Re: [libvirt-users] Need help with [virt net-create]

<Srinivas_G_Gowda@dell.com>
Tue, 20 May 2014 13:35:54 -0000

Thanks Daniel.

Why was I trying to do something like this ?
Two reasons

1. I was referring to ( Figure 18.4. Virtual network switch running dnsmasq)

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Virtualization_Administration_Guide/index.html#sect-network-protocols

   that appears to be two virtual nics sharing the same IP range .. !!!

2. was playing around "Network teaming" in a VM. But this doesnt seem
to work. Please dont beat me around the use cases for this :)

Do we have support for "Network teaming inside a  VM" ?
This seems to be well documented for VMware and Hyper-V, could not find related
document on this for libvirt.


Thanks.
G

________________________________________
From: Daniel P. Berrange [berrange@redhat.com]
Sent: Tuesday, May 20, 2014 6:31 PM
To: Gowda, Srinivas G
Cc: libvirt-users@redhat.com
Subject: Re: [libvirt-users] Need help with [virt net-create]

On Tue, May 20, 2014 at 01:59:42AM -0700, Srinivas_G_Gowda@dell.com
wrote:
> Is it possible to configure 2 virtual nics in the same ip range ?

Nope, that's unsupported. We need to key various things off the
IP address + mask used for the NIC, so you can't have multiple
nets with the same address + mask.

> Here is what I am trying.
>
>
> **** This works ****************
> cat nw1.xml
> <network>
>   <name>nw1</name>
>   <domain name='nw1' />
>   <forward mode='nat' dev='eth2'/>
>   <ip address='192.168.101.1'
netmask='255.255.255.0'>
>     <dhcp>
>       <range start='192.168.101.128'
end='192.168.101.254'/>
>     </dhcp>
>   </ip>
> </network>
>
>
> [root@localhost nw]# virsh net-create nw1.xml
> Network nw1 created from nw1.xml
>
> [root@localhost nw]# virsh net-list --all
>  Name                 State      Autostart     Persistent
> ----------------------------------------------------------
>  nw1                  active     no            no
>  default              active     yes           yes
>
>
>
> ****** FAILS when given the same ip address range of an existing virtual
interface *******
> [root@localhost nw]# cat nw2.xml
> <network>
>   <name>nw2</name>
>   <domain name='nw2' />
>   <forward mode='nat' dev='eth2'/>
>   <ip address='192.168.101.1'
netmask='255.255.255.0'>
>     <dhcp>
>       <range start='192.168.101.128'
end='192.168.101.254'/>
>     </dhcp>
>   </ip>
> </network>
>
> [root@localhost nw]# virsh net-create nw2.xml
> error: Failed to create network from nw2.xml
> error: internal error: Network is already in use by interface virbr1
>
>
>
> ****** PASS - on giving diff ip range *******
> [root@localhost nw]# cat nw3.xml
> <network>
>   <name>nw3</name>
>   <domain name='nw3' />
>   <forward mode='nat' dev='eth2'/>
>   <ip address='192.168.102.1'
netmask='255.255.255.0'>
>     <dhcp>
>       <range start='192.168.102.128'
end='192.168.102.254'/>
>     </dhcp>
>   </ip>
> </network>
>
>
> [root@localhost nw]# virsh net-create nw3.xml
> Network nw3 created from nw3.xml
>
> [root@localhost nw]# virsh net-list --all
>  Name                 State      Autostart     Persistent
> ----------------------------------------------------------
>  nw1                  active     no            no
>  nw3                  active     no            no
>  default              active     yes           yes
>
> Any suggestions on what could be wrong here ?

Can you instead explain why you're trying to setup multiple
networks with the same IP addr/mask in the first place.