Re: [Isis-wg] Question about Purge LSP in RFC 1142
mike shand <mshand@cisco.com> Fri, 19 October 2007 11:34 UTC
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Date: Fri, 19 Oct 2007 12:34:11 +0100
From: mike shand <mshand@cisco.com>
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To: "Theodore.Wang" <theodore.wang@gmail.com>
Subject: Re: [Isis-wg] Question about Purge LSP in RFC 1142
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You should not be paying any attention to RFC 1142. It is a copy of DP 10589 which is a version of ISO/IEC 10589 several stages before its final standardisation and differs from ISO/IEC 10589 is several important respects.Hi, allI have a question about Purge LSP in RFC 1142.In RFC 1142, I find the following lines:
If you want to know what the standard says, get a copy of ISO/IEC 10589:2002 from
http://standards.iso.org/ittf/PubliclyAvailableStandards/" rel="nofollow">http://standards.iso.org/ittf/PubliclyAvailableStandards/
e)An Intermediate system receiving a Link State PDU with an incorrect LSP Checksum or with an invalid PDU syntax shall
1)log a circuit notification, corruptedLSPReceived,
2)overwrite the Checksum and Remaining Lifetime with 0, and
3)treat the Link State PDU as though its Remaining Lifetime had expired
These lines define the way how to cope with the LSP with incorrect checksum, that is to flood the LSP's header with zero remaining lifetime.
In fact this behaviour has been changed in the second edition and now reads
e) An Intermediate system receiving a Link State PDU with an incorrect LSP Checksum or with an invalid PDU syntax shall
1) generate a corruptedLSPReceived circuit event,
2) discard the PDU.
see also RFC 3719 section 8, which reads
8. Purging Corrupted PDUs
While ISO 10589 requires in section 7.3.14.2 e) that any LSP received
with an invalid PDU checksum should be purged, this has been found to
be disruptive. Most implementations today follow the revised
specification, and simply drop the LSP.
In ISO 10589:2002 [1], Section 7.3.14.2, it states:
(e) An Intermediate system receiving a Link State PDU with an
incorrect LSP Checksum or with an invalid PDU syntax SHOULD
1) generate a corruptedLSPReceived circuit event,
2) discard the PDU.
It is for this reason (the purge storm) that the specification was changed!But in fact, in a huge network, it is hard to locate the router that generate the Purge LSP, and which is the situation I'm facing. A Corrupted LSP Storm is happening in the network and it lacks a efficient way to troubleshooting because we can only use "ignore checksum error" on every router to find the one that flooded the Purge LSP.
No.Therefore, is it possible to attach a new TLV in Purge LSP that defines the originator?
Thanks in advance!
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_______________________________________________ Isis-wg mailing list Isis-wg@ietf.org https://www1.ietf.org/mailman/listinfo/isis-wg
- [Isis-wg] Question about Purge LSP in RFC 1142 Theodore.Wang
- Re: [Isis-wg] Question about Purge LSP in RFC 1142 mike shand
- RE: [Isis-wg] Question about Purge LSP in RFC 1142 Manav Bhatia
- Re: [Isis-wg] Question about Purge LSP in RFC 1142 Dave Katz
- Re: [Isis-wg] Question about Purge LSP in RFC 1142 Hannes Gredler
- RE: [Isis-wg] Question about Purge LSP in RFC 1142 Les Ginsberg (ginsberg)
- Re: [Isis-wg] Question about Purge LSP in RFC 1142 mike shand