History of Computer Networking: The technological advancements in the field of computer networking started in 1969. During that time, the Advanced Research Projects Agency (ARPA) decided to implement a project called the Advanced Research Projects Agency Network (ARPANET). This was the world's first network, which only consisted of four nodes. Since then, computer networking has come a long way. Introduction to Computer Networking A computer network is literally, a network of computers. Each computer in it is connected to another via a transmission medium such as an Ethernet cable. There are many different kinds of computer networks, such a LAN, MAN or WAN. There are also many different types of network topologies, a.k.a backbone network structures. A LAN (local area network) typically consists of a few interconnected computers (typically less than hundred). The computer network in any single establishment or building will be a LAN type of connection. A metropolitan area network (MAN) is a network of many LAN's. For example, an MNC might have many buildings in the same area. Every building might have their individual LAN's. It would be highly essential to have a network between them. This is where a MAN comes into the picture. A city like New York or Chicago can have many MANs. When you connect all the above mentioned networks together, you will get a WAN (wide area network). There are also Ethernet protocols, such as TCP/IP, according to which communication in a computer network takes place. When all the above issues are taken care of, then you have a smooth running computer network. Designing a Simple Computer Network When designing a computer network, selecting the right design becomes a priority. These designs are also known as network topologies. Depending upon the number of terminals that your network is going to have, you should select the appropriate network topology. There are mainly five types of network topologies. They are, star, ring, mesh, tree and bus. In star topology, all the nodes are connected to a single node. In ring topology, every node is connected to two other nodes and they form of a circle. In mesh topology, every node is connected to every other node. In tree topology, there is a root node (or super node), to which two or more nodes are connected, and the rest of the terminals are connected in a hierarchical fashion. In bus topology, there is a common medium like a backbone, and terminals are connected to it. Transmission Media The physical channel of communication between the sender and the receiver is called the transmission media. There are two different types of transmission media: bounded and unbounded. The bounded media are those media in which communication takes place through wires. The unbounded media comprises wireless communication. Examples of Bounded Transmission Media

• Twisted pair cable
• Coaxial cable
• Fiber optic cable

Examples of Unbounded Transmission Media

• Radio links (Microwave)
• Infrared

The factors that need to be considered while selecting a transmission media are as follows.

• Bandwidth: The greater the bandwidth of the signal, the higher is the data transmission rate.
• Transmission impairments: Whatever your media, it should have minimum transmission impairments.
• Interference: Competing signals can sometimes distort or completely disrupt a signal. Interference by such signals should be minimum.

Equipment The following sheds light on some of the basic components that are used in making a computer network.

• Network Interface Card (NIC): It is a hardware add-on component for the computer. All communication signals, to and from the node, must pass through the NIC first.
• Switch: All computers in a LAN must connect to a switch. A switch is a device which is capable of maintaining a local area network between all the terminals that are connected to it. It is also responsible for sending traffic inside and outside the switched network.
• Hub: It is used to connect various components (computer as well as other devices) in the network. A USB network hub should fill the needs of a home network.
• Router: A router is a gateway device, that is responsible for establishing connection between various networks (Internal as well as external).

OSI Reference Model and TCP/IP Reference Model Protocols are a set of standard rules that are followed during various stages of communication. OSI (Open System Interconnect) reference model describes the hierarchy of various protocols that are used in computer networks. TCP/IP reference model is derived from OSI and provides a set of protocols that are used across multiple and diverse networks. The following discussion will help you understand the specific differences between layers of OSI reference model and layers of TCP/IP protocol stack. There are seven layers in OSI Reference Model, and each layer performs a very defined function:

• Application layer: This layer provides distributed information services.
• Presentation layer: Provides independence to application processes.
• Sessions layer: Provides a control structure for communication between applications.
• Transport layer: Provides reliable transfer of data between end points.
• Network layer: Provides independence to the upper layers from the lower layers
• Data-link layer: Provides reliable transfer of information across a physical link.
• Physical layer: Handles transmission of an unstructured bit stream.

There are only four layers in TCP/IP Reference Model:

• Application layer: Includes all processes and services that use transport layer to deliver data.
• Transport layer: Provides support to TCP or UDP protocol.
• Internet layer: It handles machine to machine communications.
• Host to network: Responsible for accepting and transmitting IP datagram.

The key difference between OSI reference model and TCP/IP reference model is that TCP/IP came into effect with the advent of Internet, and is the main language of communication used by it. TCP/IP is a robust protocol model that can also be effectively used in smaller private network setups. Implementing a Computer Network Design While implementing a computer network, there are two kinds of technologies that have to be thought of - client/server and peer-to-peer. In most cases, client/server technology is preferred as it provides a better capability to future growth and network expansion. Most existing computer networks are wired networks, and it is very difficult to change them. Considering future compatibility, wireless architecture proves to be better, as it provides easy scale-up, without a lot of additional cost or much degradation of performance. Some examples of wireless computer networks are, WPAN (Wireless Personal Area Network), WMAN (Wireless Metropolitan area Network), WLAN (Wireless Wide Area Network). Even the network of mobile devices is considered a part of wireless networking. Security If a computer network is carrying sensitive information, some form of data security has to be implemented. Computer networking security is a very broad topic, and immense amount of research has been done in this field. Basically the following issues must be addressed when tying to implement network security.

• Security attacks: These are actions which compromise security information.
• Security mechanisms: Methods to prevent security attacks.
• Types of computer security: These are the services that are instrumental in handling security of the apparatus. They can be categorized as:
  • Confidentiality
  • Authentication
  • Integrity
  • No repudiation
  • Access control
  • Availability

All these are applicable to wireless networks as well. Troubleshooting A systematic approach can help greatly when trying to troubleshoot a computer network that has developed a problem. You should start by checking the wiring and connections first as faulty connection is the most common cause of most network related issues. If the wired connections are all checked and still the problem persists, then the hardware equipment must be inspected. If one finds that the hardware is also performing properly, then one must check for software malfunction. By performing these basic checks, one should be able to pin-point the problem, and then proceed to the appropriate solution. Certifications The various certification courses that are available for computer networking certifications are as follows.

• CISCO
  • Cisco Certified Network Associates (CCNA)
  • Cisco Certified Network Professional (CCNP)
  • Cisco Certified Internetwork Expert (CCIE)
  • Cisco Certified Voice Professional (CCVP)
• Novell CNE
• Red Hat Certified Engineer (RHCE)
• Microsoft Certified System Engineer (MSCE)
• Certified Information Security Professional (CISSP)

Degrees The degrees that you can get in the field of computer networking are Associates Degrees in Computer Networks, Bachelors Degrees in Computer Networks and Systems, and online diplomas. Once you have the basic qualification, you can go for a Masters of Science in Computer Networking as well. Jobs Once you obtain a degree, or become a certified professional, then there are many jobs that can be applied for, like a network administrator, a network technician, a network engineer, or a network analyst. A Network Administrator's job description includes overseeing the proper functioning of the network of an entire institution. A Network Technician's job description includes establishing and maintaining the network. A Network Engineer is responsible for high level tasks such as creating, designing and maintaining the network. The network engineer and network administrator have similar jobs, but they are different in the sense that, the engineer tackles more complex tasks that an administrator cannot handle (issues with network architecture, etc). A Network Analyst's job description includes the analysis of various situations in the network, predicting the outcome, and suggesting various solutions. He is basically responsible for various occurrences in the network and finding out whether the arisen issue is normal or malicious in nature. Computer networking encompasses all the aspects of computer science (hardware, software and security). Since there is huge growth in the IT sector, the future seems bright for this field.