ICSA 341 Data communications & Computer Networks Switching In the WAN, mesh networks are not practical for geographically spread areas with many nodes we use switching systems in a “cloud” to interconnect networks or devices switches are not connected to every destination and many connections are not permanent

ICSA 341 Data communications & Computer Networks Types of Switching Message - legacy Circuit - voice networks, “nailed up” packet - data networks

ICSA 341 Data communications & Computer Networks Circuit Switching Creates a physical connection between devices total number of paths is much less than a mesh network because of the equipment used flavors: –space division –time division

ICSA 341 Data communications & Computer Networks Packet Switching For data, circuit switching is inflexible cannot adapt to varying speeds cannot usually prioritize Flavors of packet switching –datagram –virtual circuit

ICSA 341 Data communications & Computer Networks Datagram packet switching Information is broken up into small chinks or packets each has it’s own header containing addressing information so, each datagram finds it’s own way through the network switching is done node to node => datagrams may not all follow the same path

ICSA 341 Data communications & Computer Networks Virtual circuit approach All packets follow the same path through the network path is setup before user data goes out similar to circuit switching packets carry a virtual circuit identifier to indicate the path they are to follow => no routing decisions are made by intervening nodes