Jake Anderson asks: >Is DLSW supported in z16 hardware ? If you're asking whether you can get SNA traffic to/from your IBM z16 when that SNA traffic is encapsulated via DLSw, the answer is yes, probably, with caveats. But please don't stick with DLSw! Here are the details....
DLSw stands for Data-Link Switching. It's one of the 3 (or more?) ways to carry SNA traffic over an IP network. There's a Wikipedia article about DLSw available here: https://en.wikipedia.org/wiki/Data-Link_Switching Enterprise Extender (IETF RFC 2352) superseded DLSw and AnyNet SNA over TCP/IP about a quarter century ago. The IBM z16 is the last model to support the OSE CHPID type which probably prompted your question. This CHPID type is used by classic SNA and even pre-SNA protocols when they're terminated directly at the IBM Z server via Ethernet (OSA-Express). Enterprise Extender (SNA over UDP) does not use the OSE CHPID type, so that's perfectly fine. Since EE isn't limited to OSE devices it can take advantage of all the wonderful, much faster network adapters. Relatedly, z/OS 2.5 is the last release of z/OS to support the OSE CHPID type. z/OS 3.1 drops support for this CHPID type on every server. In other words, the very end of the road for OSE is the z16 running z/OS 2.5. One of the big reasons IBM presumably dropped support for non-EE SNA/pre-SNA traffic over Ethernet is that it simply cannot be secured. Yes, SNA supports encrypted connections, but the algorithm is weak and vulnerable. Enterprise Extender (over fiber and copper Ethernet) and FICON CTC links (which still support non-EE SNA traffic) can be and should be strongly encrypted. HiperSockets also remain an option for pre-EE SNA traffic within a server. To check whether your z/OS environment is configured with any links that depend on the OSE CHPID type please refer to SNA APAR OA62208 for the appropriate z/OS Health Check. OK, so what about DLSw -- and AnyNet SNA over TCP/IP for that matter? Well, IBM dropped support a long time ago for AnyNet SNA over TCP/IP. If it still somehow works for you, OK, but Enterprise Extender superseded AnyNet. Please get onto Enterprise Extender or something else via TCP/IP that's also supported. I believe Cisco, a big supporter of DLSw, dropped support for DLSw a long time ago, too. When they supported DLSw it was between their switches/routers. Between the IBM Z server and their switch or router it was classic SNA -- with the OSE CHPID type. If that's how you're using DLSw (or similar), and if for some strange reason you can't get to Enterprise Extender, there are a couple speculative options I can think of: 1. As the Wikipedia article states, Cisco supported Enterprise Extender in their switches. They called it "SNAsW." So if you configure SNAsW for the hop between the switch and your IBM Z server, and DLSw on the "front side" of that switch, that might work -- if that was ever a viable configuration Cisco offered. 2. If Cisco supported a FICON CTC link between their switch and the IBM Z server, and if there's still a FICON CTC link speed available that's compatible on both ends, then that should work. If there's too much of a gap in link speeds between the old Cisco equipment and the much newer IBM Z server then inserting a FICON switch in the middle that "straddles" FICON link speeds might work. But that's extra silly isn't it? 3. Find a software implementation of DLSw and see if you can run it on z/OS, getting "both sides" wired together. I don't recall any vendor or developer who created a DLSw software stack on z/OS, although it seems technically possible. I found one open source implementation with a little searching. ————— Timothy Sipples Senior Architect Digital Assets, Industry Solutions, and Cybersecurity IBM Z/LinuxONE, Asia-Pacific [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
