Thursday, 31 January 2013

Network Device

Network Device

Let’s now take a look at some of the devices that move traffic around the network

The approach taken in this section will be simple.  As networking technology continues to evolve, the actual differences between networking devices is beginning to blur slightly.  Routers today are switching packets faster and yielding the performance of switches.  

Switches, on the other hand, are being designed with more intelligence and able to act more like routers.  Hubs, while traditionally not intelligent in terms of the amount of software they run, are now being designed with software that allows the hub to be “intelligent” acting more like a switch. 

In this section, we’ll keep these different types of product separate so that you can understand the basics.  Let’s start off with the hub.
Network Device Hub
Network Device Hub

Star topology networks generally have a hub in the center of the network that connects all of the devices together using cabling.  When bits hit a networking device, be they hubs, switches, or routers, the devices will strengthen the signal and then send it on its way. 

A hub is simple a multiport repeater.  There is usually no software to load, and no configuration required (i.e. network administrators don’t have to tell the device what to do). 

Hubs operate very much the same way as a repeater.  They amplify and propagate signals received out all ports, with the exception of the port from which the data arrived. For example, if system 125 wanted to print on the printer 128, the message would be sent to all systems on Segment 1, as well as across the hub  to all systems on Segment 2.  System 128 would see that the message is intended for it and would process it. 

Devices on the network are constantly listening for data.  When devices  sense a frame of information that is addressed (and we will talk more about addressing later) for it, then it will accept that information into memory found on the network interface card (NIC) and begin processing the data. 

In fairly small networks, hubs work very well.  However, in large networks the limitations of hubs creates problems for network managers.  In this example, Ethernet is the standard being used.  The network is also baseband, only one station can use the network at a time.  If the applications and files being used on this network are large, and there are more nodes on the network, contention for bandwidth will slow the responsiveness of the network down.

to be continued...

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