Bulk multicast data transfer – towards the integration of FEC and ARQ using a lightweight feedback control tree

This paper describes the design of a reliable multicast framework which integrates FEC and receiverinitiated retransmit to ensure reliability. A dynamically elected control tree is used to aggregate the NAKs and tackle the NAK implosion problem. Both techniques support flow and congestion control to enable efficient, high data rate multicast data transfer as performance measurements with our prototype show. The presented protocol uses NAK-feedback to handle burst packet loss and to adjust the send rate to a level, where most of the losses can be recovered through FEC-coding. Upstream feedback is reduced to a minimum allowing scalability with very limited protocol processing. The responsibility for the reliable data transfer is completely moved to the receivers. Receivers avoid state management for other group members, which is common in the design of other treebased approaches.