Redhat just released RHEL 5.4 with KVM & Xen both supported in this release, so i have downloaded CentOS 5.4 and try to play around with KVM.
My hardware:
Dell M710 with 8 cores of Nehalem , 72G of RAMs
My OS:
CentOS 5.4 with KVM & Xen installed
My test guest:
Windows 7
The sweet thing:
- virt-manager is able to support for KVM new machine creation.
- The future for Redhat virtualization , since Redhat acquired Qumranet(company behind KVM)
The bad thingssss:
- Xen & KVM cannot run in the same time, it is either KVM or Xen
- No paravirtualization in KVM, only FULL Virtialization, Xen jhas both!
- Need driver for network in paravirtualzied mode for XP,Vista,Win7
- No network bridge setup!! Xen do this automatically for us! Network bridge allow your guest os to have their own IP without sharing with the host! I will cover this later on.
By the end of this post, you should be able to setup your bridge!
Paravirtualization is greyed!
Setting up network bridge
Here is what we need to create a bridge so the guest os is able to get IP from our LAN.
1. goto /etc/sysconfig/network-scripts
2. There is only 1 eth is enabled, so i simply backup my original config by
cp ifcfg-eth0 BAK-ifcfg-eth0
3. Then create a network bridge config called ifcfg-br0
vi ifcfg-br0
paste the config, the IPaddr use the original from eth0(your host original IP), example in this case:
DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
BROADCAST=192.168.1.255
IPADDR=192.168.1.10
NETMASK=255.255.255.0
NETWORK=192.168.1.0
ONBOOT=yes
USERCTL=no
IPV6INIT=no
PEERDNS=no
ONBOOT=yes
4. Then edit ifcfg-eth0 ,
vi ifcfg-eth0
Clear all content and replace with the line below:
DEVICE=eth0
BRIDGE=br0
ONBOOT=yes
5. restart network service or reboot.
service network restart
You should see the bridge appear in virt-manager, it was previously grey out and no selection!
Shared Device now appear!
Though my tutorial seems easy, but i spend 2 days to find out a solution. I am totally new in networking bridge 
hope this help!
And now my windows 7 guest OS is online!
Windows 7 guest is Online via Bridge!
Qumranet Paravirtualized Ethernet Adapter
Update : 11th March 2010
I faced issue bringing up the network recently. There is few minor changes.
Ensure
/etc/sysconfig/network-scripts/ifcfg-br0 has
DEVICE=br0
ONBOOT=yes
BRIDGE=eth0
HWADDR=XX:XX:XX:XX:XX:XX
&
/etc/sysconfig/network-scripts/ifcfg-eth0 has
TYPE=Bridge
IP=xxx.xxx.xxx.xxx #if you are using static
BOOTPROTO=static
Remove HWADDR if there is any!
To be frank, I couldn’t make it working using your notes, but it worked straight away using upstream docs.
So why don’t you simply follow the guide from the Red Hat website?
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.5/html/Virtualization_Guide/sect-Virtualization-Network_Configuration-Bridged_networking_with_libvirt.html
Hi man!
2 questions:
1, This method works with RHEL 5.4???
’cause i did it and the connection br0 is activated in the virt-manager, but my PC lost the connection =S, is it normal? (i don’t think so)
Hi Bro, i tried this with Redhat 5.2 if not mistaken. it should be resolved in latest RH version.
Hi Bro,
i was using 5.2 during that time if not mistaken. it should be fixed in latest redhat.