Creating an OSPFv3 Area

Create an area to subdivide the autonomous system (AS) into areas that group contiguous networks, routers that connect to these networks, and attached hosts. Subdividing the AS into areas significantly reduces the amount of routing protocol traffic compared to treating the entire AS like a single link-state domain.

About this task

A stub area does not receive advertisements for external routes, which reduces the size of the link-state database (LSDB). A stub area uses only one area border router (ABR). Any packets destined for outside the area are routed to the area border exit point, examined by the ABR, and forwarded to a destination.

A not so stubby area (NSSA) prevents the flooding of AS-External link-state advertisements into the area by replacing them with a default route. NSSAs also import small stub (non- OSPF) routing domains into OSPF.

Before you begin

Change the VRF instance as required to configure OSPFv3 on a specific VRF instance.
Note
Non-default VRFs do not support the configuration of the following parameters:
- OSPFv3 interfaces over IPv6 tunnels
- IPSec on OSPFv3 virtual link interfaces

Procedure

In the navigation tree, expand the following folders: Configuration > IPv6.
Click OSPFv3.
Click the Areas tab.
Click Insert.
Type the area ID.
Click Insert.

Areas field descriptions

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


Name	Description
Id	Specifies a 32–bit integer to uniquely identify an area. Use 0.0.0.0 for the OSPFv3 backbone.
ImportasExtern	Indicates the support for importing AS-external LSAs:: importExternal—normal area importNoExternal—stub area importNssa—not-so-stubby-area AS-scope LSAs are not imported into stub areas or NSSAs. NSSAs import AS-External data at Type 7 LSAs, which use area scope. importExternal is the default.
SpfRuns	Shows the number of times the intra-area route table was calculated using the LSDB of this area.
BdrRtrCount	Shows the number of reachable ABRs in this area. The value starts at zero (0). The system calculates this value in each SPF run.
AsBdrRtrCount	Shows the number of reachable ASBRs in this area. The value starts at zero (0). The system calculates this value in each SPF run.
ScopeLsaCount	Shows the number of area-scope LSAs in the LSDB for this area.
ScopeLsaCksumSum	Shows the sum of the checksums for the area-scope LSAs in the LSDB. Use the sum to determine if a change in the LSDB occurs, and to compare the LSDBs of the two routers.
Summary	Controls the import of inter-area LSAs into a stub area. If the value is noAreaSummary, the router does not originate nor propagate inter-area LSAs into the stub area. If the value is sendAreaSummary (the default), the router both summarizes and propagates inter-area LSAs.
StubMetric	Configures the metric value advertised for the default route to stub and NSSA areas.
NssaTranslatorRole	Indicates if the NSSA border router can perform NSSA translation of Type 7 LSAs to Type 6 LSAs. The possible values are always or candidate. The default is candidate.
NssaTranslatorState	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.
StubMetricType	Specifies the type of metric advertised as a default route. The possible values are: ospfv3Metric—OSPF metric comparableCost—external Type 1 nonComparable—external Type 2 The default is ospfv3Metric.