interesting troubleshooting

Fri Mar 20 21:33:31 UTC 2020

I just ran into an issue that I thought was worth sharing with the NANOG
community. With recently increased visibility on keeping the Internet
running smoothly, I thought that sharing this small experience could
benefit everyone.

I was contacted by my NOC to investigate a LAG that was not distributing
traffic evenly among the members to the point where one member was
congested while the utilization on the LAG was reasonably low. Looking at
my netflow data, I was able to confirm that this was caused by a single
large flow of ESP traffic. Fortunately, I was able to shift this flow to
another path that had enough headroom available so that the flow could be
accommodated on a single member link.

With the increase in remote workers and VPN traffic that won't hash across
multiple paths, I thought this anecdote might help someone else track down
a problem that might not be so obvious.

Please take this message in the spirit in which it was intended and refrain
from the snarky "just upgrade you links" comments.

-- 
Nimrod
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