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load balancing with BGP

I have a 2 serial links (each serial is E1) and they operate into bgp , but most of the time i see that the load balancing is not working well (sometimes the first link is 1.8M and the other one is 1.1M ...and vise versa ..how can i get full load balancing...)

2 REPLIES

Re: load balancing with BGP

Have you configured maximum-paths 2 for BGP ??

You might want to use cef and see how the performance is.??

ip cef ---- globally

and on each serial interface,

ip load-sharing per-packet

Silver

Re: load balancing with BGP

With BGP you get to pick between high availability and load sharing. The suggestions from "thisisshanky" are good if both your links go from one router at your site to the same router at the ISP's point of presence, which allows you to get near perfect load sharing, but makes you vulnerable to multiple single points of failure.

My assumption, since you are already running BGP, is that you are more interested in enhancing availability. In this case, the two routes are independent and per packet load balancing will lead to more performance problems than it cures (if the two links are diverse enough to provide good redundancy, they are diverse enough to introduce lots of out-of-order packet delivery unless per-destination load balancing is used).

With per-destination, you can expect to see the load balancing unbalance you are currently experiencing. By twidling with routes, you may be able to even the loading a bit more, but expecting perfection is unrealistic. And even that may be optimistic, depending upon your traffic patterns. My experience has been that getting two links within 50% of each other most of the time and averaging the same load over a longer period of time is about the best you can expect with two diverse links.

Vincent C Jones

www.networkingunlimited.com

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