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  • From: jklowden AT schemamania.org
  • To: FreeTDS Development Group <freetds AT lists.ibiblio.org>
  • Subject: Re: [freetds] Malformed Packets
  • Date: Thu, 30 Jul 2009 12:04:12 -0400

On Thu, Jul 30, 2009 at 11:29:45AM -0400, Steve Fischer wrote:
> I am a network engineer investigating a complaint of slow application
> performance. In doing a capture (using Wireshark), I noticed a fair
> number (about 125 in a 10 minute window) of responses coming from a host
> on 1433/TCP (Response Packet) with a Malformed Packet:TDS label on the
> payload. I know that 1433/TCP is the port Microsoft SQL Server uses,
> and until today, had never heard of TDS as a protocol. Can anyone here
> shed some light on this?

http://www.freetds.org/tds.html

I think the Wireshark report is likely bogus: the packet doesn't conform to
its idea of a proper TDS packet, but that's only because the Wireshark TDS
filter isn't maintained. That's my first guess.

(Improvements to that filter would be a service to the community.)

If you want to get this off your plate -- and you should, because dimes to
donughts it's not a network issue -- look at the timings for queries arriving
a the server and the server's response. Unless the network is seriously
overloaded or misconfigured, almost all the delay is in the the server
response time.

The solution to "slow application performance" is almost never at the network
layer. Rather, it's almost always in normalized logical design, proper
selection of indexes at the physical layer, and careful use by the
application of the server, i.e. minimizing query results and round-trips to
the server.

HTH.

--jkl




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