Re: [Xen-users] please explain to me the networking of Xen & Xen guests

[Sadique Puthen <sputhenp@xxxxxxxxxx>]

Rudi Ahlers wrote:
> Sadique Puthen wrote:
> > Rudi Ahlers wrote:
> > > Hi all
> > >
> > > I'm rather new to Xen, and want to understand the networking behind it.
> > >
> > > Let's say my server has the following IP addresses: 192.168.10.10/24 
> > > - 192.168.10.20/24 and these are all setup on the same NIC, as eth0, 
> > > eth0:1, eth0:2, etc etc.
> > > Do I assign a static IP address to a Xen guest from this pool? And 
> > > will this then be bridged, or how does it work?
> > > Or do I rather un-assign the IP address(es) in question, and just 
> > > set them up in the Xen guest?
> > Yes, You need to unassign these ips from dom0 and set them up in the 
> > Xen guest.
> Ok, so the main machine will only have 1 or 2 IP's for itself, and the 
> rest will be assigned to the VM's directly,
Yes.

> no bridging?
With bridging. Bridging is what enables networking between guests, dom0 
and the rest of the network. You have to create a bridge - which is 
automatically creted. The bridge would act like a switch where the 
eth0/peth0 (physical interface of dom0) would be its uplink and vifx.x 
would be deemed as virtual ports which connects to the virtual eth0, 
eth1 and etc of the guests through a virtual cable.
> > > Lastly, if I had mrtg / munin / Nagios on the main server, who will 
> > > it be able to graph each Xen guest's traffic individually?
> > I think you can do this by monitoring traffic through the vifx.x 
> > interface which handles the network traffice for the guest.
> I saw the vifx.x interfaces, but they don't have IP's:
It shouldn't have an ip address. As explained before, these are the 
switch ports. There won't usually be an ip address for a port in a switch.
> vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
>          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
>          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
>          RX packets:61077 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:75812 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:0
>          RX bytes:18054893 (17.2 MiB)  TX bytes:44011369 (41.9 MiB)
>
> vif35.0   Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
>          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
>          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
>          RX packets:7 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:1569 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:32
>          RX bytes:412 (412.0 b)  TX bytes:252960 (247.0 KiB)
>
> vif36.0   Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
>          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
>          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
>          RX packets:2687 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:3294 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:32
>          RX bytes:214391 (209.3 KiB)  TX bytes:359955 (351.5 KiB)
>
>
> How would I know which one is which one?
Match it with the domain id of the guest. Do "xm list". If you see 
guest1 has and ID of two, then vif2.0 is the virtual port for eth0 in 
the guest, vif2.1 for eth1 of the guest and etc. You can statically 
specify the vifname by passing vifname= in the guest configuration file.
--Sadique

> > --Sadique
> >
> >
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> > Xen-users@xxxxxxxxxxxxxxxxxxx
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