By default, the cost of the default route to the stub area is 1.
----End
Checking the Configuration
Run either of the following commands to check LSDB information.
l display ospf [ process-id ] lsdb [ brief ]
l display ospf [ process-id ] lsdb [ router | network | summary | asbr | ase | nssa | opaque-
link | opaque-area | opaque-as ] [ link-state-id ] [ originate-router [ advertising-router-
id ] | self-originate ] [ age { min-value min-age-value | max-value max-age-value }
*
]
Run either of the following commands to check routing table information.
l display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ] [ interface
interface-type interface-number ] [ nexthop nexthop-address ]
l display ospf [ process-id ] routing router-id [ router-id ]
Run the display ospf [ process-id ] abr-asbr [ router-id ] command to check ASBR and ABR
information.
4.8 Configuring an NSSA
Configuring a non-backbone area on the border of an AS as an NSSA does not transmit routes
learned from other areas in the AS but imports AS external routes. This reduces bandwidth and
storage resource consumption on the switch.
Applicable Environment
An NSSA is configured in the scenario where AS external routes are to be imported but not
forwarded to save system resources.
The NSSA is a new type of OSPF area. Neither the NSSA nor the stub area transmits routes
learned from other areas in the AS it resides. The stub area does not allow AS external routes to
be imported, whereas the NSSA allows AS external routes to be imported and forwarded in the
entire AS.
Type 7 LSAs are used to carry imported AS external routing information in the NSSA. Type 7
LSAs are generated by the ASBRs of NSSAs and flooded only in the NSSAs where ASBRs
reside. The ABR in an NSSA selects certain Type 7 LSAs from the received ones and translates
them into Type 5 LSAs to advertise AS external routing information to the other areas over the
OSPF network.
To configure an area as an NSSA, configure NSSA attributes on all the switches in this area.
Pre-configuration Tasks
Before configuring an NSSA, complete the following tasks:
l Configuring IP addresses for interfaces to ensure that neighboring switches are reachable
at the network layer
l Configuring Basic OSPF Functions
S6700 Series Ethernet Switches
Configuration Guide - IP Routing 4 OSPF Configuration
Issue 01 (2012-03-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
118
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