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Beginner

Two default routes with BGP

We are runing BGP with our upstraem providers and receiving the default route and the IPS's subnets, when i check the next hop for the defaul route i can see two defaul routes as shown below

* 0.0.0.0 x.x.x.x (ISP1)

*> x.x.x.x (ISP2)

so all the outgoing traffic is going thtough ISP2 as its the best path.

my question, is it possible to load balance the outgoing traffic to both ISPs?

Note that I'm able to do so using the static route?

Appreciate your help with regard to this issue.

2 REPLIES 2
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Cisco Employee

Normally IOS will prevent multiple paths to be used for BGP multi-path if these paths were not advertised by the same AS.

A new know has been introduced by CSCea19918 and lets you do multi-path even if the path are not from the same AS.

The know is "bgp bestpath as-path multipath-relax". Note that this is a hidden command. You still need to configure "maximum-paths 2" if you want the 2 paths to be installed in the RIB.

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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Enthusiast

You can load balance the outgoing by using route-maps , i think the otherway you can't as the BGP always selects the best path for forwarding the traffic .

route-map outgoing permit 10

match ip address Prefix_A

set ip next-hop ISP_A ISP_B

!

route-map outgoing permit 20

match ip address Prefix_B

set ip next-hop ISP_B ISP_A

you can use also PBR with object tracking for avoding the problem of losing connectivity to any of the upstreams