Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 197)

Multi-Service IronWare Routing Configuration Guide 169
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Configuring OSPF
If you are testing an OSPF configuration and are likely to disable and re-enable the protocol, you
might want to make a backup copy of the startup configuration file containing the protocol’s
configuration information. This way, if you remove the configuration information by saving the
configuration after disabling the protocol, you can restore the configuration by copying the backup
copy of the startup configuration file onto the flash memory.
Assign OSPF areas
Once OSPF is enabled on the system, you can assign areas. Assign an IP address or number as the
area ID for each area. The area ID is representative of all IP addresses (subnets) on a router port.
Each port on a router can support one area.
An area can be normal, a stub, or a Not-So-Stubby Area (NSSA):
• Normal – OSPF routers within a normal area can send and receive External Link State
Advertisements (LSAs).
• Stub – OSPF routers within a stub area cannot send or receive External LSAs. In addition, OSPF
routers in a stub area must use a default route to the area’s Area Border Router (ABR) or
Autonomous System Boundary Router (ASBR) to send traffic out of the area.
• NSSA – The ASBR of an NSSA can import external route information into the area.
• ASBRs redistribute (import) external routes into the NSSA as type 7 LSAs. Type-7 External
LSAs are a special type of LSA generated only by ASBRs within an NSSA, and are flooded
to all the routers within only that NSSA.
• ABRs translate type 7 LSAs into type 5 External LSAs, which can then be flooded
throughout the AS. You can configure address ranges on the ABR of an NSSA so that the
ABR converts multiple type-7 External LSAs received from the NSSA into a single type-5
External LSA.
When an NSSA contains more than one ABR, OSPF elects one of the ABRs to perform the
LSA translation for NSSA. OSPF elects the ABR with the highest router ID. If the elected
ABR becomes unavailable, OSPF automatically elects the ABR with the next highest router
ID to take over translation of LSAs for the NSSA. The election process for NSSA ABRs is
automatic.
Example
To set up the OSPF areas shown in Figure 8 on page 158, use the following method.
Brocade(config-ospf-router)# area 192.5.1.0
Brocade(config-ospf-router)# area 200.5.0.0
Brocade(config-ospf-router)# area 195.5.0.0
Brocade(config-ospf-router)# area 0.0.0.0
Brocade(config-ospf-router)# write memory
Syntax: [no] area num | ip-addr
The num | ip-addr parameters specify the area number, which can be a number or in IP address
format. If you specify a number, the number can be from 0 – 2,147,483,647.
In versions of the Multi-Service IronWare software prior to version 03.2.01, up to 18 OSPF areas
are supported. Version 03.2.01 of the Multi-Service IronWare software and later support up to 200
OSPF areas