[c-nsp] Load-sharing with two links to the same ISP

[Ivan Pepelnjak]

This might help:

http://www.nil.com/ipcorner/LoadBalancingBGP/

Ivan Pepelnjak
blog.ioshints.info / www.ioshints.info

> -----Original Message-----
> From: Matthew Melbourne [mailto:matt at melbourne.org.uk]
> Sent: Friday, February 05, 2010 12:33 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Load-sharing with two links to the same ISP
> 
> Hi,
> 
> What techniques are available to load-share traffic on two links (of
> equal bandwidth) to the same ISP  (same AS) given that BGP only enters
> the best path into the RIB? We could announce our prefixes over both
> links, but splitting the preferred path announcements over the two
> links, either using MED or ISP communities, but this only really
> addresses inbound traffic. More of an issue is trying to load-share
> outbound traffic; we assume we'll learn the same set of prefixes over
> both links from the same ISP - one technique may be to simple split
> the IPv4 address space in half and local-pref accordingly to prefer
> one link or the other depending on the destination IP prefix?
> 
> Cheers,
> 
> Matt
> 
> --
> Matthew Melbourne