eBGP Load Balancing

Unanswered Question
Aug 29th, 2008

I have an eBGP connection between two routers, I want to add another link for load balancing. The 2 new routers will run eBGP between them as well. How do I achieve load balancing between the two links. Do I need to set up any parameters, or does BGP load balance by default?

Thanks for the help, and let me know if i need to give more details

I have this problem too.
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Giuseppe Larosa Fri, 08/29/2008 - 08:39

Hello Gary,

you need to perform some configuration to take advantage of both links.

There are two ways of doing this:

a) move the eBGP session to loopback addresses and with two static routes on each router with destination the neighbor router's loopback address

b) define a second eBGP session on the physical ip addresses of both routers and add the command maximum-paths 2 under router bgp x on both routers

a) config


int loop1

ip address

desc ebgp loop


router bgp X

neighbor remote-as y

neighbor update-source loop1

neighbor ebgp-multihop 2


ip route s0/0

ip route s0/1

the same must be done on the second router define loop1 wiht ip add static routes for net uing the links define in the same way the eBGP session

b) config

nothing special

config a has to be preferred because only one copy of each advertisement is received for example when you receive a full BGP internet table.

note: in this case you see only one route for each prefix but there are two routes for the eBGP next-hop and recursion provides load-balancing.

config b uses the maxim-paths and in this case you see two B routes for each prefix in the routing table.

Hope to help



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