tuning igb 82257 in FreeBSD 8.0

[Dmukha Nikolay]

Hello.
The server is L2 bridge.
uname -a:
FreeBSD 8.0-STABLE-201005 FreeBSD 8.0-STABLE-201005 #1: Wed Jun 23 12:29:30 UTC 2010  /usr/src/sys/amd64/compile/MYKERNEL  amd64
The network adapter is: Intel Gigabit ET Quad Port Server Adapter (Ethernet controller Intel 82257).

Default drivers version in FreeBSD 8.0-STABLE-201005 is Intel(R) PRO/1000 Network Connection version - 1.9.5. 
We try to set up options below in /boot/loader.conf:
if_igb_load="YES"
hw.igb.rxd=4096
hw.igb.txd=4096
hw.igb.num_queues=0  
hw.igb.enable_aim=1
hw.igb.low_latency=1000
hw.igb.ave_latency=2000
hw.igb.bulk_latency=4000
hw.igb.rx_process_limit=100
hw.igb.fc_setting=0
hw.igb.lro=0

The system boots successfully with drivers 1.9.5. But there are no specified earlier options in sysctl -a | grep igb.0, for example.
sysctl -a|grep igb.0:
dev.igb.0.%desc: Intel(R) PRO/1000 Network Connection version - 1.9.5
dev.igb.0.%driver: igb
dev.igb.0.%location: slot=0 function=0
dev.igb.0.%pnpinfo: vendor=0x8086 device=0x10e8 subvendor=0x8086 subdevice=0xa02b class=0x020000
dev.igb.0.%parent: pci3
dev.igb.0.debug: -1
dev.igb.0.stats: -1
dev.igb.0.flow_control: 3
dev.igb.0.enable_aim: 1
dev.igb.0.rx_processing_limit: 100

We try to change drivers version to 1.8.4 from official site. The system boots successfully too and I can see this options in sysctl -a | grep igb.0.
But there was some problem: I can explore only some sites through internet browser, for exmaple yandex.ru. Most of the sites I can`t see through the internet browser. But I can "ping" these sites by DNS name, I get DNS query successfully and I can see by tcpdump server replies.

Next we have changed the drivers version to 1.7.4. But wih these options the system does not boot. There was an error:
GET BUF: dmamap load failure - 12

I try to change hw.igb.rxd and hw.igb.txd in /boot/loader.conf like:
1.hw.igb.rxd=2048
  hw.igb.txd=4096;
2.hw.igb.rxd=1024
  hw.igb.txd=1024 

- the same error.

Also the same error with drivers version 1.7.3.

But!!! We have another server: L2 bridge too with the same network adapter.
uname -a:
FreeBSD 7.2-STABLE-200906 FreeBSD 7.2-STABLE-200906 #1: Tue Oct  6 10:26:41 MSD 2009 /usr/src/sys/amd64/compile/MYKERNEL  amd64
And we have no such problems like in bridge FreeBSD 8.0.

Can anyone help me? Maybe I shouldn`t initialize such options in /loader.conf? Maybe in somewhere else?
Thanks fo reply.