In a previous article we discussed the basics of what a router did. We're now going to get into a more detailed, and yes technical, explanation of how packets are transmitted as well as a few other tech specs of how routers work. So put on your learning caps because you're in for a real mind bender.
Internet data, whether it be in the form of a web page, a downloaded file or an email message, travels over what is called a packet switching network. Basically what happens is that the data is broken up into individual packets because there is only so much data that can be transmitted at one time. Each packet is about 1500 bytes long. Each packet contains quite a bit of information including the sender's address, the receiver's address and of course the information being sent which includes the order of each packet how it should be put back together so that the end user can make sense of the data. The packet is sent off to its destination based on what the router believes to be the best route to follow, which is usually the route with the least amount of traffic and if possible, the shortest route. Each packet may actually given a different route depending on conditions at the time, which in a high traffic network can change every second. By doing this, the router can balance the load across the network so that no one segment gets overloaded. Also, if there is a problem with one piece of equipment in the network, the router can bypass this piece of equipment and send the packet along another route. This way if there is a problem, the entire message will still arrive intact.
In conducting this process, routers have to speak to each other. They tell each other about any problems on the network and make recommendations on routes to take. This way, paths can be reconfigured if they have to be. However, not all routers do all jobs as routers come in different sizes and have different functions.
There are what we call simple routers. A simple router is usually used in a simple small network. Simple routers simply look to see where the data packet needs to go and sends it there. It doesn't do much else.
Slightly larger routers, which are used for slightly larger networks, do a little bit more. These routers will also enforce security for the network, protecting the network from outside attacks. They are able to do a good enough job of this that additional security software is not needed.
The largest routers are used to handle data at major points on the Internet. These routers handle millions of packets of information per second. They work very hard to configure the network as efficiently as possible. These are stand alone systems and actually have more in common with supercomputers than with a simple server one might have in a small office.
In our next instalment we'll look at how to actually trace the path that a message has taken and some examples of transmitting packets.
in Networks
Source: http://www.readbud.com/Articles/Networks/Router-_45_-Transmitting-Packets
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