Basic hardware and terminology in networks

If you explore more on computer networks, you will come across with a huge list of terminology associated with networks. Let us look at the basic terminology used in the subject of computer networks in brief. It is worth to note here that all networks are made up of basic hardware building blocks to interconnect network nodes.

Node.Any device attached to the network capable of communicating with other network devices is called a Node. A node can be a computer or some other device, such as a printer. Every node has a unique network address, sometimes called a Data Link Control (DLC) address or Media Access Control (MAC) address.

Client.A device or application that uses the services provided by a server is called a Client in the network. A client may be a PC or a workstation on a network using services provided from the network file server, or it may be that part of an application program that runs on the workstation supported by additional software running on the server. One of the most familiar clients is the Web browser.

Server.Any computer that makes access to files, printing, communications, and other services available to users of the network is called a Server in the network. In large networks, a dedicated server runs a special network operating system; in smaller installations, a non-dedicated server may run a personal computer operating system with peer-to-peer networking software running on top.

A server typically has a more advanced processor, more memory, a larger cache, and more disk storage than a single-user workstation. A server may also have several processors rather than just one and may be dedicated to a specific support function such as printing, e-mail, or communications. Many servers also have large power supplies, UPS (uninterruptible power supply) support, and fault-tolerant features, such as RAID technology. On the Internet, a server responds to requests from a client, usually a Web browser.

Following Figure 7 shows the client and server in a network.

Figure 7- Client and Server

Hub.A device used to extend a network so that additional workstations can be attached. In some star networks, a hub is the central controlling device. Hubs typically provide from 4 to 24 connections, allowing anything from 2 to 24 devices to communicate with one another. Following Figure 10 shows the use of a hub in a Star network (You will learn what a star network is in the latter part of this session) while the Figure shows an enlarged view of an 8-port hub.

Figure 8- Hub in a Star network Figure 9- 8-port Hub

IP Address.An Internet Protocol (IP) address is a numerical identification (logical address) that is assigned to devices participating in a computer network utilizing the Internet Protocol for communication between its nodes. Although IP addresses are stored as binary numbers, they are often displayed in more human-readable notations, such as 192.168.100.1(for IPv4). The role of the IP address has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."

A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.

Bridges.A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.

Routers.A router is a networking device that forwards packets between networks using information in protocol headers and forwarding tables to determine the best next router for each packet. Routers work at the Network Layer of the OSI model and the Internet Layer of TCP/IP.

2.Stack protocols: TCP/IP, OSI. IP addressing. Local and wide area networks.Wire and wireless network technologies.