Internet DRAFT - draft-raggarwa-l3vpn-tunnel-attribute
draft-raggarwa-l3vpn-tunnel-attribute
Network Working Group R. Aggarwal
Internet Draft Juniper Networks
Expiration Date: April 2006
October 2005
Signaling Tunnel Identifiers and Capabilities in BGP
draft-raggarwa-l3vpn-tunnel-attribute-00.txt
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Abstract
This document proposes a mechanism that allows a router to signal the
identifiers of IP/MPLS Tunnels, for which it is the headend, using
Border Gateway Protocol (BGP). One application of this mechanism is
multicast in BGP - Multi-Protocol-Label Switching (MPLS) Virtual
Private Networks (VPNs). This document also proposes a mechanism
that allows a router to signal its tunnel enapsulation/decapsulation
capabilities using BGP. One application of this is signaling MPLS
upstream label assignment capability when BGP is used to advertise
MPLS upstream assigned labels.
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Table of Contents
1 Specification of requirements ......................... 2
2 Introduction .......................................... 2
3 BGP Tunnel Identifier Attribute ....................... 3
4 BGP Tunnel Capabilities Extended Community ............ 3
5 IANA Considerations ................................... 4
6 Security Considerations ............................... 4
7 Acknowledgements ...................................... 4
8 References ............................................ 5
8.1 Normative References .................................. 5
8.2 Informative References ................................ 5
9 Author Information .................................... 5
10 Intellectual Property Statement ....................... 6
11 Full Copyright Statement .............................. 6
1. Specification of requirements
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 [RFC2119].
2. Introduction
This document proposes a mechanism that allows a router to signal the
identifiers of IP/MPLS Tunnels, for which it is the headend, using
Border Gateway Protocol (BGP). This information is signaled using a
new BGP attribute [BGP]. One application of this mechanism is multi-
cast in BGP - Multi-Protocol-Label Switching (MPLS) Virtual Private
Networks (VPNs) [MVPN].
This document also proposes a mechanism that allows a router to sig-
nal its tunnel enapsulation/decapsulation capabilities using BGP.
These capabilities are signaled using a new BGP extended community
[BGP-EXT-COM]. One application of this is signaling MPLS upstream
label assignment capability when BGP is used to advertise MPLS
upstream assigned labels [MPLS-UPSTREAM].
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3. BGP Tunnel Identifier Attribute
A router advertises its tunnel identifiers in BGP using a new
optional Tunnel Attribute. This attribute is transitive across
Autonoumous System Boundary with type code to be assigned by IANA.
This attribute can be attached to a NLRI advertisement. For example
this new attribute may be attached to a BGP-MVPN NLRI advertisment
[BGP-MVPN]. The tunnel identifier is interpreted in the context of
the NLRI that it is attached to. For example if the NLRI advertises a
MVPN, that the advertising PE is a member of, the attribute signals
the tunnel identifier of the tunnel used by the advertising PE to
send data traffic for the MVPN [MVPN].
The value field of the attribute contains a Tunnel Identifier with
the following format:
+---------------------------------+
| Tunnel Type (2 octets) |
+---------------------------------+
| Tunnel Identifier (variable) |
+---------------------------------+
The tunnel type identifies the type of the tunneling technology used
to establish the tunnel. The type determines the syntax and semantics
of the tunnel identifier field. The tunnel types and identifiers are
to be defined in appliaction specific documents.
4. BGP Tunnel Capabilities Extended Community
We define a BGP opaque extended community that can be attached to a
BGP NLRI advertisement to indicate the MPLS or other encapsulation
capabilities of such a NLRI. It is referred to as the Tunnel Encapsu-
lation Capabilities extended community. It is transitive across the
Autonomous System boundary. For example this new extended community
may be attached to a BGP-MVPN NLRI advertisment [BGP-MVPN] to indi-
cate that the originating PE supports MPLS upstream label assignment
[MPLS-UPSTREAM].
The Tunnel Encapsulation Capabilities community is of an extended
type. The value of the high-order octet of the Type Field is 0x43.
The value of the low-order octet of the Type field of this extended
community is to be assigned by IANA [BGP-EXT-COM].
The Tunnel encapsulation extended community has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x43 |Sub-Type = TBD | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Encapsulation Capabilities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The encapsulation capabilities bit-mask indicates all the encapsula-
tions supported by the BGP speaker for the advertised NLRI. The
usage of these capabilities is to be defined in application specific
documents. The following encapsulation capabilities are defined as of
now:
0x00000001 MPLS Upstream Label Capability
0x00000002 Multicast Shared Root
5. IANA Considerations
This document defines a new BGP Tunnel Attribute and the type code of
this attribute is to be assigned by IANA. This document also defines
a BGP Tunnel Encapsulation Capabilities extended community and the
sub-type of this extended community is to be assigned by IANA. The
tunnel types in the Tunnel Attribute are to be assigned by IETF con-
sensus and IANA is to maintain a registry for these tunnel types. The
encapsulation capabilities in the tunnel encapsulation extended com-
munity are to be assigned by IETF consensus as well and IANA is to
maintain a registry for these capabilities. IANA is requested to
assign the bits 0x00000001 - 0x00000002 in this registry, as defined
in section 4.
6. Security Considerations
This document does not introduce any new security issues. The secu-
rity issues identified in [BGP-EXT-COM], [BGP] are still relevant.
7. Acknowledgements
This document has evolved over a period of time and several individu-
als have contributed to the ideas that have been distilled in this
document. Thanks to Robert Raszuk for his contribution. Thanks to the
authors of [PPVPN-SIG] for their contribution. We would also like to
thank Enke Chen, Jenny Yuan, Naiming Shen, Acee Lindem,and Ravi Chan-
dra for their cntribution.
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Thanks to Yakov Rekhter for his comments and suggestions.
8. References
8.1. Normative References
[RFC2119] "Key words for use in RFCs to Indicate Requirement Lev-
els.", Bradner, March 1997
[BGP] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)",
RFC 1771, March 1995.
[BGP-EXT-COM] S.R. Sangli et. al., "BGP Extended Communities
Attribute", draft-ietf-idr-bgp-ext-communities-09.txt.
8.2. Informative References
[MVPN] E. Rosen, R. Aggarwal [Editors], Multicast in BGP/MPLS VPNs"
draft-ietf-l3vpn-2547-mcast-00.txt
[MPLS-UPSTREAM] R. Aggarwal, Y. Rekhter, E. Rosen, "MPLS Upstream
Label Assignment and Context Specific Label Space", draft-raggarwa-
mpls-upstream-label-01.txt
[BGP-MVPN] R. Aggarwal, C. Kodeboniya, Y. Rekhter, E. Rosen, "BGP
Encodings for Multicast in BGP/MPLS VPNs", draft-raggarwa-
l3vpn-2547-mcast-bgp-00.txt
[MPLS-MCAST-ENCAPS] T. Eckert, E. Rosen, R. Aggarwal, Y. Rekhter,
draft-rosen-mpls-codepoint-01.txt
[PPVPN-SIG] R. Aggarwal, R. Raszuk, F. L. Faucheur, C. Geoffrey, J.
D. Clercq, "Signaling Tunnel Encapsulation/Decapsulation Capabili-
ties", draft-raggarwa-ppvpn-tunnel-encap-01.txt
9. Author Information
Rahul Aggarwal
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089
Email: rahul@juniper.net
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10. Intellectual Property Statement
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pertain to the implementation or use of the technology described in
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11. Full Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
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This document and the information contained herein are provided on an
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