Red Hat Bugzilla – Bug 603185
On default install, guest network conflicts with KVM host NAT network
Last modified: 2010-06-11 15:46:03 EDT
Description of problem:
On default install of RHEL 6 Snapshot 1 and above, running as KVM guest on a RHEL 5.x host, the default network configuration conflicts between guest and host.
Service libvirtd comes enabled by default, and uses 192.168.122.1 as the virbir0 interface. This is the same IP range used by the KVM host when the network is set to NAT.
Version-Release number of selected component (if applicable):
Host: RHEL 5.5, NAT network
Guest: RHEL 6 Snapshot >= 1
Steps to Reproduce:
1. Install RHEL 5.5 as host.
2. Use virt-manager to create a new guest with type RHEL 6.
3. Install RHEL 6 on the guest.
4. Boot guest.
5. ping any IP on the "real" network. ping will stop after 10 packages or so.
6. service libvirtd stop
7. service network restart
8. ping works forever
After 10 ping packets or so, network communications stall.
Network should work out of the box.
I suggest there should be a way to detect if the installed system is a guest under KVM, and do one of the options:
a) disable libvirtd
b) use a different IP on the guest's virbr0 interface
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux major release. Product Management has requested further
review of this request by Red Hat Engineering, for potential inclusion in a Red
Hat Enterprise Linux Major release. This request is not yet committed for
(In reply to comment #0)
> Additional info:
> I suggest there should be a way to detect if the installed system is a guest
> under KVM, and do one of the options:
> a) disable libvirtd
You don't want to do this; you can, in theory, run guests in a guest (it's called Nested Virtualization).
> b) use a different IP on the guest's virbr0 interface
We actually already have a patch for this queued up for the next RHEL-6 release. Closing as a dup.
*** This bug has been marked as a duplicate of bug 594494 ***