summary (RIP)
Function
The summary command enables RIP classful aggregation. The aggregated routes are advertised as the routes with the natural mask.
The undo summary command cancels classful aggregation to perform routing between subnets. Subnet information is then advertised. Route aggregation reduces the amount of information in the routing table.
By default, classful aggregation is enabled for RIP-2.
Parameters
| Parameter | Description | Value |
|---|---|---|
| always | Enables auto summary irrespective of split horizon configuration. | - |
Usage Guidelines
Classful aggregation does not take effect in RIP-1. When RIP-2 is applied, you can run the undo summary command to cancel classful aggregation.
Route aggregation in RIP-2 greatly improves scalability and efficiency of large-scale networks. Aggregating IP addresses implies that there is no sub-route entry in the RIP routing table. That is, there is no route entry that is composed by a single IP address. With route aggregation, the size of the routing table is reduced and the FW can process more routes.
When classful aggregation is enabled, a FW aggregates subnet addresses to the natural network boundary when advertising routes outside the natural network boundary. Route aggregation is invalid when split horizon or poison reverse is configured if not use the always. When the aggregated routes are sent outside the natural network boundary, split horizon or poison reverse in related views needs to be disabled.
Although classful aggregation is enabled by default for RIP-2, route aggregation is invalid when split horizon or poison reverse is configured. When the aggregated routes are sent outside the natural network boundary, split horizon or poison reverse in related views needs to be disabled.
summary always command enables classful aggregation irrespective of split horizon or poison reverse configuration.
Route summary applied on the interface has high priority over that applied on the RIP process. rip summary-address command has high priority over summary command.
When both interface summary and RIP summary coexists, then RIP summary is advertised only when few child routes fall outside the interface summary boundary.