basic concepts. line configuration line configuration topology topology transmission mode...
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Basic ConceptsBasic Concepts
Basic ConceptsBasic Concepts
Line ConfigurationLine Configuration TopologyTopology Transmission ModeTransmission Mode Categories of NetworksCategories of Networks InternetworksInternetworks
Line ConfigurationLine Configuration
The way two or more communication The way two or more communication devices attach to the devices attach to the linklink
The The linklink = physical pathway that = physical pathway that transfers data from one device to transfers data from one device to anotheranother
Point-to-PointPoint-to-Point MultipointMultipoint
Point-to-PointPoint-to-Point
workstation
workstation workstation
workstation
workstation
server
link
link
link
MultipointMultipoint
link
server
workstation
workstation
Capacity of the channel is shared
spatially shared line several devices can use the link simultaneously
time-shared line users must take turn
Basic ConceptsBasic Concepts
Line ConfigurationLine Configuration TopologyTopology Transmission ModeTransmission Mode Categories of NetworksCategories of Networks InternetworksInternetworks
TopologyTopology
Topology = the way a network is laid Topology = the way a network is laid outout PhysicallyPhysically LogicallyLogically
MeshMesh StarStar TreeTree BusBus RingRing
Relationship StatusRelationship Status
Peer-to-peerPeer-to-peer The devices share the link equallyThe devices share the link equally
Primary-secondaryPrimary-secondary One device control traffic and the other One device control traffic and the other
must transmit through itmust transmit through it Ring and mesh topology Ring and mesh topology peer-to- peer-to-
peer transmissionpeer transmission Star and tree topology Star and tree topology primary- primary-
secondarysecondary Bus Bus both both
Mesh Mesh
Advantages:
no shared link, each communication carries its own data load
robust – if one link is unusable, there are still other links to use
privacy and security
fault identification and fault isolation -- easy
MeshMesh
DisadvantagesDisadvantages Requires many cables, ports, hardwareRequires many cables, ports, hardware N devices requireN devices require
N(N-1)/2 physical channelsN(N-1)/2 physical channels N-1 I/O ports for each deviceN-1 I/O ports for each device
Star Star
hub
Central control
Each device needs only one link, one I/O port
Easy to install, reconfigure
Less cables
Fault detection /isolation easy
robust
Tree Tree
hub
Central control
hubhubhub
hub
(Active hub)
BusBus
Tap Tap Tap
Cable end
Cable end
Tap
Drop line
Drop line
backbone
BusBus
Advantages
easy to install
less cables
Disadvantages
fault isolation is difficult
difficult to add new devices
Basic ConceptsBasic Concepts
Line ConfigurationLine Configuration TopologyTopology Transmission ModeTransmission Mode Categories of NetworksCategories of Networks InternetworksInternetworks
Transmission ModeTransmission Mode
Defines the direction of signal flow Defines the direction of signal flow between two linked devicesbetween two linked devices
Three typesThree types SimplexSimplex Half-duplexHalf-duplex Full-duplexFull-duplex
Transmission ModeTransmission Mode SimplexSimplex
Unidirectional, like a one way streetUnidirectional, like a one way street Only one device can transmit, the other Only one device can transmit, the other
only receives only receives
monitorserver
Direction of data
Transmission ModeTransmission Mode
Half-duplexHalf-duplex Each station can both transmit and receive but Each station can both transmit and receive but
not at the same timenot at the same time When one device is sending, the other can When one device is sending, the other can
only receiveonly receive E.g. Walkie-talkie E.g. Walkie-talkie
Direction of data at time 2
Direction of data at time 1
Transmission ModeTransmission Mode
Full-duplexFull-duplex Both stations can transmit and receive Both stations can transmit and receive
simultaneouslysimultaneously E.g. telephone networkE.g. telephone network
Direction of data at the time
Basic ConceptsBasic Concepts
Line ConfigurationLine Configuration TopologyTopology Transmission ModeTransmission Mode Categories of NetworksCategories of Networks InternetworksInternetworks
Categories of NetworksCategories of Networks
LAN (Local Area Network)LAN (Local Area Network) MAN (Metropolitan Area Network)MAN (Metropolitan Area Network) WAN (Wide Area Network)WAN (Wide Area Network)
InternetworksInternetworks
Two or more networks are connectedTwo or more networks are connected
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