Date post: | 20-Dec-2015 |
Category: |
Documents |
View: | 213 times |
Download: | 0 times |
LOCAL AREA NETWORK
Presented by :
Tan Teng MengWET010148
Chan Choi Ngor WET020019
Philip Lim Loong HinWET020144
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
What is LAN?
High speed, fault-tolerant data network Cover a relatively small geographic area Connects workstations, personal computers,
printers, and others devices.
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
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. Unicast - a single packet is sent from the source to a destination on a network.
2. Multicast - consists of a single data packet that is copied and sent to a specific subset of nodes on the network
3. 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
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
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 MbpsMedia and connector size – smallMaximum 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 mediumUses 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.
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