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1
Dammam Community College
Chap 5 Part 2
Network Overview
2
Advantages of networks
• Enable sharing of files
• Enables sharing of resources
• It saves time
• Internet access
3
What is a Network ?
• Two or more computers connected together by a cable.
• LAN - Local Area Network
• MAN - Metropolitan Area Network
• WAN - Wide Area Network
4
Basic Network Components
• Network Interface Cards - NIC• Network cabling & connections• Servers & Workstations• Network Operating System – NOS
5
Extending a LAN
• Repeaters
• Bridges
• Routers
• Gateways
6
Network Interface CardAssignment for the students about following:
• Interrupt (IRQ) request line
• Base I/O port address
• Base memory address
• Direct memory access (DMA) request line
7
Basic Types of LAN’s
• Peer-to-Peer: Two computers participating equally in the network.
• Server Based: Security and other network functions are provided by a dedicated server.
8
Network Elements
• Sending Computer
• Receiving Computer
• Protocol
• Media - Wire or Wireless
9
Network Protocols • A protocol is a set of rules that govern network
communication.• A protocol suite is a group of protocols that can be
used together.• The standard protocols are
– Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)
– Networked Basic Input/Output System/NetBIOS Enhanced User Interface (NetBEUI)
– Transmission Control Protocol/Internet Protocol (TCP/IP)– AppleTalk– Data Link Control (DLC)
10
Protocols SummaryProtocols - A set of rules for a network Examples:
– TCP/IP– TELNET– IPX/SPX– NET BEUI
To cater for the following types of networking technology:
Ethernet Fast Ethernet Token Ring FDDI
11
Main Types of Cable
• Coaxial Cable
• Twisted Pair
• Fiber Optic
12
Network Cabling
13
Three different types of network cabling and their advantages are:1. Twisted pair cable is readily available, easy to install and inexpensive2. Coaxial cable is standard technology that resists rough treatment and EMI, can transmit over longer distance than twisted pair3.Fibre Optic cable is immune to EMI and detection outside and provides reliable and secure media with high bandwidth
Cabling types and advantages
14
Types of Cable Connectors
• BNC Connector
• RJ-45 Connector
• Duplex SC Connector
15
Ethernet Cable SummarySpecification Cable Type Maximum length
10BaseTUnshielded Twisted Pair 100 meters
10Base2 Thin Coaxial 185 meters
10Base5 Thick Coaxial 500 meters
10BaseFFiber Optic 2000 meters
16
LAN Communication
• Ethernet uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as well as bus topology.
• Token ring allows only the station holding the token to transmit data.
17
LAN TopologyTopology is the way the network is
connected physically. Following are topologies:
• Bus Topology
• Ring Topology
• Star Topology
• Mesh Topology
• Hybrid Topology
18
BUS TOPOLOGY
WORKSTATION 1 WORKSTATION 2 WORKSTATION 3 SERVERPRINTER
T-CONNECTOR TERMINATOR
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Workstation 1Workstation 2
Workstation 3
Workstation 4
Workstation 5
server
printer
RINGTOPOLOGY
20
HUB
WORKSTATION 1
WORKSTATION 2
WORKSTATION 3WORKSTATION 4WORKSTATION 5
WORKSTATION 6
SERVERPRINTER
PRINTER
STAR TOPOLOGY
21
Workstation 1Workstation 2
Workstation 3
Workstation 4
Workstation 5
server
printer
MESHTOPOLOGY
22
HYBRID TOPOLOGY
Workstation 1Workstation 2
Workstation 3
Workstation 4
Workstation 5
server
printer
RINGTOPOLOGY
HUB
WORKSTATION 1
WORKSTATION 2
WORKSTATION 3WORKSTATION 4WORKSTATION 5
WORKSTATION 6
SERVERPRINTER
PRINTER
STAR TOPOLOGY
23
Networking Essentials
• Local Area Network (LAN)–Usually limited to short distances
–Owned by the organization that uses it
–Usually employs solid cable
–Transmission rates tend to be high in the range of 1Mbps to 100Mbps
24
Networking Essentials
Local Area Network
25
Networking Essentials
• Wide Area Network (WAN)– Usually owned by major telephone companies– Cover extremely large areas– Most common WAN protocol is TCP/IP
(common for internet)– Transmission rates are usually slower than
LAN or MAN rates (2400bps to 128Kbps)– Technology such as ATM is improving data
transmission rates
26
Networking Essentials
Wide Area Network
27
Networking Essentials• Network Components
–Network Interface Card (NIC)• Usually found in the form of an
expansion card
• Can have multiple connector types
• Can be integrated into the motherboard
• Can be 8-bit, 16-bit ISA, VLBus or PCI
• Is used to connect the computer or PC to the network
28
Networking Essentials• Network Components (cont.)
