LOCAL AREA NETWORK Presented by : Tan Teng MengWET Chan Choi Ngor WET 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

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 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 AdvantagesDisadvantages 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

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 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