consistent policy != consistent announcements

John Scudder jgs at
Fri Mar 14 17:14:44 UTC 1997

> > >                     M
> > >                   /   \
> > >                  A     B      * Peer link
> > >                  |     *      | Customer link
> > >                  RRRRRRR
> > >           Point1 *     * Point2
> > >                  VVVVVVV
> R could request A to provide it with a list of ASes for indirect
> customers behind A.  (R probably already does that.)  That would be
> sufficient information for R's router at the R/B interconnection to tag
> M's routes as customer routes.  Essentially, when R's router at the R/B
> interconnection receives a route with path "B M", it could use the fact
> "M is an indirect customer" rather than "B is a non-customer" to tag the
> route appropriately.

Furthermore, R could provide sufficient incentive for A to provide a
list of indirect customers by accepting only registered routes (or AS
paths).  (This should sound familiar.)  E.g. (A) and (A M) routes would
be accepted but all other (A *) would not be in this example.

Alternately, R could audit routing tables at Point1 and Point2 from
time to time, as I mentioned earlier.  It ought to be rather simple to
find routes which are in Point1 as "exportable" and Point 2 as
"non-exportable", or vice-versa.  The rest follows.



More information about the NANOG mailing list