Networks ignoring prepends?

Wed Jan 24 13:23:34 UTC 2024

Once upon a time, William Herrin <bill at herrin.us> said:
> On Tue, Jan 23, 2024 at 4:00 PM Chris Adams <cma at cmadams.net> wrote:
> > Once upon a time, William Herrin <bill at herrin.us> said:
> > > Nevertheless, in the protocol's design, the one expressed in the
> > > RFC's, AS path length = distance.
> >
> > The RFC doesn't make any equivalence between AS path length and
> > distance.  You are the one trying to make that equivalence,
> 
> Respectfully Chris, you are mistaken.
> 
> https://datatracker.ietf.org/doc/html/rfc4271#section-9.1.2.2
> 
> "a) Remove from consideration all routes that are not tied for having
> the smallest number of AS numbers present in their AS_PATH
> attributes."
> 
> So literally, the first thing BGP does when picking the best next hop
> is to discard all but the routes with the shortest AS path.

That's literally not the first thing - you skipped section 9.1.1.

It also literally says nothing about distance.

-- 
Chris Adams <cma at cmadams.net>