Configuring area ranges on an ABR to reduce advertisements to the backbone

You can configure area ranges to reduce inter-area advertisements by summarizing a range of IP addresses into a single route advertisement. This action prevents an ABR from advertising specific networks or subnets to the backbone area.

Prerequisites

You must be in the router configuration context, as indicated by the switch(config-router)# prompt.

Procedure

Summarize inter-area or NSSA paths using the following command. For command details, see area <AREA-ID> range.

area <area-id> range <ip-prefix> type {inter-area | nssa} [no-advertise]

For example, use the following command to summarize routes matching the area range 172.77.114.0/24 using inter-area as the type of address aggregation.

switch(config-router)# area 1 range 172.77.114.0/24 type inter-area

In another example, use the following command to specify DoNotAdvertise status for routes matching the area range 172.77.114.0/24. Use nssa as the type of address aggregation.

switch(config-router)# area 1 range 172.77.114.0/24 type nssa no-advertise