TCP congestion

Thu Jul 12 19:43:26 UTC 2007

owner-nanog at merit.edu wrote on 07/12/2007 02:07:00 PM:

> Typical Problem Scenario: Data transmission is humming along
> consistently at 2 Mbps, all of a sudden transmission rates drop to
> nothing then pickup again after 15-20 seconds. Prior to the drop off
> (based on packet capture) there is usually a DUP ACK/SACK coming
> from the receiver followed by the Retransmits and congestion
> avoidence. What is strange is there is nothing prior to the drop off
> that would be an impetus for congestion (no high BW utilization or
> packet loss).

Perhaps you're filling buffers by flowing from a 1Gbps link into a 9Mbps
circuit. Dropped packets induces slow-start/congestion avoidance.

Joe
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