You can set a routing expiration time by using the NW SNMP SET command to set a value for the RIProutetimeout MIB object. This MIB object enables you to inquire on and set the value (in seconds) of the routing expiration timer so that if a route becomes unreachable, your system can switch to alternate routing paths more quickly.

Background Information

IP routers send out routing updates on a regular basis, usually every 30 seconds as recommended in RFC 1058. These routings are used by neighboring systems for the time period specified by the RIProutetimeout attribute, after which they expire if not “refreshed” by another routing update. A routing expiration time of 180 seconds is recommended by RFC 1058.

If a router fails, neighboring systems continue to attempt to use the router until its routings expire. If the system has multiple routings available, you might want to reduce the value of RIProutetimeout in order to switch to an alternate routing more quickly.

The value of RIProutetimeout on your system should always be higher than the routing update times used by neighboring routers, to prevent routings from expiring unnecessarily due to timing differences or delays in sending/processing routing updates.

To set the value for the routing expiration timer, enter the following command:

NW SNMP SET RIProutetimeout=<value>

The variable is described as follows.