Network Bridge causes extrem slow TCP transfer in one direction

Question

Duplicate from: https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/network-bridge-causes-extrem-slow-tcp-transfer-in/cb4fe248-2f4d-4605-b6a6-b856948dbe45

Host:

Edition Windows 10 Enterprise

Version 20H2

Installed at 22.10.2021

Build 19042.1348

Windows Feature Experience Pack 120.2212.3920.0

Guest system (VMware image):

OS Name Microsoft Windows 10 Enterprise

Version 10.0.18362 Build 18362

System Model VMware7,1

1) Without bridge (left VM, right host system): 970Mbit/s

2) With bridge (set the bridge to static IP, no change on host): 3.3Mbit when sending from guest system (VM, left) to host

3) Deactivating the 2nd network adapter (which is not used at all): ~3Mbit

4) Deactivating the 2nd network adapter (which is not used at all) in the bridge: ~3Mbit

5) the other direction, from host (right in image) to guest system: ~250Mbit

The network settings of the network bridge:

I set the Jumbo Packet to 9014 bytes, when it is set to "disabled" the bandwidth is much lower (around 0.2Mbit).

I dumped the output of "Get-NetAdapterAdvancedProperty -Name "Network Bridge" -AllProperties | Format-Table -AutoSize | Out-File -Width 300 "network.txt"" to

https://pastebin.com/raw/xPm8QX6E

Wireshark from guest system:

Wireshark of same experiment from host system:

I tried pretty much all advanced network adapter settings in the guest system to improve the bandwidth, nothing improved it to usable speeds. (buffer sizes, MTU, link speed, rss)

I do not fully understand why just the existence of the network bridge reduces the bandwidth so much by causing many TCP retransmissions.

What else can I do?

Best wishes![no-bridge.png][8]

Answer 1

In case anyone get similar problem. I was able to solve the problem with the solution in this webpage. https://community.intel.com/t5/Wireless/Hyper-V-External-Virtual-Switch-Bridge-Mode-Slow-download-speeds/td-p/1222149

Answer 2

Many consumer-grade network adapters do a poor job of hosting an external virtual switch so expect some slowness. That being said I'd ask for help with vmware in dedicated forums over here.
https://communities.vmware.com/

--please don't forget to upvote and Accept as answer if the reply is helpful--

Answer 3

same behavior can be observed on an industrial PC as well, it seems to be related to the multiplexer software

Sounds good, I'd try asking for help with vmware in dedicated forums over here.
https://communities.vmware.com/

--please don't forget to upvote and Accept as answer if the reply is helpful--

Answer 4

I'm sorry I expressed myself wrong.
I meant: As the same problem (extreme low network bandwidth through bridged adapters) can be reproduced on a PC without VMware , bare metal, it is not related to VMware.
So it must be related to the MS-multiplexer software (part of the windows bridging feature).

Answer 5

extreme low network bandwidth through bridged adapters can be reproduced on a PC without VMware

I'd raise this issue with the pc or hardware manufacturer.

--please don't forget to upvote and Accept as answer if the reply is helpful--