Chapter 19
| Unicast Routing
Configuring the Open Shortest Path First Protocol (Version 2)
Configuring
Summary Addresses
(for External AS
Routes)
Figure 501: Importing External Routes
To show the imported external route types:
1.
Click Routing Protocol, OSPF, Redistribute.
2.
Select Show from the Action list.
3.
Select the process ID.
Figure 502: Showing Imported External Route Types
Redistributing routes from other protocols into OSPF normally requires the router
to advertise each route individually in an external LSA as described in the
preceding section. The reduce the number of protocol messages required to
redistribute these external routes, an Autonomous System Boundary Router (ASBR)
can instead be configured to redistribute routes learned from other protocols into
all attached autonomous systems.
To reduce the amount of external LSAs sent to other autonomous systems, you can
use the Routing Protocol > OSPF > Summary Address (Add) page to configure the
router to advertise an aggregate route that consolidates a broad range of external
addresses. This helps both to decrease the number of external LSAs advertised and
the size of the OSPF link state database.
Command Usage
◆
If you are not sure what address ranges to consolidate, first enable external
route redistribution via the Redistribute configuration screen, view the routes
– 736 –