BigIron RX Series Configuration Guide 71153-1002253-01Configuring OSPF 25This example shows two routes. Both of the routes are directly attached, as indicated in the Typecolumn. However, one of the routes is shown as type “*D”, with an asterisk (*). The asteriskindicates that this route is a candidate default network route.Modify SPF timersThe BigIron RX uses the following timers when calculating the shortest path for OSPF routes:• SPF delay – When the BigIron RX receives a topology change, the software waits before itstarts a Shortest Path First (SPF) calculation. By default, the software waits 0 (zero) seconds.You can configure the SPF delay to a value from 0 – 65535 seconds. If you set the SPF delay to0 seconds, the software immediately begins the SPF calculation after receiving a topologychange.• SPF hold time – The BigIron RX waits for a specific amount of time between consecutive SPFcalculations. By default, the BigIron RX waits ten seconds. You can configure the SPF hold timeto a value from 0 – 65535 seconds. If you set the SPF hold time to 0 seconds, the softwaredoes not wait between consecutive SPF calculations.NOTEOSPF incrementally updates the OSPF routing table when new Type-3 or Type-4 Summary, Type-5External or Type-7 External NSSA LSAs are received.You can set the delay and hold time to lower values to cause the BigIron RX to change to alternatepaths more quickly in the event of a route failure. Note that lower values require more CPUprocessing time.You can change one or both of the timers.To change the SPF delay and hold time, enter commands such as the following.BigIron RX(config-ospf-router)# timers spf 10 20The command in this example changes the SPF delay to 10 seconds and changes the SPF holdtime to 20 seconds.Syntax: timers spf The parameter specifies the SPF delay.The parameter specifies the SPF hold time.To set the timers back to their default values, enter a command such as the following.BigIron RX(config-ospf-router)# no timers spf 10 20Modify redistribution metric typeThe redistribution metric type is used by default for all routes imported into OSPF unless youspecify different metrics for individual routes using redistribution filters. Type 2 specifies a bigmetric (three bytes). Type 1 specifies a small metric (two bytes). The default value is type 2.To modify the default value to type 1, enter the following command.BigIron RX(config-ospf-router)# metric-type type1Syntax: metric-type type1 | type2The default is type2.
