Transcript wret2104_1_LAN

LOCAL AREA NETWORK
Presented by :
Tan Teng Meng
Chan Choi Ngor
Philip Lim Loong Hin
WET010148
WET020019
WET020144
Table of Contents
 LAN Definition
Presented by Tan Teng Meng
 LAN Topology and Device
Presented by Chan Choi Ngor
 LAN Cabling, ATM and wireless LAN
Presented by Philip Lim
Local Area Network (LAN)
What is LAN?
 High speed, fault-tolerant data network
 Cover a relatively small geographic area
 Connects workstations, personal computers,
printers, and others devices.
LAN Technologies
Ethernet
Token Ring
FDDI
Ethernet
 Most widely-installed
 Specified in a standard, IEEE802.3
 Connected to the cable and compete for access using a
CSMA/CD protocol
 shared media - media access is controlled on a “first come,
first serve” basis
 10BASE-T provides transmission speeds up to 10 Mbps
 100BASE-T provides transmission speeds up to 100 Mbps
Token Ring
 Second most widely-used
 Specified as IEEE 802.5
 Connected in a ring or star topology
 Provides for data transfer rates of either 4 or 16
Mbps
FDDI
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A set of ANSI and ISO standards for data transmission
Can extend in range up to 200 km
Based on the Token Ring protocol
Used on the backbone for a WAN
Advantages and Disadvantages with LANs
Advantages
Disadvantages
Recourse Sharing
Vulnerability
Communication
Poor password
Central and routine back-ups
costs
Users can login from wherever
Installation
security
Maintenance
Less Expensive Systems
Training
Performance
Types of LANs
 Server-based LAN
Has a dedicated machine/computer, that has the file
server software located on it.
All the workstations point towards this computer for
accessing the resources
 Peer-to-Peer LAN
Small & has the files server software installed on each
of the workstations
Acting as both a file server & a workstation.
LAN Transmission Methods
1.
2.
3.
Unicast - a single packet is sent from the source to
a destination on a network.
Multicast - consists of a single data packet that is
copied and sent to a specific subset of nodes on
the network
Broadcast - consists of a single data packet that is
copied and sent to all nodes on the network
LAN Topologies
Physical topologies
Bus topology
Ring topology
Star topology
Extended star topology
Hierarchical topology
Mesh topology
Logical topologies
Broadcast topology
Token passing
Bus Topology
 uses a single backbone segment (length of
cable)
 the hosts connect to it directly.
Ring Topology
 connects one host to the next and the last host
to the first
Star Topology
 connects all cables to a central point ( Hub or
Switch )
Extended Star topology
 links individual stars together by linking the hubs
or switches
 extend the length and size of the network
Hierarchical topology
 similar to an extended star
 linking the hubs/switches together, the system is
linked to a computer
 The computer controls the traffic on the topology
Mesh topology
 is used when there can be absolutely no break
in communications.
Broadcast topology
 Each host sends its data to all other hosts on the
network medium
 First come, first serve
 Is the way that Ethernet works
Token Passing
 Controls network access by passing an
electronic token sequentially to each host
 The host receives the token can send data on
the network
 If the host has no data to send, it passes the
token to the next host & the process repeats
itself
Devices in LAN
A LAN consists of PC and external
hardware, named hosts.
Apart from hosts, there are other devices
functioning as the connecting medium :
Repeater
Hub
Bridge
Switch
Router
Network Interface Card
 Printed circuit board, also called network adapter.
 Carries a MAC address ( Layer 2 device )
 Each hardware and PC in the network must have a NIC
to be connected to a network.
Repeater
 Used to lengthen the range in the network.
 Layer 1 device which receive and transmit the
data.
 Will not check for error, or determine the
destination.
Hub
 Layer 1 device also called multi-port repeater
 Receive and transmit data without checking for
error or consistency of data packet.
 Advantage – decrease wiring and increase
reliability.
Bridge
 Operates via MAC address ( Layer 2 device )
 Connect different part of the LAN while filtering
the traffic to keep local traffic local, yet allow
connectivity to other parts.
 Keeps track on MAC address on each side
Switch
 Layer 2 device also called multi – port bridge.
 Filters data by switching data only to the port
where the appropriate destination is located
 Can be used to segment networks.
Router
 Layer 3 device used to regulate traffic
 Forward the data packet to appropriate host via
IP address.
 It also examine data packets and choose the
best path for it.
 Can connect different Layer 2 technologies.
Wire / Cable
 Another essential component of a network,
example LAN
 There are different wire / cable types to be
chose based on the range and bandwidth the
network requires.
 Example of cable :
UTP
STP
Fiber Optic
Coaxial Cable
Unshielded Twisted Pair
 Consists of 2 – 4 unshielded copper solid or stranded wires.
 Most network protocol using the UTP will require 2 pairs of wires,
one for transmission and one for reception.
 General choice of wiring in office and home, with the RJ45
connectors
 Comes in 5 categories based on the EIA/TIA standards
Unshielded Twisted Pair ( cont )
Advantage – Inexpensive and easy to
work with. Flexible and can fit in full
conduits. Many people familiar with UTP.
Disadvantage – Prone to interference.
Short range of distance.
Speed and throughput – 10 – 100 Mbps
Media and connector size – small
Maximum range of connection – 100m
Shielded Twisted Pair
 Similar to the UTP in operation and design.
 Reduction of noise and interference, from both within and
outside.
 More expensive and difficult to install compared to UTP
Fiber Optic
Cable with glass and plastic medium
Uses light ( laser ) to transmit data.
Multimode fiber is often used in LAN.
Has a low error rate and degrading is
lower. High performance and longer range.
Expensive and difficult to implement.
Normally used as backbone in a LAN.
Fiber Optic Cable
Coaxial Cable
 Consists of a central copper core encased in a plastic
sheath
 Quite easy to implement, and popular choice in LAN
 Speed and throughput – 10 – 100 Mbps
 Media and connector size – medium
 Maximum cable length – 50m
Coaxial Cable
Divided into 2 types :
Baseband
One channel – single message a time at a high
speed
Able to handle 10 – 80 Mbps
An important component in Ethernet
Easy to plug in / out a network without disturbing
network flow
500m optimum range
Unable to send integrated signals
Coaxial Cable
Broadband
Can carry several different signals broadcasted at
different frequency simultaneously
Possible to allocate 6-346 MHz for forward and 25
MHz for reception channels
Can be single cable or dual – cable.
Can have 50 channels broadcast at 5 Mbps
maximum
Require more planning, and installation of amplifiers
are needed
Asynchronous Transfer Mode
Another popular networking technology
working in a different way compared to
LAN
It is possible to implement ATN in a LAN,
and vice – versa, by emulating the 2
technologies.
Differences between LAN and ATM
 Connection :
LAN is connectionless, ATM is connection – oriented.
 Size of transmission :
LAN have variable packet size, up to 1.5 kilobytes,
while in ATM, each cell is 53 bytes.
 Broadcast :
LAN support broadcast and MAC address, while ATM is
switch-based
 Mode :
LAN work in best – effort mode, ATM is similar except
how it provide effective congestion control
Wireless LAN
A traditional LAN uses electricity and light
as medium of data transmission.
Wireless technology uses the atmosphere
as transmission medium
While it is applicable, wireless LAN is
costly, and have high error rate