Network layer protocols such as the Internet protocol (IP) offer an unreliable, best-effort multicast datagram service in internetworks. In order to use this point-to-multipoint communication service for the software update of peripheral file servers, it has to be enhanced to guarantee a reliable delivery of files. While many other multicast applications have less stringent reliability requirements it is essential for this application that either peripheral file servers receive a file correctly, or a failure can be detected and signalled to the user. We propose an end-to-end application layer protocol building on top of a thin transport layer (UDP) and a best-effort network layer multicast service (IP), that delivers such a service and is geared towards the use in heterogeneous campus area networks. It employs sender-based implosion avoidance, and rate-based flow control in order to adapt to changing network conditions.

The authors study packet loss in high speed networks interconnecting conventional local area networks (LANs). They consider two different techniques to control contention at the station where packets leave the high speed network and must wait for service by the LAN. One technique is based on a backoff strategy where packet transmission to a temporary overloaded station is interrupted for a randomly chosen time. The other technique studied uses rate-based flow control. A discussion of results for both fiber distributed data interface (FDDI) and distributed queue dual bus (DQDB) shows protocol-specific peculiarities requiring different solutions to different problems. Packet loss characteristics obtained for FDDI and DQDB are very close to each other.>