Lsa Group Pacing - Cisco Catalyst 9500 series Configuration Manual

Configuring IP Unicast Routing
• Virtual links: In OSPF, all areas must be connected to a backbone area. You can establish a virtual link
• Default route: When you specifically configure redistribution of routes into an OSPF routing domain,
• Domain Name Server (DNS) names for use in all OSPF show privileged EXEC command displays
• Default Metrics: OSPF calculates the OSPF metric for an interface according to the bandwidth of the
• Administrative distance is a rating of the trustworthiness of a routing information source, an integer
• Passive interfaces: Because interfaces between two devices on an Ethernet represent only one network
• Route calculation timers: You can configure the delay time between when OSPF receives a topology
• Log neighbor changes: You can configure the router to send a syslog message when an OSPF neighbor

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.
Loopback Interfaces
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
in case of a backbone-continuity break by configuring two Area Border Routers as endpoints of a virtual
link. Configuration information includes the identity of the other virtual endpoint (the other ABR) and
the nonbackbone link that the two routers have in common (the transit area). Virtual links cannot be
configured through a stub area.
the route automatically becomes an autonomous system boundary router (ASBR). You can force the
ASBR to generate a default route into the OSPF routing domain.
makes it easier to identify a router than displaying it by router ID or neighbor ID.
interface. The metric is calculated as ref-bw divided by bandwidth, where ref is 10 by default, and
bandwidth (bw) is specified by the bandwidth interface configuration command. For multiple links
with high bandwidth, you can specify a larger number to differentiate the cost on those links.
between 0 and 255, with a higher value meaning a lower trust rating. An administrative distance of 255
means the routing information source cannot be trusted at all and should be ignored. OSPF uses three
different administrative distances: routes within an area (interarea), routes to another area (interarea),
and routes from another routing domain learned through redistribution (external). You can change any
of the distance values.
segment, to prevent OSPF from sending hello packets for the sending interface, you must configure the
sending device to be a passive interface. Both devices can identify each other through the hello packet
for the receiving interface.
change and when it starts the shortest path first (SPF) calculation and the hold time between two SPF
calculations.
state changes, providing a high-level view of changes in the router.
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
LSA Group Pacing
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