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Diploma in Information Technology
Module IV: Fundamentals in Networking
Rasan SamarasingheESOFT Computer Studies (pvt) Ltd.No 68/1, Main Street, Pallegama, Embilipitiya.
Content1. What is a computer network?2. Types of computer networks3. Personal Area Network 4. Local Area Network 5. Metropolitan Area Network6. Wide Area Network 7. Networking Topologies8. Physical Topologies9. Physical Point to Point 10. Physical Bus Topology11. Physical Ring Topology12. Physical Star Topology13. Physical Mesh Topology14. Physical Tree Topology15. Physical Hybrid topology16. Logical Topologies17. Ethernet
18. Local Talk19. Token Ring20. FDDI21. ATM22. Transmission Media23. Networking Cables24. Coaxial Cables25. Twisted Pair Cables26. Fiber Optic Cables27. Network Devices28. NIC-Network interface card29. Hub30. Network Switch31. Router32. Bridge33. IP Address34. Activities
What is a computer network?
Computer network is an interconnection of two or more computers and other devices. Devices on a network can be linked by cables, telephone lines, radio waves or infrared waves.
Advantages of computer networks
• Files sharing• Devices sharing• Communication • Services sharing
Disadvantages of computer networks
• Virus attacks• Hacker attacks• Failures of a server may effect to the entire
network
Types of computer networks
Based on the network size, networks can be categorized into several types
1. Personal Area Network (PAN)2. Local Area Network (LAN)3. Metropolitan Area Network (MAN)4. Wide Area Network (WAN)
Personal Area Network (PAN)
• PAN is wireless network connected with mobile devices such as mobile phones, PDAs, Bluetooth printers, Headsets, etc.
• The technology using in here is Bluetooth or infrared.
Local Area Network (LAN)
• Coverage is about within 1km. • Ex: a company network within a building or
may be within two or more buildings.
Metropolitan Area Network (MAN)
• Coverage is about more than 1km and less than 10km.
• Ex: A network of a large town.
Wide Area Network (WAN)
• Coverage is about more than 10km.• Satellites may be use to expand this network.• Ex: Internet.
Networking Topologies
Topology is the way that we connect computers and other devices. In other words topology is the map of the network.
Networking Topologies
Topologies can be divided into two sections
1. Physical Topologies2. Logical Topologies
Physical Topologies
Physical arrangement of the network is known as physical topology
• Physical Point to Point Topology• Physical Bus Topology• Physical Ring Topology• Physical Star Topology• Physical Mesh Topology• Physical Tree Topology• Physical Hybrid Topology
Physical Point to Point Topology
This is the simplest topology that uses a permanent link between two end devices. It also known as peer to peer topology.
Physical Point to Point Topology
Characteristics• Using twisted pair cables.• Using RJ-45 connectors.• Maximum segment length is 100m.
Physical Point to Point Topology
Advantages• Low cost.• No additional devices or servers needed.• Easy to implement.
Physical Point to Point Topology
Disadvantages• Maximum 2 computers can be connected.• Cable breaks will affect to the whole network.
Physical Bus Topology
Each computers and devices are connected to a single cable called “backbone”.
Physical Bus Topology
Characteristics• Both thin net and thick net coaxial cables are
used.• Segment length of thin net coaxial cable is
200m.• Segment length of thick net coaxial cable is
500m.• BNC Connectors are used.• Maximum data transfer speed is 10mbps.
Physical Bus Topology
Advantages• Easy to implement.• Easy to expand.• Low cost (no additional devices).
Physical Bus Topology
Disadvantages• Maximum speed is 10mbps only.• Number of PCs will affect to the performance
of the network.• If backbone breaks, the entire network will be
failed.• Not suitable for heavy traffic.• Hard to find faults of the network.
Physical Ring Topology
Each computers and devices are connected each other forming a large circle.
Physical Ring Topology
Characteristics• Using coaxial or twisted pair cables.• Using BNC or RJ-45 connectors.• Maximum data transfer speed is between 4 -
16mbps.
Physical Ring Topology
Advantages• No need of a server.• Even the load of the network increases, it still
perform better than bus topology.
Physical Ring Topology
Disadvantages• If the cable breaks, entire network will be
failed.• If one station goes down, it will be affected to
the entire network.• Low speed.
Physical Star Topology
All the components of the network are connected to the central device called hub or switch.
Physical Star Topology
Characteristics• Twisted pair cables are using.• Connectors are RJ-45.• Channel accessing method is depends on the
central device.
Physical Star Topology
Advantages• Higher data transfer speed than previous
topologies. 100 - 1000mbps.• Central device make it easy to manage the
network.• Cable breaks will not affect to the entire
network.• Easy to expand.• More computers and devices can be connected.
Physical Star Topology
Disadvantages• Single point of failure type network.• The central device using is increases the cost
of the network.
Extended Star Topology
Physical Mesh Topology
Each networking nodes are interconnected with each other.
Physical Mesh Topology
Characteristics• It allowing most transmissions to be
distributed, even one of the connections goes down.
