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Re: [Xen-users] DomU's unable to connect to vnet0 / bridge

I'm trying to get some XEN VMs working on my CentOS 5.3 server. The VM's are installed and everything is working but for the network. I believe my problem is with the bridge. I have two ethernet adapters.
eth0 - external NIC running routable IP
eth1 - internal NIC running 10.0.xxx.xxx network

perhaps you should configure the bridge as a trusted interface in firewall settings.

I'm working now. I talked with one of the NOC nerds here at work and he had JUST fought through the same problems the previous weekend so had the solution at hand. In the end, it seems that the XEN bridge scripts for RHEL 5.3 will ONLY work for ETH0. I made a number of changes along the way, so I'm not 100% sure exactly which modifications were required to get things working, but this is the best guess at the mods made that got me working:
1)  Switched over my named.conf to only listen on lo, eth0, and eth1.

2)  Set dnsmasq.conf to only listen on vnet1 and exclude lo, eth0, and eth1.

3)  Set the network-bridge script to have hardcoded values for:

4)  Uncomment the line for the network-bridge device in the
    xend-config.sxp script:
    [root@cerberus xen]# grep eth1 xend-config.sxp
    # To use a different one (e.g. eth1) use
    (network-script 'network-bridge netdev=eth1')

5)  Replace all references from eth0 to eth1 in /etc/xen/scripts:
    [root@cerberus scripts]# grep eth1 /etc/xen/scripts/*
    /etc/xen/scripts/network-bridge:          netdev=eth1
    /etc/xen/scripts/network-bridge-bonding:  netdev=${netdev:-eth1}
    /etc/xen/scripts/network-nat:             netdev=${netdev:-eth1}
    /etc/xen/scripts/vif-common.sh:           local nd=${netdev:-eth1}

6)  Give up on trying to use dnsmasq or dhcpd for DHCP on the VMs and just
    hardcode them for static IP's in 10.0.2.xxx space.

It seems my attempts to use 192.168.122.xxx for the VM space (as explained to me) was unnecessary, as I could ignore that and just use my 10-net for the VMs...

I've got one CentOS and one Windows Server 2003 VMs currently running, and all seems to be well. I would have been nice if there was some sort of how-to doc on the wiki (I searched and was unable to find anything) for switching over from eth0 over to an eth1 config, but maybe that's not as common of a configuration as I thought it might have been. {shrug}

From what I hear, RHEL / CentOS will be moving away from XEN and moving
over to KVM (this was new news for me, certainly way old for y'all tho I'm guessing) so who knows... maybe with the 5.4 updates (or maybe RHEL 6) it'll all be moot anyway... I certainly like the performance of XEN and am not looking forward to a VM akin to VMWare (which it seems KVM is more akin to) but my guess is I've got a few years at least before I need to worry about how that's all going to play out and I'll deal with it all on my next server buildout... which with any luck, will not be for at least 4-5 years. :)

- Matt Schreiner                      o
Cyber@xxxxxxxxxxxxxxxxxxx            =\>
MidnightFantasy Photography     ...O=>\O...
When the last moment comes, and my life flashes before my eyes,
it's gonna be one hell of a show!

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