Internet Architecture

With the help of routers it is possible for an organization to choose network technologies appropriate for each need,and to use routers to connect all networks into a single network.As all we know that router is used exactly two connections but commercial routers can connect more than two networks.Thus,a single router could connect any number of networks.However,an organization seldom uses single router to connect all of its networks.There are two main reasons behind it:

1.As all we know that router must forwarded each packet,the processor in given router is insufficient to handle the traffic passing among an arbitrary number of networks.

2.The second reason behind this is redundancy,because redundancy improves reliability.To avoid a single point of failure,protocol software continuously monitors internet connection,and instructs the routers to send traffic long alternative paths when a network or router fails.

Thus,when planning an internet,an organization must choose a design that meet's the organization's need for reliability,capacity and cost.In particular,the exact details of internet topology often depends on the bandwidth of the physical networks,the expected traffic,the organization's reliability requirements,and the cost and performance of available router hardware.