Changing Lsa Group Pacing; Configuring A Loopback Interface - Cisco WS-C3560-48PS-S Software Configuration Manual

Chapter 30 Configuring IP Unicast Routing
Command
Step 10 timers spf spf-delay spf-holdtime
Step 11
ospf log-adj-changes
Step 12
end
Step 13 show ip ospf [process-id [area-id]] database Display lists of information related to the OSPF database for a
Step 14 copy running-config startup-config

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.
Beginning in privileged EXEC mode, follow these steps to configure OSPF LSA pacing:
Command
Step 1 configure terminal
Step 2
router ospf process-id
Step 3 timers lsa-group-pacing seconds
Step 4 end
Step 5
show running-config
Step 6
copy running-config startup-config
To return to the default value, use the no timers lsa-group-pacing router configuration command.

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.
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Purpose
(Optional) Configure route calculation timers.
• spf-delay—Enter an integer from 0 to 65535. The default is 5
seconds; 0 means no delay.
• spf-holdtime—Enter an integer from 0 to 65535. The default is
10 seconds; 0 means no delay.
(Optional) Send syslog message when a neighbor state changes.
Return to privileged EXEC mode.
specific router. For some of the keyword options, see the
"Monitoring OSPF" section on page
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enable OSPF routing, and enter router configuration mode.
Change the group pacing of LSAs.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Catalyst 3560 Switch Software Configuration Guide
Configuring OSPF
30-36.
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