How trustworthy are existing BGP AS Paths?
Thu Sep 29 18:24:50 CET 1994
Dale, The reason for routes with different AS origins is not due to configuration errors but routing arrangement between ASs. When two ASs speak IGP between themselves but each BGPs with other ASs, such as the Michnet and UMnet situation, this would occur. Anyother problematic ASpath scnerarios? --jessica ------- Forwarded Message Return-Path: dsj at merit.edu Received: from ncc.ripe.net (ncc.ripe.net [22.214.171.124]) by merit.edu (126.96.36.199/merit-1.0) with SMTP id NAA19465; Thu, 29 Sep 1994 13:09:30 -0400 Received: from merit.edu by ncc.ripe.net with SMTP id AA27687 (5.65a/NCC-2.8); Thu, 29 Sep 1994 18:09:21 +0100 Received: (dsj at localhost) by merit.edu (188.8.131.52/merit-1.0) id NAA19443 for rr-impl at ripe.net; Thu, 29 Sep 1994 13:09:19 -0400 Date: Thu, 29 Sep 1994 13:09:19 -0400 From: "Dale S. Johnson" <dsj at merit.edu> Message-Id: <199409291709.NAA19443 at merit.edu> To: rr-impl at ripe.net Subject: How trustworthy are existing BGP AS Paths? RIPE Folks, In discussions about how to generate GateD configs for the Route Servers, we're coming up with choices between hard-configured net lists (like the PRDB), lists of ASs, AS-Path expressions, and "interpreted" AS lists (creating net lists by listing the Route objects which reference the given ASs). A couple of questions keep coming up in these discussions: How Trustworthy are the AS-Paths actually seen in current routing packets? How secure are they? (Can they be easily misconfigured?) Last winter we noticed that there were a fair number of BGP Paths that claimed by be complete, but which disagreed with each other about what the origin ASs for certain nets were. I believe Tony or Marten also said that they had investigated determining Origin ASs from BGP packets, and had found that the information currently being routed was frequently wrong. Is my memory correct on this? Does anyone know if there are still lots of misleading AS-paths being routed? Further vague memories: Did someone say that some ASs were intentionally fudging the AS-Paths, e.g., to make multiple ASs look like a single AS, for policy reasons? [Do I sound like Gordon Cook?] Also, AS-Path expressions are presumably not useful for expressing policy about EPG speakers. (?) All in all, if these things are true, do folks here have feelings about how advisable it is to implement policy in terms of AS-path expressions in 4Q94? Guesses about 3Q95? - --Dale - ---------- PS: After we get Dale's memory sorted out, it might be interesting to take this same question to BGPD. ------- End of Forwarded Message -------- Logged at Thu Sep 29 18:42:52 MET 1994 ---------
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