Routers – how they work and how their used

Routers are specialized devices that links and routes everyone’s information over networks and the Internet through thousands of pathways. The main processes of the router include locating a pathway to create a link to and transmitting packets through this path. This process is done by routing data from a computer to a LAN through any number of routers to reach its destination. The router has proven itself to be one of the main components in the success of the Internet. Routers make networking possible by connecting large groups of people in a unified environment. (McGraw)The router is the one device that oversees all the data delivered over a network.

The router uses a tool called the configuration table to determine the path to send the packet. A configuration table contains information on which connections lead to particular groups of addresses, priorities for connections to be used, and rules for handling both routing and special cases of traffic. Configuration tables will vary in the number of lines depending on how big the capability of the router is. (McGraw)Data transmitted over the Internet, travels over the system of the packet-switching network.

This system breaks down data and information files into packages of about 1500 bytes. The data package carries the sender’s IP address, the receivers IP address, information on how many packets the data is broken down to, and the information on rebuilding the package. Each packet also contains the data of the Transmission Control Protocol/Internet Protocol (TCP/IP) for using the Internet. The packet is then sent off through the network using routers to find the best available route. Since each packet is sent separately, all the packets may end up taking different routes to reach its destination. The main advantages of using this method compared to sending all the packets over one dedicated line is that the network can balance the load across various parts of the network and avoid congesting certain areas. Depending on when and where you are accessing from, some networks may be busier than others so the routers will communicate with each other and utilize the less congested routes.

This enables the networks to function at full capacity and at anytime these packets can be rerouted through a different path if there is a problem. This method ensures delivery of the packets because of the various routes that can be taken to reach its destination. (Curt)There are many devices that pass signals from computers and networks but routers are the only devices that analyze and direct the destination of each data bundle. All devices that are used to connect to a network have a unique physical address. This address is called a MAC (Media Access Control) address and consists of 6 bytes. The first 3 bytes are used to identify the company that produced the device. The second 3 bytes are the unique serial number for the device itself. This enables the router to send information addressed to your computer through routers. (McGraw)Routers also have two main types of routing protocols, the distance vector routing and the link state routing protocols. The distance vector protocol first determines the distance that the package must travel then calculates the best route to take.

The second routing protocol link state protocol works similar but takes into consideration variables such as band width, delay, reliability, and load time. The routing protocols also specify the rules of layer 3 of the OSI model devices, which pass information within the topology of the network to decide which path is the best possible route to send the packets over the network. The protocols also states a specific format of the addresses used, how many bytes are allowed in a package, and disassembling and reassembling of packets sent over the network. (Roozbeh)The routing protocols use routing algorithms in order to determine the best route. The distance vector protocol uses the decentralized routing algorithms, where each router already has information on all the routers that it’s directly connected to. The link state protocol uses the global routing algorithms, where every router has the complete information on all the other outer in the network.

In order to find the best path the router sends echo packs throughout the network so that it can measure the time of delay. Once all the routers over the network have the information of each other they use the dijkstra shortest path algorithm. This algorithm uses the information of all the routers over the network and builds a graph, then assigns all the links on the graph with a weight or cost. Then all the router needs to do is choose the path with either the lowest weight or cost in order to determine the best path to take. (Roozbeh)Routers consist of a CPU, memory, and ports used to hook up external peripherals and devices. On the larger routers you can directly hook up a monitor to view the routers system. Although routers consist of all these elements their functions does not include creating, storing, or displaying any of the information it routes. Its main purpose is to route and filter packets to their final destinations.

Many routers are also capable of having different modules plugged in to its slots. These are called interface modules, which are layer 2 protocols and are used for networking in specific environments. (Curt)There has been many times that popular websites and their routers have received the denial of service attack. This attack prevents users from accessing the requested site by flooding the servers and routers with vast amounts of requests from the same address. By overcrowding the network with requests from one address in a short period of time, the router overloads and is forced to discard the remainder of the requests. In order to prevent this problem most routers now include rules in the configuration table that will disregard abnormally high amounts of requests from the same address. (McGraw)There are many different types of routers, where they all have different functions depending on how big and advanced they are.

For example the most basic type of router maybe having one computer hooked up to the Internet, and use that computer to route the Internet connection to another computer. This is the most basic type of router where there is just two devices connected. There are the routers that are a little more advanced and are usually stand-alone devices that are capable of connecting numerous computers to Internet, while enforcing security over the network. The security provided by the router is similar to a firewall but is mainly used to prevent access to unauthorized users. The biggest routers are designed to handle millions of packets per second and are usually used with systems such as the backbone of the Internet to handle the major traffic points of the Internet. (Curt)

Works Cited

McGraw Hill. “Routers” Cisco: A Beginner’s guide 2004 Time inc. 20 March 2007.

http://www.devhardware.com/c/a/Networking-Hardware/Router-Overview/Curt Franklin. “How Routers Work.” 31 July 2000. Time inc. 20 March 2007.

http://computer.howstuffworks.com/router.htmRoozbeh Razavi. “How Routing Algorithms Work.” November 19, 2002 Time inc. 20 March 2007.

http://www.howstuffworks.com/routing-algorithm.htm