CHAPTER 8 Switching A network is a set of connected devices.Whenever we have multiple devices,we have the problem of how to connect them to make one-to-one communication possible.One solution is to make a point-to-point connection between each pair of devices (a mesh topology)or between a central device and every other device (a star topology).These methods,however,are impractical and wasteful when applied to very large networks. The number and length of the links require too much infrastructure to be cost-efficient, and the majority of those links would be idle most of the time.Other topologies employing multipoint connections,such as a bus,are ruled out because the distances between devices and the total number of devices increase beyond the capacities of the media and equipment. A better solution is switching.A switched network consists of a series ofinterlinked nodes,called switches.Switches are devices capable of creating temporary connections between two or more devices linked to the switch.In a switched network,some of these nodes are connected to the end systems(computers or telephones,for example).Others are used only for routing.Figure 8.1 shows a switched network. Figure 8.1 Switched network B A The end systems (communicating devices)are labeled A,B,C,D,and so on,and the switches are labeled I,II,III,IV,and V.Each switch is connected to multiple links. 213￾    !!"#$%$&! !%'$"!!""((""#%'$) $#"%((%'!%*"! %$+,-'$,!*%$+,-! "!&!&"%$#$!%%$,$+ !#"'$+!!$.#"#!##'(& !"/,!$#$'$"!")!%$+ "%$,+"#$%&#!'#&#$#'#! '!$#"'',!%! ".#%" '$#!+!$ &$$!0!%'$+"%, '"$!!1!&"! !,"*"%#$%!&2"%$-)! #$,#+3+#4!! 3+#4 56789:;<=;86>?@ !,"*""#+-$'$&A&￾&B&&! !$'$1&11&111&1C&C!!"#$%$$ D4E