Well, on my 192.168.20.x mask 255.255.255.0 network, one server's working config files are:
Ifcgf-br1: DEVICE=br1 TYPE=Bridge BOOTPROTO=none ONBOOT=yes
Ifcgf-br2: DEVICE=br2 TYPE=Bridge BOOTPROTO=none ONBOOT=yes
ifcfg-eth0: # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ DEVICE=eth0 ONBOOT=yes HWADDR=xx:xx:xx:xx:xx:xx BOOTPROTO=none BROADCAST=192.168.20.255 IPADDR=192.168.20.30 NETMASK=255.255.255.0 NETWORK=192.168.20.0 GATEWAY=192.168.20.1 TYPE=Ethernet
ifcfg-eth1: # Intel Corporation 82541PI Gigabit Ethernet Controller DEVICE=eth1 BOOTPROTO=none HWADDR=xx:xx:xx:xx:xx:xx ONBOOT=yes BRIDGE=br1 TYPE=Ethernet
ifcfg-eth2: # 3Com Corporation 3c905C-TX/TX-M [Tornado] DEVICE=eth2 BOOTPROTO=none HWADDR=xx:xx:xx:xx:xx:xx ONBOOT=yes BRIDGE=br2 TYPE=Ethernet