From: Voss, David (dvoss@heidrick.com)
Date: Sun Sep 29 2002 - 19:00:55 GMT-3
I'm finding that in most every case, it is best to use the AS_SET feature
when aggregating BGP routes. I understand the situtations in which it may
cause issues, but those issues can be relived by using advertise-maps.
Specifically, if a no-export is set for a specific route within the
aggregate address, then it needs to be addressed with an advertise-map so
that the aggregate does not inherit your no-export route.
EXAMPLE:
AS 500 --SENDING 5 ROUTES------------ AS 200-----AGGREGATE THE ROUTES TO AS
5-------- AS 5
AS 100 --SENDING 1 ROUTE, NO EXPORT-----|
In the above example, where AS500 and AS100 are sending routes to AS200, it
can cause problems when aggregating because the NO EXPORT feature of AS100
would then stop all aggregate routes from being sent to AS5. With the
advertise-map, we can allow the 1 route from AS100 to be sent, thus AS5
received the aggregate address.
I am interested to see if there is anyone out there who does NOT use AS_SET
when aggregating and can you specify the reasons why you have found this to
be a prefered method over the one described above?
-David Voss
This archive was generated by hypermail 2.1.4 : Mon Oct 07 2002 - 07:44:07 GMT-3