Network Working Group Gargi Nalawade
Internet Draft Arjun Sreekantiah
Expires: January 2005 Cisco Systems
MDT SAFI
draft-nalawade-idr-mdt-safi-01.txt
1. Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
2. Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
3. Abstract
There is a need for transporting Multicast Tunnel attributes within
and across Autonomous Systems. This draft defines a new Address-
Family that can be used to do the distribution.
4. Introduction
Two end-points of a Multicast Tunnel need to know the end-point
information and its binding to a network address and the Multicast
Tunnel used for the respective VRF at the remote PE. Normally, Tunnel
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endpoint addresses can be statically configured. But in case of a
large network with large number of VPNs where there may be a need for
a large number of endpoints and a large number of VRFs, the amount of
information that needs to be exchanged and maintained between PEs for
Multicast Tunnels for VPNs, is quite large. It therefore needs a
mechanism that can maintain and support Multicast Tunnel based VPNs
in a flexible, scalable manner. Also, in inter-AS and inter- provider
scenarios, this mechanism needs to be supported across autonomous
systems and provider domains.
5. The MDT SAFI
A new Subsequent-Address Family called the MDT SAFI is being defined.
The NLRI for this SAFI, will contain the address of the nexthop which
will be used by the multicast source PE to send the PIM Join for the
default MDT address to.
The NLRI format is 8-byte-RD:IPv4-address followed by the MDT group
address. i.e. The MP_REACH attribute for this SAFI will contain one
or more tuples of the following form :
+------------------------------+
| |
| RD:IPv4-address (12 octets) |
| |
+-------------------------------+
| MDT Group-address (4 octets) |
+-------------------------------+
where :
Route-Distinguisher : is the RD of the VRF to which this MDT
attribute belongs.
MDT Group Address : is the Group-address of the MDT-Group that a VRF
is associated to. This can be variable length. But for
IPV4 addresses - this will be 4 octets.
6. The Connector Attribute
An Optional Transitive Connector attribute is being defined to link a
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BGP AFI/SAFI with another AFI/SAFI, so that the prefix of one
AFI/SAFI could derive an information entity that is dependant on the
NLRI advertised through another AFI/SAFI. An example of this is as
illustrated in [MT-DISC] where the original NEXTHOP attribute
advertised by a PE router is preserved across one or more domains,
so that the PE router at the other end can deduce the originator PE.
The attribute contains one or more tuples of the form :
+------------------------------+
| |
| Type (2 octets) |
+------------------------------+
| |
| Length (2 octets) |
+------------------------------+
| |
| Value (Variable) |
| |
+------------------------------+
where :
Type : is the Type of the data contained in this TLV.
Length : is the Length of the Value portion in the TLV.
Value : is a variable length field defined by the AFI/SAFI carried in
this tuple, which would be used by the AFI/SAFI in this tuple.
When the Type is 1, the length contains the number 4 and the value in
the TLV will contain the IPv4 address of the PE sourcing the CE-
learnt VPNv4 prefixes, and this attribute will accompany the VPNv4
prefix advertisement. The usage of this attribute for the Type-code 1
is described in [MT-DISC].
7. Capability Advertisement
A BGP speaker that wishes to exchange the MDT SAFI, MUST use the
MP_EXT Capability Code as defined in [BGP-MP], to advertise the
corresponding (AFI, SAFI) pair.
A BGP speaker MAY participate in the distribution of MDT information.
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8. Operation
A BGP Speaker that receives the Capability for the MDT SAFI, MAY
advertise the MDT SAFI prefixes to that peer. The prefixes in the MDT
SAFI are populated by the PEs that advertise their CE-learnt
prefixes.
9. Security Considerations
This extension to BGP does not change the underlying security issues.
10. Acknowledgements
The authors would like to thank IJsbrand Wijnands for his contr-
ibution towards the Connector Attribute needed for the IPv4-MDT SAFI
as described in [MT-DISC]. The authors would also like to thank Shyam
Suri, Ruchi Kapoor, Shyam Suri, Yiqun Cai, Dan Tappan, Jennifer Li,
Yi Chou, Arjen Boers for their comments and contrib- utions. We would
also like to thank Bhavani Parise for his review and comments.
11. Normative References
[BGP-4] Rekhter, Y. and T. Li (editors), "A Border Gateway Protocol
4 (BGP-4)", Internet Draft draft-ietf-idr-bgp4-17.txt, January 2002.
[BGP-CAP] Chandra, R., Scudder, J., "Capabilities Advertisement with
BGP-4", draft-ietf-idr-rfc2842bis-02.txt, April 2002.
[BGP-SSA] Kapoor R., Nalawade G., ôBGPv4 SAFI-Specific Attributeö,
draft-nalawade-kapoor-bgp-ssa-00.txt, June 2003.
[MULTI-BGP] Bates et al, Multiprotocol Extensions for BGP-4, draft-
ietf-idr-rfc2858bis-02.txt, work in progress.
[MT-DISC] Wijnands, I., Nalawade, G., Multicast Tunnel discovery and
RPF connector, wijnands-mt-discovery-00.txt, work in progress.
12. Author's Addresses
Gargi Nalawade
170 Tasman Drive
San Jose, CA, 95134
E-mail: gargi@cisco.com
Arjun Sreekantiah
170 Tasman Drive
San Jose, CA, 95134
E-mail: asreekan@cisco.com
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13. Intellectual Property Statement
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document. If any standards arising from this document are or become
protected by one or more patents assigned to Cisco Systems, Cisco
intends to disclose those patents and license them on reasonable
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14. Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved.
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15. Expiration Date
This memo is filed as <draft-nalawade-idr-mdt-safi-01.txt>, and
expires January 2005.
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