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New Member

bgp control traffic

I have a multihomed connectivity to two ISPs.Traffic is flowing through both the links but I want to control the traffic coming into our router from the outside world from one ISP with higher prefernce as compared to other ISP link.

For outbound traffic for the desired networks we can use policy based routing but how to control the traffic which is flowing into our AS???

Can somebody pls suggest some solutions or provide some desired links from where I can get the solutions.

4 REPLIES

Re: bgp control traffic

Manipulate MED to advertise routes with lower metric via one ISPs link and a higher metric via the other ISPs link. Also you could prepend AS PATH information with dummy AS numbers. When traffic comes from an end user, it will take the path with shorter AS number. (You should only prepend dummy AS to the provider whom you want to use as backup route or least preferred)

New Member

Re: bgp control traffic

Can you mention abt some confiquration to manipulate the traffic or some site where I can get the information to manipulate the traffic as were using two core routers connected to different ISP.

Re: bgp control traffic

Cisco Employee

Re: bgp control traffic

In a case like this one where you connect via to different ISPs, the MED will not help. You should try using AS path prepending to achieve your goals. By prepending your own AS number multiple times on prefixes advertised to the less prefered ISP you should be able to attain your goal.

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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