openstack 不能访问外网

[yuifoon]

按官方文档进行安装
http://docs.openstack.org/havana/install-guide/install/yum/content/nova-network.html

不过只有一个网卡。
配置如下
network_manager = nova.network.manager.FlatDHCPManager
firewall_driver = nova.virt.libvirt.firewall.IptablesFirewallDriver
network_size = 254
allow_same_net_traffic = False
multi_host = True
send_arp_for_ha = True
share_dhcp_address = True
force_dhcp_release = True
flat_interface = eth0
flat_network_bridge = br100
public_interface = eth0

启动实例后，在计算节点与虚拟机可以通信，虚拟机不能访问外网
外部了ping不到 网桥 11.0.0.1

[root@controller ~]# ifconfig
br100 Link encap:Ethernet HWaddr 00:50:56:99:2F:62
inet addr:11.0.0.1 Bcast:11.0.0.255 Mask:255.255.255.0
inet6 addr: fe80::8819:c4ff:fe6f:a026/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:7481 errors:0 dropped:0 overruns:0 frame:0
TX packets:2143 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:514926 (502.8 KiB) TX bytes:217497 (212.3 KiB)

eth0 Link encap:Ethernet HWaddr 00:50:56:99:2F:62
inet6 addr: fe80::250:56ff:fe99:2f62/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:8724 errors:0 dropped:0 overruns:0 frame:0
TX packets:2503 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:702225 (685.7 KiB) TX bytes:257402 (251.3 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:18435 errors:0 dropped:0 overruns:0 frame:0
TX packets:18435 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:5017823 (4.7 MiB) TX bytes:5017823 (4.7 MiB)

virbr0 Link encap:Ethernet HWaddr 52:54:00:F4:43:99
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

vnet0 Link encap:Ethernet HWaddr FE:16:3E:37:76:57
inet6 addr: fe80::fc16:3eff:fe37:7657/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:436 errors:0 dropped:0 overruns:0 frame:0
TX packets:5964 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:60367 (58.9 KiB) TX bytes:472516 (461.4 KiB)

有哪位大哥知道哪里出错的么