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I'm using Ubuntu server 12.04, on a server with 6 NICs, grouped in 2 bundles :

  • eth0 and eth2 are bundled using bonding mode 1, under interface name bond0 which has IP [network].8
  • eth1, eth3, eth4 and eth5 are bundled using bonding mode 4 (802.3ad), under interface name bond1

bond1 will be used to connect VMs to our network : it is bridged through br0, which has IP [network].

Now, when I ping [network].5 from our network, everything seems to works, but our VMs have no network access.

After poking around for a while, I noticed that br0's IP ([network].5) is associated with bond1's MAC address, i.e.:

arping <[network].5>

returns

Unicast reply from <[network].5> [<bond0's MAC address>]  0.710ms

Also, while I'm pinging [network].5 :

tcpdump -i br0 icmp

Shows no ICMP traffic,

tcpdump -i bond1

show no traffic either, but

tcpdump -i bond0

shows the ICMP packets I'm sending using ping.

It's pretty obvious that packets are sent down the wrong tube. My question here is : why is it so and how can I fix that ?

Here is the content of my /etc/network/interfaces file :

# bond0 part :

auto eth0
    iface eth0 inet manual
    bond-master bond0

auto eth2
    iface eth2 inet manual
    bond-master bond0

auto bond0
    iface bond0 inet static
    address [network].8
    gateway [network].254
    netmask 255.255.254.0
    # bonding mode 1 :
    bond-mode balance-rr
    bond-slaves none

auto eth1
    iface eth1 inet manual
    bond-master bond1

auto eth3
    iface eth3 inet manual
    bond-master bond1

# bond1 and br0 part :

auto eth4
    iface eth4 inet manual
    bond-master bond1

auto eth5
    iface eth5 inet manual
    bond-master bond1

auto bond1
    iface bond1 inet manual
    # bonding mode 4 :
    bond-mode 802.3ad
    bond-slaves none
    bond-miimon 100
    bond-downdelay 200
    bond-updelay 200        
    bond_xmit_hash_policy layer2
    bond_lacp_rate fast

auto br0
    iface br0 inet static
    address [network].5
    netmask 255.255.254.0
    gateway [network].254
    bridge_ports bond1
    bridge_maxwait 5
    bridge_stp off
    bridge_fd 0

Please note that :

  • 802.3ad link aggregation has been configured on the swich side
  • We have verified muliple times that the right ports are connected
  • The same issue occurs on 2 servers with the exact same hardware+software configuration

[EDIT] After several reboots, the opposite happens : bond0 is associated with bond1's mac address. This seems to happen randomly. When it does, VMs behind the bridge have access to our network and Internet.

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1 Answer 1

After more searching, it appears the root of my problem is what is discussed here :

Serverfault : arp responses always go out a sinle NIC

As this question is much more precise and has several answers, that's where you should look if you have the same problem than me

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