AIS Router AI2524 - Manual (Page 144)

AI2524 Router Card User’s Manual
Page 8-6 August 1997
2524UM
Implementation Considerations
Before implementing this feature, consider these items:
z You can set a Type 7 default route that can be used to reach exter-
nal destinations. When configured, the router generates a Type 7
default into the NSSA by the NSSA ABR.
z Every router within the same area must agree that the area is NS-
SA; otherwise, the routers will not be able to communicate with
each other.
z If possible, avoid using explicit redistribution on NSSA ABR be-
cause confusion may result over which packets are being translat-
ed by which router.
Configure Route Summarization between OSPF Areas
Route summarization is the consolidation of advertised addresses.
This feature causes a single summary route to be advertised to other
areas by an ABR. In OSPF, an ABR will advertise networks in one
area into another area. If the network numbers in an area are assigned
sequentially, you can configure the ABR to advertise a summary route
that covers all the individual networks within the area that fall into the
specified range.
To specify an address range, type this command in router configura-
tion mode:
area area-id range address mask
Configure Route Summarization When Redistributing
Routes into OSPF
When redistributing routes from other protocols into OSPF, each route
is advertised individually in an external link state advertisement
(LSA). However, you can configure the Cisco IOS software to adver
tise a single route for all the redistributed routes covered by a specified
network address and mask. Doing so helps decrease the size of th
OSPF link state database.
To have the software advertise one summary route for all redistributed
routes covered by a network address and mask, type this command in
router configuration mode:
summary-address address mask