Process sends request to enter CR to all other processes. Contains name of critical region, process number and time. If receiver is in CR it queues request. When process exits CR it sends OK to all processes on its queue. If any process crashes it will not respond to requests.
Sender resends requests periodically then assumes dest.
Must track all in group. Less efficient than centralized. Token circulates around the ring. When you get token you have option to enter critical region. Upon exit pass token.