Introduction to Routing and Switching Essay

1. Introduction – Computer Network A computer network is a setup which comprises of multiple computers and devices to create connection in order to support the communication of all such devices. This facilitates sharing of information and resources to all the users present in the network. The following are the main purposes that the network provides to its users:  · Communication- networks allow free flow of communication among all the users. These include chat, messages, emails, conferences, etc.  · Sharing of Resources – Resources can be shared among all the users within a network. These include: o Hardware – The different computers in a network can also make use of a single hardware attached to the network. Consider the example of a shared printer attached to multiple devices in the network like in case of a university or office environment. o Software- Network also allows users to share software application programs through their computers o Files and other data – Files and data can be shared among systems in a network environment through authorized access. This helps members to work and submit tasks on the same domain and within deadlines, thus saving from hassles. 2. The Open Systems Interconnection OSI Model The hardware components of the network operate at the layers of the OSI model which are briefly discussed below: Physical layer This is concerned with the functions that carry a stream of bits over a physical medium at the mechanical and electrical level. Hubs and Repeaters operate at the physical layer of the OSI model. Data link Layer This layer categorizes data from network layer (upper layer) into frames and handles errors of the physical layer to provide to the network layer. The Bridges operate at the Data link layer of the OSI Model. Network Layer The delivery of the packet is the responsibility of the network layer which can include multiple links. Network layer can be used in cases of multiple networks where there are some links between the networks. Routers operate at the Network layer of the OSI model. Transport Layer The transport layer is also responsible for delivery of packets but it also recognizes relationship between messages. This is done in proper order and the layer also ensures control of error and flow at the source as well as the destination. Session Layer This layer controls dialog and synchronizes interaction within the network. Presentation Layer This layer is also one of the most important layers as it is looks into the syntax and semantics of the data being transferred within the network. Application Layer This layer involves interfaces and other supporting frames for the user to access the network. 3. Hardware Components within a Network The following re the basic hardware components within a network to interconnect devices (Sosinsky 33): 3.1 Network Interface Cards (NICs) These are the components used to connect to another networking medium. The NIC has a unique identification number known as Media Access Control address (MAC address) that is provided by the manufacturer. 3.2 Repeaters Repeater is a device used to transmit signals after cleaning them by regenerating the original bit pattern. 3.3 Hubs Hub connects multiple devices in the network so that they appear as a single device, therefore, it has multiple ports. 3.4 Bridges These are also hardware components that connect multiple segments of the network. 4. Network Hardware Components – Routers and Switches Routers and switches are important components of the computer network that support the above mentioned purpose of a network. These are discussed in details as under: 4.1 Routers Router is a software or device that helps in transmitting data between users in a predefined manner, thus helping in serving the purpose of the network. The data is in the form of packets that travels along the network, where the routers process the data present in the packet. In many cases there is a pre-defined forwarding or routing table used to direct the information to the appropriate destination (Beasley 62). The main tasks of the routers include:  · Ensures information forwarding to the required destination  · Keeps track and avoids information from reaching where not needed 4.1.1 Characteristics The following are the characteristics of Routers:  · The routers correspond to internet Protocols such as the internet Protocol, internet Control message Protocol, etc.  · Provides interfaces between the packet networks through the required functions  · Sends and receives datagrams  · Chooses destination for the datagram according to the routing database  · Provides support facilities for network management which includes status and exception reporting, debugging, etc. 4.1.2 Routing Routing is the process of sharing information by connecting networks and translating protocols between them. It functions at the network layer of the OSI model, acquiring addresses from the IP header of the layer to get the sources and destination. Here the Routing Protocols are used. Routers also use the routing tables to decide the destination of the packets. The routing tables include:  · Address information  · Connection Priorities  · Traffic Rules Routing differs in its delivery schemes which include the following:  · Delivery to a single node (unicast) where the node is predefined.  · Delivery to multiple specified nodes (multicast)  · Delivery to all the nodes that are part of the network (Broadcast)