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Re: [Idr] RFC-4893 handling malformed AS4_PATH attributes

"John G. Scudder" <jgs@juniper.net> Tue, 16 December 2008 21:01 UTC

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From: "John G. Scudder" <jgs@juniper.net>
To: Paul Jakma <paul@clubi.ie>
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Subject: Re: [Idr] RFC-4893 handling malformed AS4_PATH attributes
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On Dec 16, 2008, at 12:07 PM, Paul Jakma wrote:
> b) It's no doubt implied, but perhaps any RFCbis should make it clear
>   that AS_TRANS MUST be considered to match all ASNs > 65535 when
>   doing AS-Path (in the abstract) loop detection.

Seems to me that this is not required in order to preserve the loop  
free property. We have two possible cases:

1. All the ASes in the path are 4-byte capable, in which case the  
issue does not exist.
2. At least one AS in the path is not 4-byte capable. In that case, if  
there is a loop it will eventually be caught by the regular 2-byte  
AS_PATH.

In neither case is what you describe needed, AFAICT.

--John
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