[Qemu-devel] [Bug 785668] Re: bonding inside a bridge does not update ARP correctly when bridged net accessed from within a VM

[Thomas Huth]

** No longer affects: qemu

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https://bugs.launchpad.net/bugs/785668

Title:
  bonding inside a bridge does not update ARP correctly when bridged net
  accessed from within a VM

Status in linux package in Ubuntu:
  Confirmed
Status in qemu-kvm package in Ubuntu:
  Invalid

Bug description:
  Binary package hint: qemu-kvm

  Description: Ubuntu 10.4.2
  Release: 10.04

  When setting a KVM host with a bond0 interface made of eth0 and eth1
  and using this bond0 interface for a bridge to KVM VMs, the ARP tables
  do not get updated correctly so it is not possible for a VM to reach
  an IP on the bridged network up until that remote system has pinged
  the VM itself.

  Reproducible: 100%, with any of the load balancing mode

  How to reproduce the problem

  - Prerequisites:
  1 One KVM system with 10.04.02 server,  configured as a virtual host is 
needed. The following /etc/network/interfaces was used for the test :

  # grep  -v ^# /etc/network/interfaces
  auto lo
  iface lo inet loopback

  auto bond0
  iface bond0 inet manual
   post-up ifconfig $IFACE up
   pre-down ifconfig $IFACE down
   bond-slaves none
   bond_mode balance-rr
   bond-downdelay 250
   bond-updelay 120
  auto eth0
  allow-bond0 eth0
  iface eth0 inet manual
   bond-master bond0
  auto eth1
  allow-bond0 eth1
  iface eth1 inet manual
   bond-master bond0

  auto br0
  iface br0 inet dhcp
   # dns-* options are implemented by the resolvconf package, if installed
   bridge-ports bond0
   bridge-stp off
   bridge-fd 9
   bridge-hello 2
   bridge-maxage 12
   bridge_max_wait 0

  One VM running Maverick 10.10 server, standard installation, using the
  following /etc/network/interfaces file :

  grep -v ^# /etc/network/interfaces

  auto lo
  iface lo inet loopback

  auto eth0
  iface eth0 inet static
          address 10.153.107.92
          netmask 255.255.255.0
          network 10.153.107.0
          broadcast 10.153.107.255

  --------------
  On a remote bridged network system :
  $ arp -an
  ? (10.153.107.188) à 00:1c:c4:6a:c0:dc [ether] sur tap0
  ? (16.1.1.1) à 00:17:33:e9:ee:3c [ether] sur wlan0
  ? (10.153.107.52) à 00:1c:c4:6a:c0:de [ether] sur tap0

  On KVMhost
  $ arp -an
  ? (10.153.107.80) at ee:99:73:68:f0:a5 [ether] on br0

  On VM
  $ arp -an
  ? (10.153.107.61) at <incomplete> on eth0

  1) Test #1 : ping from VM (10.153.107.92) to remote bridged network
  system (10.153.107.80) :

  - On remote bridged network system :
  address@hidden:~$ arp -an
  ? (10.153.107.188) à 00:1c:c4:6a:c0:dc [ether] sur tap0
  ? (16.1.1.1) à 00:17:33:e9:ee:3c [ether] sur wlan0
  ? (10.153.107.52) à 00:1c:c4:6a:c0:de [ether] sur tap0

  - On KVMhost
  address@hidden:~$ arp -an
  ? (10.153.107.80) at ee:99:73:68:f0:a5 [ether] on br0

  - On VM
  address@hidden:~$ ping 10.153.107.80
  PING 10.153.107.80 (10.153.107.80) 56(84) bytes of data.
  From 10.153.107.92 icmp_seq=1 Destination Host Unreachable
  From 10.153.107.92 icmp_seq=2 Destination Host Unreachable
  From 10.153.107.92 icmp_seq=3 Destination Host Unreachable
  ^C
  --- 10.153.107.80 ping statistics ---
  4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3010ms
  pipe 3
  address@hidden:~$ arp -an
  ? (10.153.107.61) at <incomplete> on eth0
  ? (10.153.107.80) at <incomplete> on eth0

  2) Test #2 : ping from remote bridged network system (10.153.107.80)
  to VM (10.153.107.92) :

  - On remote bridged network system :
  $ ping 10.153.107.92
  PING 10.153.107.92 (10.153.107.92) 56(84) bytes of data.
  64 bytes from 10.153.107.92: icmp_req=1 ttl=64 time=327 ms
  64 bytes from 10.153.107.92: icmp_req=2 ttl=64 time=158 ms
  64 bytes from 10.153.107.92: icmp_req=3 ttl=64 time=157 ms
  ^C
  --- 10.153.107.92 ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2003ms
  rtt min/avg/max/mdev = 157.289/214.500/327.396/79.831 ms
  address@hidden:~$ arp -an
  ? (10.153.107.188) à 00:1c:c4:6a:c0:dc [ether] sur tap0
  ? (16.1.1.1) à 00:17:33:e9:ee:3c [ether] sur wlan0
  ? (10.153.107.52) à 00:1c:c4:6a:c0:de [ether] sur tap0
  ? (10.153.107.92) à 52:54:00:8c:e0:3c [ether] sur tap0

  - On KVMhost
  $ arp -an
  ? (10.153.107.80) at ee:99:73:68:f0:a5 [ether] on br0

  - On VM
  arp -an
  ? (10.153.107.61) at <incomplete> on eth0
  ? (10.153.107.80) at ee:99:73:68:f0:a5 [ether] on eth0

  3) Test #3 : New ping from VM (10.153.107.92) to remote bridged network 
system (10.153.107.80) :
  - On remote bridged network system :
  $ arp -an
  ? (10.153.107.188) à 00:1c:c4:6a:c0:dc [ether] sur tap0
  ? (16.1.1.1) à 00:17:33:e9:ee:3c [ether] sur wlan0
  ? (10.153.107.52) à 00:1c:c4:6a:c0:de [ether] sur tap0
  ? (10.153.107.92) à 52:54:00:8c:e0:3c [ether] sur tap0

  - On KVMhost
  address@hidden:~$ arp -an
  ? (10.153.107.80) at ee:99:73:68:f0:a5 [ether] on br0

  - On VM
  address@hidden:~$ ping 10.153.107.80
  PING 10.153.107.80 (10.153.107.80) 56(84) bytes of data.
  64 bytes from 10.153.107.80: icmp_req=1 ttl=64 time=154 ms
  64 bytes from 10.153.107.80: icmp_req=2 ttl=64 time=170 ms
  64 bytes from 10.153.107.80: icmp_req=3 ttl=64 time=154 ms
  ^C
  --- 10.153.107.80 ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2003ms
  rtt min/avg/max/mdev = 154.072/159.465/170.058/7.504 ms

  tcpdump traces are available for those tests. Test system is available
  upon request.

  Workaround:

  Use the bonded device in "active-backup" mode

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04.02
  Package: qemu-kvm-0.12.3+noroms-0ubuntu9.6
  Uname: Linux 2.6.35-25-serverr x86_64
  Architecture: amd64

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