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Switching network

Switching network. Simple switching network. Communication Network Node. provide switching facility (routing). Network Station. end node (source &destination). Commuincations is achieve by transmitting data from source to destination through a network of switching nodes.

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Switching network

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  1. Switching network

  2. Simple switching network Communication Network Node • provide switching facility (routing) Network Station • end node (source &destination) Commuincations is achieve by transmitting data from source to destination through a network of switching nodes Communication Network

  3. Switching technology • Circuit switching • need a connection establishment between end nodes • connection is maintained until one of end nodes terminates • Connection is dedicated to the communication between two nodes • Example : Public Switch Telephone Network (PSTN) • Packet switching • data are transmitted in short message called packet • a connection between the two end-nodes is not maintained • a node-to-node link can be dynamically shared by may packets • Example : Public Data Network (PDN) likes X.25, Frame Relay

  4. Keys different Keys Circuit switching Public switching datadedicated single route different routes message by pass temporary store at each node node status both must be ready sender ready to send is enough connection dedicated shared utilization poor good data rate fixedvary Prioritisation not support support

  5. Routing in circuit switch • Alternate routing • need a connection establishment between end nodes • connection is maintained until one of end nodes terminates • Connection is dedicated to the communication between two nodes • Example : Public Switch Telephone Network (PSTN) • Adaptive routing • data are transmitted in short message called packet • a connection between the two end-nodes is not maintained • a node-to-node link can be dynamically shared by may packets • Example : Public Data Network (PDN) likes X.25, Frame Relay

  6. Public Switching Telephone Network end offic subscriber loop Long-distance office subscriber loop (local loop) link between subscriber and network Intercity trunk connecting trunk (exchanges) switching center; localized support subscriber Intercity trunk (trunks) branches between exchanges; carry multiple voice circuits connecting trunk

  7. PSDN • PSDN is designed specifically for the transmission of data rather than voice • Comunication is shared LAN PSDN= Public Switched Data Network LAN PSDN = LAN

  8. Packets data header data header data header data packet packet packet • Messages is broken up into a series of packets • Header is used to route the packet through the network

  9. PSDN switching approach • Virtual Circuit • network protocol establish a logical route called virtual circuit • packets use the same route; data arrive in the order • similar to circuit switching ! but the route is not dedicated • need call setup • Datagram • each packet is transmitted independently • network protocols route each packet as though it were a separate message • packet may not arrive in the order; need protocol to ensure ordering • call setup is not required

  10. 1.1 1.2 1.3 1.1 1.2 1.3 2.1 2.2 2.3 2.3 2.2 2.1 4 2 1 3 5 Virtual circuit B • A logical connection known as • virtual circuit (VC) is set up • between two stations. • Packets are labled with • a virtual circuit number and • a sequence number A C virtual circuit #1 B A C virtual circuit #2

  11. B.1 B.2 B.3 B.1 B.2 B.3 C.1 C.2 C.3 C.3 C.2 C.1 B.2 B.3 4 2 C.1 1 B.1 3 5 C.2 C.3 Datagram B • Aeach packet is transmitted • independently. • Packets are labled with • a destination address and • may arrive out of sequence A C B A C

  12. Routing in packet switch • Fixed routing • each packet is transmitted independently • Flooding • network protocol establish a logical route called virtual circuit • packets use the same route; data arrive in the order • Random routing • the route taken is a random • Adaptive routing • the route reacts to changing conditions within the network

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