Introduction

Ethernet is a standard that enable two or more computer to share information and communicate. Ethernet network, also known as local area network (LAN), connects computers which can transfer data at the speed of 10Mbps or more. Since its invention, Ethernet standard has evolved a lot. Improved media access control methods, alternate physical medium and higher bandwidth are some of examples of evolution. This paper describes the network hardware which is used for establishing Ethernet connection. The pricing of the hardware is reducing day by day and they are very easy to maintain.

Network interface cards (NIC)

Most PC motherboard manufacturers offer a built-in Network Interface Card (NIC), also known as Ethernet Card, as Ethernet is now omnipresent and the twisted pair Ethernet requires small panel space. However, if a computer doesn’t have NIC, it requires installation of a separate network card; CPU of the computer cannot process information at network speed. NIC is a kind of network adapter. It supports the Ethernet standard for high-speed network connections via cables; a connector in conjunction with NIC accepts cable to physical network. NIC come programmed with a globally unique 48-bit address, identified as MAC address of the machine. In the IEEE 802 LAN, the MAC addresses are used to identify both the source and the destination of each data packet. Generally, NICs do not accept packets addressed to other machines.

NIC cards have evolved over the years; however, its different forms are used even today in older computers and these types of cards are available in market yet. Large ISA cards were the foremost standard for PCs and their installation required opening computer case. Modern Ethernet cards use the PCI standard and are usually installed inside the computer by the manufacturer. For laptop and mobile computers, smaller PCMCIA Ethernet cards that resemble credit cards are available. External USB Ethernet adapters are also available and they look like small boxes instead of cards. They are mostly used with video game consoles and as alternative to PCI cards.

Transceiver: Ethernet interface can be either with 10BaseT or AAUI (Apple Attachment Unit Interface) connectors, in case of MAC computer. If there is AAUI port, then there is need to have a transceiver, actually AAUI-10BaseT transceiver. The transceiver has an AAUI cable at one end and 10BaseT connector jack at the other end.

Cables

Ethernet cables consists cable of at least Category 5 (Cat. 5) and 8P8C (often recognized as RJ45) connectors. This type of cables is used to connect all computers with Ethernet interface with 10BaseT connectors. CAT 5 UTP wire is required for basic 10/100 Mbps speed, whereas Cat 5e supports gigabit (1000BaseT) operation. Category 5 is the most popular of all twisted pair cables employed today and is the fifth generation of twisted pair Ethernet technology. Either Unshielded Twisted Pair (UTP) or STP (Shielded Twisted Pair) cable can be used; later is used for extra resistance to external interference. Twisted Pair cable comes mainly in two varieties, solid and stranded. Stranded cables are better applicable in short-distance usage and patch applications for desktop use. They are more pliable and resilient than solid one. Solid Ethernet cable is used in longer length runs and in fixed wirings such as office building. Newer cable technologies like CAT6 and CAT7 are in development. Though Cat 6 or higher offers future proofing measure, CAT5 / CAT5e Ethernet cable stays the popular choice for most wired local area networks (LANs) as it gives enough speed and is affordable.

Due to their physical resemblance, the 8P8C modular connectors are often called RJ45. It looks like a large phone plug with an 8-position modular connector. These connectors come in a few variations; the primary variation is based on whether the connector is meant for solid or stranded wire.

Hubs

More than two computers in the LAN cannot be easily connected without using hub. Hub is a small, inexpensive and passive device that connects all devices and allows only one device on the network to talk at a time. To connect the computers to Ethernet hub, an Ethernet cable is first connected into hub and then other end is connected to each computer’s NIC. RJ-45 connectors are accepted by all Ethernet hubs. All devices must be running at the same speed on a hub. Ethernet Hubs vary depending on the speed they support. Earlier, hubs supported just 10 Mbps speed whereas today, hubs supporting 100 Mbps speed are easily available. Some also support dual speeds i.e. 10 Mbps and 100 Mbps. The number of ports supported by hub also varies. Hubs supporting 4-5 ports (for home usage) to 16 ports (for small office usage) are available. In order to increase the network to incorporate more devices, Ethernet hubs can also be connected to each other, to routers or switches.

Bridge

 A bridge is a hardware device which filters data traffic at a network boundary. Bridges divide the traffic on a LAN in two segments and thus reduce the amount of traffic. This device functions at the layer 2 of the OSI model – data link layer. Bridge scrutinizes incoming traffic and takes decision whether to discard or forward it. For example, an Ethernet bridge looks thoroughly each incoming Ethernet frame for its destination and source MAC addresses, and sometimes the frame size and accordingly makes independent forwarding decisions. In fact, Bridges serve a similar function as switches; both operate at Layer 2. Conventional bridges support one network boundary, whereas switches generally offer four or more hardware ports.

Switch

Like hub, switch also allows to connect multiple computers within a LAN. However, it operates at Data Link layer and permits multiple devices to talk at the same time. Switch can perform automatic speed conversations. Switch has more intelligence than a hub. Switches can inspect data packets as they are obtained, decide the destination and source device for each packet and forward them accordingly. A network switch gives better performance than hub as it preserves network bandwidth by delivering messages only to the device intended.

Traditional Ethernet switches support either 10/100 Mbps speed or Gigabit Ethernet (10/100/1000) standards. There are various models of network switches which support varying number of connected devices; generally most of network switches offer either four or eight connections for Ethernet devices. To add increasingly larger number of devices to a LAN, switches can be connected to each other – this approach is also called daisy chaining method.

Router

Router is a physical device that connects multiple networks together. They look just like hubs and switches, small, box-type piece of equipment which numerous computers can connect to. However, compared to switch or hub, a router is far more sophisticated network device. Conventional routers are designed to connect multiple area networks such as WANs and LANs. For example, on a large corporate network or on the Internet, routers work as midway destinations for network traffic. They receive TCP/IP packets, look into each packet to recognize the source and destination IP addresses and then forward these packets as needed to make sure the data attains its final target. Technically, a router works at the layer 3 of the OSI model, network layer and works as a gateway. Home networkers often use an Internet Protocol (IP) router as IP is the widest employed OSI network layer protocol. An IP router, like a cable modem router or DSL, connects the home’s LAN with the WAN of the Internet.