3. Fasi CC con Careful Resume

Phase	Role	Key exits or actions
Observing	Save CC parameters for a Remote Endpoint	MUST NOT retain more than one set; SHOULD update or replace later observations
Reconnaissance	Confirm the saved path while using normal CC	stop on congestion, path change, expired Lifetime, reused saved_cwnd, or minimum RTT <= saved_rtt / 2
Unvalidated	Tentatively jump CWND using paced transmission	jump_cwnd <= Min(max_jump, saved_cwnd/2); all packets MUST use pacing based on current RTT
Validating	Check whether unvalidated packets arrived without congestion	enter Safe Retreat on packet loss or ECN-CE; exit after last unvalidated packet is acknowledged
Safe Retreat	Recover safely after congestion from unvalidated packets	delete saved parameters; CWND <= PipeSize/2; CWND MUST NOT increase; ssthresh <= PipeSize * Beta

Se i parametri scadono, il path non corrisponde, viene rilevata congestione, saved_cwnd e gia usato, o minimum RTT <= saved_rtt / 2, il mittente ferma Careful Resume e torna a normal CC.