Abstract: We propose a mechanism for providing long term quality of service in deflection networks. Our proposed protocol is in fact a call admission control (CAC) scheme based on session probing combined with a feedback technique that allows a station originating a new session to notify other stations about its bandwidth requirements. This CAC scheme works in an environment in which there are no explicit connections or calls. No resources are reserved in advance and no bandwidth is wasted on passing tokens, which means that our protocol is easily scalable. With the increasing size and/or capacity of the network, only the normalized duration of the setup phase has to be extended. This setup phase of our protocol loosely corresponds to a connection setup phase in a connection-oriented store-and-forward network, e.g., ATM. However, we do not set up actual connections: all packets in the underlying network are routed according to the standard and simple deflection rules.