Subject: Re: Pathologic Solaris TCP behavior

From: der Mouse <[email-masked]>
Date: Tue, 21 Mar 2000 01:42:22 -0500 (EST)

> Has anyone experienced problems with Solaris TCP where you basically
> get modem-speed performance over a full duplex ethernet link?

This sounds to me a lot more like broken full-duplex than like a broken
TCP stack.  I had very similar performance problems with a NetBSD/alpha
machine on 100baseTX until I disabled autonegotiation, hardwiring both
ends to 100/full.  In another case I know of, the problem was that the
OS (a Linux variant, in this case) claimed the card was in full-duplex
but it was not in fact so.

Do you have the switch set to autonegotiate?  The Netras?  Try
hand-configuring full-duplex.  If that fails try hand-configuring
half-duplex.  Also try hand-configuring the speed, if the cards are
100-capable; if your wiring is not up to scratch it may work at 10 but
produce piles of errors at 100.

> On the incoming interface of the destination machine (which is
> completely unloaded) I get a large number of Ierrs.....

This is a very strong indication that the problem is high packet loss
caused by broken hardware behavior, not a TCP stack problem at all.
The stack is probably doing as well as it can given the high loss rates
it's faced with.  My first guess is a duplex mismatch; my second is
attempting 100baseTX over wiring that's not up to spec for 100Mbit.

					der Mouse

			       [email-masked]
		     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B