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New Member

BGP prefering local hop for a less specific prefix

Hi,

I have a customer who is sending me a network with a prefix of /20 and I am also learing the same network with a prefix of /22 from one of my IX peers.

So if any one on my network wants to get to the customers network it uses the IX peer as the next hop instead of the customer since that is where I m learning a more specific prefix. The customer is not ready to send the specific prefix directly to me. Now I could modify my filters to stop learning the /22 from the IX peer but I dont want to do that as I use a pre-defined template for all the IX peers and dont want to mess around with that.

Is there any way to prefer the customer as the next hop for the more specific prefix?

P.S. The customer is setup with a local-pref of 210 and the IX peers are set with local-pref of 200.

Let me know,

Thanks

3 REPLIES
Cisco Employee

Re: BGP prefering local hop for a less specific prefix

The only way to prefer the prefix from the customer is actually to receive that specific prefix from the customer as well as from the IX peer or to filter it out from the IX peer. Otherwise, the more specific prefix received from the IX peer will always be preferred as expexted.

Hope this helps,

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
New Member

Re: BGP prefering local hop for a less specific prefix

Hi,

I think u can play with the Weight Attribute to prefer the /20 path instead of the more specific path /22.Weight has more preference than Local preference in BGP path selection.Im not sure what equipment ur using but remember Weight is a Cisco-proprietary attribute and is local to the router.

Cisco Employee

Re: BGP prefering local hop for a less specific prefix

Playing with weight won't help here since these are two different prefixes and will therefore not be compared by BGP.

Hope this helps,

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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