How to Aggregate Routes and Advertise via BGP
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Created On 09/26/18 13:55 PM - Last Modified 06/16/23 17:21 PM
Resolution
- Route aggregation allows you to combine groups of routes with common addresses into a single entry in the routing table. This decreases the size of the routing table as well as the number of route advertisements sent by the routing device.
- Route aggregation works when it has one or more contributing route.
- A contributing route is an active route that is a more specific match for the aggregate destination.
- Example: for the aggregate destination 50.20.200.0/24 , route 50.20.200.64/26 is a contributing route, while 50.20.200.208/28 ,50.20.200.224/28 are not.
Requirement
- Aggregate Route : 50.20.200.0/24
- Contributing route : 50.20.200.64/26
- Non-Contributing route 50.20.200.208/28 ,50.20.200.224/28
Routing Table
Step1: Configure the Redistribution Profiles with Destination as the Routes that need to be aggregated or summarized.
Step 2: Configure the Aggregate section with the aggregated route. This route would be a summary of the Destinations configured in Redistribution Profile and advertised to the EBGP neighbor.
Step 3: Configure the Redistribution Rule selecting the Redistribution Profile configured with Step1 and commit the changes. .
Verification
- Check the Local RIB which shows the component of the Aggregated Route present in the Routing Table.
- RIB Out shows the Aggregated Route 50.20.200.0/24 being advertised.
owner: akawimandan