08R2 WDS slow PXE TFTP to physical clients

[DigeratiPrime]

I am getting slow TFTP transfers from WDS to physical NICs, but not to virtual NICs. I've checked with a managed switch and the port link is 1000FDX when this is happening, a Netmon capture shows that WDS is sending empty and duplicate packets and taking a long time to receive packets from the client. This happens with 3 different physical machines with nvidia, yukon, and intel adapters, but not with vmware pxe boot on the same clients. WDS is running on Server 2008 R2 build 7600 child partition, parent is Server 2008 R2 RC (7100) still.

In the trace below I copied the Boot folder from the REMINST share to the parent partition and a Win7 client on LAN, and later tried to PXE boot the same client.

[cluberti]

Is the server in question a 2003 or 2008 (or 2008 R2) WDS server? Also, are you sharing the NIC between the hyper-v hosts and the OS? If you've got a NIC that isn't bound to hyper-v, try that as well to see if it changes anything.

[DigeratiPrime]

I am using R2 for parent and child partitions, parent is RC 7100, child's RTM 7600.

The parent has it's own physical adapter, child uses an external network adapter which is not shared with the mangement operating system.

Here is a screenshot of the problem, notice the time offset:

What's interesting is the packets themselves appear identical between clients that have and do not have the problem.

Also this only starts happening when Boot.SDI is being sent.

I restarted the WDS server but it's the same.

Also I could post a CAP file if desired.

[cluberti]

Well, if you can repro it with an RTM parent (I'd suggest testing), I'm guessing you'd have found an issue to file.

[DigeratiPrime]

Well, if you can repro it with an RTM parent (I'd suggest testing), I'm guessing you'd have found an issue to file.

Did a clean install of R2 7600 for the parent and child partitions, same behavior. I'll try setting up R2 7600 as a VMware guest to see if the Client deployment is still slow.

[DigeratiPrime]

This continues to not make sense, I added a child with a legacy network adapter on the same external virtual network as the WDS server and it PXE boots fast. So virtual machines are still booting fast and real nics still slow, seemingly regardless of the topology.

[mpietsch]

same issue here. forcing the clients gbit-networkcard to 100mbits (via switch console) makes it a bit faster but not much.

happens here with intel onboard cards. however i'm using a few new pcs with an nvidia onboard gbit-networkcard which tftp-boot very fast from the same server on the same switch.

tried everything from disabling tcp offloading to change buffers - no luck.

Edited October 19, 2009 by mpietsch