[c-nsp] ECMP failing over time?

[John Neiberger]

I hate to answer my own question, but I think I figured it out. We're
using s-g-hash basic, which is prone to polarization. I think that's
what we're seeing. Our traffic has become polarized and has developed
an affinity for a subset of links in our "bundles". I'm recommending
that we switch to s-g-hash next-hop-based to see if that resolves the
problem.

On Sat, Oct 2, 2010 at 2:18 PM, John Neiberger <jneiberger at gmail.com> wrote:
> We converted several connections last week from Etherchannels to
> routed links with ECMP. We verified that traffic was load-sharing over
> those links after making the change. Now, a week later, we are seeing
> instances where traffic is preferring one or two links out of each
> "bundle". In some cases all the traffic is flowing over a single link
> in a four-link setup. This is overloading those connections and we
> can't figure out why. We are using s-g-hash basic. Should we switch to
> s-g-hash next-hop-based?
>
> This is causing production issues right now, so I've opened up a TAC
> case, but I thought I'd ask here, as well, just in case someone had
> seen this before.
>
> Thanks,
> John
>