""Casey, Paul (6822)"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hello, > > Anyone any thought on the following lab Im working on, > > AS 1 and AS2 are connected to AS3 via EBGP as well as each other. > (Triangular fashion) > AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP > to AS3 > > > Objective: > Ensure that AS3 routes to 81.0.0.0/8 via AS 1. > Local preference or AS-path attributes may NOT be modified.
OK, so you can't set local-pref or prepend the AS string... Things that spring immediately to mind in no particular order are: 1) If both ebgp peerings in AS3 are on the same router, then just set a weight preferencing the AS1 route over the AS2 route. If there are multiple peering routers you could set the weight and a community, and use that community to set a weight on the other BGP routers via a route-map on the iBGP peering. 2) You could set a med, and use the bgp always-compare-med option. 3) You could use a filter/prefix list to refuse accepting that prefix from AS2 in the first place. > I'm thinking to do this, to use policy routing, or is there another way to > deal with a situation like this. There are a lot of ways to do most things in BGP. local-pref and as-prepend are the most common ways to do this particular type of traffic management, but if you know the decision algorithm and the various prefix-list/distribute-list/filter-list/route-map options that can be applied to a peering there are plenty of other answers to be found. > Any help appreciated. > Kind regards. > Paul. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54438&t=54429 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
