On Tuesday, 06/01/2010 at 03:20 EDT, Tom Burkholder
<[email protected]> wrote:

> If anybody is sharing OSA's with z/VM and z/OS lpars I'd be interested
in
> getting some more information or ideas if possible.  One of my biggest
concern
> is being able to keep the same 192.168.xxx.yyy currently being used by
z/VM on
> the single OSA onto the other OSAs/Switches if possible.
>
> Kind of a high-level diagram of what we got:
> zVMa lpar chpid 09 -------- CISCO switch XXXXXX using 192.168.xxx.yyy
addresses.
> zOSa  lpar chpid 05 -------  CISCO switch ZZZZZ-a\
> zOSa lpar chpid 08 --------  CISCO switch ZZZZZ-b/

In order to be useful, network diagrams need subnet numbers and masks. But
based on your description of the physical setup, I assume that zVMa is on
Subnet A with a single adapter and IP address, and zOSa is on Subnet B
with two adapters and two IP addresses (likely with ospf).

> I'd like to SHR chpids 05/08, not screw up existing zOSa, be able to
configure
> z/VM with the same 192.168.xxx.yyy addresses and update
VSWITCH/controllers to
> use active/standby on chipds 05/08 (and free up chpid 09 OSA).
>
> I found the following pdf  to be a good source, but I need some more
> information or help from the network side (e.g. can we share and keep
the same
> 192.168.xxx.yyy subnet)
> http://linuxvm.org/present/misc/vswitch.pdf

The thing to remember is that a shared OSA is a shared cable.  Every
configuration decision logically follows from that basic understanding.
Let us say that you select OSA chpid 05 ("OSA-05") to share.  That means:
o OSA-05 must be able to carry traffic for both Subnet A and Subnet B. Let
us further declare that Subnet A is associated with IEEE VLAN-A and Subnet
B with VLAN-B.
o The switches that OSA-05 and OSA-09 are plugged into must be trunked
together (just like OSA-08 and -05) and authorized to carry the needed
traffic (VLANs)
o The port OSA-05 is plugged into needs to be reconfigured as a TRUNK port
and authorized to carry data for VLAN-A and VLAN-B.
o z/OS CS needs to have the interface on OSA-05 configured for VLAN-B in
profile.tcpip.
o The port OSA-09 is plugged into needs to be reconfigured as a TRUNK
port, authorized for VLAN-A.  You cannot mix VLAN-aware and VLAN-unaware
interfaces on the same VSWITCH.  (Well, you can, but you won't like the
results.)
o The VSWITCH must be defined with "VLAN 666", where "666" is a VLAN ID
specifically NOT authorized for the port.  Essential point: Do not try to
use the VLAN parameter on DEFINE VSWITCH to set the VLAN id of guests.
o Guest authorizations for the VSWITCH must be updated to specify VLAN
vlan-A (via ESM or SET VSWITCH GRANT)

Et voila.  At this point you will have
o Three switches, all trunked together carrying traffic for VLANs A and B
as needed to the correct ports
o Redundant OSA connections in case of OSA failure
o Redundant switches in case of switch failure
o z/OS on its original Subnet B and z/VM on its original Subnet A
o No additional investment in OSA
o No ability to use Link Aggregation on the VSWITCH in case you need > 1
OSA's worth of bandwidth (can't share OSA with LinkAg)

Alan Altmark
z/VM Development
IBM Endicott

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