Creating stubby or not-so-stubby OSPF areas

Import information from other areas to learn their OSPF relationships. Perform this procedure to create normal, stubby, or not-so-stubby areas (NSSA).

Before you begin

Change the VRF instance as required to configure OSPF on a specific VRF instance. The VRF must have an RP trigger of OSPF. Not all parameters are configurable on non-default VRFs.

About this task

Place stubby areas or NSSAs at the edge of an OSPF routing domain. Ensure that you configure all routers in the stubby or NSSA as stubby or NSSA, respectively.

Procedure

In the navigation pane, expand Configuration > IP.
Click OSPF.
Click the Areas tab.

The backbone ID has an area ID of 0.0.0.0.
Click Insert.
Configure the area ID.
Select an option in the ImportAsExtern area.

To add a not-so-stubby (NSSA) area, select importNssa. To import external LSAs (create a normal OSPF area), select importExternal. To not import external LSAs (create a stubby area), select importNoExternal.
Click Apply.

Areas field descriptions

Use the data in the following table to use the Areas tab.


Name	Description
AreaId	Specifies a 32-bit integer that uniquely identifies an area. Area ID 0.0.0.0 is the OSPF backbone. For VLANs, using the default area on the interface causes LSDB inconsistencies.
ImportAsExtern	Specifies the method to import ASE link-state advertisements. The value can be importExternal (default), importNoExternal, or importNssa.
SpfRuns	Specifies the number of SPF calculations performed by OSPF.
AreaBdrRtrCount	Specifies the number of area border routers reachable within this area. Each SPF pass calculates this value, initially zero.
AsBdrRtrCount	Specifies the number of autonomous system border routers reachable within this area. Each SPF pass calculates this value, initially zero.
AreaLsaCount	Specifies the total number of link state advertisements in this area LSDB, excluding AS-external LSAs.
AreaLsaCksumSum	Specifies the number of link-state advertisements. This sum excludes external (LS type 5) link-state advertisements. The sum determines if a change occurred in a router LSDB and compares the LSDB of two routers.
AreaSummary	Specifies whether to send summary advertisements in a stub area.
ActiveifCount	Specifies the number of active interfaces in this area.
AreaNssaTranslatorRole	Indicates if the NSSA border router can perform NSSA translation of Type 7 LSAs to Type 5 LSAs. The possible values are always or candidate. The default is candidate.
AreaNssaTranslatorState	Indicates if and how an NSSA border router translates Type 7 LSAs to Type 5 LSAs. The possible values are: enabled — the border router always translates the LSAs elected — a candidate border router translates the LSAs disabled — a candidate border router does not translate the LSAs
AreaNssaTranslatorStablilityInterval	Specifies number of seconds after an elected translator determines its services are no longer required.
AreaNssaTranslatorEvents	Specifies the number of translator state changes that have occurred since the last boot up.