Friday, April 05, 2013

The philosophical doctrine that every state of affairs, including every human event, act, and decision is the inevitable consequence of antecedent states of affairs.

Thursday, April 04, 2013

Deterministic Networks

In local area networks (LANs), a non-contentious medium access control (MAC) convention that allows both the centralized master station, which commonly is in the form of a server, and each slaved station to determine the maximum length of time that passes before a station gains access to the network, perhaps on the basis of programmed access priorities. Deterministic access employs token passing, a protocol in which a token, which consists of a specific bit pattern, indicates the status of the network -- available or unavailable.The token is generated by a centralized master control station and transmitted across the network.The station in possession of the token (the last station to receive the message containing the token) controls the access to the network. That station may either transmit or require other stations to respond. Transmission is in the form of a data packet of a predetermined maximum size, determined by the number of nodes on the ring and the traffic to be supported. After transmitting, the station passes the token to a successor station, in a predetermined sequence. Token passing is complex and overhead-intensive, but the associated high level of network control avoids data collisions.Token Ring is a deterministic LAN protocol.