What Is Part Of Network Hardware

Network Hardware:- 

It is now time to turn our attention from the applications and social aspects of networking to the 

technical issues involved in network design. there is no generally accepted taxonomy in to which 

all computers networks fit, but two dimension stand out as important: transmission technology and scale. we will now examine ease of these in turn.

    Broadly speaking, there are two types of transmission technology:

1- Broadcast Networks.

2- Point-To-Pont Networks.  

Broadcast networks have a single communicaton channel that is shared bu all the machine on the 

network. short messages, called packets in certain contexts, sent by any machine are received by 

all the others. an address and field within the packets specifies for whom it is intended. upon 

receiving a packet, a machine checks the address field. if the packets is intended for itself, it 

processes the packets; if the packets is intended for some other machine, it is just ignored.

     As an analogy, consider someone standing at the end of of a corridor with many room off it and 

shouting "Watson, come here. i want you." Although the packet may actually be received (heard) 

by many people, only Watson responds. The others just ignore it. another example is an airport 

announcement asking all flight 644 passengers to report to get 12.

   Broadcast system generally also allow the possibility of addressing a packets to all destinations 

by using a special code in the address field. when a packet with this code is transmitted, it is 

received and processed by every machine on the network. this mode of operation is called 

broadcasting. some broadcast system also support transmission to a subset of the machines, 

something known as multicasting. one possible scheme is to reserved one bit to indicate 

multicasting. The remaining n-1 address bits can hold a group number. Each Machine can 

"Subscribe" to any or all of the groups. when a packet is sent to a certain group, it is delivered to 

all machine subscribing to that group.

   In contrast, point to point networks consist of many connections between individual pairs of 

machine. to go from the source to the destination, a packet on this type of network may have to 

first visit one or more intermediate machines.

  Often multiple routs of different lengths are possible, so routing algorithms play in important role 

in point-to-point networks. as a general rule (although there are many exceptions) smaller, 

geographycally localized networks tend to use broadcasting, whereas larger networks usually are point-to-point.

     An alternative criterion for classifying networks is there scale. In Figure 2nd we give a 

classification of multiple processors system arranged by there physical size. At the top are data 

flow machines, highly parallel computers with many functional units all working on the same 

program. Next come the multicomputers, system that communicate by sending messages over 

very short, very fast buses. Beyond the multicomputers are the true networks, computers that 

communicate by exchanging message over longer cables. These can be divided in to local, 

metropolition, and wide area networks. finally the connection of two or more networks is called an 

internetwork. The world wide internet is a well known example of an internetwork. Distance is 

important as a classification metric because different techniques are used at different scales. In 

this book we will be concerned with only the true networks and their interconnection. below we 

give a brief introduction to the subject of networkhardware....