area nssa
(OSPFv3)
Creates a not-so-stubby area (NSSA) or modifies its parameters.
Syntax
area
{
ip-addr
|
decimal
}
nssa
[
metric
]
[
default-information-originate
[
metric
num
]
[
metric-type
{
type1
|
type2
}
]
]
[
no-redsitribution
]
[
no-summary
]
[
translator-always
]
[
translator-interval
interval
]
Command Default
No areas are created.
Parameters
-
ip-addr
- Area address in IP address format.
-
decimal
- Area address in decimal format.
-
metric
- Additional cost for using a route to or from this area. Valid values range from 1 through 1048575.
-
default-information-originate
- When configured on the ABR, this parameter injects a Type 7 default route into the NSSA area. As a result, the other NSSA routers install the default route through the advertising NSSA ABR. By default the NSSA ABR does not originate a default route to the NSSA.
-
metric-type
- Specifies how the cost of a neighbor metric is determined.
- type1
- The metric of a neighbor is the cost between itself and the router plus the cost of using this router for routing to the rest of the world.
- type2
- The metric of a neighbor is the total cost from the redistributing routing to the rest of the world.
-
no-redistribution
- The no-redistribution parameter prevents an NSSA ABR from generating external (type-7) LSA into a NSSA area. This is used in the case where an ASBR should generate type-5 LSA into normal areas and should not generate type-7 LSA into a NSSA area. By default, redistribution is enabled in a NSSA.
-
no-summary
- When configured on the NSSA area border router (ABR), this parameter prevents any Type 3 and Type 4 summary link-state advertisement (LSA) from being injected into the area. The only exception is that a default route is injected into the NSSA by the ABR, and strictly as a Type 3 LSA (not a Type 7, because that could cause intra-AS traffic to get routed out the AS). This makes the NSSA a NSSA totally stubby area, which can only have Type 1, 2 and 7 LSAs.
Note: This parameter is disabled by default, which means the default route must use a Type 7 LSA.
-
translator-always
- Configures the translator-role. When configured on an ABR, this causes the router to unconditionally assume the role of a NSSA translator. By default, translator-always is not set, the translator role by default is candidate.
-
translator-interval
interval
- Configures the time interval for which an elected NSSA translator continues to perform its duties even after its NSSA translator role has been disposed by another router. Valid values range from 10 through 60 seconds. By default the stability-interval is 40 seconds.
Modes
OSPFv3 router configuration mode
OSPFv3 router VRF configuration mode
Usage Guidelines
NSSAs are typically needed when one-way transmission of Type-5 LSAs (out of the area) is desired but injection of the same LSAs into the area is not acceptable.
Once created, the type of the area cannot be changed. The only exception to this rule is that a NSSA or stub area can be changed to a totally NSSA or a totally stub area, respectively.
The
no
form of the command deletes a NSSA.
Examples
The following example sets an additional cost of 4 on a NSSA identified as 8 (in decimal format), and prevents any Type 3 or Type 4 summary LSAs from being injected into the area.
device# configure terminal
device(config)# ipv6 router ospf
device(config-ipv6-router-ospf-vrf-default-vrf)# area 8 nssa 4 no-summary
