We introduce a new method, called priority encoding transmission, for sending messages over lossy packet-based networks. When a message is to be transmitted, the user specifies a priority value for each part of the message. Based on the priorities, the system encodes the message into packets for transmission and sends them to (possibly multiple) receivers. The priority value of each part of the message determines the fraction of encoding packets sufficient to recover that part. Thus even if some of the encoding packets are lost en-route, each receiver is still able to recover the parts of the message for which a sufficient fraction of the encoding packets are received. For any set of priorities for a message, we define a natural quantity called the girth of the priorities. We develop systems for implementing any given set of priorities such that the total length of the encoding packets is equal to the girth. On the other hand, we give an information-theoretic lower bound that shows that for any set of priorities the total length of the encoding packets must be at least the girth. Thus the system we introduce is optimal in terms of the total encoding length. This work has immediate applications to multimedia and high-speed networks applications, especially in those with bursty sources and multiple receivers with heterogeneous capabilities. Implementations of the system show promise of being practical.

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No abstract available.

We introduce a novel approach for sending messages over lossy packet-based networks. The new method, called Priority Encoding Transmission, allows a user to specify a different priority on each segment of the message. Based on the priorities, the sender uses the system to encode the segments into packets for transmission. The system ensures recovery of the segments in order of their priority. The priority of a segment determines the minimum number of packets sufficient to recover the segment. We define a measure for a set of priorities, called the rate, which dictates how much information about the message must be contained in each bit of the encoding. We develop systems for implementing any set of priorities with rate equal to one. We also give an information-theoretic proof that there is no system that implements a set of priorities with rate greater than one. This work has applications to multi-media and high speed networks applications, especially in those with bursty sources and multiple receivers with heterogeneous capabilities.>

This paper describes considerations for potential future public data communication services interconnecting users on private local area networks belonging to different administrative domains. The relevant management issues are addressed in an architecture consisting of distributed software modules organized in a hierarchical structure supporting network administration functions. The authors describe an experimental internetworking unit being built to explore the functional capabilities needed to interface ethernet networks to systems operating at OC-3 SONET/SDH rates of 155.22 Mb/s with basic asynchronous transfer mode (ATM) transport capabilities. They describe bandwidth allocation, address screening, address translation, and traffic monitoring service aspects in the experimental prototype.>

A novel architecture is described for point-to-multipoint distribution using coherent detection and a totally passive fiber bus. Coherent technology is used initially to provide transmission at rates of a few hundred Mb/s without the need for a local oscillator at each station. It is expected that this architecture can then be expanded via WDM (wavelength-division multiplexing) to transport multiple wavelengths as coherent technology matures. The performance of the proposed topology is analyzed and compared to that of previous bus structures using variable and fixed taps with direct-detection receivers. This performance analysis consists essentially of a loss budget calculation intended to determine the relative numbers of stations which each of the architectures could support. Because the rates and loop lengths are modest and the spectral width of the sources associated with coherent communication are very small, dispersion (or rise-time budgeting) is not expected to present any real limitation for the systems considered here. A performance analysis and comparison of three tree structures is presented. Engineering issues and open questions are discussed.>