Cisco IE 4000, Software Configuration Manual

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Configuring IP Unicast Routing
Configuring OSPF
Switch(config)#
router ospf 201
Switch(config-router)# summary-address 10.1.0.0 255.255.0.0
Switch(config-router)# end
Changing LSA Group Pacing
The OSPF LSA group pacing feature allows the router to group OSPF LSAs and pace the refreshing, check-summing,
and aging functions for more efficient router use. This feature is enabled by default with a 4-minute default pacing
interval, and you will not usually need to modify this parameter. The optimum group pacing interval is inversely
proportional to the number of LSAs the router is refreshing, check-summing, and aging. For example, if you have
approximately 10,000 LSAs in the database, decreasing the pacing interval would benefit you. If you have a very small
database (40 to 100 LSAs), increasing the pacing interval to 10 to 20 minutes might benefit you slightly.
BEFORE YOU BEGIN
Do not change the packet pacing timers unless all other options to meet OSPF packet flooding requirements have been
exhausted. Specifically, network operators should prefer summarization, stub area usage, queue tuning, and buffer
tuning before changing the default flooding timers. Furthermore, there are no guidelines for changing timer values; each
OSPF deployment is unique and should be considered on a case-by-case basis. The network operator assumes the risks
associated with changing the default timer values.
DETAILED STEPS
To return to the default value, use the no timers pacing lsa-group router configuration command.
EXAMPLE
The following example configures OSPF group packet-pacing updates between LSA groups to occur in 60-second
intervals for OSPF routing process 1:
Switch(config)# router ospf 1
Switch(config-router)# timers pacing lsa-group 60
Configuring a Loopback Interface
OSPF uses the highest IP address configured on the interfaces as its router ID. If this interface is down or removed, the
OSPF process must recalculate a new router ID and resend all its routing information out its interfaces. If a loopback
interface is configured with an IP address, OSPF uses this IP address as its router ID, even if other interfaces have higher
IP addresses. Because loopback interfaces never fail, this provides greater stability. OSPF automatically prefers a
loopback interface over other interfaces, and it chooses the highest IP address among all loopback interfaces.
BEFORE YOU BEGIN
The IP address for the loopback interface must be unique and not in use by another interface.
Command Purpose
1. configure terminal Enter global configuration mode.
2. router ospf process-id Enable OSPF routing, and enter router configuration mode.
3. timers pacing lsa-group seconds Change the group pacing of LSAs.
4. end Return to privileged EXEC mode.
5. show running-config Verify your entries.
6. copy running-config startup-config (Optional) Save your entries in the configuration file.