bgp guru

[whanson]

I am trying to impact the incoming traffic on a particular subnet. I have two connections to the same ISP same AS at different locations and another connction to a separate ISP. I use filter list to control the advertised routes and all is well but there is one subnet that comes in location A isp A and I want it to come in location B isp A so I added a route map at location A for the specific subnet and set the metric so I should theoretically come in location B but instead I lost all connectivity for all subnets. If I use a route-map out does that override a filter list? As ever thx

[whanson]

Thanks all for all the help I got it. Sorry I appeared so dense to some.

[Peter Paluch]

Bill,

It's ok. You are always welcome.

Best regards,

Peter

[whanson]

Peter,

last question for now. I see from the order of route selection that metric and local pref really are only for the same AS so if I have two networks I am advertising and I want return traffic to favor isp a over isp b it sounds like expanding the as-path is the only way.

[Peter Paluch]

Hello Bill,

Yes, you are right. In certain cases, if you have multiple connections to a single provider, you could influence his routing using the MED attribute, however, in general case if you have more distinct ISPs, the AS-PATH prepending is usually the only choice simple enough.

Best regards,

Peter