Dear All, I have the following configuration and I have ping from bridge : ///////////////////////////////////////////////////// iface eth0 inet static address 192.168.1.4 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 192.168.1.1 auto ivbr0 iface ivbr0 inet static address 192.168.1.4 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 192.168.1.1 bridge_ports eth0 bridge_stp on bridge_maxwait 0 bridge_fd 0 ///////////////////////////////////////////// # brctl show bridge name bridge id STP enabled interfaces ivbr0 8000.18037360b44e yes eth0 ///////////////////////////////////////////// my network xml file : <network> <name>myintranet</name> <uuid>465ce6cb-0a69-4f89-92ba-629349741e73</uuid> <forward mode='nat'> <interface dev="eth0" /> </forward> <bridge name='ivbr0' stp='on' delay='0' /> <mac address='52:54:00:0f:f4:f0'/> <ip address='192.168.1.4' netmask='255.255.255.0'> <dhcp> <range start='192.168.1.3' end='192.168.122.254'/> </dhcp> </ip> </network> //////////////////////////////////////////// Now , I have ping of my modem and internet. Then I did the following command : # ip l set dev ivbr0 down # brctl delbr ivbr0 # virsh net-start myintranet Network myintranet started According to above , myintranet network has been started. But with the following IP address : # ip a show dev ivbr0 17: ivbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default link/ether 52:54:00:0f:f4:f0 brd ff:ff:ff:ff:ff:ff inet 192.168.122.1/24 brd 192.168.122.255 scope global ivbr0 valid_lft forever preferred_lft forever //////// 192.168.122.1 ? Question is , Where I change this address?(I set in myxml file.) --best regards Mohsen