Data Communication & networking

This blog is for undergraduate/graduate students who require some basic information about their subjects or any other topic related to data communication.

Monday, 28 March 2011

Circuit Switching

In circuit switching a dedicated communication path is established between two devices through one or more intermediate switching nodes. Communication via circuit switching involves three phases.

1- Circuit Establishment: Before any signal can be transmitted, an end-to-tend circuit must be establishes. hence a station requests connection from nodes. Node determine best route, sends message to the next link. Each subsequent node continues the establishment of the path. Once the node has established the connection test message is sent to determine if receiver is ready or able to accept message.

2- Data Transfer: Point to point information is transfer from source to node. The path link is internal switching and multiplexed the information from node to node.Hence again data is transferred point to point from node to receiver. Generally the connection is full duplex.

3-Circuit Disconnect: After some period of data transfer, the connection is terminated usually by the action of one of the two stations. Signal must be propogated to all nodes used to transit in order to free up resources.

Circuit switching can be rather inefficient, channel capacity is dedicated for the duration of a connection even if no data is being transferred.
Circuit switching was developed to handle voice traffic, but it is now used for data traffic.The best known example of circuit switching is PSTN.

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