[owl-users] Abnormal behavior ethernet Intel Corporation 82599EB 10-Gigabit adapter

Dear colleagues,

Thank you for answers on my previous question. Now I've got new question about network abnormal behavior.
Strange is according to "Owl router 2" on the schema below of this letter. This box based on Owl-current-20110312-x86_64.iso with compiled kernel from sources by instruction on http://openwall.info/wiki/Owl/kernel-build page. I've compiled network adapters as modules and MPTSAS driver in kernel and other settings have kept as was in Owl.
Router 2 has follow components:
MotherBoard: Intel S5000VSA
Processors: 2xIntel(R) Xeon(R) CPU E5410
Eth1: Intel Corporation 82599EB 10-Gigabit Network Connection [8086:10fb]
Eth0: Intel Corporation 82546EB Gigabit Ethernet Controller (Copper) [8086:1010]
Strange is according to low speed between client1 and client2 is approx 20-60 Kbytes/s and between Client2 and Router1 speed is 1-2kByte/s.
Between routers speed is 46 MBytes/s and between Client1 and Router2 speed is 6-8 MBytes/s.
I try all things like offer in articles http://download.intel.com/design/network/applnots/319935.pdf  and http://www.redhat.com/promo/summit/2008/downloads/pdf/Thursday/Mark_Wagner.pdf but these changes have not improve situation.
However, when I change eth1 adapter on Router 2 to "Intel Corporation 82572EI Gigabit Ethernet Controller (Fiber) [8086:107e]" speed between clients increase to normal level.

Schema
| Client1 | ----|Eth0   "Owl router1"  Eth1 |-------|Eth1   "Owl router2"  Eth0 |----|Client2|

Have you got any ideas what happen with speed?

Oleg Malykh