Virtual Links; Router Priority And Cost - Dell C9000 Series Networking Configuration Manual

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require reduced intervals for LSA transmission and acceptance. Throttling timers allow for this improved

convergence times.

The LSA throttling timers are configured in milliseconds, with the interval time increasing exponentially until a

maximum time has been reached. If the maximum time is reached, the system, the system continues to

transmit at the max-interval until twice the max-interval time has passed. At that point, the system reverts to

the start-interval timer and the cycle begins again.

When you configure the LSA throttle timers, syslog messages appear, indicating the interval times, as shown

below for the transmit timer (45000ms) and arrival timer (1000ms).

Mar 15 09:46:00: %STKUNIT0-M:CP %OSPF-4-LSA_BACKOFF: OSPF Process 10,Router lsa id

2.2.2.2 router-id 2.2.2.2 is backed off to transmit after 45000ms

Mar 15 09:46:06: %STKUNIT0-M:CP %OSPF-4-LSA_BACKOFF: OSPF Process 10,Router lsa id

3.3.3.3 rtrid 3.3.3.3 received before 1000ms time

Virtual Links

In the case in which an area cannot be directly connected to Area 0, you must configure a virtual link

between that area and Area 0.

The two endpoints of a virtual link are ABRs, and you must configure the virtual link in both routers. The

common non-backbone area to which the two routers belong is called a transit area. A virtual link specifies

the transit area and the router ID of the other virtual endpoint (the other ABR).

You cannot configure a virtual link through a stub area or NSSA.

Router priority and cost is the method the system uses to "rate" the routers.

For example, if not assigned, the system selects the router with the highest priority as the DR. The second

highest priority is the BDR.

Priority is a numbered rating 0 to 255. The higher the number, the higher the priority.

Open Shortest Path First (OSPFv2 and OSPFv3)