Administrator Guide

Loopback interface is treated as a stub Host.
Dell#
Configuring Stub Areas
OSPF supports different types of LSAs to help reduce the amount of router processing within the areas.
Type 5 LSAs are not flooded into stub areas; the ABR advertises a default route into the stub area to which it is attached. Stub
area routers use the default route to reach external destinations.
To ensure connectivity in your OSPFv2 network, never configure the backbone area as a stub area.
To configure a stub area, use the following commands.
1. Review all areas after they were configured to determine which areas are NOT receiving type 5 LSAs.
EXEC Privilege mode
show ip ospf process-id [vrf] database database-summary
2. Enter CONFIGURATION mode.
EXEC Privilege mode
configure
3. Enter ROUTER OSPF mode.
CONFIGURATION mode
router ospf process-id [vrf]
Process ID is the ID assigned when configuring OSPFv2 globally.
4. Configure the area as a stub area.
CONFIG-ROUTER-OSPF-id mode
area area-id stub [no-summary]
Use the keywords no-summary to prevent transmission into the area of summary ASBR LSAs.
Area ID is the number or IP address assigned when creating the area.
To view which LSAs are transmitted, use the show ip ospf database process-id database-summary command in
EXEC Privilege mode.
Dell#show ip ospf 34 database database-summary
OSPF Router with ID (10.1.2.100) (Process ID 34)
Area ID Router Network S-Net S-ASBR Type-7 Subtotal
2.2.2.2 1 0 0 0 0 1
3.3.3.3 1 0 0 0 0 1
Dell#
To view information on areas, use the show ip ospf process-id command in EXEC Privilege mode.
Configuring LSA Throttling Timers
Configured link-state advertisement (LSA) timers replace the standard transmit and acceptance times for LSAs.
The LSA throttling timers are configured in milliseconds. The interval time increases exponentially until a maximum time is
reached. If the maximum time is reached, the system continues to transmit at the maximum interval. If the system is stable for
twice the maximum interval time, it reverts to the start-interval timer. The cycle repeats.
To configure the LSA throttling timers, use the following commands.
1. Specify the interval times for all LSA transmissions. CONFIG-ROUTER-OSPF-id mode. timers throttle lsa all
{start-interval | hold-interval | max-interval} To set the minimum interval between initial sending and
resending the same LSA, use the keywords start-interval. To set the next interval to send the same LSA, use the
keywords hold-interval. The hold-interval is the time between sending the same LSA after the start-interval is
attempted. To set the maximum amount of time the system waits before sending the LSA, use the keywords max-
interval. The interval range is 0 to 600,000 milliseconds.
650
Open Shortest Path First (OSPFv2 and OSPFv3)