This is a complicated problem, so please bear with the long preamble.... I have a VM TCPIP stack running level 520 on a z/VM 5.4.0 system. It is connected to an OSA on one side and a guest lan on the other. (It acts as a router for the guest lan.) It uses OSPF, so I have a MPROUTE machine going too. There is a bunch of stuff on the guest lan too, but they don't figure into this problem. The OSA is shared with a Linux guest which acts as a firewall for a bunch of Linux servers on a guest lan. So, here's the picture, 1 OSA shared between 1 VM TCPIP stack and 1 Linux stack. The Linux firewall is running zebra for dynamic routing.
All is good, everyone talks to everyone else, until I upgrade the VM TCPIP stack to level 540. (Same config files.) Both the TCPIP and MPROUTE machines come up fine. NETSTAT GATE shows that the routes are there and everything looks OK. The IP on the OSA side pings, no problem. However, the IP on the guest lan side can't be seen by the network. Pings fail. Traceroutes go off into the ether. To make things even weirder, the Linux firewall starts having the same problem. All the Linux servers behind it suddenly disappear from the network as well. At first, I thought this might be a VM TCPIP problem, but now I'm not sure. Could this be affecting the routing tables in the OSA? (Its an OSA Express1 Gbe on a z/990.) I'm at a loss on this one. As soon as I switch the VM stack back to 520 level, everything shows up again, including the Linux servers on the other guest lan. Any ideas? Am I doing something naughty? Martha
