Public bug reported: We've found that having vhost_net module and using bridged networking breaks DHCP and (some?) guests do not get an IP address.
The issue has been properly described in the following RH doc: http://docs.redhat.com/docs/en- US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/ch11s02.html "11.2.1. Checksum correction for older DHCP clients" Their workaround works in Precise too in fact. Another workaround is to disable/unload the vhost_net module so new guests do not make use of it. RH has fixed this stuff in libvirt apparently: "This iptables rule is programmed automatically on the host when the server is started by libvirt, so no further action is required" My apologies if this stuff does not belong to libvirt. Some info from our environment: compute-002:~# lsb_release -rd Description: Ubuntu 12.04 LTS Release: 12.04 compute-002:~# uname -a Linux compute-002 3.2.0-27-generic #43-Ubuntu SMP Fri Jul 6 14:25:57 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux compute-002:~# dpkg -l|egrep "kvm|libvirt|dhcp|dns" ii dnsmasq-base 2.59-4 Small caching DNS proxy and DHCP/TFTP server ii dnsmasq-utils 2.59-4 Utilities for manipulating DHCP leases ii dnsutils 1:9.8.1.dfsg.P1-4ubuntu0.1 Clients provided with BIND ii isc-dhcp-client 4.1.ESV-R4-0ubuntu5.1 ISC DHCP client ii isc-dhcp-common 4.1.ESV-R4-0ubuntu5.1 common files used by all the isc-dhcp* packages ii kvm-ipxe 1.0.0+git-3.55f6c88-0ubuntu1 PXE ROM's for KVM ii libdns81 1:9.8.1.dfsg.P1-4ubuntu0.1 DNS Shared Library used by BIND ii libnet-dns-perl 0.66-2ubuntu3 Perform DNS queries from a Perl script ii libvirt-bin 0.9.8-2ubuntu17.2 programs for the libvirt library ii libvirt0 0.9.8-2ubuntu17.2 library for interfacing with different virtualization systems ii munin-libvirt-plugins 0.0.6-1 Munin plugins using libvirt ii nova-compute-kvm 2012.1+stable~20120612-3ee026e-0ubuntu1.2 OpenStack Compute - compute node (KVM) ii python-libvirt 0.9.8-2ubuntu17.2 libvirt Python bindings ii qemu-kvm 1.0+noroms-0ubuntu14 Full virtualization on i386 and amd64 hardware We've also tested this with kernel 3.5 backport from Quantal: Linux compute-002 3.5.0-6-generic #6~precise1-Ubuntu SMP Tue Jul 24 14:45:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux The guest is running Debian Squeeze: debian-squeeze-amd64-ext3:~$ uname -a Linux debian-squeeze-amd64-ext3 2.6.32-5-amd64 #1 SMP Mon Jan 16 16:22:28 UTC 2012 x86_64 GNU/Linux debian-squeeze-amd64-ext3:~$ dpkg -l|grep dhcp ii isc-dhcp-client 4.1.1-P1-15+squeeze3 ISC DHCP client ii isc-dhcp-common 4.1.1-P1-15+squeeze3 common files used by all the isc-dhcp* packages ** Affects: libvirt (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1029430 Title: KVM guests networking issues when bridge and vhost_net kernel modules loaded To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1029430/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
