On Wed, 18 Oct 2023 11:50:21 -0500, John S. Giltner, Jr. <gil...@gmail.com> wrote:
>When TCPIP on z/OS allocates a IP address that address is registered in the >OSA > so that the OSA has a list of every IP address that is open and which LPAR it > is opened on. This tells us that in addition to SNA, the OSA is also functioning as an internet router. As for "OPEN IP addresses", I believe it registers all "defined IP addresses". Prior to DVIPA, each application needed its own IP addresses because you couldn't depend upon 2 applications moving to the same LPAR. If you have 100 applications moving between 2 LPARs, you needed 100 IP addresses. IP addresses are a very limited resource. I'm guessing that IBM now uses port number routing. All 100 applications would use the same IP address with different ports. >So if you have a VIPA that is defined in the DYNAMIC VIPA range that opens on >LPARA, > the OSA knows that IP address is valid and is on LPARA, when it sees > packet for that address it sends it to the TCPIP stack on LPARA. I interpret this as packets are sent to the LPAR where the application port is active. Move the application to another LPAR, then packets will be sent to that LPAR. > If the STC that allocated that address stops and TCPIP unregisters it from > theOSA. > If that STC is started on LPARB, then the address is registered on the OSA as > belonging to LPARB and any traffic for that address is now sent to LPARB. The OSA detects if the LPAR fails and stops sending it packets. If the application stops (port inactive) or the DVIPA address is deleted, then TCP notifies OSA not to send packets (unregister). As soon as the app is started on another LPAR, that LPAR notifies OSA the port is active (register). >Now if the traffic is routed, this normally means that the OSA's addresses are > in a different subnet from the VIPA's addresses. > You will need OMPROUTE and OSPF setup so the z/OS can tell the distributed > router that it is connected Before looking at OMPROUTE, I would suggest investigating TCP capabilities using the coupling facility. Does it support DVIPA routing and will it correctly route data (DVIPA addresses/ports) when a primary adapter is down? The network people would have set this up as a failure recovery which does not require router changes for the sysplex. If the coupling facility has DVIPA capability, then the network people simply configure the DVIPA address just like the LPAR routes even though it has a different subnet. If my suspicion is correct, as long as the packets get to a valid OSA, the OSA, TCP and coupling facility should handle the rest. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
