Assignment Overview

What is a Router?



A router is a computer and has many of the common hardware components found on other types of computers. A router also includes an operating system. Examining some of the basic hardware and software components will give you a better understanding of the routing and packet-forwarding process.



Routers are Computers



A router is a computer, just like any other computer, including a PC. The first router, which was used for the Advanced Research Projects Agency Network (ARPANET), was the IMP (Interface Message Processor). The IMP was a Honeywell 516 minicomputer that brought the ARPANET to life on August 30, 1969.



Figure 2 shows the front side of a Cisco 1800 series Integrated Services Router. Routers have many of the same hardware and software components that are found in other computers, including



CPU

RAM

ROM

Operating system





Figure 2. Cisco 1841 Integrated Services Router



Routers are at the Network Center



A typical user might be unaware of the presence of numerous routers in his or her own network or in the Internet. Users expect to be able to access web pages, send e-mails, and download music, whether the server they are accessing is on their own network or on another network halfway around the world. However, networking professionals know that it is the router that is responsible for forwarding packets from network to network, from the original source to the final destination.



A router connects multiple networks. This means that it has interfaces that belong to different IP networks. When a router receives an IP packet on one interface, it determines which interface to forward the packet on its way to its destination. The interface that the router uses to forward the packet can be the network of the final destination of the packet (the network with the destination IP address of this packet), or it can be a network connected to another router that is used to reach the destination network.



Each network that a router connects to typically requires a separate interface. These interfaces are used to connect a combination of both local-area networks (LAN) and wide-area networks (WAN). LANs are commonly Ethernet networks that contain devices such as PCs, printers, and servers. WANs are used to connect networks over a large geographical area. For example, a WAN connection is commonly used to connect a LAN to the Internet service provider (ISP) network.



Figures 3 and 4 show routers in LANs.







Figure 3. A router in a LAN







Figure 4. Two routers connecting 2 LANs.



Figure 5 shows that Routers R1 and R2 are responsible for receiving the packet on one network and forwarding the packet out another network toward the packet’s destination network.







Figure 5. Routers are the center of a network



To learn more about routers, check the following sites:



Introduction to Routers (http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/249-introduction-routers.html)

Medhi, D & Ramasamy, K (2007) Networking and Network Routing: An Introduction (http://www.networkrouting.net/docs/mr-chapter_1.pdf)

Introduction to Routers (http://www.slideshare.net/santosh9702/introduction-to-routers)

Introduction to Routers (http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/249-introduction-routers.html)



Case Assignment

You are required to review the case materials and conduct your own research (at least three additional sources of materials. Please be sure to use appropriate citations for materials that you collect on your own), please write a 2- to 3-page paper (excluding the cover page and reference page) to describe, in your own words, what routers are and when routers are used in network design.



Assignment Expectations

Your paper should be between two and three pages. You are expected to understand the concept of routers and the components of a router.



Upload the assignment when you are finished.