> Alternatively, take your favorite test programs, such as John's,
quoted text
> and make a second pair that reverses the direction the data is 
> sent.  So one pair is server sends, the other is server receives,
> try both.  That's where we started, BitKeeper, my stripped down test,
> and John's test all exhibit the same behavior.  And the rsh test
> is just a really simple way to demonstrate it.

Netperf TCP_STREAM - server receives.  TCP_MAERTS (STREAM backwards) - server sends:

[root@hpcpc106 ~]# netperf -H 192.168.2.107
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.2.107 
(192.168.2.107) port 0 AF_INET : demo
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

  87380  87380  87380    10.17     941.46
[root@hpcpc106 ~]# netperf -H 192.168.2.107 -t TCP_MAERTS
TCP MAERTS TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.2.107 
(192.168.2.107) port 0 AF_INET : demo
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

  87380  87380  87380    10.15     941.35

The above took all the defaults for socket buffers and such.

  [root@hpcpc106 ~]# uname -a
Linux hpcpc106.cup.hp.com 2.6.18-8.el5 #1 SMP Fri Jan 26 14:16:09 EST 2007 ia64 
ia64 ia64 GNU/Linux

[root@hpcpc106 ~]# ethtool -i eth2
driver: e1000
version: 7.2.7-k2-NAPI
firmware-version: N/A
bus-info: 0000:06:01.0

between a pair of 1.6 GHz itanium2 montecito rx2660's with a dual-port HP A9900A 
(Intel 82546GB) in slot 3 of the io cage on each.  Connection is actually 
back-to-back rather than through a switch.  I'm afraid I've nothing older installed.

sysctl settings attached

Where I do have things connected via a switch (HP ProCurve 3500 IIRC, perhaps a 
2724) is through the core BCM5704:

[root@hpcpc106 netperf2_work]# netperf -H hpcpc107
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to hpcpc107.cup.hp.com 
(16.89.84.107) port 0 AF_INET : demo
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

  87380  87380  87380    10.03     941.41

[root@hpcpc106 netperf2_work]# netperf -H hpcpc107 -t TCP_MAERTS
TCP MAERTS TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to hpcpc107.cup.hp.com 
(16.89.84.107) port 0 AF_INET : demo
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

  87380  87380  87380    10.03     941.37

[root@hpcpc106 netperf2_work]# ethtool -i eth0
driver: tg3
version: 3.65-rh
firmware-version: 5704-v3.27
bus-info: 0000:01:02.0

rick jones