I have a couple of servers at Hetzner running Xen. In each case, the
dom0 has one public IP, and I have also been allocated a /29 from
Hetzner, from which I have 5 available IPs. These addresses are
routed to the respective servers, on which I have Xen VMs running
which each use one of the IPs.
This works just as I expect it to on both servers, with packets
addressed to one of the IPs from the /29 landing on the eth0
interface, and being transferred by Xen bridging to the relevant VM.
However, I have another server at a different provider, with the same
IP allocation i.e. 1 + 8, and it runs the same OS as the Hetzner
servers i.e. Debian etch with kernel 2.6.18-1-xen-k7, which is up to
As far as I can see, the configuration of the dom0sis identical on
both machines, with the output of ip a s being the same except for:
The IP address, of course
The existence of an eth1 interface on the machine whose domUs don't work
The last interface showing as 16: vif5.0: on the working server
and 12: vif1.0: on the non-working, but AIUI that's solely down to
having stopped and started VMs.
The problem with the other provider's box is that networking doesn't
work correctly - the domUs can't ping their default routes. Again,
the configuration of a working domU appears to be the same as that of
a non-working one. Networking has been setup correctly the provider
because if I add one of the public IPs to eth0 on the dom0, I can
acces that IP from the world.
I'm stumped - any ideas?
P.S. I did ask Unclde Google, and one thing I turned up was this page
which describes a setup like what I have, IP wise - http://
However, my Hetzner boxes don't use this dummy interface and they
work just nicely. I did try that dummy interface approach, but it
didn't work for me either.
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