Jumbo Frames

[Ronnie Turrentine]

My company has an application that utilitizes gigabit jumbo frames for
tranferring data from a device to the local computer. We need to use jumbo
frames to obtain the performance we need. This works fine on XP and on some
Vista systems.

The Vista system that it works on is a low end system running Vista
Business. I have a high end laptop with Vista and it does not work. I've
tried Vista 32 and Vista 64.

The interesting thing is if I boot into safe mode with networking enabled,
it works. I tried booting with all services and startup programs disabled
and it didn't work.

Any suggestions? I have aero turned off. I wonder if Vista security is
doing something to "help" me out. I also have the firewall turned off.

 

[Jack \(MVP-Networking\).]

Hi
Vista by default is set to TCP/IP auto-tuning.
MTU is part of TCP/IP. Jumbo Frames usually entails MTU of 9000.
Maybe this can Help, http://www.speedguide.net/faq_in_q.php?qid=247
Jack (MS, MVP-Networking)

 

[Ronnie Turrentine]

Thanks for the pointer but that didn't seem to help.

I wonder if it could be something in the GUI for Vista. I've disabled aero.
I've installed Vista 32 and Vista 64 on two other systems and it works fine.
Those systems do have slower CPUs, lower RAM and standard graphics.

The laptop is a high end ASUS G50 gaming system. Again, it works in safe
mode but not normal mode. The gigabit ethernet driver has the Realtek
chipset in it.

My app updates a counter on it's GUI when receiving the data. The data is
being received in another thread.

Something that really confuses me is this scenario....
I have another application open (like Acrobat Reader) with a reasonable file
open so I can scroll using the arrow keys.
If I select the other app and scroll using the arrow keys, the counter in my
app starts updating and it receives the data.

I tried using Wireshark to watch the data and I can see the jumbo framesize
is negotiated correctly. I can see I'm getting a lot of retransmissions and
dropped packets. I'm not a networking guru so I'm not sure how to read all
of the data.

Any other suggestions?