Configuring Ospf Areas; Configuration Prerequisites; Configuring A Stub Area - HP 6125G Configuration Manual

Configuring OSPF areas

After splitting an OSPF AS into multiple areas, configure some areas as stub areas or NSSA areas as
needed.
If no connection can be achieved between the backbone and a non-backbone area, or within the
backbone itself, you can configure virtual links to solve it.

Configuration prerequisites

Before you configure an OSPF area, complete the following tasks:
Configure IP addresses for interfaces, and make sure that all neighboring nodes can reach each
•
other at the network layer.
Configure OSPF basic functions.
•

Configuring a stub area

Configure a non-backbone area at the AS edge as a stub area by configuring the stub command on all
the routers attached to the area. In this way, Type-5 LSAs will not be flooded within the stub area,
reducing the routing table size. The ABR generates a default route into the stub area so all packets
destined outside of the AS are sent through the default route.
To further reduce the routing table size and routing information exchanged in the stub area, configure it
as a totally stub area by using the stub [ no-summary ] command on the ABR. In this way, neither AS
external routes nor inter-area routing information will be distributed into the area. All the packets destined
outside of the AS or area will be sent to the ABR for forwarding.
To configure OSPF areas:
Step
1. Enter system view.
2. Enter OSPF view.
3. Enter area view.
4. Configure the area as a stub
area.
5. Specify a cost for the default
route advertised to the stub
area.
Command
system-view
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ]
*
area area-id
stub
[ default-route-advertise-always |
no-summary ] *
default-cost cost
68
Remarks
N/A
N/A
N/A
Not configured by default.
You must use the stub command on
routers attached to a stub area.
The backbone area cannot be a
totally stub area.
A (totally) stub area cannot have
an ASBR because AS external
routes cannot be distributed into
the stub area.
Optional.
1 by default.
The default-cost command takes
effect only on the ABR of a stub
area.