[ILUG] Virtualisation, what the point?

[paul at clubi.ie]

On Wed, 7 Jun 2006, JMcCarthy at mortgagelink.ie wrote:

> So what about network cars/ports. Is one shared between all the 
> guest OSes or does each OS need it's own port?

It's virtualised:



 	(domain0)<----->(domain1)
 	 D	 <-----> ....
 	 |	 <----->(domainN)
 	 |
 	(bare metal)


The hardware concerned is made accessible to one, and only one, 
domain (domain0 typically). It uses a normal device driver for that 
hardware.

Other domains implement a device driver which use the Xen 
inter-domain IPC as their 'hardware'. The domain0 OS has 'backend' 
network drivers to handle that communication (the 'vif' driver - 
Virtual Interface). The domain0 OS then uses existing bridging or 
routing layers to switch/forward traffic between other domains and 
the real network. E.g.:

                      Domain0                             Guest Domains
(physical)<---->([NIC]                )               (              )
(ethernet)      ([normal driver]      )               (              )
 		([OS networking stack])               (    <etc>     )
 		(                     )               (              )
 		(                     )               ([OS Net stack])
 		(['Virtual' NIC]      )<--(Xen IPC)-->([Virtual NIC] )



Clearer?

<snip horrendously long and stupid disclaimer>

Please could you post to ILUG from some other email account? 
(Free webmail accounts are widely available. You can still receive 
email to other accounts obviously).

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
Arbitrary systems, pl.n.:
 	Systems about which nothing general can be said, save "nothing
 	general can be said."