–Network cable• Coaxial cable
• Thinnet (10Base-2) and Thicknet (10Base-5)
• RG-59 used in broadband networks to support video and data
29
• Twisted pair–Is used by dial-up modems for dial up
connection to the internet–Unshielded and Shielded twisted pair
(UTP and STP)–Category 1 to 6
• Fiber optic
30
Networking Essentials• Network Protocols
• TCP/IP– Transmission Control Protocol/Internet
Protocol– The most widely used protocol suite in the
world– Most major NOSs support the use of TCP/IP– Originally designed for WAN use
– Routable protocol that offers true internetworking and interoperability between disparate NOSs
31
Common Topologies• Bus Topology
– Computers in the network are connected to a single cable
– Main cable is called the backbone– Signals from computers travel in both
directions– Cable must be properly terminated at both
ends– Only a single computer can transmit a signal
at any given time
32
Common Topologies
Bus Topology
33
Common Topologies
• Bus Topology–Advantages
• Easy to apply and maintain
• Requires minimal amount of cabling
• Easy to extend by adding cable or adding repeaters
• Can be extended with the addition of hubs connected to the bus
34
Common Topologies• Bus Topology
– Disadvantages• The speed of the network is directly related to
the number of computers connected to the bus
• Damage to the cable at any location may bring down the entire network
• The network usually has to be taken down to add additional computers
• It may be difficult to locate a break or short in the cable without specialized equipment
35
Common Topologies• Star Topology
– All computers are connected to a central device called a hub
– Each signal is initially sent to the central hub and then either out to all computers (broadcast star network) or to the recipient computer (switched star network)
– Several star networks can be linked together
36
Common TopologiesStar Topology
37
Common Topologies
• Star Topology– Advantages
• Easy to expand• If one computer fails or one cable
connecting a computer fails, the rest of the network stays up
• Hubs can support different types of cable• UTP is the least expensive type of cable
38
Common Topologies
• Star Topology– Disadvantages
• Failure of the central hub results in failure of the entire network
• Separate cables are required to connect each workstation to a hub
• The initial cost of the equipment is more than with a straight bus topology due to the added expense of the hubs and running separate cables to each computer
39
Common Topologies
• Ring Topology– All computers in the network are joined in a logical
ring– The actual appearance may look like the star topology– The central network device, called an MAU, has a
loop inside of it, which creates the ring– utilises token-ring to transmit data around the
network. If a token is free of data a transmitting computer grabs it to send data by it and on the receiving end the data is removed and free token passed on to the network
40
Common Topologies
• Ring Topology– Advantages
• Ring networks handle collisions more efficiently than bus networks
• No single computer can end up using the network all the time. This is theoretically possible in the bus topology.
• It is faster than the star topology• Can be very long because each computer
reinforces the message
41
Common Topologies
• Ring Topology– Disadvantages
• On a physical ring network, you must down the entire network to add or remove computers
• On a physical ring network, if a computer goes down the entire network may go down
• It may not be easy to locate a faulty computer or device on the physical ring network
42
Common Topologies
Ring Topology
43
Connectivity Within Networks
• Hubs– Hubs can be used to connect networks but
are more commonly used to extend a network– Most hubs will simply rebroadcast signals to
all ports– Intelligent hubs rebroadcast signals only to
the actual destination port
44
Connectivity Within Networks
• Repeaters–Amplify signals on networks
–Most commonly used to increase the length of the network backbone
–Normally signals should not pass through more than two repeaters before reaching their destination
45
Connectivity Within Networks• Bridges
– Selectively sends signals from one segment to the other
– Can filter signals based on the protocol type– Transparent bridges contain the addresses
of each computer and calculate the shortest route to the destination computer
– Source-routing bridges—sender determines the proper route
46
47
Connectivity Between Networks
• Routers–Connect independent networks–Dynamic and static routers–Distance-vector routing
• Each router sends its table to all other routers at regular intervals
–Link-state routing• Instead of sending the entire table, only
the changes are sent
48
Connectivity Between Networks
•Gateways• Provides all the connectivity, and even greater functionality of routers and bridges• usually resides on a dedicated computer and acts as a translator between two completely dissimilar systems or applications• Are slower than bridges or routers• Also provide access to special services such as e-mail or fax functions
49
Maintaining and Troubleshooting Networks
• Reduced bandwidth
• Loss of data• Slow loading of
programs and files• Unauthorized
software
• Traffic overloads
• Common mode failures
• Network security violations
50
51
•A network provides connections, communications, and services.•Networks are either peer-to-peer or server-based. •Network topology types are star, bus, and ring.•A NIC connects the computer to the network.•Network cable types are twisted-pair, coaxial, and fiberoptic.•A network protocol provides the rules for network communications.•Networks can be extended with repeaters, bridges, routers, and gateways.
Summary