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[Xen-users] domU network packets get lost on the way to dom0

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Subject: [Xen-users] domU network packets get lost on the way to dom0
From: Florian Schmaus <flo4lists@xxxxxxxxxx>
Date: Mon, 27 Jul 2009 16:30:06 +0200
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I am experiencing a strange network problem. It looks like some packets get lost on the way from frontend network device in domU to the backend vifx.x in dom0.

But first my configuration:
- Xen 3.4.0 from the gentoo ebuild and the pvops dom0 kernel from jeremy/xen.git - The system has two physical network interfaces called gblan (Gigabit Ethernet) and felan (Fast Ethernet) - Two network bridges in dom0: gbbridge with the gblan interface and ppoebr with the felan interface
- The felan interface is directly connected to the DSL modem
- the gblan interface is for the home network (
- Two domUs: One is for pppoe (DSL) routing and connected to the two Bridges in dom0. The other domU is just connected to the gbbridge

The routing domU is able to establish a pppoe connection, ping and everything else works like a charm. But if the other domU tries to ping a server eg. yahoo it CAN do the DNS lookup but there is no PING reply.

I was able to follow the ping request via tcpdump: They requests leave the domU and arrive at the routing domU, where the get encapsulated via PPPoE and leave the routing domU on eth1. But hey never arrive at the corresponding vifx.1 in dom0. Tcpdump on vifx.1 in dom0 shows the DNS lookups, the pings from the routing domU BUT no pings from the other domU. They are just vanished,....

I had the same problem a few years ago, the solution at this time was "ethtool -k iface tx off". I disabled everything with ethtool on the various interfaces and domains. After that the other domU was unable to do even a DNS lookup while the routing domU was still able to ping servers on the Internet.

Any ideas or helpful suggestions?


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