OMPROUTE considerations for the intraensemble data network

In an ensemble environment with dynamic routing where a z/OS® stack is the router for the ensemble, you can control whether the subnet of the intraensemble data network (IEDN) is advertised.

• If you want to prevent external traffic from being routed to this VLAN, then do one of the following items so that OMPROUTE does not advertise the intraensemble subnet:
  • Define the OSA-Express for zBX (OSX) interface to OMPROUTE using an INTERFACE statement or IPV6_INTERFACE statement, and do not enable the IMPORT_DIRECT_ROUTES function of AS boundary routing. This function is disabled by default, so ensure that the IMPORT_DIRECT_ROUTES parameter of the AS_BOUNDARY_ROUTING statement or the IPV6_AS_BOUNDARY_ROUTING statement is not set to YES.
  • Do not define the OSX interface to OMPROUTE, and ensure that GLOBAL_OPTIONS IGNORE_UNDEFINED_INTERFACES is configured to OMPROUTE.

  You might also want to install IPSec filter rules to restrict which traffic can flow on this network.

• If you want to allow external traffic to be routed to this VLAN, then define the OSX interface to OMPROUTE as an OSPF_INTERFACE or IPV6_OSPF_INTERFACE, and code a nonzero value for the ROUTER_PRIORITY parameter on the interface. As long as no other hosts on that OSX VLAN have coded their interfaces as OSPF interfaces, then OMPROUTE advertises the subnet (or IPv6 prefixes) of the IEDN into the OSPF network. This advertisement makes all addresses that fall into the intraensemble subnet (or IPv6 prefixes) reachable using OSPF. In addition, if you have a subset of hosts on the IEDN with VIPAs that are not in the intraensemble subnet, which you want to be able to reach over the IEDN, you can define the OSX interfaces on those hosts as OSPF interfaces; OMPROUTE communicates with them (and only them) and can route to their VIPAs, while still preserving the ability to route to the other hosts by subnet only.