Foundry NetIron M2404C and M2404F Metro Access Switches
Configuring Advanced Routing Information (Rev. 03)
Open Shortest Path First (OSPF)
© 2008 Foundry Networks, Inc
Page 24 of 68
Argument Description
area-id
OSPF area ID as a decimal value in the range <0-4294967295>.
A.B.C.D
OSPF area ID in IP address format.
import-list ACL-NAME
Routing access list name for filtering.
Configuring an OSPF Area as NSSA
The
area nssa
command, in Router OSPF Configuration mode, sets the specified OSPF area as
NSSA. The
no
form of this command removes the area definition.
OSPF supports RFC 1587 (
The OSPF NSSA Option
) and
draft-ietf-ospf-nssa-update-10
, where
OSPF NSSA option is described.
NSSA allows importing of type 7 autonomous system external routes within NSSA area by
redistribution. If the router is elected as an NSSA translator, then it translates all Type 7 LSAs
from its database into Type 5 LSAs and floods them into the other areas. When the router is an
ASBR in NSSA area, it automatically redistributes all external routes as Type7 LSAs into the area.
Use NSSA to simplify administration if the user is an Internet Service Provider (ISP) or a network
administrator that must connect a central site using OSPF to a remote site that is using a different
routing protocol.
Command Syntax
device-name
(config-router)#
area
{<
area-id
> |
A.B.C.D
}
nssa
[
no-summary
]
[
translate-always
|
translate-never
|
translate-candidate
]
device-name
(config-router)#
no area
{<
area-id
> |
A.B.C.D
}
nssa
[
no-
summary
]
Argument Description
area-id
OSPF area ID as a decimal value in the range <0-4294967295>.
A.B.C.D
OSPF area ID in IP address format.
no-summary
(Optional). Prevents injection of inter-area routes into NSSA.
translate-always
(Optional). If the router is an ABR, the command always translates
type7 LSA into type 5 LSA and floods type 5 LSA into the AS.
translate-never
(Optional). Prevents translating type7 LSA into type 5 LSA.
translate-candidate
(Optional). If the router is ABR, it will participate in the NSSA
translator-election procedure.
Specifying a Stub Area
The
area stub
command, in Router OSPF Configuration mode, defines the specified area to be a
stub area. The
no
form of this command removes the definition.
Stub areas are areas into which information on external routes is not sent. Instead, there is a default
external route, generated by the ABR, into the stub area for destinations outside the autonomous
system. To take advantage of the OSPF stub area support, default routing must be used in the stub
area. To further reduce the number of LSAs sent into a stub area, the user can configure the
no-
summary
keyword of the area stub router configuration command on the ABR to prevent it from
sending summary link advertisements (LSAs type 3) into the stub area.