Nssa - 3Com 5500-EI PWR Reference Manual

nssa

Syntax
nssa [ default-route-advertise | no-import-route | no-summary | translate-always ] *
undo nssa
View
OSPF area view
Parameters
default-route-advertise: Redistributes a default route into an NSSA.
no-import-route: Redistributes no routes into an NSSA.
no-summary: Advertises only a default route in a Type-3 summary LSA into the NSSA area and
disables the ABR from transmitting any other Type-3 LSAs to an NSSA
translate-always: Specifies the ABR as the Type-7 LSAs translator of the NSSA area. This keyword
takes effect only on the ABR of an NSSA area.
Description
Use the nssa command to configure an OSPF area as an NSSA area.
Use the undo nssa command to cancel the function.
By default, no NSSA area is configured.
For all the routers connected to the NSSA area, the nssa command must be used to configure the area
as an NSSA.
The default-route-advertise keyword is available only on an NSSA ABR or ASBR. If this keyword is
configured on an NSSA ABR, the ABR generates a default route in a Type-7 LSA into the NSSA
regardless of whether the default route is available. If it is configured on an ASBR, only when a default
route is available on the ASBR can it generate the default route in a Type-7 LSA into the attached area.
The no-import-route keyword is usable only on an NSSA ABR that is also the ASBR of the OSPF
routing domain. It disables redistributed routes from entering the NSSA area, but allows them to enter
other OSPF areas.
The no-summary keyword is usable only on an NSSA ABR to advertise only a default route in a Type-3
summary LSA into the NSSA area. In this way, all the other summary LSAs are not advertised into the
area. Such an area is known as an NSSA totally stub area.
The translate-always keyword is used to specify the ABR of an NSSA area as the Type-7 LSAs
translator.
In the NSSA area, the Type-7 LSAs translator state determines whether the ABR needs to translate
Type-7 LSAs into Type-5 LSAs. You can use the display ospf brief command to display the Type-7
LSAs translator state.
If the translate-always keyword is not used on the ABR, the ABR will take part in the Type-7 LSAs
translator election among all the ABRs in the NSSA area.
If the Type-7 LSAs translator state is Elected after the election, the ABR translates Type-7 LSAs
into Type-5 LSAs.
If the Type-7 LSAs translator state is Disabled after the election, the ABR does not translate
Type-7 LSAs into Type-5 LSAs.
4-34