Re: [Qemu-discuss] Unable to establish TCP sessions between guests using virtio-net on Linux 3.12 and above

[Peter Kieser]

On 2014-06-27 12:19 PM, Peter Kieser wrote:
> Hello,
>
> Kernel versions tested: 3.13, 3.14, 3.15
> Related debian bug report: 
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=738863
>
> I'm not sure if this is a problem specific to openvswitch or KVM. I 
> have a network setup where I have one openvswitch bridge setup, with 
> various ports with VLAN tags and a firewall running as a guest. After 
> upgrading to Linux 3.13, all guests with virtio interfaces with TSO 
> enabled (the default) are unable to establish TCP connections via the 
> guest firewall. ICMP ping works fine. If I disable TSO on the vnet 
> interfaces (as outlined in the bug report above) guests are then able 
> to communicate with each other.
>
> Is there a patch for this issue that hasn't made it into mainline that 
> I should test out? Is this an issue specific to KVM, or is it an 
> openvswitch issue?
>
> Than kyou,
>
> -Peter

Hello,

Some further testing:

* Disabling vhost-net (vhost=off) for a particular VM has no effect to 
this issue
* Changing from virtio to e1000 for the NIC completely resolves this issue

-Peter

smime.p7s
Description: S/MIME Cryptographic Signature