User's Manual
435
60.3.6 Configure OSPF domain
Configurable area parameters include: authentication, designating Stub area, designating metric for default
summary route. Authentication adopts protection based on passwords.
Stub areas are those that don’t distribute external routes in them. Instead, ABR generates a default external
route to enter the stub area, enable it to enter the external network of the autonomous system. in order to
utilize the features OSPF Stub support, you should use default route in the Stub area. In order to additionally
reduce LSA number sent into the Stub area, you can prohibit gathering ABR to reduce the sending of summary
LSA (type3) entered into the Stub area.
Under router configuration mode, use the following command to define the area parameter:
Command Purpose
area
area-id
authentication simple
Activates OSPF area authentication
area
area-id
authentication message-digest
Enables OSPF to use MD5 for authentication
area
area-id
stub
[
no-summary
]
Defines a Stub area
area
area-id
default-cost
cost
Sets metric for default route in Stub area.
60.3.7 Configuring the NSSA Area of OSPF
The NSSA area is similar to the STUB area. However, the NSSA area allows external routes to be entered.
The route summary and packet filtration are also supported during transmission. If ISP requires to use the
remote network with different routing protocols, the NSSA can simplify management.
The enterprise-core boundary router cannot run in the STUB area of OSPF if NSSA is not applied. That’s
because the routes of the remote network cannot be forwarded to the STUB area. The simple routing protocols
such as RIP can be advertised, but two kinds of routing protocols need be maintained. NSSA can put the
center router and the remote router in the same NSSA area and OSPF thus be applied to the remote network.
When the NSSA area is used, note that the route generated by the ABR router can enter the NSSA area once
NSSA is configured. Each router in the same area must admit that they are in the NSSA area, or different
routers cannot communicate with each other. The displayed release must be used on ABR to avoid packet
transmission confusement of the router.
Run the following command in router configuration mode to set the NSSA area of OSPF:
Command Purpose
Area area-id nssa
[
no-redistribution
][
no-
summary
][
default-information-originate
]
Configures the OSPF NSSA area.
60.3.8 Configuring Route Summary Within OSPF Domain
This feature enables ABR to broadcast a summary route to other areas. In OSPF, ABR will broadcast every
network to other areas. If the network number can be allocated according to a certain method, and be
continuous, you can configure ABR to broadcast a summary route to other areas. A summary route can cover
all networks within a certain range.
Under router configuration mode, use the following commands to define the address ranges: