLRI in question
cannot be distributed to that client. For sound routing in certain cannot be distributed to that client. For sound routing in certain
scenarios, this will require that all the RR clients be able to scenarios, this will require that all the RR clients be able to
handle whatever encodings any of them may generate. handle whatever encodings any of them may generate.
5. Usage Examples 5. Usage Examples
5.1. IPv4 over IPv6 Core 5.1. IPv4 over IPv6 Core
The extensions defined in this document may be used as discussed in The extensions defined in this document may be used as discussed in
[I-D.wu-softwire-mesh-framework] for the interconnection of IPV4 [I-D.ietf-softwire-mesh-framework] for the interconnection of IPV4
islands over an IPv6 backbone. In this application, Address Family islands over an IPv6 backbone. In this application, Address Family
Border Routers (AFBR) (as defined in Border Routers (AFBR) (as defined in [RFC4925]) advertise IPv4 NLRI
[I-D.ietf-softwire-problem-statement]) advertise IPv4 NLRI
information in the MP_REACH_NLRI along with an IPv6 next hop. information in the MP_REACH_NLRI along with an IPv6 next hop.
The MP_REACH_NLRI is encoded with: The MP_REACH_NLRI is encoded with:
o AFI=1 o AFI=1
o SAFI=1 o SAFI=1
o Length of Next Hop Network Address = 16 (or 32) o Length of Next Hop Network Address = 16 (or 32)
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[I-D.ietf-idr-dynamic-cap] [I-D.ietf-idr-dynamic-cap]
Chen, E. and S. Sangli, "Dynamic Capability for BGP-4", Chen, E. and S. Sangli, "Dynamic Capability for BGP-4",
draft-ietf-idr-dynamic-cap-09 (work in progress), draft-ietf-idr-dynamic-cap-09 (work in progress),
November 2006. November 2006.
[I-D.ietf-l2vpn-signaling] [I-D.ietf-l2vpn-signaling]
Rosen, E., "Provisioning, Autodiscovery, and Signaling in Rosen, E., "Provisioning, Autodiscovery, and Signaling in
L2VPNs", draft-ietf-l2vpn-signaling-08 (work in progress), L2VPNs", draft-ietf-l2vpn-signaling-08 (work in progress),
May 2006. May 2006.
[I-D.ietf-softwire-problem-statement] [I-D.ietf-softwire-mesh-framework]
Dawkins, S., "Softwire Problem Statement",
draft-ietf-softwire-problem-statement-03 (work in
progress), March 2007.
[I-D.wu-softwire-mesh-framework]
Wu, J., "Softwire Mesh Framework", Wu, J., "Softwire Mesh Framework",
draft-wu-softwire-mesh-framework-02 (work in progress), draft-ietf-softwire-mesh-framework-02 (work in progress),
March 2007. July 2007.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434, IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998. October 1998.
[RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur, [RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
"BGP-MPLS IP Virtual Private Network (VPN) Extension for "BGP-MPLS IP Virtual Private Network (VPN) Extension for
IPv6 VPN", RFC 4659, September 2006. IPv6 VPN", RFC 4659, September 2006.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route R., Patel, K., and J. Guichard, "Constrained Route
Distribution for Border Gateway Protocol/MultiProtocol Distribution for Border Gateway Protocol/MultiProtocol
Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
Private Networks (VPNs)", RFC 4684, November 2006. Private Networks (VPNs)", RFC 4684, November 2006.
[RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur, [RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur,
"Connecting IPv6 Islands over IPv4 MPLS Using IPv6 "Connecting IPv6 Islands over IPv4 MPLS Using IPv6
Provider Edge Routers (6PE)", RFC 4798, February 2007. Provider Edge Routers (6PE)", RFC 4798, February 2007.
[RFC4925] Li, X., Dawkins, S., Ward, D., and A. Durand, "Softwire
Problem Statement", RFC 4925, July 2007.
Authors' Addresses Authors' Addresses
Francois Le Faucheur Francois Le Faucheur
Cisco Systems Cisco Systems
Greenside, 400 Avenue de Roumanille Greenside, 400 Avenue de Roumanille
Sophia Antipolis 06410 Sophia Antipolis 06410
France France
Email: flefauch@cisco.com Email: flefauch@cisco.com
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