LAN (Local Area Networks) A LAN is a computer network that covers a small area (home, office, building, campus) o a few kilometers LANs have higher data rates (10Mbps to 10Gbps) as compared to WANs LANs (usually) do not involve leased lines; cabling and equipments belong to the LAN owner. A LAN consists of o Shared transmission medium • now so valid today due to switched LANs o regulations for orderly access to the medium o set of hardware and software for the interfacing devices
WORKING OF LAN LAN usually broadcast their message to all hosts on that LAN. This hosts shares a single transmission media. This broadcast network can be a static or dynamic method. In this static method each host is given a fixed time slides to send the information. This is the most popular method used.
In the dynamic method a host can send a frame any time. If the two hosts send a frame at the same time the two frames could collide with each other. Dynamic method can be further sub-divided in 2 categories: 1. Centralized a. Carrier Sensing b. Token Passing 2. Decentralized: Protocols are used to implement media access control.
LAN Protocol Architecture Corresponds to lower two layers of OSI model o But mostly LANs do not follow OSI model Current LANs are most likely to be based on Ethernet protocols developed by IEEE 802 committee IEEE 802 reference model o Logical link control (LLC) o Media access control (MAC) o Physical
LAN InterconnectionTraditional LAN interconnection devices Repeater – it operates at OSI layer 1 and transmits data bits over a physical medium. Bridge – it operates at OSI layer 2 and is commonly used to connect similar LAN segments. Switch – it operates at OSI layer 2 or layer 3 and is used to interconnect multiple similar or dissimilar LANs. Router – it operates at OSI layer 3. A router is used to interconnect individual networks whose sizes vary from very small to very large. Routers may be categorized into backbone router (or core router), border router and access router depending on their role in the network.
LAN Architecture TOPOLOGIES • Star • Bus • Ring Transmission medium Layout Medium access control
Advantages Long Distances Possible10 Base-5 allows distances up to 500 meters (1650 feet). Thismakes it very useful as a "backbone" technology for wiringtogether multiple locations within a building without the use ofrepeaters Noise ImmunitySince 10 Base-5 uses a very heavily shielded cable, it can be usedin electrically noisy environments which can cause other networktypes to fail. Conceptually SimpleSince all devices on a 10 Base-5 network are simply chainedtogether on a common coaxial cable, it is a simple matter to planthe routing of the cable
Disadvantages Inflexible10 Base-5 networks do not lend themselves well to installationswhere the setup of the network will change much after the initialinstallation. It can be very difficult to add or move a node once itis connected to the coaxial cable. Fault IntolerantSince 10 Base-5 uses a common physical cable to interconnect allthe nodes, the failure of any part of the coaxial cable or any nodehas the ability to cause the collapse of the entire network.
Bluetooth Birth The Name –Bluetooth? The name is attributed to Harald Bluetooth was king of Denmark around the turn of the last millennium.Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
What Is Bluetooth?• Designed to be used to connect both mobile devices and peripherals that currently require a wire.• “USB without wires”• Short range wireless radiotechnology.- operate range of 100 meters. Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Who Started Bluetooth? Ericsson Mobile Communication • Bluetooth Special Interest Group (SIG) -5 founding members -Ericsson, Nokia, IBM, Intel & Toshiba • Promoter’s Group - 3COM, Lucent, Microsoft, Motorola • Now over 1900 members Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
How Does It Work?• Bluetooth is a standardfor tiny, radio frequencychips that can be pluggedinto your devices• These chips were designed totake all of the information thatyour wires normally send, andtransmit it at a special frequency to a receiver Bluetooth chip. Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Bluetooth @ Home er gita lC ame ra NO WIRES Computer ScannDi Inkjet Printer xDSL Access Point Player MP3 Home Audio System PDA Cordless Phone Cell Phone Base Station Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Bluetooth Products 1• Bluetooth-enabled PC Card Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Bluetooth Products 2• Bluetooth-enabled PDA Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Bluetooth Products 3• Bluetooth-enabled Cell Phone Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Bluetooth Products 4• Bluetooth-enabled Head Set Created by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Advantages (+)• Wireless (No Cables)• No Setup Needed• Low Power Consumption (1 Milliwat)• Industry Wide SupportCreated by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
Disadvantages (-)• Short range (10 meters)• Small throughput rates - Data Rate 1.0 Mbps• Mostly for personal use (PANs)• Fairly ExpensiveCreated by Matt Romita and Mohammed Hasham for BCS 312 and used in BCS 555
WIRELESS LANIntroductionWireless TechnologyWireless LANConfigurationDifferences between wired LAN vswireless LAN
INTRODUCTIONData communications systemAlternates wired LANTransmits and receives data over the air Minimize the need for wired connectionsBecome more popular in general-purposealternative of business customers.Benefited several industries in productivityand mobility
MOBILITYReal-time information access fromanywhere at any timeIncreases productivity and flexibility
HOW IT WORKSUse electromagnetic airwaves tocommunicate informationData imposed on radio carrier (radio wave)RF electromagnetic wave can easilypass through ordinary wall, it needs toimplement with heavy concrete or metalscreening.
WIRELESS TECHNOLOGY Satellite-Based System – Geosynchronous Earth Orbiting (GEO) – Low Earth Orbiting (LEO) Land-Based Network Access System – Wireless WAN – Wireless LAN
WIRELESS WANProvide nationwide or citywidecoverageExample: Ricochet Micro-Cell
WIRELESS LANWireless LAN Topology– 2 main components Access Points Adapters– RoamingWireless LAN Technology– Types– Standard– Configuration
ACCESS POINTSConnects to the wired networksingle access point can support a smallgroup of users within a range of severalhundred feet Wireless Clients Connected to LAN via Access Point
INFRARED (IR) TECHNOLOGYLittle used in commercial wireless LANsUse very high frequenciesInexpensive, but provide very limitedrange (3ft)Typically used for personal areanetworksUsed only to implement fixedsubnetworks
CONFIGURATIONPeer-to-peer networkClient and Access pointMultiple access points and roamingUsing an extension pointUsing directional antennas
Star Topology:• The star network configuration is the most popular physical topology• In a star configuration, all computers or stations are wired directly to a central location: – Concentrator (a.k.a. hub) – Multistation Access Unit (MAU)• A data signal from any station goes directly to this central device, which transmits the signal according to the established network access method for the type of network
Star topology advantages:– A break in one cable does not affect all other stations as it does in bus technologies– Problems are easier to locate because symptoms often point to one station– The second-easiest topology to design and install– Does not require manual termination • Instead the media is terminated in the station at the transceiver on the NIC and in the hub or MAU
Star topology disadvantages:– Hubs, which are required for a star topology, are more expensive than bus connectors– A failure at the hub can affect the entire configuration and all connected stations– Uses more cable than bus topologies