Network Hardware and Physical Media

1. Network Hardware and Physical Media • Network hardware includes: • Computers • Peripherals • Interface cards and • Other equipment needed to perform data processing and communications within the network

2. File servers • A very fast computer with a large amount of RAM and storage space along with a fast network interface card • The network operating system software resides on this computer

3. Workstations • All computers connected to the file server on a network are called workstations

4. Network interface cards • The network interface card (NIC) provides the physical connection between the network and the computer workstation. • Most NICs are internal with the card fitting into an expansion slot in the computer. • Three common network interface connections are Ethernet cards, Local Talk connectors and Token Ring cards

5. Ethernet cards • The most common Network Interface Cards are Ethernet cards • They contain connections for either coaxial or twisted pair cables, or both Co-axial cable Twisted pair cable

6. Concentrators / Hubs • A concentrator is a device that provides a central connection point for cables from workstations, servers and peripherals • Hubs are multi-slot concentrators

7. Switches • hubs provide an easy way to scale up and shorten the distance that the packets must travel to get from one node to another • they do not break up the actual network into discrete segments. That is where switches come in.

8. Switches (continued) • A vital difference between a hub and a switch is • all the nodes connected to a hub share the bandwidth among themselves. • while a device connected to a switch port has the full bandwidth all to itself. • Think of a switch as a ‘clever’ hub

9. Repeaters • A signal loses strength as it passes along a cable, so it is often necessary to boost the signal with a device called a repeater • A repeater might be a separate device, or might be part of a concentrator

10. Bridges • A bridge is a device that allows you to segment a large network into two smaller, more efficient networks

11. An example of a network with a bridge Router Hub Bridge Segment Node Hub Internet

12. Routers • A router translates information from one network to another • The router directs traffic to prevent “head-on” collisions • If you have a LAN that you want to connect to the Internet, you will need a router to serve as the translator between information on your LAN and the Internet

13. Routers (continued)

14. Physical Media • Physical media provide the connections between network devices that make networking possible • There are four main types of physical media in widespread use today: • Coaxial Cable • Twisted Pair • Fiber Optic Cable • Wireless Media

15. LAN Technologies Ethernet • Physical Media :- • 10 Base5 - Thick Co-axial Cable with Bus Topology • 10 Base2 - Thin Co-axial Cable with Bus Topology • 10 BaseT - UTP Cat 3/5 with Tree Topology • 10 BaseFL - Multimode/Singlemode Fiber with Tree Topology • Maximum Segment Length • 10 Base5 - 500 m with at most 4 repeaters (Use Bridge to extend the network) • 10 Base2 - 185 m with at most 4 repeaters (Use Bridge to extend the network) • 10 BaseT - 100 m with at most 4 hubs (Use Switch to extend the network)

16. Thick Coaxial Cable • Used in the first Ethernet networks • Type RG-11 / 10Base5 • Usually orange/black • Thickness of a small garden hose • Very expensive and heavy cable • Two strands along the axis • Conductor down the center • Insulator surrounds conductor • Shielded mesh serves as outside

17. Thin Coaxial Cable • Alternative to Thick Ethernet Cable • Type RG-58 / 10Base2 / “Cheapnet” • Usually black • Thickness of a pencil • More flexible than thick Ethernet • Reduced the cost of the cabling • Flexible

18. Coaxial cable connectors • The most common type of connector used with coaxial cables is the BNC connector

19. Twisted Pair Cable • Phone Systems • Twisted Pair Cable consists of two copper wires, usually twisted around each other to cancel out any noise in the circuit • Two main type of Twisted Pair Cabling • Shielded Twisted Pair (STP) • Unshielded Twisted Pair (UTP)

20. RJ-45 Shielded Twisted Pair (STP) • STP is the original media used for token ring networks • STP can be used for high-speed networks, such as FDDI or ATM, where shielding is important.

21. Unshielded Twisted Pair (UTP) • UTP has four pairs of wires inside the jacket • Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs

22. UTP (Continued) • Most commonly used twisted pair cable • Uses common telephone wire • UTP was standardized by the IEEE 802.3 committee in October of 1990 • UTP for LANs is now classified as: • Category 3 - used for LANs up to 10 Mbps • Category 4 - used for LANs up to 16 Mbps • Category 5 - used for LANs up to 100 Mbps

23. Fiber Optic Cable • Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials • It transmits light rather than electronic signals • It is the standard for connecting networks between buildings, due to its immunity to the effects of moisture and light

24. Fiber Optic (continued) • Fiber optic cable has the ability to transmit signals over much longer distances than coaxial or twisted pair • It can also carry information at vastly greater speeds • Fiber optic cable is more difficult to install than other cabling

25. Wireless LANS • Wireless networks use high frequency radio signals to communicate between the workstations and the fileserver or hubs. • Disadvantages of wireless networks are: • they are expensive (relatively), • provide poor security, • are susceptible to interference and • are slower than cabled networks