connection duration

[fgtest1]

HI,
I am trying to understand a 5minutes peer connection
context 2 peers establish connection by having P2 to dial P1, connection established

After 180sec (3 min) the communication drop following the swarm config

let swarm = libp2p::SwarmBuilder::with_existing_identity(id_keys)
    .with_tokio()
    .with_tcp(
        tcp::Config::default(),
        noise::Config::new,
        yamux::Config::default,
    )?
    .with_behaviour(|_| MyBehaviour {
        request_response,
        kademlia,
    })?
    .with_swarm_config(|c| c.with_idle_connection_timeout(Duration::from_secs(180)))  //60 keepaline
    .build();

However, every 5 minutes there an automatic dial between the 2 peers
where P2 dial P1 again again...

There is no reason, nor traffic -the session-connection is first when P2 dial P1 and nothing more.

P1 and P2 will only communication when a file transfer will be triggered (which is working) fine.

Any default parameters timers /duration /sleep or timeout

Thanks