WAN Technology and Protocols
A company runs a group of 100 cookie stores. At the end of each day, each store burns about 3 MB of sales and inventory data onto a CD-R and express-mails the CD-R to headquarters, which uses the data to ship new inventory and plan marketing campaigns. The company has decided to move to a wide area network for data. Which alternative of wide area networks for data (shown on screenshots 1 and 2) would you recommend? Why?
15.1 Relative Men t Circuit Switching and Packet Switching of Data Circuit Switching Advantages tible with voice. Economies of scale can be d by using the same network for voice and data. network properly. The problem is less severe with the isadvantages Subject to blocking. This makes it difficult to size the monality of calling procedures for voice and No special user training or communication ocols are needed to handle data traffic. table, constant rate for data traffic. use of dynamic nonhierarchical routing techniques. Requires subscriber compatibility. The devices at cach end of a circuit must be compatible in terms of Pre tocol and data rate, since the circuit is a transpar- ent connection. Large processing and signal burden. For transaction- type applications, data calls are of short duration and need to be set up rapidly. This proportionally increases the overhead burden on the network. Packet Switching Advantages Disadvantages nversion. Two attached devices with Complex routing and control. To achieve ein ay exchange data; the network and resilience, a packet-switched network must employ buffers the data and delivers them at the appropriate a complex set of routing and control algorithms. data rate Appears nonblocking. As the network load increases, it is variable the delay increases, but new exchanges are usually permitted Efficient utilization. Switches and trunks are used on demand rather than dedicating capacity to a particular call Logical multiplexing. A host system can have simultaneous conversations with a number of terminals over a single line Delay. Delay is a function of load. It can be long and With all of these choices, and with the constantly changing prices attached to the various choices, it is difficult to generalize. What can be said is that business relies heavily on the public telephone networks and related services. Private networks are appropriate for an organization with a number of sites and with a substantial amount of voice traffic between them A new entry in the competition is voice over IP (VoIP). VoIP uses a packet transmission approach over Internets and intranets. VolP is enjoying gradually growing acceptance as an alternative. We discuss VoIP in Section 15.5 Wide Area Networks for Data For data traffic, the number of wide area networking choices is even broader Roughly, we can list the following categories as alternatives: Public packet-switching networks: There are a number of such networks in the United States and at least one in most industrialized countries. Typically the user must lease a line from the user's computing equipment to the nearest packet-switching node
