[libvirt-users] virtual networking - virbr0-nic interface

Shantanu Pavgi pavgi at uab.edu
Mon Sep 10 21:09:44 UTC 2012

I need some help in understanding libvirt's virtual networking. I have configured bridged networking (shared physical device) on libvirt+KVM system which is working fine. Also, I am using default NAT network on with virbr0 bridge device and virbr0-nic. I would like to get better understanding on virbr0-nic works in this virtual network configuration. I understand that traffic from virbr0 bridge is forwarded through host system's physical interface eth0 using iptables rules, but I am not following virbr0-nic's working here. I see it attached to virbr0 bridge device though.

$ brctl show
bridge name      bridge id	                 STP enabled	   interfaces
br0               8000.14feb5dc4f06	     no                      eth0

virbr0           8000.525400f5a4ed         yes                 virbr0-nic


Any pointers on how virbr0 and virbr0-nic work would be really helpful.


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