On Wednesday, 05/01/2002 at 09:28ZE10, Vic Cross <[EMAIL PROTECTED]>
wrote:
> Romney White wrote:
>
> > Broadcast on a QDIO Guest LAN sends
> > datagrams to all guests whose NICs are connected to that LAN.
>
> Just what I'd expect broadcast to do! ;-)  However, broadcast packets
are
> really just packets sent to a special IP address, that the stack(s) and
the
> network treat in a special way.  So, since the z/VM support is "the
network"
> in this case, the question is does it handle both local-net broadcast
(i.e.
> address 192.168.0.255 on the 192.168.0.0/24 network) and "all-Fs"
broadcast
> (as used by DHCP clients)?
>
> > You'll want to put your DHCP server and its clients on the Guest LAN.
>
> Exactly!  So I'm assuming that both types of broadcast are supported,
and
> that DHCP will work...

Vic, at the adapter level, there is no difference between an "all-Fs"
broadcast and a subnet-directed broadcast.  The adapter doesn't know
subnets from a hole in the ground.  It's all handled at the IP layer, not
the media.  That is, a subnet-directed broadcast is simply a datagram
unicast to the router, which forwards it (if you are lucky) until the
target subnet router receives it and converts it to a local media
broadcast.

Alan Altmark
Sr. Software Engineer
IBM z/VM Development

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