RE: [mpls] Proposed reforming of LSP Ping TLV processing
<neil.2.harrison@bt.com> Sat, 28 July 2007 08:54 UTC
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Subject: RE: [mpls] Proposed reforming of LSP Ping TLV processing
Date: Sat, 28 Jul 2007 09:54:02 +0100
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Thread-Topic: [mpls] Proposed reforming of LSP Ping TLV processing
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From: neil.2.harrison@bt.com
To: tnadeau@cisco.com, adrian@olddog.co.uk
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Adrian/guys, Just an observation of what the real architectural problem is here (though I hasten to add we can do nothing about this now...too late): When one designs a layer network (any mode/technology) one MUST ensure that the characteristic information (CI - which is a term from func arch that has a very specific meaning, but I can't really get into detail of what this means here) that is created/removed at trail/flow termination points is ALWAYS consistent (and a key corollary of this is that the CI MUST be client independent). One rather important observation here is that the OAM of a layer network is injected/extracted at trail/flow termination points and thus forms an intrinsic part of the CI of a layer network. MPLS does not have consistent CI for a whole raft of reasons, eg the label field can take on different semantics depending on what protocol/use-case generated it....I can list at least 4 different semantics here. What this means practically is that under misconnectivity defects the true intended meaning of a functional field in a traffic unit can be misunderstood by whichever node terminates the offending misconnected traffic units.....which also includes the OAM pkts. So yes, Tom is right to point out that there are potential security implications here.....but just be aware that this is a symptom/consequence of not having consistent CI in the 1st place, and its a bigger problem than just the one being discussed. Don't want start a debate on this as there is nothing much we can do about it...because as I already noted it's too late.....but I did want to point out what the underlying architectural issue is here. regards, Neil > -----Original Message----- > From: Thomas D. Nadeau [mailto:tnadeau@cisco.com] > Sent: 23 July 2007 19:38 > To: Adrian Farrel > Cc: mpls@lists.ietf.org > Subject: Re: [mpls] Proposed reforming of LSP Ping TLV processing > > > > It looks like your Security Considerations section is > a little light. *) > > --Tom > > > Hi, > > > > I should have introduced this sooner... > > > > George and I have thrown together a draft that we have been talking > > about for some time. "Future-Proof TLV Codepoint Space for LSP > > Ping" (http://www.ietf.org/internet-drafts/draft-farrel-mpls-lsp- > > ping-tlvs-00.txt) is intended to allow LSP Ping extensions to be > > backward compatible by defining processing rules for TLVs based on > > the ranges from which the Type value is allocated. Or, phrased a > > different way, to set aside two bits from the TLV Type to define > > the processing rules. > > > > This first version of the draft is pretty rough, but we hope that > > the ideas will carry forward and gain working group consensus. If > > so, the main impact would be to update the IANA registry. New LSP > > Ping TLVs (and sub-TLVs) would then have to indicate the > processing > > rules when the TLV is not understood. > > > > If you have any questions then please send mail, or corner me or > > George during the week. > > > > Thanks, > > Adrian > > > > > > > > _______________________________________________ > > mpls mailing list > > mpls@lists.ietf.org https://www1.ietf.org/mailman/listinfo/mpls > > > _______________________________________________ > mpls mailing list > mpls@lists.ietf.org > https://www1.ietf.org/mailman/listinfo/mpls > _______________________________________________ mpls mailing list mpls@lists.ietf.org https://www1.ietf.org/mailman/listinfo/mpls
- [mpls] Proposed reforming of LSP Ping TLV process… Adrian Farrel
- Re: [mpls] Proposed reforming of LSP Ping TLV pro… Thomas D. Nadeau
- RE: [mpls] Proposed reforming of LSP Ping TLV pro… Nitin Bahadur
- RE: [mpls] Proposed reforming of LSP Ping TLV pro… neil.2.harrison