• Mesh topologies are either partially or fully connected.
• Uses in the internet.
Physical Mesh Topology
Advantages• Supports for high traffic.• Cable breaks will not affect to the
communication.• Expansions and modifications can be done
without disrupting other devices.
Physical Mesh Topology
Disadvantages• Overall cost of the network is high.• Setup, maintaining and administrating this
network is very tough.
Physical Tree Topology
A tree topology is essentially a combination of bus topology and star topology. The nodes of bus topology are replaced with star topology networks.
Physical Tree Topology
Advantages• Secondary nodes allow more devices to be
connected. • Having different levels of the network makes it
more manageable.
Physical Tree Topology
Disadvantages• Maintenance of the network is difficult.• If the backbone fails, the entire network will
be failed.
Physical Hybrid Topology
The combination of more topologies is known as hybrid topology.
Physical Hybrid Topology
Advantages• Flexible to expand and modify.• Very effective.
Disadvantages• Very complex.• Costly infrastructure.
Logical Topologies
Logical topology represents the way that data travel through the computer network.
• Ethernet• Local Talk• Token Ring• FDDI• ATM
Ethernet
Ethernet
• Ethernet is a local area network technology.• Physical Bus Topology and Physical Star Topology
(Hub as central device) uses Ethernet.• CSMA/CD (Carrier Sense Multiple Access / Collision
Detection) describes how the Ethernet protocol regulates communication among nodes.
• The number of devices and segment length of media affects the efficiency of Ethernet.
• Ethernet first standardized in 1983 as IEEE 802.3• 100Base-T and Gigabit Ethernet are the newest
versions of Ethernet.
Ethernet
• Physical Bus Topology is an Ethernet.
Ethernet
• Logical Bus Topology implemented as physical star topology is an Ethernet.
Hub
Ethernet
• By using segmentation the network diameter and the efficiency can be increased.
Local Talk
• Local Talk is a network protocol that was developed by Apple Computer, Inc. for Macintosh computers.
Local Talk
• The method used by Local Talk is called CSMA/CA (Carrier Sense Multiple Access / Collision Avoidance).
• Local Talk transmits data up to 230 kbps only.• Each Local Talk Mac or printer has its own
Local Talk adapter to connect each other as a chain.
• Two Mac computers can use a serial port instead of Local Talk adapters.
Local Talk uses CSMA/CA
Token Ring
Token Ring
• Token Ring also a local area network technology.
• Physical Ring Topology and Physical Star Topology (MSAU as central device) uses Token Ring.
• It uses a special three-byte frame called a token that travels around the ring.
• No collisions occurred.• It is standardized with protocol IEEE 802.5.
Token Ring
Token Ring
• Logical Ring Topology implemented as physical star topology is a Token Ring.
MSAU
FDDI - Fiber Distributed Data Interface
FDDI - Fiber Distributed Data Interface
• FDDI uses a dual ring physical topology for sending data over fiber optic cables.
• FDDI networks are token-passing networks, and support data rates of up to 100 Mbps.
• FDDI can extend in range up to 200 km.• FDDI uses two rings to achieve better results
and less chance of failure.• FDDI is used mainly in mission critical and high
traffic networks.
FDDI - Fiber Distributed Data Interface
FDDI - Fiber Distributed Data Interface
Dual-attach FDDI board
FDDI - Fiber Distributed Data Interface
• If a station goes down, the signals are routed around it by a loop formed from the rings.
ATM - Asynchronous Transfer Mode
ATM - Asynchronous Transfer Mode
• ATM supports to carry a complete range of user traffic, including voice, data, and video signals.
• ATM transmitting relatively small and fixed data packets compared to units used with other technologies.
• The data transfer rates on ATM are either 155 Mbps or 622 Mbps.
• ATM is a key component of broadband ISDN.
Comparison of Logical TopologiesProtocol Cable Speed TopologyEthernet Twisted Pair,
Coaxial, Fiber10 Mbps Bus, Star, Tree
Fast Ethernet
Twisted Pair, Fiber
100 Mbps Star
Local Talk Twisted Pair 0.23 Mbps Bus or StarToken Ring Twisted Pair,
Coaxial4 Mbps - 16 Mbps
Ring
FDDI Fiber 100 Mbps Dual ringATM Twisted Pair,
Fiber155 - 622 Mbps
Bus, Star, Tree
Transmission Media
When choosing the transmission media consider the following
• Transmission speed• Segment length• Cost• Resistance to environment conditions
Networking Cables
There are several kind of networking cables
• Coaxial Cables• Twisted Pair Cables• Fiber Optic Cables
Coaxial Cables
Coaxial Cables
Coaxial cables are two types• Thin net coaxial cables• Thick net coaxial cables
Outer cover
Outer copper shield
Inner insulatorInner inductor
Thin net coaxial cables
• Use to connect computers and devices in bus topology and ring topology.
• Well flexible.• Maximum segment length is 200m (185m).
