I have an ubuntu lucid host and an ubuntu lucid guest. Under heavy network load the guest network stalls and is only able to come back after running "sudo /etc/init.d/networking restart" on the guest.
Here are some (hopefully) helpful details. ------------------------------------Host--------------------------- # uname -a Linux virtserv 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC 2010 x86_64 GNU/Linux # ifconfig -v br0 Link encap:Ethernet HWaddr 00:e0:4d:20:1f:86 inet addr:192.168.100.145 Bcast:192.168.100.255 Mask:255.255.255.0 inet6 addr: fe80::2e0:4dff:fe20:1f86/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1254011 errors:0 dropped:0 overruns:0 frame:0 TX packets:1070096 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:439139185 (439.1 MB) TX bytes:836663432 (836.6 MB) eth0 Link encap:Ethernet HWaddr 00:e0:4d:20:1f:86 inet6 addr: fe80::2e0:4dff:fe20:1f86/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:124712767 errors:0 dropped:0 overruns:0 frame:0 TX packets:91086029 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:162562714983 (162.5 GB) TX bytes:36005498601 (36.0 GB) Interrupt:29 Base address:0x8000 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:83577 errors:0 dropped:0 overruns:0 frame:0 TX packets:83577 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:15722576 (15.7 MB) TX bytes:15722576 (15.7 MB) virbr0 Link encap:Ethernet HWaddr 5a:f3:dc:99:84:ee inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0 inet6 addr: fe80::58f3:dcff:fe99:84ee/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:468 (468.0 B) vnet0 Link encap:Ethernet HWaddr ca:8b:d8:66:e6:f5 inet6 addr: fe80::c88b:d8ff:fe66:e6f5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:81138964 errors:0 dropped:0 overruns:0 frame:0 TX packets:111911797 errors:0 dropped:0 overruns:100 carrier:0 collisions:0 txqueuelen:500 RX bytes:31177137669 (31.1 GB) TX bytes:147190153358 (147.1 GB) # dpkg -l |grep qemu ii kvm 1:84+dfsg-0ubuntu16+0.12.4+noroms+0ubuntu3~ppa1 dummy transitional pacakge from kvm to qemu-kvm ii qemu-common 0.12.4+noroms-0ubuntu3~ppa1 qemu common functionality (bios, documentation, etc) ii qemu-kvm 0.12.4+noroms-0ubuntu3~ppa1 Full virtualization on i386 and amd64 hardware I installed the 0.12.4 qemu-kvm package that was built for lucid and uploaded here: https://edge.launchpad.net/~ubuntu-virt/+archive/ppa/+packages # cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet dhcp auto br0 iface br0 inet dhcp bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0 ------------------------------Guest------------------------------- uname -a Linux torrents 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC 2010 x86_64 GNU/Linux # ifconfig -v eth0 Link encap:Ethernet HWaddr 52:54:00:1e:6e:b4 inet addr:192.168.100.203 Bcast:192.168.100.255 Mask:255.255.255.0 inet6 addr: fe80::5054:ff:fe1e:6eb4/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:39410626 errors:0 dropped:0 overruns:0 frame:0 TX packets:28376412 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:52260862769 (52.2 GB) TX bytes:10005355703 (10.0 GB) 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:14096 errors:0 dropped:0 overruns:0 frame:0 TX packets:14096 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:67362075 (67.3 MB) TX bytes:67362075 (67.3 MB) # cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet dhcp Notes: The TX and RX amounts are different from guest to host because I have restarted the guest 'recently'. One interesting thing I found was that the command 'arp -an' returns nothing on the guest while it is stalled. On 0.12.3 I was getting network stalls every 1-3 minutes with out fail. After upgrading to 0.12.4 I still get the stalls mostly every 1-5 minutes but some times it lasts over an hour between stalls. -William King