network throughput very slow between windows network client and windows 7 guest

[Randy Syring]

Setup Summary:

Host:

• Core 2 Quad, 8 GB ram, RAID 5 hardware controller
• Xubuntu 9.10 64-bit

Guests:

• Windows 7 (32 or 64 bit, problem occurs with both)
• Ubuntu 8.10 Server (no problems here)

Network Clients (gigabit network):

• Windows Vista (has problem)
• Windows 2003 Server (has problem)
• CentOs 5.4 (no problem)

Problem:

• Download throughput from a Windows 7 guest to a Windows network client is very slow.
• This problem also occurs with vmware workstation windows guests.
• Linux guests do not have this problem.
• Linux clients do not have this problem.

Example Throughput:

​http://docs.google.com/leaf?id=0Ahofo9Qth-tXdFFEaFN3YnRLWVdtQVlTaXN6aVZXdGc&sort=name&layout=list&num=50

Other Info

• I tried several different flavors of ubuntu x86/x86_64 and slackware64 and three different host machines. The problem was evident in all of them.
• I also tried VirtualBox 3.08 on Slackware64 and the problem was present there as well.

[Randy Syring]

Update: I did some testing with the network connection settings on my vista network client. It had an entry for "Deterministic Network Enhancer" (DNE). When I unchecked that item, download speeds from the windows guest came in at 16-20 MB/s. FYI, the DNE is part of VPN clients including Cisco's client.

My windows 2003 box does not have that entry and the downloads are still in the 1-3 MB/s range.