[CentOS-virt] Xen domU default gateway missing/ARP table full

Ken Bass kbass at kenbass.com
Thu Nov 19 18:07:09 UTC 2009

Pasi Kärkkäinen wrote:
> Yes, the routing table is correct for my domUs.
> I have never noticed/seen GATEWAY getting ignored..
> Maybe your netmask is wrong, so the GATEWAY IP is unreachable?

Well, the netmask for the domU is since the domU is 
allocated a single official IP address and packets are routed to it from 
the dom0.

It is a bit confusing, but my dom0 is [ip address 
changed for privacy]
My domU is (single host)
Another domU is (a few hosts)

There is a router in the ISP that routes the domU's via my dom0 "router".

The domU gateway is which is outside the subnet mask of 
the domU. But that should be legal right? Is this just some Centos/RHEL 
network script that is not flexible enough? Obviously I can add the

/sbin/route add -net netmask gw

which works. Since these IP addresses and netmasks are official assigned 
to me, I dont think it is proper to be using IP address outside the 
range allocated to me. Does this make sense?

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