[c-nsp] Troubleshoot UDP out-of-sequence

[Persio Pucci]

Hi folks,

I am having some problems trying to figure out what could be causing UDP
packets get out-of-sequence on some multicast streams (market data) between
Sao Paulo and New York.

There is no part of this path with parallel, load-balanced connections,
which could be a obvious cause. What else could I check? The packets do
arrive, so they are not being dropped on the way, but they arrive out of
sequence, being useless to the application.

Also, we are monitoring on both ends sniffed data so I know I receive them
in order in Sao Paulo, but not in New York. This is affecting a really small
percentage of the data (less than 0,001%), but I believe this should be 0,
and so do my customers (with reason).

Any ideas or tips?