kvm problem: bonding network interface breaks dhcp

[Harald Dunkel <harald.dunkel@aixigo.de>]

Hi folks,

I am trying to use a bonding network interface as a bridge
for a virtual machine (kvm). Host and guest are both running
2.6.31.5. Problem: The guest does not receive the DHCPOFFER
reply sent by my dhcp server. There is no such problem if
the host uses just a single network interface instead of
bond0.

Looking at tcpdump on the Linux guest there are several dhcp
discover packages like

15:17:44.005306 00:16:36:2f:f1:d2 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:16:36:2f:f1:d2, length 300, xid 0x4c31213d, secs 10, Flags [none]
          Client-Ethernet-Address 00:16:36:2f:f1:d2 [|bootp]

The dhcp server receives these packages, and sends out
a reply

15:17:45.927589 00:16:36:2f:f1:d2 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:16:36:2f:f1:d2, length 300, xid 0x4c31213d, secs 10, Flags [none]
          Client-Ethernet-Address 00:16:36:2f:f1:d2 [|bootp]
15:17:45.927658 00:15:17:94:16:65 > 00:16:36:2f:f1:d2, ethertype IPv4 (0x0800), length 364: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 350) 172.19.96.123.67 > 172.19.97.243.68: BOOTP/DHCP, Reply, length 322, xid 0x4c31213d, secs 10, Flags [none]
          Your-IP 172.19.97.243
          Client-Ethernet-Address 00:16:36:2f:f1:d2 [|bootp]

This reply never shows up on the guest.


iptable is not set, of course. sysctl.conf says

net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0


Any helpful comment would be highly appreciated.


Many thanx

Harri