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New Member

BGP Load Sharing


We have a router running bgp, and two t1 going to two different ISPs. That way if one T1 goes down, we're not without internet coverage. However, we are in the process of changing our connection to having one T1 going to one ISP, and a 10mbps ethernet connection going to the other isp which is located here on campus.

I have two questions:

1. How do we configure the router so that if the serial T1 goes down the Ethernet picks up, and vice versa?

2. How do I setup some type of load balancing so that the load is equally shared, or to send most of the traffic on the ethernet interface and about 30 percent on the serial.

Thanks in advance for your answers.

New Member

Re: BGP Load Sharing


In BGP load balancing occur only when 2 routes come from the same External AS & have the same IGP metric to those neigbors & if maximum path is larger than 1 . Your situation is not so. In your situation you can advirtise your prefix to both peers. But you can change attributes ( AS path ) to impact incoming traffic into your AS. So in case of any peer failure your prefixes are advirtised through other peer. Much like the same you can change some attributes ( local pref ) of the comming BGP updates into your AS to affect your outgoing traffic. Load balancing is a see and try. You can change your parameters for different prefixes to be able to balance your incoming & outgoing traffic more better. document may help you to understand the features you can use.