Configuring a system for IP routing

Follow these steps:

1. Determine whether the machine being configured will serve as a router or nonrouter. Set the IPFORWARDING kernel variable for a router, either with inconfig(ADMN) or by using the Network Configuration Manager to specify that the interface is a gateway.

2. Determine the routing protocols to be used to communicate with other machines. For a nonrouting host, typically use the IRD protocol or the RIP protocol (not both). For a router, typically use the IRD protocol and at least one internal routing protocol (RIP or OSPF). For an exterior router of an autonomous system, also choose an exterior routing protocol (BGP or EGP).

3. Select the routing daemon that implements the protocols selected in the previous step. Use of the IRD protocol requires use of the IRD daemon (irdd). Either the routed or gated daemon can be used for the RIP protocol.

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   WARNING: Never run irdd with routed or gated on a nonrouting host. This combination is appropriate only for a router.

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   If you need also to use any of the following protocols in conjunction with RIP (OSPF, EGP, or BGP), you must use gated to implement RIP. It is recommended that routed be used only for very simple networks. Remember that routed and gated cannot both be used; they are exclusive of each other.

4. Edit the TCP/IP default configuration file /etc/default/tcp, specifying the selected daemon's executable file and options. For example:
   
   ROUTERDAEMON0="/etc/routed -g"

   For more information, see the tcp(SFF) manual page.

5. Edit the configuration files for the routing daemon(s) selected. To configure irdd, see ``Configuring irdd''. To configure routed, see ``Configuring routed''. To configure gated, see ``Configuring gated''.