Hardware Concepts Chapter 4 Contents Explain the different
- Slides: 30
Hardware Concepts Chapter 4
Contents • Explain the different types of network topology • Describe the different types of network cabling • Describe and distinguish between the 802. 2, 802. 3, 802. 5, and 802. 11 IEEE networking standards
Topology
Topology • A topology describes how computers connect to each other
Types of Topologies • Bus – All computers connect via a main line, called a bus cable • Ring – All computers attach to a central ring of cable • Star – All computers connect to a central wiring point, usually a hub • Mesh – Each computer has a dedicated line to every other computer
Types of Topologies
Network Technologies • A network technology is a practical application of a topology to get data from one computer or network to another – Ethernet – Token Ring – FDDI-(Fiber Distributed Data Interface) is a standard for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km
Bus Topology • Ethernet was the first network technology that used the bus topology • Each computer on the network is connected to the single cable
Bus Topology • If there is a break in the cable, the entire network would stop functioning – It has no fault tolerance to survive a problem
Star Topology • Each computer is connected to a central device such as a hub – If a cable breaks only the one computer is affected
Star Bus Topology • A star bus topology is a hybrid topology – Uses a physical star topology – Uses a logical bus topology – Most common topology used today
Token Ring Topology • Token ring uses a star ring topology – Uses a physical star topology – Uses a logical ring topology – Declining in popularity
Cabling
Coax • Coaxial cable (or coax) contains a central conductor wire, surrounded by an insulating material, which in turn is surrounded by a braided metal shield
EMI • Electro-magnetic interference (EMI) is caused by lights, fans, copy machines, and other devices • EMI corrupts the signal flowing through the cable • The braided shield helps to reduce the effects of EMI
Types of Coax Cable • The Ohm rating is a measure of resistance in the cable and differentiates different types of coaxial cable • RG-8, RG-62, and RG-58 are used in computer networks
RG-8 • RG-8 cable is also called Thick Ethernet – Oldest type of coax still in use – Rated at 50 ohms – Yellow or orange/brown color
RG-62 • RG-62 cable is never installed in networks today – Was used with ARCnet
RG-58 • RG-58 is also called Thin Ethernet – Still in widespread use today
Twisted Pair • Shielded Twisted Pair (STP) and Unshielded Twisted Pair (UTP) are the most common types of cabling used today – Composed of multiple pairs of wires twisted together to reduce interference from adjacent wires, called crosstalk
Shielded Twisted Pair (STP) • Twisted pairs of wires surrounded by shielding to protect them from EMI – Only used in older Token Ring networks
Unshielded Twisted Pair (UTP) • Most common type of cabling used in networks – Twisted pairs of wires surrounded by a plastic jacket – Inexpensive and flexible
CAT Ratings • Twisted pair cabling varies by things like the number of twists per foot • Cables are rated in categories or CAT ratings (or levels)
CAT Ratings CAT Rating Bandwidth Typical Throughput in Networks CAT 1 <1 MHz Analog phone lines – not data CAT 2 4 MHz Speeds up to 4 Mbps CAT 3 16 MHz Speeds up to 16 Mbps CAT 4 20 MHz Speeds up to 20 Mbps CAT 5 100 MHz Speeds up to 100 Mbps CAT 5 e 100 MHz Speeds up to 1000 Mbps CAT 6 200 -250 MHz Speeds up to 10000 Mbps
CAT Usage • Most new installations use CAT 5 e cable since it is cheaper than CAT 6 cable CAT level
Fiber Optic • Fiber optic cabling transmits light rather than electricity – Immune to EMI – Very long distances – Consists of the fiber, cladding, and insulating jacket – Defined by fiber and cladding measurements – Most common is 62. 5/125 µm – Fiber generally requires two cables
Light Sources • Fiber optic cables use two possible light sources – Light Emitting Diodes (LEDs) – called multimode – Lasers – called single-mode • Supports faster speeds and longer lengths
Networking Industry Standards
IEEE • Institute of Electrical and Electronic Engineers (IEEE) defines industry-wide standards • Organized the 802 committee in February of 1980 to define networking standards – Split up into smaller subcommittees
IEEE Subcommittees IEEE 802 LAN/MAN Overview & Architecture IEEE 802. 2 Logical Link Control (LLC) IEEE 802. 3 CSMA/CD access method (Ethernet) IEEE 802. 3 ae 10 Gigabit Ethernet IEEE 802. 5 Token Ring access method and Physical layer specifications IEEE 802. 8 Fiber Optic IEEE 802. 11 Wireless LAN Medium Access Control (MAC) and Physical layer specifications There are more subcommittees than listed in this table.
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