[libvirt-users] Networking problem - multiple guests using MacVTap in bridge mode
Dear list, I am getting strange problems using a setup outlined in the subject. I want to run three guests on a single kvm host. The guests are connected through macvtap directly to the network device 'eth0' of the host using this configuration: <interface type='direct'> <mac address='52:54:00:86:3f:24'/> <source dev='eth0' mode='bridge'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> Each guest is assigned a static ip address, no DHCP is involved. When I start the guests the macvtap links are generated automatically, ifconfig outputs this: macvtap2 Link encap:Ethernet HWaddr 52:54:00:86:3f:24 inet6 addr: fe80::5054:ff:fe86:3f24/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:98 errors:0 dropped:0 overruns:0 frame:0 TX packets:31 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:10946 (10.6 KiB) TX bytes:2184 (2.1 KiB) However, depending on the startup order, only the first two guests are able to reach the network! I can't access the third one. After the initial startup, the last host won't connect to the network even if I restart all the guests in a differnt order. I can only reset this by restarting the host. As far as I have tested this, it really depends on the initial startup order of the guests after a host restart. This seems very strange to me. As I am quite new to all of this, I have no clue how to start searching for the problem here. Can anyone provide me with some hints?
On 02/01/2013 08:26 AM, Filip Korzeniowski wrote:
Dear list,
I am getting strange problems using a setup outlined in the subject. I want to run three guests on a single kvm host. The guests are connected through macvtap directly to the network device 'eth0' of the host using this configuration:
<interface type='direct'> <mac address='52:54:00:86:3f:24'/> <source dev='eth0' mode='bridge'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface>
Each guest is assigned a static ip address, no DHCP is involved.
When I start the guests the macvtap links are generated automatically, ifconfig outputs this:
macvtap2 Link encap:Ethernet HWaddr 52:54:00:86:3f:24 inet6 addr: fe80::5054:ff:fe86:3f24/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:98 errors:0 dropped:0 overruns:0 frame:0 TX packets:31 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:10946 (10.6 KiB) TX bytes:2184 (2.1 KiB)
However, depending on the startup order, only the first two guests are able to reach the network! I can't access the third one. After the initial startup, the last host won't connect to the network even if I restart all the guests in a differnt order. I can only reset this by restarting the host.
Assuming that each guest's interface definition has a unique MAC address, this really sounds like a bug in macvtap on your kernel. There is probably some limit on the number of macvtap interfaces attached to a single physical interface, but it's certainly much higher than 3, and if you hit it you'd be more likely to get an error when attempting to create the macvtap device.
participants (2)
-
Filip Korzeniowski -
Laine Stump