Circuit Switching · Circuit switching There is a dedicated communication path between two stations (end-to-end) The path is a connected sequence of links between network nodes On each physical link, a logical channel is dedicated to the connection Communication via circuit switching has three phases: Circuit establishment (link by link) Routing resource allocation( dm or TDm) Data transfer Circuit disconnect Deallocate the dedicated resources The switches must know how to find the route to the destination and how to allocate bandwidth channel)to establish a connection 6
6 Circuit Switching • Circuit switching: — There is a dedicated communication path between two stations (end-to-end) — The path is a connected sequence of links between network nodes. On each physical link, a logical channel is dedicated to the connection. • Communication via circuit switching has three phases: — Circuit establishment (link by link) • Routing & resource allocation (FDM or TDM) — Data transfer — Circuit disconnect • Deallocate the dedicated resources • The switches must know how to find the route to the destination and how to allocate bandwidth (channel) to establish a connection
Circuit Switching Properties Inefficiency Channel capacity is dedicated for the whole duration of a connection If no data, capacity is wasted Delay Long initial delay: circuit establishment takes time Low data delay: after the circuit establishment, information is transmitted at a fixed data rate with no delay other than the propagation delay. the delay at each node is negligible. Developed for voice traffic(public telephone network) but can also applied to data traffic. For voice connections the resulting circuit will enjoy a high percentage of utilization because most of the time one party or the other is talking. But how about data connections?
7 Circuit Switching Properties • Inefficiency — Channel capacity is dedicated for the whole duration of a connection — If no data, capacity is wasted • Delay — Long initial delay: circuit establishment takes time — Low data delay: after the circuit establishment, information is transmitted at a fixed data rate with no delay other than the propagation delay. The delay at each node is negligible. • Developed for voice traffic (public telephone network) but can also applied to data traffic. — For voice connections, the resulting circuit will enjoy a high percentage of utilization because most of the time one party or the other is talking. — But how about data connections?