The NSSA region is similar to the OSPF stub region and does not spread from the backbone type 5 external link status advertisement (ISA) to the region, but can introduce AS external routing in a limited form within the region.
NSSA can introduce external routes of Type 7 AS in the NSSA area through redistribution, and then translate Type 7 LSA into Type 5 LSA, which is distributed to the entire routing domain by the NSSA area boundary router (ABR). It can be summarized and filtered in translation.
For Internet Service Providers (ISPs) or network administrators, they must use OSPF to connect the central site to remote sites using different routing protocols, so NSSA makes management easier.
Before NSSA, since the routes to the remote site cannot be reassigned to the stub area, the connection between the common site boundary router and the remote router cannot be managed according to the OSPF stub area. Redistribution issues are usually handled using a simple RIP-like protocol, which means that two routing protocols must be maintained. Define the common router and remote router as NSSA, extending OSPF to cover remote connections.
If necessary, in router configuration mode, specify the following regional parameters and set the NSSA of OSPF:
Command | Function
------------------------------------------------------------------------------------
area area-id nssa[no-redistribution][default-information-originate] |Define the area as NSSA.
In the ABR (regional boundary router) router configuration mode, execute the following command to convert the Type 7 LSA (link status advertisement) to Type 5 LSA (link status advertisement) and summarize and filter
Command | Function
-------------------------------------------------------------------------------
summary address prefix mask [notadvertise][tag tag] |Summary and filtering during conversion (optional).
When setting this feature, consider the following factors:
Type 7 default routes can be set to achieve external destination sites. When configured in this way, the NSSA ABR router generates a Type 7 default route to NSSA.
Any router in the same area must support the NSSA zone, otherwise the routers cannot communicate with each other.
Note that try not to use explicit redistribution on NSSA ABR. Because the packages converted through this router are easily confused. Article entry: csh Editor in charge: csh
NSSA can introduce external routes of Type 7 AS in the NSSA area through redistribution, and then translate Type 7 LSA into Type 5 LSA, which is distributed to the entire routing domain by the NSSA area boundary router (ABR). It can be summarized and filtered in translation.
For Internet Service Providers (ISPs) or network administrators, they must use OSPF to connect the central site to remote sites using different routing protocols, so NSSA makes management easier.
Before NSSA, since the routes to the remote site cannot be reassigned to the stub area, the connection between the common site boundary router and the remote router cannot be managed according to the OSPF stub area. Redistribution issues are usually handled using a simple RIP-like protocol, which means that two routing protocols must be maintained. Define the common router and remote router as NSSA, extending OSPF to cover remote connections.
If necessary, in router configuration mode, specify the following regional parameters and set the NSSA of OSPF:
Command | Function
------------------------------------------------------------------------------------
area area-id nssa[no-redistribution][default-information-originate] |Define the area as NSSA.
In the ABR (regional boundary router) router configuration mode, execute the following command to convert the Type 7 LSA (link status advertisement) to Type 5 LSA (link status advertisement) and summarize and filter
Command | Function
-------------------------------------------------------------------------------
summary address prefix mask [notadvertise][tag tag] |Summary and filtering during conversion (optional).
When setting this feature, consider the following factors:
Type 7 default routes can be set to achieve external destination sites. When configured in this way, the NSSA ABR router generates a Type 7 default route to NSSA.
Any router in the same area must support the NSSA zone, otherwise the routers cannot communicate with each other.
Note that try not to use explicit redistribution on NSSA ABR. Because the packages converted through this router are easily confused. Article entry: csh Editor in charge: csh