Please describe the problem:
I have eth0 bridged, and a tun/tap device sharing the bridge. However, my main traffic runs through eth1. Eth1 is on a completely different subnet, it's a Cisco VPN router. Both ethernet cards are set to roaming in the NetworkManager so I can access both the local subnet and the remote (VPN) subnet. When the VPN goes down, NetworkManager falls back to eth0, and sets up the routing table incorrectly. I can fix this by hand, but it appears that every time quanta NetworkManager wakes up and checks it's connections, it resets the routing table, so it's only a temporary fix. It almost looks like it ignores br0, and only knows about eth0. If I kill NetworkManager after the temporary fix is applied, it won't reset the routes.

Steps to reproduce:
1. Setup both eth0 and eth1 as described. See further info below.
2. Pull the wire from eth1, NetworkManager falls back to eth0.
3. The routing table sets the default via eth0, instead of default via br0.


Actual results:
I can not access any external networks, local network still is accessible. (Sometimes the local network isn't accessible, I'm not sure why)

Expected results:
I expect NetworkManger to do the same thing as when it is first booted, which is assign defaults via br0. It should route through eth1 for system access, and allow me to bridge through eth0 for virtualization.

Does this happen every time?
Yes. Quite annoyingly, as the VPN only fails once every few months or so.

Other information:
$ cat /etc/network/interfaces
auto tap0
iface tap0 inet manual
      up ifconfig $IFACE 0.0.0.0 up
      down ifconfig $IFACE down
      tunctl_user kjmph

auto br0
iface br0 inet dhcp
      bridge_ports eth0 tap0

$ ping www.google.com
PING www.google.com (74.125.19.147) 56(84) bytes of data.
From death.local (192.168.2.17) icmp_seq=1 Destination Host Unreachable

--- www.google.com ping statistics ---
2 packets transmitted, 0 received, +1 errors, 100% packet loss, time 999ms

$ ifconfig
br0       Link encap:Ethernet  HWaddr 00:e0:81:72:ed:68  
          inet addr:192.168.2.17  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::2e0:81ff:fe72:ed68/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:308103 errors:0 dropped:0 overruns:0 frame:0
          TX packets:64729 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:81163468 (77.4 MB)  TX bytes:46099697 (43.9 MB)

eth0      Link encap:Ethernet  HWaddr 00:e0:81:72:ed:68  
          inet addr:192.168.2.17  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::2e0:81ff:fe72:ed68/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:308859 errors:0 dropped:0 overruns:0 frame:0
          TX packets:65740 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:85696143 (81.7 MB)  TX bytes:46557328 (44.4 MB)
          Interrupt:248 Base address:0x8000 

eth1      Link encap:Ethernet  HWaddr 00:e0:81:72:ed:69  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:1645051 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1391601 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1759535808 (1.6 GB)  TX bytes:176975872 (168.7 MB)
          Interrupt:249 Base address:0xa000 

eth1:avahi Link encap:Ethernet  HWaddr 00:e0:81:72:ed:69  
          inet addr:169.254.8.250  Bcast:169.254.255.255  Mask:255.255.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          Interrupt:249 Base address:0xa000 

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:11313 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11313 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2387283 (2.2 MB)  TX bytes:2387283 (2.2 MB)

tap0      Link encap:Ethernet  HWaddr 00:ff:3b:e0:8f:69  
          inet6 addr: fe80::2ff:3bff:fee0:8f69/64 Scope:Link
          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:261420 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

vbox0     Link encap:Ethernet  HWaddr 00:ff:c1:e6:ed:fe  
          inet6 addr: fe80::2ff:c1ff:fee6:edfe/64 Scope:Link
          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:261354 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

$ sudo ip route
192.168.2.0/24 dev br0  proto kernel  scope link  src 192.168.2.17 
192.168.2.0/24 dev eth0  proto kernel  scope link  src 192.168.2.17 
169.254.0.0/16 dev eth1  proto kernel  scope link  src 169.254.8.250 
169.254.0.0/16 dev eth0  scope link  metric 1000 
default via 192.168.2.1 dev eth0
default via 192.168.2.1 dev br0  metric 100
default dev eth1  scope link  metric 1000 
$ sudo ip route del default via 192.168.2.1 dev eth0
$ sudo ip route flush cache
$ ip route
192.168.2.0/24 dev br0  proto kernel  scope link  src 192.168.2.17 
192.168.2.0/24 dev eth0  proto kernel  scope link  src 192.168.2.17 
169.254.0.0/16 dev eth1  proto kernel  scope link  src 169.254.8.250 
169.254.0.0/16 dev eth0  scope link  metric 1000 
default via 192.168.2.1 dev br0  metric 100
default dev eth1  scope link  metric 1000 
$ ping www.google.com
PING www.l.google.com (64.233.169.147) 56(84) bytes of data.
64 bytes from yo-in-f147.google.com (64.233.169.147): icmp_seq=1 ttl=244 time=114 ms