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Re: TCP congestion

  • From: Philip Lavine
  • Date: Thu Jul 12 16:31:39 2007
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I just don't understand how if there is 1 segment that gets lost how this could
translate to such a catastrophic long period of slow-start. How can I minimize t
he impact of  the inevitable segment loss/out of order over a WAN. Is QoS the on
ly option?

----- Original Message ----
From: Stephen Wilcox <[email protected]>
To: Philip Lavine <[email protected]>
Cc: nanog <[email protected]>
Sent: Thursday, July 12, 2007 1:09:24 PM
Subject: Re: TCP congestion

Well, if its out of order its the same as if its lost or delayed, it needs to se
e that missing segment before the window is full

As mentioned you need to get dumps from both ends, you will almost definitely fi
nd that you have packet loss which tripped tcp's slow start mechanism.


On Thu, Jul 12, 2007 at 12:02:49PM -0700, Philip Lavine wrote:
> Even if the segment was received out of order what would cause congestion avoi
dance to starve the connection of legitimate traffic for 15 to 20 seconds? That
is the core of the problem.
> ----- Original Message ----
> From: Fred Baker <[email protected]>
> To: Brian Knoll <[email protected]>
> Cc: Philip Lavine <[email protected]>; nanog <[email protected]>
> Sent: Thursday, July 12, 2007 11:56:06 AM
> Subject: Re: TCP congestion
> On Jul 12, 2007, at 11:42 AM, Brian Knoll ((TTNET)) wrote:
> > If the receiver is sending a DUP ACK, then the sender either never
> > received the first ACK or it didn't receive it within the timeframe it
> > expected.
> or received it out of order.
> Yes, a tcpdump trace is the first step.
> ______________________________________________________________________________
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