Network Working Group Rajiv Asati
Internet Draft Cisco Systems, Inc.
Expiration Date: December 2007
Bob Thomas
Cisco Systems, Inc.
June 2007
LDP End-of-LIB
draft-asati-mpls-ldp-end-of-lib-00.txt
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Copyright Notice
Copyright (C) The IETF TRUST (2007).
Abstract
There are situations following LDP session establishment where it
would be useful for an LDP speaker to know when its peer has
advertised all of its labels. These include session re-establishment
following loss of an LDP session when LDP graceful restart is in use
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and session establishment when LDP-IGP sync is in use. The LDP
specification provides no mechanism for an LDP speaker to notify a
peer when it has completed its initial label advertisements to that
peer. This document specifies means for an LDP speaker to signal
completion of its initial label advertisements following session
establishment.
Table of Contents
1 Introduction .......................................... 2
2 Specification Language ................................ 3
3 Signaling Completion of Initial Label Advertisement ... 3
4 IANA Considerations ................................... 4
5 Security Considerations ............................... 4
6 References ............................................ 4
7 Author Information .................................... 5
8 Intellectual Property Statement ....................... 5
9 Full Copyright Statement .............................. 6
1. Introduction
There are situations following LDP session establishment where it
would be useful for an LDP speaker to know when its peer has
advertised all of its labels. For example, after an LDP session is
re-established when LDP graceful restart [RFC3478] is in effect it
would be helpful for each peer to signal the other after it has
advertised all its label bindings. Similarly when an LDP speaker is
using LDP-IGP synchronization procedures [LDPSynch] it would be
useful for the speaker to know when its peer has completed
advertisement of its IP label bindings.
The LDP specification [RFC3036] provides no mechanism for an LDP
speaker to notify a peer when it has completed its initial label
advertisements to that peer.
This document specifies use of a Notification message with the "End-
of-LIB" Status Code for an LDP speaker to signal completion of its
label advertisements following session establishment.
RFC3036 implicitly assumes that new Status Codes will be defined over
the course of time. However, it does not explicitly define the
behavior of an LDP speaker which does not understand the Status Code
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in a Notification message. To avoid backward compatibility issues
this document specifies use of the LDP capability mechanism [LDPCap]
at session establishment time for informing a peer that an LDP
speaker is capable of processing Notification messages that carry the
"End-of-LIB" Status Code.
2. Specification Language
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].
3. Signaling Completion of Initial Label Advertisement
An LDP speaker MAY include a Capability Parameter in an
Initialization message to inform a peer that it is capable of
processing Notification Messages that carry a Status TLV with the
End-of-LIB Status Code.
The Capability Parameter for the End-of-LIB capability is a TLV with
the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| End-of-LIB (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| Reserved |
+-+-+-+-+-+-+-+-+
where:
U and F bits: As specified by RFC3036.
End-of-LIB: TLV code point to be assigned by IANA.
S-bit: Must be 1 (indicates that cability is being advertised).
An LDP speaker MUST NOT send a Notificiation which carries a Status
TLV with the End-of-LIB Status Code unless its peer had advertised
the End-of-LIB capability during session establishment.
If its peer had advertised the End-of-LIB capability during session
establishment an LDP speaker MAY signal completion of its label
advertisements to the peer by means of a Notification message. Such
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a Notification message MUST carry:
- An "End-of-LIB" Status Code in the Status TLV. This is a new
Status Code.
- A FEC TLV with the Typed Wildcard FEC Element [TypedWC] that
identifies the FEC type for which initial label advertisements
have been completed. In terms of Section 3.5.1 of RFC3036 this
TLV is an "Optional Parameter" of the Notification message.
4. IANA Considerations
This draft introduces a new LDP Status Code and a new LDP Capability
both of shich require IANA assignment.
5. Security Considerations
No security considerations beyond those that apply to the base LDP
specification and described in [RFC3036] apply to use of the Typed
Wildcard FEC Element defined in this document.
6. References
Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, March 1997.
[RFC3036] Andersson, L., Doolan, P., Feldman, N., Fredette, A. and
Thomas, B., "LDP Specification", RFC 3036, January 2001.
[LDPCap] Thomas, B., Aggarwal, S., Aggarwal, R., Le Roux, J.L.,
"LDP Capabilities", draft-ietf-mpls-ldp-capabilities-00, Work in
Progress, May 2007.
[TypedWC] Thomas, B., Minei, I., "LDP Typed Wildcard FEC", draft-
ietf-mpls-ldp-typed-wildcard-01, Work in Progress, May 2007.
Informative References
[LDPCap] Thomas, B., Aggarwal, S., Agarwal, R., Le Roux, J.L., "LDP
Capabilities", Work in Progreaa, May 2007.
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[LDPSynch] Jork, M., Atlas, A., Fang, L., "LDP IGP
Synchronization", draft-jork-ldp-igp-sync-02, Work in Progress,
June 2006.
[RFC3478] Leelanivas, M., Rekhter, Y., Aggarwal, R., "Graceful
Restart Mechanism for Label Distribution Protocol", February 2003.
7. Author Information
Rajiv Asati
Cisco Systems, Inc.
Mail Stop RTP6P/2/1
7025-6 Kit Creek Road PO Box 14987
Research Triangle Park , NORTH CAROLINA 27709-4987
Email: rajiva@cisco.com
Bob Thomas
Cisco Systems, Inc.
1414 Massachusetts Ave.
Boxborough MA 01719
Email: rhthomas@cisco.com
8. Intellectual Property Statement
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9. Full Copyright Statement
Copyright (C) The IETF Trust (2007).
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