Wireshark-users: Re: [Wireshark-users] Slow gigabit network
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From: Hansang Bae <hbae@xxxxxxxxxx>
Date: Tue, 17 Mar 2009 16:30:59 -0400
At 11:09 AM 3/10/2009, Scott Chapman wrote:
>I have experimented with forcing 1000/full explicitly on both sides with out any effect.
>
>Incidentally, I do occasionally get 20MB/sec.
>
>Before I go buy anew switch I was hoping to learn how to use wireshark to see what is going on, perhaps to help point the finger somewhere...


Scott,
Divide and conquer.  I don't recall if you tried netperf or UDP based testing tools or not.  The slowness could be your NIC, it could be the protocol in use, or it could be the switch.  Does performance stats (like perfmon if using wintel) show that cpu is shooting high?  Do you have tcp off loading enabled?  Did you try disabling it?  Did you try applying the latest NIC drivers?  

Did you try using ports 1 and 2 (not 1 and 25)?  If the are right next to each other, did you try separating them (if on 1 and 2, move it to 1 and 13) to rule out ASIC based issues?  Have you monitored netstat or switch counters (if avail) for packet drops?

hsb