Thick net coaxial cables
• Used as backbone cables and outdoor laying.• Not well flexible.• Maximum segment length is 500m (485m).
Coaxial cable connectors
BNC Connectors
Twister Pair Cables
Twister Pair Cables
• Most popular network cable in networking.• There are two types called:
1. Unshielded twisted pair cables.2. Shielded twisted pair cables.
• Maximum segment length is 100m.• Data transferring speed varied on cable
categories.
Unshielded Twister Pair Cables (UTP)
Shielded Twister Pair Cables (STP)
Twisted pair cable categories
Category Speed
CAT 1 Voice grade
CAT 2 4 Mbps
CAT 3 16Mbps
CAT 4 100Mbps
CAT 5 1000Mbps
CAT 5e 1000Mbps
CAT 6 1000Mbps
CAT 7 1000Mbps
Twisted pair cable connectors
RJ-45 Connectors RJ-45 Base
Twisted Pair / RJ-45 Cabling Types
Fiber Optic Cables
Fiber Optic Cables
• Fiber optic cables uses light pulses to send and receive data.
• Have very higher data transfer speed. Ex: 10Gbps or 100Gbps.
• There are two types of fiber optic cables mainly– Single Mode Fiber (SMF)– Multi Mode Fiber (MMF)
Fiber Optic Cable Structure
Single Mode Fiber Optic Cables
• Transmit one light pulse at a time for one direction.
• Because of this reason devices need two cables for full duplex communication.
Multi Mode Fiber Optic Cables
• Transmit more than one light pulse.• Because of that full duplex communication can
achieve using a single cable.• These cables are not suitable for long distance
data transfer.
Submarine Cable Map
Fiber Optic Media Converters
Fiber Optic Connectors
Network Devices
Devices of a network can be classified as
• End user devicesProvide services to the user directly.
Computers, printers, scanners and other.
• Network devicesConnect end user devices together.
Network Devices
• NIC-Network interface card• Hub• Network Switch• Router• Bridge
Network Interface Card (NIC)
Network Interface Card (NIC)
• Every computer should have a network interface card to connect to the network.
• There are several things to consider before buying a NIC.1. Network interface (connectors)2. Internal interface (PCI, USB)3. Network architecture
Hub
Hub
• Hub is use to connect all computers and other devices together.
• Hub is a broadcasting device.• Maximum data transfer speed is 10Mbps.• There are two types of hubs:
1. Active Hubs2. Passive Hubs
Active Hubs
When active hubs receive a signal in one port, it boost the signal and remove the electromagnetic noises before send that to other devices.
Passive Hubs
In passive hubs, it do not amplify the signal or remove noise before send data to other computers.
Network Switch
Switches are also use to connect computers in physical star topology and these devices are intelligent than hubs.
How network switch works?
1. Switches maintain a small table in there RAM to identify computers that related with the port numbers.
2. When switch receives a data packet, it reads the packet header to identify destination address.
3. After that it will search the entire table to find the related port for that address.
4. Then it can directly forward that data packet to the related computer rather than broadcasting.
Network Switch Types
• Layer 2 switches (unmanaged switches)Using MAC addresses of connected devices.
• Layer 3 switches (managed switches)Using IP addresses of connected devices.Providing more features than layer 2 switches and
expensive.
Routers
Routers
• Routers are use to connect networks together.• Routers are more intelligent devices and it use
IP addresses to deal with the packet.• Routers are responsible for:
Identify proper networks and sub networks.Forward data packets using the best path.Network Address Translation (NAT).Destroying TTL data packets. Etc
Bridge
Bridge can use to connect different topologies together or can use to connect different cable types together.
IP Address (Internet Protocol)
• IP address is an unique address that use to identify computers and devices.
• There are two IP versions called IPv4 and IPv6• IPv4 is the common version that used in most
networks.• IPv4 is made up with 4 decimal numbers and
each are separated by dots. (###.###.###.###) and each number can be in between 0 to 255.
• IP versions, rules and regulations are created and maintain by IANA (Internet Assigned Number Authority)
IP Classes (IPv4)
• Class A• Class B• Class C• Class D (reserved for multicasting purposes)• Class E (reserved for experimental purposes)
Can use in our networks
IP Address
IP Addresses are made up with two sections1. Network Address (network portion)2. Host Address (host portion)
N H H H N N H H N N N H
N N N H N N N H
Class A Class B Class C
Class D Class E
IP Ranges in each classes
IP ClassFirst Octate
IP AddressReceived Bits Range (min-max)
Class A 0####### 00000000-01111111(1-126) 1-126 0-255 0-255 0-255
Class B 10###### 10000000-10111111(128-191) 128-191 0-255 0-255 0-255
Class C 110##### 11000000-11011111(192-223) 192-223 0-255 0-255 0-255
Class D 1110#### 11100000-11101111(224-239) 224-239 0-255 0-255 0-255
Class E 1111#### 11110000-11111111(240-255) 240-255 0-255 0-255 0-255
Activities
Assigning IP address to connect two computers
User accountsSharing filesSharing printer
The End
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