[libvirt-users] Guests can't connect to each other

[Laine Stump]

On 04/13/2012 08:33 AM, Anthony Bourguignon wrote:
> Hi,
>
> I'm using libvirt and qemu on Debian Wheezy. I'm having a strange
> behavior. Guests can't connect to each other when they're on the same
> host.
>
> On the host I'm using bonding (in active / backup mode) and vlan. It
> looks like this :
> eth0 \                / macvtap0
>      bond0 --- vlan222
> eth1 /                \ macvtap1
>
> So I've got two guests, let's say A and B. When I try to ping B from A,
> it works :
> # ping -s 3000 -c 5 78.109.95.11
> PING 78.109.95.11 (78.109.95.11) 3000(3028) bytes of data.
> 3008 bytes from 78.109.95.11: icmp_req=1 ttl=64 time=0.065 ms
> 3008 bytes from 78.109.95.11: icmp_req=2 ttl=64 time=2.19 ms
> 3008 bytes from 78.109.95.11: icmp_req=3 ttl=64 time=1.43 ms
>
> --- 78.109.95.11 ping statistics ---
> 5 packets transmitted, 5 received, 0% packet loss, time 4001ms
> rtt min/avg/max/mdev = 0.065/0.960/2.197/0.760 ms
>
> But nothing happens when I try to ssh it (not even a timeout). You'll
> find enclosed the tcpdump captures on the source and the destination.
> It's the same when I use netcat in udp.

Your config looks fine (the important part is that you're using bridge
mode for macvatap rather than private). I would suspect some sort of bug
related to using macvtap on a vlan device (or, even more, a vlan
connected to a bond). Try changing your network config to use
1) a vlan connected directly to eth0 or eth1, rather than the bond, 2)
bond0 directly, and 3) eth0 or eth1 directly. This will hopefully give
you an idea of which part of the equation isn't working.