Charles Hights wrote:
>I am trying to find a replacement for SNA Link in Z/OS 2.5. My problem, I have
>4 LPAR's on one physical CPU. Normally to IP between the LPAR's we would just
>FTP to that LPAR's IP address and we had no issue. Now all of sudden the 
>traffic
>is timing out. My routes are very simple, just a default route that sends
>everything to the switches that the OSA's connect to. I have spoken to the 
>Switch
>support team and they say since the mainframes are on the same IP Segment it
>is not being passed to the FW. Unfortunately the switch team doesn't have any
>tools that will show what is happening to the traffic once the switch gets it. 
>So
>I wanted to bypass the switches and setup an SNA Link type replacement. I see
>that feature is not defined in Z/OS 2.5. On another client we use Hiper Sockets
>to bypass the switches for internal IP between the LPAR's. On this particular 
>CPU,
>Hiper Sockets devices are not configured in the IO Gen. So is there something 
>in
>Z/OS 2.5, besides Hiper Sockets, that support a device and link type statements
>to all traffic between LPAR's on the same CPU?

Obviously you should try to solve the extant networking problem. If your 
network switches are misconfigured that’d be bad. In the meantime/in addition, 
you have options (examples):


  1.  Yes, you can configure HiperSockets. You can also pair HiperSockets with 
SMC-D connections — and you should if your machine model supports SMC-D. SMC-D 
was introduced in z/OS 2.2 (with PTFs) and on the IBM z13 family of servers 
(with a firmware update).
  2.  If your z/OS LPARs are configured to share one or more OSA-Express ports, 
and if they are otherwise suitably configured, then traffic can hop from stack 
to stack via OSA-Express but without flowing through the network switch. See 
here for the entry point into the z/OS 2.5 documentation on that subject:
https://www.ibm.com/docs/en/zos/2.5.0?topic=attachment-osa-express-port-sharing
In short, make minor adjustments to your routing if you’re sharing OSA ports. 
Then that should take the switches out of the loop.
  3.  I think it’s still possible to configure TCP/IP connections over CTC 
(IPv4 only) or XCF. If you happen to have CTC or XCF connectivity between z/OS 
LPARs then that’s an option, albeit a little “off the beaten path” these days.
  4.  If you have at least one OSA-Express 1000BASE-T adapter with port (X) 
available to z/OS LPAR (X) and port (Y) available to z/OS LPAR (Y) then I 
suppose you could connect a cable directly between ports, bypassing any network 
switches. IBM doesn’t necessarily recommend this, and you might need a 
crossover cable (depending on how the OSA-Express adapters are configured). Can 
you also do this for fibre cables? I don’t know; I’ve never tried it.

—————
Timothy Sipples
Senior Architect
Digital Assets, Industry Solutions, and Cybersecurity
IBM zSystems/LinuxONE, Asia-Pacific
[email protected]


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