Bridge May Not Work With a Non-Promiscuous Mode Network Adapter


Some network interface cards (NICs) may not work after you try to create a network bridge. Specifically, the bridge seems to be created but it does not work (traffic is not passed).


This problem occurs because some NICs do not automatically enter into Promiscuous mode to create a successful network bridge.


To work around this behavior, force the adapter into Compatibility mode:

  1. At a command prompt, type netsh bridge show adapter.
  2. Locate the identification number of the NIC that is not responding.
  3. If the NIC is not in Compatibility mode, you can change it manually if you type the following command, where 1 is the number of the NIC that is displayed in the first step:
    netsh bridge set adapter 1 forcecompatmode=enable
  4. Run the netsh bridge show adapter command again to verify that the ForceCompatabilityMode field for the NIC is displayed as Enabled.

More Information

The following NICs may exhibit this behavior:

  • Proxim Symphony Cordless PnP ISA card
  • DWL-120 USB 802.11b
  • 5.8GHz RadioLAN card
Additionally, contact the manufacturer or check their Web site for more information about possible updates.

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Article ID: 302348 - Last Review: Oct 23, 2008 - Revision: 1