91.207.218.0/23 prefix in DFZ - AS3.21 / AS196629 - announced with AS_CONFED_SEQUENCE in AS4_PATH - propagated by 35320

Thu Dec 11 22:46:44 UTC 2008

On Thu, Dec 11, 2008 at 01:28:46PM +0100, bjorn at mork.no wrote:
> No you can't rely on that.  But still, RFC4271 doesn't seemt to allow
> ignoring it.  Which must be a bug in the RFC, or my reading of it.
> Hopefully the latter.  Great if someone could correct the interpretation
> below. 
> 
> IMHO, an optional transitive attribute with the partial bit set should
> not cause session tear-down, since the attribute is forwarded across one
> or more routers not handling it and therefore not filtering it.
>
> However, RFC4271 does not make such an exception for optional +
> transitive + partial AFAICS:
[..... copy/paste deleted .....]
> Which basically means that you can take down every RFC-compliant 4-byte
> ASN honouring router today by injecting a bogus AS4_PATH attribute into
> the mostly 2-byte-ASN-only Internet...
> 
> Or did I miss something?  I certainly hope I did.

this was brought up in the IETF IDR mailing list today. i've attached
the response from that thread that addresses your reading of the RFC.

-- bill

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Subject: Re: [Idr] RFC-4893 handling malformed AS4_PATH attributes
Date: Thu, 11 Dec 2008 13:36:21 -0500
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