Interconnecting Computers: Architecture, Technology, and Economics
Butler W. Lampson
Citation: Interconnecting computers: Architecture, technology, and economics. Proc. Conference on Programming Languages and System Architectures, Lecture Notes in Computer Science 782, Springer, 1994, pp 1-20.
Modern computer systems have a recursive structure of processing and storage elements that are interconnected to make larger elements:
Functional units connected to registers and on-chip cache.
Multiple processors and caches connected to main memories.
Computing nodes connected by a message-passing local area network.
Local area networks bridged to form an extended LAN.
Networks connected in a wide-area internet.
All the computers in the world exchanging electronic mail.
Above the lowest level of transistors and gates, the essential character of these connections changes surprisingly little over about nine orders of magnitude in time and space. Connections are made up of nodes and links; their important properties are bandwidth, latency, connectivity, availability, and cost. Switching is the basic mechanism for connecting lots of things. There are many ways to implement it, all based on multiplexing and demultiplexing. This paper describes some of them and gives many examples. It also considers the interactions among the different levels of complex systems.