Agreed by me.. the trick is it seems that we want to remove AS1 from the
AS-path without filtering the whole IP Block. As long as AS2 Can Create the
route you want advertised to R3,(Network Statments pointing to Null route
injections will do this and put it in the BGP table). You can then filter
routes originating in AS1 that has to traverse AS2 to get to AS3, without
disrupting routes originated in other AS's besides AS1 that DO traverse AS2
to get to AS3. This is plain vanilla as-path filtering to me.
EX:
(routesnotwanted) (routeswanted)-->
AS1--------------->AS2------------------>AS3
/
/
/
/
/
AS4-----------^
(routeswanted)
If the main objective is to filter routes orgininating in AS1 but not 2 then,
_200_ & ! _200_ 100$ is a way to go. You then just have to keep in mind
where the routes get originated.
All the best,
Sal
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=66949&t=66928
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