CoAP does not currently have a keepalive function. You could create your own keepalive using resource monitoring and sending a notification every x times.
In addition, the Http keepalive Http concept is to support a single TCP connection so that many requests and responses can be exchanged instead of using multiple connections. CoAP is mainly used over UDP, so the connections cannot be saved, so in reality it will not achieve the same goal.
CoAP TCP ( ), ( NAT, ). . , , .