NETWORK HARDWARE CABLES NETWORK INTERFACE CARD (NIC)

Cable Cables are commonly used as a medium for transmitting data across networks. The most commonly used cables are coaxial, twisted-pair, and optical fiber cables. Cables are commonly used as a medium for transmitting data across networks. The most commonly used cables are coaxial, twisted-pair, and optical fiber cables.

NIC- Network Interface Card NIC is a hardware device that acts as an interface through which a computer connects to a network. NIC is usually an expansion card on the computer with a port to plug in the network cable. NIC converts the data into electrical/optical signals and transfers them through cables from one computer to another on the network. On receiving the data, the NIC on the destination computer converts the electrical signals back to data. NIC is a hardware device that acts as an interface through which a computer connects to a network. NIC is usually an expansion card on the computer with a port to plug in the network cable. NIC converts the data into electrical/optical signals and transfers them through cables from one computer to another on the network. On receiving the data, the NIC on the destination computer converts the electrical signals back to data.

4 Internetworking devices Increasing power and complexity  Repeaters:  Hubs  Bridges  Switches  Routers

Repeaters: The signals transmitted can be attenuated due to some problem in the transmission media or the distance between the two locations. Attenuation of signal means the gradual weakening of signal strength across long distances. A repeater is a device that amplifies the incoming signals, create a new copy of it, and transmits the signal back on the network. Repeaters are required in networks where the computers are apart from each other that the signal from the source computer attenuates, and does not reach the destination computer. The signals transmitted can be attenuated due to some problem in the transmission media or the distance between the two locations. Attenuation of signal means the gradual weakening of signal strength across long distances. A repeater is a device that amplifies the incoming signals, create a new copy of it, and transmits the signal back on the network. Repeaters are required in networks where the computers are apart from each other that the signal from the source computer attenuates, and does not reach the destination computer.

Hub, Switch, Bridge, Router  Hubs, switches, bridge and routers are all devices that let you connect one or more computers to other computers, networked devices, or even other networks.  Each has two or more connectors called ports into which you plug in the cables to make the connection.

HUB A hub is typically the least expensive, least intelligent, and least complicated of the four. Its job is very simple – anything that comes in one port is sent out to the others. A hub interconnects two or more workstations into a local area network. Hubs expand one Ethernet connection into many. For example, a four-port hub connects up to four machines Every computer connected to the hub “sees” everything that every other computer on the hub sees. The computers themselves decide if they are the targeted recipient of the message and when a message should be paid attention to or not.

Here, the first computer prints to the laser printer, but the message is broadcast to all of the computers on the network. This causes more traffic and collisions over the network.

Hubs - cont Hubs operate at physical layer of the OSI model, simply repeating the information they receive. There are three types of hub: Stand-alone hubs Stackable hubs Modular hubs

Hubs - cont Stand-alone hubs Small networks Final group segment of larger networks 4-, , 16-, 24- and 32-ports Cheaper

Hubs - cont Stackable hubs Supports hierarchical structure Maximum of four hubs or levels and five cable lengths between any workstation and the server for 10BaseT and maximum of two hubs or levels and three cable lengths for 100BaseT levels Similar to stand-alone hubs but can add ports at the same level by joining the backplanes on the hubs and acts as one hub More expensive than stand-alone hubs

Hubs - cont Modular hubs Also called enterprise hub Is a large chassis or cabinet with power supply and backplane into which you can plug many different boards, including hubs, switches, bridges, and routers Expensive

SWITCH  Like hub, has number of ports from 2 to 32  An intelligent device that looks at the physical destination address of the frame flowing into it and directs the frame to the correct port for that destination  Like bridges, segment a network to reduce the traffic and collisions, and ultimately increasing the throughput

 Using switches computers can talk with each other on private connections so multiple conversations can be carried on at the same time.  Here, the first computer and laser printer make a private connection during printing, while the fourth computer transfers a file to the fifth computer over another connection.  This reduces traffic and collisions over the network.

Difference Between a Hub and a Switch The hub is basically the least expensive and the least intelligent. Basically, anything that comes to one port is sent out to the others. A switch does what a hub does, but way better. By paying attention to the traffic and other things that come along, it can learn and study where the addresses are.

BRIDGES A bridge is used to either segment a network or join two networks bridge A bridge looks at the physical or MAC address in a frame – if the frame address belongs to the other side of the bridge, the frame is passed on to the other side –Otherwise ignores It operates at the Data Link layer of OSI model (one layer above the hub operates)

Bridge - cont The purpose of a bridge is to reduce traffic in a network by segmenting it, although it is still one network Hub replacing a bridge – increasing collisions and decreasing the throughput A bridge also allows additional hub layers above four-hub limit in a simple Ethernet network –Cross the bridge and travel through four more hubs Simple device and is limited to a single network and to a single cabling or media type

Bridge allows additional hub layers

20 Bridge interconnecting two identical LANs

21 A bridge interconnecting two dissimilar LANs

ROUTER A router can perform the same segmenting and joining functions as a bridge, but at a higher level using logical address. –Routers connect separate networks, leaving them independent with their own addressing –Routers connect different types of networks; for example, 100BaseF and 100BaseT –Routers select from among alternative routes a through a complex network in order to get to an end destination Basically, in a particular network, a router determines the fastest way possible,router which is also usually the shortest way possible.

Router - cont Routers clean up network traffic by checking if a frame is corrupted or lost; if so, the frame is removed from the network Routers clean up network traffic by checking if a frame is corrupted or lost; if so, the frame is removed from the network  For these reasons, routers are used to connect to the Internet and within the Internet, and to connect a WAN to a LAN  They are generally intelligent devices with a processor and memory.  At the low end, routers process over 250,000 packets per second

Routers are called "smart" networking devices. Routers can assign IP addresses to computers, filter websites, block unauthorized traffic and route communication from one section of the network to another. The router is used as a gateway between the internal network and the Internet. It can help protect the internal network from hackers. Router - cont

Wireless connections: Access Point as a Bridge 25

Hardware Needed For LAN and WAN Network Interface Card – connects the device to the network and allows communication between computers Wireless Access Point (WAP) – connected to the network by a cable and positioned so that it can send and receive the wireless signal Hub – joins lots of computers to the network via a single link. Signals received on any port are transmitted to all other ports. Switch – receives data, examines it and then sends it to the appropriate port.

Hardware cont. Gateway – A gateway is a device or service that translates communication protocols and enables two similar or dissimilar LANs, such as Ethernet and Token Ring, to communicate with each other. Bridge – Connects and passes packets between two network segments that use the same communication protocols Router – Sends info between networks using the topology by selecting the best path. Translates information between networks. Can connect a LAN to a WAN Repeater – Used to strengthen a signal as it is passed along a network cable. Over a distance, a signal would degrade