Multiple ACK windows providing congestion control in reliable multicast protocol

摘要

A multicast repair tree is established, the repair tree having one sender station and a plurality of repair head stations. A repair head station has an affiliated group of member stations. A repair head station retransmits a lost message to its affiliated group of member stations upon receipt from a member station of a NACK message indicating that the selected message was not received. Acknowledgment windows (ACK windows) are established in a member station for transmission of ACK or NACK message by the member station. A number of messages transmitted by the sender station during a transmission window is established. Also a same size of ACK window is established in the receiving stations, with a slot in the ACK window corresponding to each message transmitted by the repair head station. Each receiving station is assigned a slot in the ACK window during which time that receiving station transmits its ACK or NACK messages. Thus the ACK window slots assigned to receiver stations for transmission of ACK/NACK windows are staggered so that different receiver stations transmit their ACKNACK messages at different times. The slot for a particular receiver station to use may be assigned by a random process.