Cisco NCS 5500 Series

Example:
RP/0/RP0/CPU0:router#clear ospf 100 vrf vrf_1 process
Clears OSPF route table.
Step 11 clear { ospf | ospfv3 }[ process-name ] statistics [ neighbor [ type interface-path-id ] [ ip-address ]]
Example:
RP/0/RP0/CPU0:router# clear ospf 100 statistics
(Optional) Clears the OSPF statistics of neighbor state transitions.
Stub Area
A stub area is an area that does not accept route advertisements or detailed network information external to
the area. A stub area typically has only one router that interfaces the area to the rest of the autonomous system.
The stub ABR advertises a single default route to external destinations into the stub area. Routers within a
stub area use this route for destinations outside the area and the autonomous system. This relationship conserves
LSA database space that would otherwise be used to store external LSAs flooded into the area.
Not-so-Stubby Area
A Not-so-Stubby Area (NSSA) is similar to the stub area. NSSA does not flood Type 5 external LSAs from
the core into the area, but can import autonomous system external routes in a limited fashion within the area.
NSSA allows importing of Type 7 autonomous system external routes within an NSSA area by redistribution.
These Type 7 LSAs are translated into Type 5 LSAs by NSSA ABRs, which are flooded throughout the whole
routing domain. Summarization and filtering are supported during the translation.
Use NSSA to simplify administration if you are a network administrator that must connect a central site using
OSPF to a remote site that is using a different routing protocol.
Before NSSA, the connection between the corporate site border router and remote router could not be run as
an OSPF stub area because routes for the remote site could not be redistributed into a stub area, and two
routing protocols needed to be maintained. A simple protocol like RIP was usually run and handled the
redistribution. With NSSA, you can extend OSPF to cover the remote connection by defining the area between
the corporate router and remote router as an NSSA. Area 0 cannot be an NSSA.
Configure Stub and Not-So-Stubby Area Types
This task explains how to configure the stub area and the NSSA for OSPF.
SUMMARY STEPS
1. configure
2. Do one of the following:
• router ospf process-name
• router ospfv3 process-name
Routing Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.3.x
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Implementing OSPF
Stub Area