Linux Router: TCP slow, UDP fast
chris at ghostbusters.co.uk
Sun Feb 15 09:24:50 UTC 2009
Thanks, Karl, Allen and Nickola.
I failed-over to another router last night and briefly had full expected
throughput but this morning despite dropping providers and moving between
routers again for trial and error I still see _outbound_ TCP at about the
same 300 - 600kbps per session.
I eliminated conntract modules firstly, then iptables as a whole. I've
eliminated TSO and checksumming (which caused very sticky connections) on
the e1000 NIC.
The failover router has a slightly older kernel and was working before
Christmas so it's not most likely not kernel versions. I've also tried
removing FIB_TRIE as a stab in the dark with no success. And the failover
router connects using FE not GE so I've eliminated NICs and connection
speeds to a front-facing switch.
The only constant is the front-facing switch (it's negotiating perfectly at
FD though) so all I can think of is removing that from the equation.
It's definitely only _outbound_ TCP getting buffered though ! I've pushed
92Mbps on a FE link with UDP and uploaded at 16Mbps on a 16Mbps link.
Any last ideas appreciated before causing headaches removing switches would
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