[c-nsp] BGP load balancing (outbound)

[Peter Rathlev]

On Tue, 2010-05-18 at 09:58 -0400, Randy McAnally wrote:
> I can find very little info on 'bgp bestpath as-path multipath-relax'
> 
> Is this per-packet, or per-flow load balancing?

It just makes it possible for BGP to install more routes into the RIB.
Just like regular BGP multipath, but now "breaking" the normal selection
criteria.

The specific load balancing algo depends on the platform, but typically
it's CEF deterministic based on L3 or L3/L4 information.

> How much memory usage would it increase assuming 2-3 full tables in memory
> already (around 400Mb usage, 1Gb RAM)?  Looks like you've got 2 defaults only.

Memory consumed by BGP isn't changed, but RIB and FIB/LFIB memory (TCAM
space) usage is increased. With a PFC3BXL you might be safe there
though.

-- 
Peter