[CentOS-virt] KVM: bridge configuration for static IP address

Sat Dec 12 10:51:19 UTC 2009
rewing <rewing at howfortune.com>

>To: Discussion about the virtualization on CentOS
><centos-virt at centos.org>
Message-ID:
><448255702.63.1260531144350.JavaMail.root at mail.chi.ldsys.net>
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>----- "rewing" <rewing at howfortune.com> wrote:
>> I need to allocate public IP address to two guest os.
>> 
> >I have only 2 network card Interface on server. say eth0 and eth1.
> >
> >I set eth1 a public IP address. so it should in
>> 
>> # vi /etc/sysconfig/ifcfg-eth1
> >
> >DEVICE=eth1
> >BOOTPROTO=static
> >HWADDR=00:1a:4d:83:ad:00
> >BROADCAST=202.127.29.0
> >IPADDR=202.127.29.5
> >NETMASK=255.255.255.0
> >NETWORK=202.127.29.0
> >ONBOOT=yes
> >TYPE=Ethernet
> >
> >Question 1: do I have to add GATEWAY=202.127.29.1 to above setting?

>GATEWAY probably belongs in /etc/sysconfig/network...

>> Question 2: do I need to add the rest 2 IP addresses in br0?

>Nope.

>> or I
>> should keep br0 with no IP address and set IP in guest OS directly?

>Yep. However, if you do that, you will need something acting as the gateway. If your host is going to be the gateway, it will need an address set in ifcfg->br0 and packet forwarding turned on. If eth1 and br0 are both in the same [public] network, you should just set the public IP address on br0 and add both eth0 and eth1 to the bridge and turn on STP.
>(I don't see why you need eth0 in this mix at all if you are just using it for guests on the local machine.)
>-- 
>Christopher G. Stach II
>http://ldsys.net/~cgs/

Hi,Christopher,

Thanks, But still I'm a little confused.

Actually I don't need host to be a gateway. There're should be gate way's on that IDC center. So the gate way should be add to /etc/sysconfig/network, right?

And still, I have 2 ehtnet interface on my mainboard. So I should allocate eth1 an IP address for host, and only make eth0 as br0, and set guest OS IP address in guest OS network configuration, right?

Please help to check if this is the correct setting as bellow

/etc/sysconfig/ifcfg-eth1
DEVICE=eth1
BOOTPROTO=static
HWADDR=00:1a:4d:83:ad:00
BROADCAST=202.127.29.0
IPADDR=202.127.29.5
NETMASK=255.255.255.0
NETWORK=202.127.29.0
ONBOOT=yes
TYPE=Ethernet

/etc/sysconfig/ifcfg-eth0
DEVICE=eth0
HWADDR=00:1a:4d:83:ad:50  
ONBOOT=yes
BRIDGE=br0

/etc/sysconfig/ifcfg-br0
DEVICE=br0
TYPE=Bridge
BOOTPROTO=none
ONBOOT=yes
DELAY=0

will this work so host os and 2 guest oses all got their IP address? or I should modify something?
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