In BGP, Keepalive messages are used to maintain BGP peer relationships.

 BGP Keepalive Message Behavior

Keepalive messages are used to maintain the Established state of a BGP peer relationship.

The Keepalive timer determines the frequency of these messages and defaults to 60 seconds , as per the BGP specification.

 HCIP-Datacom-Core Reference

The Keepalive timer default value is covered in the BGP configuration and operational principles​​.