Situation is 3 windows 2003 servers (32bit) one was DC, one was a TS and the other was a ISA (& default gateway). Introduced 4 new boxes. One new DC W2k8Standard, 2 W2k8 Enterpriseservers acting as virtual hosts for 4 virtual servers each and one w2k3 box running isa 2006 within a VM on a server running w2k8 standard. All network connections a gigabit. All new servers are 64 bit apart from the one for the ISA server and running SP2 Transferred all DC roles to new DC and network speed was fine before the default gateway was switched from old isa server to new isa server then the following has occurred. File transferred from new DC to any other server (except new isa) fine (500mb in approx ten seconds). Files transferred between any virtual server and another virtual server fine with the same speeds as file from the DC. Files transferred from new ISA server to any other server except new DC also fine. However files transferred to new DC or new isa from any other server crawl. Transferring the same 500mb takes about 10 minutes. I have already tried:disable receive-side scalingdisable chimney offload statedisable receive window auto tuningdisable offloading in the network adapter propertiesdisable ipv6 in the network adapter

Have you tried disabling SMBv2 ?Look: http://social.technet.microsoft.com/Forums/en-US/winserverfiles/thread/d9c254f8-bebf-4a11-8578-7fe27e24364dLeonardo Fagundes

Hello, Thank you for your post here. From the description, the new DC and new ISA server experience slow transform speed after you switched from the old ISA serer to the new one. 1. Is the new DC located in the internal network that other Windows Server 2008 servers reside in? 2. As the issue happens after the introduction of new ISA server, I'd like to suggest you check how everything works if you temporarily disable the ISA firewall. To do that: a. At the command prompt, run net stop fweng /y to stop the Firewall Packet Engine and the other firewall components, which opens the ISA server to all network traffic. To protect your network from external network, please make sure that you have disabled the NIC to Internet before you disable Firewall Packet Engine. b. Check how it works if you copy a file from ISA to DC. c. You may reset the ISA server to restore the ISA services. If you have any questions or concerns, please do not hesitate to let me know.

1. Ye sit resides on the same internal network2. Stopping the firewall makes no difference. slow file transfers are not between the isa and new dc but any server to new dc or any server to isahost (the isa is running in a virtual 2k3 server). file transfer speeds between isahost and new dc are fine.

Hi, Thanks for the update. To isolate the issue from network connectivity problems, I'd like to suggest you to check how it works if you disable TCP Chimney Offload, RSS and NetDMA on the problematic ISAhost and the new DC. You may refer to the following KB to disable the those advanced networking features. Information about the TCP Chimney Offload, Receive Side Scaling, and Network Direct Memory Access features in Windows Server 2008 http://support.microsoft.com/kb/951037 Slow performance when you try to access resources on your Virtual Server 2005 host computer from a guest virtual machine http://support.microsoft.com/kb/888750 If you have any questions or concerns, please do not hesitate to let me know.