Subject: [Idr] missing text

From: Yakov Rekhter <[email-masked]>
Date: Thu, 03 Jun 2004 06:50:19 -0700

Folks,

As John Scudder pointed recently the following text in 5.1.2 is 
incomplete, as it does not cover the case when the route that
is to be advertised was received with empty AS_PATH attribute
(this could happen if the route was originated elsewhere in the AS 
and received via IBGP):

    b) When a given BGP speaker advertises the route to an external
       peer, then the advertising speaker updates the AS_PATH attribute
       as follows:

          1) if the first path segment of the AS_PATH is of type
          AS_SEQUENCE, the local system prepends its own AS number as the
          last element of the sequence (put it in the leftmost position
          with respect to the position of octets in the protocol mes-
          sage). If the act of prepending will cause an overflow in the
          AS_PATH segment, i.e. more than 255 ASs, it SHOULD prepend a
          new segment of type AS_SEQUENCE and prepend its own AS number
          to this new segment.

          2) if the first path segment of the AS_PATH is of type AS_SET,
          the local system prepends a new path segment of type
          AS_SEQUENCE to the AS_PATH, including its own AS number in that
          segment.

So, to fix this I'd like to propose to add at the end of the above
text the following:

         3) if the AS_PATH is empty, the local system creates
         a path segment of type AS_SEQUENCE, places its own AS
         into that segment, and places that segment into the AS_PATH.

Please comment on this. The deadline for comments is June 17, 2004.

Yakov.

_______________________________________________
Idr mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/idr

---

From: Jeffrey Haas <[email-masked]>
Date: Thu, 3 Jun 2004 16:06:41 -0400

>          into that segment, and places that segment into the AS_PATH.

This looks fine to me.

-- 
Jeff Haas 
NextHop Technologies