It is assumed your installation has already made the network design decision to use default routing or dynamic routing.
The difference between default routing and dynamic routing is whether a routing daemon is used.
Dynamic routing allows a TCP/IP stack to respond to network topology changes.
A daemon is a UNIX term for a background server process.
OMPROUTE is the recommended routing daemon application for z/OS Communications Server IP.
OMPROUTE implements the OSPF protocol described in the RFC 1583 (OSPF Version 2), the OSPF subagent protocol described in RFC 1850, and the RIP protocol described RFC 1058 (RIP Version 1).
If you choose direct routing only, TCP/IP discards any data that is not addressed to a node on a link defined on this host. Otherwise, TCP/IP can send such data to:
A default router you configure statically; this approach eliminates the host's participation in the exchange of routing protocols, but may reduce your ability to route around failed links.
A router selected dynamically by the Routing Information Protocol (RIP) version 1; this older protocol is often available in networks where OSPF has not yet been deployed.
A router selected dynamically by the Open Shortest Path First (OSPF) protocol; this approach is generally the most responsive to network changes.