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Re: [Xen-users] dom0 eth0:0, eth0:1, eth0:2 network setup alias ips

Thanks, here's what I'm trying to do:

1. consolidate 8 or so servers into one xen box (dual quad core, 20gb RAM, two gigabit network ports)

I have three separate internet connections, and a lan:
a. dsl line, with 5 fixed ip addresses, a default gateway, and dns
b. cable modem #1, with a unique set of 5 fixed ip addresses, a default gateway, and dns
c. cable modem #2, with a unique set of 5 fixed ip addresses (different from cable modem #1), and a default gateway (different from cable modem #1), and dns settings
d. a private lan, with 192.168.0.xxx, a default gateway, and dns of one of the cable modems.

I have xen domu's that need to be configured with one or two ethernet ports. (this part I've figured out how to do)
a. one configuration is with two network connections, one to a public IP (i have boxes that need to be on any one of the three public ip sets (a., b., c.) , and have a private IP on my lan
b. the other configuration is for private "LAN only" connections.

The problem I'm having is that I have only two gigabit ethernet ports on my new server, so I want to setup the public ips (three sets), on one of the physical ports, and the lan on the other physical port.
XEN wants to take over the network configuration, and I can get only one of the public ip sets to work at a time on the 'public' ethernet port. i.e., either public ips a, or b, or c work, because I can only setup one 'default gateway' on the physical port.

My thinking is that either this is not possible to do (limitations of mac hardware addresses, etc, and the cablemodem/routers),  or I need to do some 'fancy footwork' of setting up the network manually.
About the only solution that I can visualize is to have the physical port NOT to have an IP assigned, and hook it to multiple (3)  Dom0 bridges, each bridge would be assigned one of the three sets of ip addresses/gateway, and then configure the domUs to one of the three dom0 bridges, based on the ip address that it needs to have.

If all else fails, I can get a multiport network card for the machine, and it should be pretty straight forward to configure. 
Regardless of getting the multiport card (which seems pretty attractive at this point), I'd like to get my question resolved one way or the other for me, and anyone that might follow. If it works, I can document it and post it somewhere where it can be found...

Any suggestions if this is even possible to configure using only two physical ports, connecting to 4 separate networks, each network having it's own default gateway and dns settings?)

Thanks so much!

Fajar A. Nugraha wrote:
On Wed, Mar 24, 2010 at 1:41 AM, Dan Waterloo <dan@xxxxxxx> wrote:
I was wondering if there was a way to setup the physical eth0 with only a
mac address, then put a bridge in
dom0 with the eth0 mac address, and some virtual eth ports, each with a
public IP/netmask/gateway?

I'm thinking that I'd need to do this manually...?

You need to provide some examples, as your earlier explanation is
somewhat confusing.

Here's an example though. Let's say you have three different IP
address available,,102,and 103, netmask
All these IPs use gateway as gateway (as they're on the
same network) and as DNS. Setting this is easy.

First pick one IP you want to use in dom0. Say Put it
on eth0, and use xen's default network bridge script. You should end
up with a bridge called eth0 or xenbr0 (depends on your xen version).

Next create two domUs using the xenbr0 bridge, assign them each one of
the remaining IPs ( and Use the same DNS
and gateway as you do on dom0.

That should be it.


Dan Waterloo
Interface Technologies
a div of Waterloo Engr. Grp. LLC
111 N 10th Ave
Melrose Park, IL 60160

e: dan@xxxxxxx	t: (708) 366-4411
w: www.i-t.com	f: (708) 366-4413
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