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

Matthew Melbourne matt at melbourne.org.uk
Fri Feb 5 06:32:33 EST 2010


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?



Matthew Melbourne

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