Multiple equal-cost routes

When the TCP/IP main route table is used to route traffic, multiple routes exist in the TCP/IP main route table for a destination, and the IPCONFIG MULTIPATH or IPCONFIG6 MULTIPATH statement is specified in PROFILE.TCPIP, outbound traffic for that destination is distributed across all of the routes. The same is true when a policy-based route table is used to route traffic, multiple routes exist in the policy-based route table for a destination, and the Multipath parameter on the RouteTable policy statement indicates that multipath support should be provided for the policy-based route table. This traffic distribution is done on either a packet-basis or connection-basis, depending on the type of multipath support configured. For information on configuring different types of multipath support using the IPCONFIG and IPCONFIG6 statements, and the RouteTable policy statement, see z/OS Communications Server: IP Configuration Reference.

When OMPROUTE is being used to provide dynamic routing for a TCP/IP stack, multiple routes to the same destination can be dynamically added to a TCP/IP stack route table, based upon the routing information learned from other routers. These multiple routes will be added when the route calculation for each has resulted in the same route cost value. No more than 16 equal-cost routes will be added for each destination. For RIP and IPv6 RIP, multiple equal-cost routes will be added only to directly-connected destinations over redundant interfaces. The RIP and IPv6 RIP protocols will generate no more than one indirect route to a destination.