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Re: [Xen-users] xen 3.4.2 networkings - multiple nics to multiple VMs

To: fpt stl <fptstl@xxxxxxxxx>
Subject: Re: [Xen-users] xen 3.4.2 networkings - multiple nics to multiple VMs
From: Steven Timm <timm@xxxxxxxx>
Date: Wed, 06 Oct 2010 20:06:54 -0500 (CDT)
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You need to modify the default network-bridge to start more
than one bridge.  You can start as many as you want.
Here's how I do two:

In xend-config.sxp

(network-script my-network-bridge)

In the my-network-bridge script

[root@fermigrid1 xen]# more scripts/my-network-bridge
# start bridges on both eth0 and eth1


$XENDIR/network-bridge "$@" netdev=eth0 bridge=xenbr0 vifnum=0
$XENDIR/network-bridge "$@" netdev=eth1 bridge=xenbr1 vifnum=1


I export both of those bridges to all of my vm's but wouldn't need to
do so.

In my xen1.cfg

vif = [ 'mac=00:16:3e:05:01:01, bridge=xenbr0', 'mac=00:16:3E:05:01:09, 
bridge=xenbr1' ]

Steve Timm

On Wed, 6 Oct 2010, fpt stl wrote:

Greetings all,

I do have some "basic" Xen networking questions, and please help me clarify
some misunderstandings.

I have a system with 2 built-in nics (Broadcom) and an add-on network card
(Intel) with another 4 nics.
Dom0 is CentOS 5.5 64bit with Xen 3.4.2 installed with the default settings
(minus cpu pinning to Dom0 and memory setup for 2GB).
I have 2 guest VMs - VM1 and VM2 - [HVMs] both being CentOS 64bit.
Currently eth4 (Broadcom) is used for all 3 VMs because of the default
bridge in xend-config.sxp:

(network-script network-bridge)

(vif-script vif-bridge)

I would really appreciate if anyone of the smart people here can indicate
how one can obtain a configuration with Dom0 using eth4 on one bridge, VM1
using eth0 on another bridge and VM2 using eth1 on another bridge.

Here is an example of a config file I used with "xm create":

[root@Dom0 xen]# more VM1
name = "VM1"
maxmem = 4096
memory = 4096
vcpus = 2
builder = "hvm"
kernel = "/usr/lib/xen/boot/hvmloader"
boot = "c"
pae = 1
acpi = 1
apic = 1
localtime = 0
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
device_model = "/usr/lib64/xen/bin/qemu-dm"
sdl = 0
vnc = 1
vncunused = 1
keymap = "en-us"
disk = [ "phy:/dev/mapper/VG1-VM1_volume1,hda,w" , ",hdc:cdrom,r" ]
vif = [ "mac=00:12:34:56:78:90,bridge=xenbr0,script=vif-bridge" ]
parallel = "none"
serial = "pty"

The sole reason for multiple bridges and each one with its dedicated nic is
to obtain separation between VMs.
All the Ethernet connections will end in one switch.

I have looked all over the net and I could not find a clear howto for this

Please give me some examples because I am very new to this issue.


Steven C. Timm, Ph.D  (630) 840-8525
timm@xxxxxxxx  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Assistant Group Leader.

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