This is "pxn1" (please ignore the misleading host name "proxmox2")!

root@proxmox2:~# cat /etc/debian_version
7.7
root@proxmox2:~# uname -a
Linux proxmox2 2.6.32-34-pve #1 SMP Sat Nov 8 09:38:26 CET 2014 x86_64 GNU/Linux
root@proxmox2:~# ifconfig
bond0     Link encap:Ethernet  HWaddr 02:00:0a:01:01:c5
          inet addr:172.16.1.2  Bcast:172.16.1.255  Mask:255.255.255.0
          inet6 addr: fe80::aff:fe01:1c5/64 Scope:Link
          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1462  Metric:1
          RX packets:42 errors:0 dropped:0 overruns:0 frame:0
          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2160 (2.1 KiB)  TX bytes:4276 (4.1 KiB)

eth0      Link encap:Ethernet  HWaddr b4:b5:2f:92:6e:94
          inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::b6b5:2fff:fe92:6e94/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6806 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6568 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1098181 (1.0 MiB)  TX bytes:732879 (715.7 KiB)

eth1      Link encap:Ethernet  HWaddr 00:05:1b:00:56:e1
          inet addr:10.1.1.197  Bcast:10.1.1.255  Mask:255.255.255.0
          inet6 addr: fe80::205:1bff:fe00:56e1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:37998 errors:0 dropped:0 overruns:0 frame:0
          TX packets:38455 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:7989414 (7.6 MiB)  TX bytes:8099041 (7.7 MiB)

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:12584 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12584 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1352991 (1.2 MiB)  TX bytes:1352991 (1.2 MiB)

venet0    Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet6 addr: fe80::1/128 Scope:Link
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:3 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

vpn_br    Link encap:Ethernet  HWaddr 02:00:0a:01:01:c5
          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1462  Metric:1
          RX packets:42 errors:0 dropped:0 overruns:0 frame:0
          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2160 (2.1 KiB)  TX bytes:4276 (4.1 KiB)

vpn_gre_pxn2 Link encap:Ethernet  HWaddr 1a:73:32:7f:36:5f
          inet6 addr: fe80::1873:32ff:fe7f:365f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1462  Metric:1
          RX packets:88 errors:0 dropped:0 overruns:0 frame:0
          TX packets:108 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5808 (5.6 KiB)  TX bytes:8032 (7.8 KiB)

root@proxmox2:~# ip route show
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.2
172.16.1.0/24 dev bond0  proto kernel  scope link  src 172.16.1.2
10.1.1.0/24 dev eth1  proto kernel  scope link  src 10.1.1.197
default via 10.1.1.11 dev eth1
root@proxmox2:~# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: vpn_br
MII Status: up
MII Polling Interval (ms): 1000
Up Delay (ms): 0
Down Delay (ms): 0

Slave Interface: vpn_br
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 0
Permanent HW addr: 1a:73:32:7f:36:5f
Slave queue ID: 0
root@proxmox2:~# brctl show
bridge name     bridge id               STP enabled     interfaces
vpn_br          8000.02000a0101c5       no              vpn_gre_pxn2