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Configuring a VM “Bridge”

Horst Mundt, one of our technical account managers in Germany, recently queried the VMware internal “network” alias for suggestions on a simple virtual appliance that acts as an Ethernet bridge. A flurry of replies ensued. Horst collated the replies into the list below that I thought was worth sharing.

Note: do this in your lab, not in your production network! A bridge will create a loop in your network if run across two uplinks (vmnics). You’ve been warned! Also note, you will need to alter the port security settings on the bridge to allow for forged transmits.

Here is Horst’s list:

1. If you’re also in need of monitoring capabilities, I’d recommend Network Security Toolkit VA    http://www.vmware.com/appliances/directory/141

2. Linux bridge module. It can be used to act as a bridge between 2 vnics.

3. Wanem (WAN Emulator) although main purpose is to emulate a wide area network with delay/drop/reordering/etc.

4. You can even use Windows 2003 to bridge multiple NICs. You can highlight multiple interfaces and bridge them. You create the bridge in the "network" window (where you see "Local Area Connection 1", etc. Just shift click on the NICs in question and you can right click and select bridge. (BTW this also works with XP)

5. The community version of Vyatta.
ISO and VA are available.

6. Use a basic linux VM and setup the bridge as follows (to bridge eth1 and eth2):
brctl addbr br0
brctl addif br0 eth1
brctl addif br0 eth2
ifconfig br0 up

7. you might want to consider Freesco, http://www.freesco.org/

3 thoughts on “Configuring a VM “Bridge”

  1. Ankit

    The sixth method doesn’t seems to be working for me.
    I have created separate virtual switches for each of the bare metal (UCS) NIC card, and am trying to bridge those switches on linux using brctl. But somehow it seems, linux is not able to bridge the packets. Any help ?

  2. Ankit

    I was able to fix the issue. Seems we need to allow the promiscious mode on both virtual switches and NIC Card for this to work,


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