Re: [Idr] Revised text on how to construct the AS path info

Enke Chen <enkechen@cisco.com> wrote:
> 
> Attached is the revised text on how to construct the AS path information.

   I welcome this clarification. It's much easier to determine whether
a particular algorithm matches this description.

> Please comment if you see any issue.
> ----------------------------------------------------------------------
> 
> The exact AS path information can be constructed by taking as many AS
> numbers and path segments as necessary from the leading part of the
> AS_PATH attribute,

   This much is clearly correct.

> and then prepending them to the NEW_AS_PATH attribute so that the
> AS path information has an identical number of AS numbers as the
> AS_PATH attribute.

   It's very important to be clear that the AS_PATH "length" MUST be
the same as the AS_PATH received from the OLD BGP speaker.

   This algorithm should be appropriate, provided a reasonable test
for consistency between AS_PATH and NEW_AS_PATH is performed. (I'd
be happy to discuss my ideas for such a test.)

   I think we need to add a provision that the NLRI MAY (or even
SHOULD) be discarded if the two are inconsistent.

> The number of AS numbers is calculated...

   I'd prefer not to comment on this part: I haven't examined it in
detail. At first blush, it looks right.

--
John Leslie <john@jlc.net>

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