Troubleshooting TCP performance tutorial

Joe Hamelin joe at
Sat Sep 18 00:33:40 UTC 2010

In a situation like yours I found Internet Core Protocols: The
Definitive Guide by Eric Hall an easy to read guide to insuring that
what you are seeing via wireshark.  I was able to find an issue with
the DF bit in a load balancer that was causing confounding headaches
in a network using wireshark and this book.

Walk it through the syn-ack dance and don't trust that the devices are
handling it correctly. Start at one end and work your way through and
insure to YOUR satisfaction that every device proscribes to the
protocol.  Don't rush, don't jump to conclusions.  Just follow the
packet.  That's the best advice I can give you.
Joe Hamelin, W7COM, Tulalip, WA, 360-474-7474

On Fri, Sep 17, 2010 at 5:06 PM, Abel Alejandro
<aalejandro at> wrote:
> Greetings,
> This past week I have been trying to find the root cause of tcp
> performance problems of a few clients that are using a third party metro
> Ethernet for transport. RFC2544 tests (Layer 2) and iperf using UDP give
> good symmetric performance almost 100% the speed of the circuit. However
> all kind of TCP tests result in some kind of asymmetrical deficiency,
> either the upstream or downstream of the client is hugely different. The
> latency is not a huge factor since all the metro Ethernet connections
> have less than 2 ms.
> So the question basically if is there a good tutorial or white paper for
> troubleshooting tcp with emphasis of using tools like Wireshark to debug
> and track this kind of problems.
> Regards,
> Abel.

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