On Friday, 03/12/2004 at 02:25 EST, someone offline wrote:
>> If you want a separate network, the VSWITCH isn't involved.  You would
>> use a Guest LAN with a virtual router.  (You could connect the virtual
>> router to the real network via the VSWITCH if desired.)
>
> Would this offload some tcp/ip-related CPU from the guests to CP?  From
> the share presentations, I remember something like this when VSWITCHes
> were discussed, but I wasn't sure if the change was a Guest LAN vs.
> VSWITCH or a z/VM 4.3 vs. 4.4 thing.  I thought it was a VSWITCH thing.

The VSWITCH eliminates the virtual router.  Yes, CP has to some extra
work, but it is far less than the overhead of a virtual router.

I should have also mentioned that virtual routers aren't absolutely
necessary in the "separate subnet/network" configuration.  You can always
do outboard routing in combination with the VSWITCH, a useful
configuration if you want firewalls, but don't want to run them on
zSeries.

When combined with the power of IEEE VLANs, the facility blossoms fully. A
single VSWITCH (with multiple OSA attachments for failover, of course),
can securely carry traffic for multiple VLAN IDs.  This is the preferred
configuration.  I do not recommend creating a separate VSWITCH for each
network.  Use VLANs instead; that's what they're for.

Alan Altmark
Sr. Software Engineer
IBM z/VM Development

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