Traffic Engineering (fwd)

Thu Sep 18 21:03:47 UTC 1997

Sean M. Doran writes:
...
> That is, if I stuffed 9999 into the AS_PATH of an
> announcement I generated or learned from elsewhere, AS
> 9999 would never hear the announcement from anyone who
> heard it only from me.
...

This isn't quite correct (though it's peripheral to your main
argument).  An EBGP speaker is free to advertise routes containing
9999 to 9999.  Furthermore, 9999 is free to accept routes containing
9999.  Whether 9999 chooses to do this or not is, as the saying
goes, "purely a local matter."  Likewise whether 9999's peers choose
to refrain from sending such routes.

Some BGP implementations, gated for one, may be configured to accept
routes with the router's own AS number in the path.  Loop suppression
is still provided by limiting the number of times it may appear.
(Hi, Dennis.)

This is actually useful in some circumstances.

Regards,

--John

--
John G. Scudder                       email:  jgs at ieng.com
Internet Engineering Group, LLC       phone:  (313) 213-4939 ext 14
122 S. Main, Suite 280                fax:    (313) 669-8661
Ann Arbor, MI  48104                  www:    http://www.ieng.com