Post on 14-Apr-2018
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Basics of Comm. Networks
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Wires (or RF, IR) connecting together the devices that make up a
Twisted pairos common:
y STP: shielded twisted pairy
UTP: unshielded twisted pair(e. . Tele hone cable, Ethernet 10BaseT)
Coaxial cabley Thin (similar to TV cable)y Thick (e.g., 10Base5, ThickNet)
Fiber
Wireless
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, ,Hub
y Device that acts as a central oint for LAN cables
y
Take incoming data from one port & send to all other portsSwitchy Moves data from input to output port.
y Ana yzes pac et to etermine estination port an ma es a virtua connectionbetween the ports.
Concentrator or repeatery Re enerates data assin throu h it
Bridgey Connects two LANs or two segments of a LAN
y Connection at data link layer (layer 2)
Routery Determines the next network point to which a packet should be forwarded
y Connects different types of local and wide area networks at network layer (layer 3)
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Bus Network
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Tree Network
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Star Network
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Ring Network
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Mesh Network
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Standardized by IEEE as 802.3 standard
Spee s: 100 M ps - 1 G ps typica to ayy Ethernet: 10 Mbps
y Fast Ethernet: 100 Mbps
y Gigabit Ethernet: 1 Gbps
y 10 Gbps, 100 Gbps
Network access method isCarrier Sense Multiple Access with Collision Detection(CSMA/CD)y Node first listens to network to see if busy
y Send
y Sense if collision occurred
y Retransmit if collision
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Ethernet media
Bus topology (original design)
y originally thick coax (max 500m): 10Base5
y
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Wireless Ethernet mediaWire ess (star topo ogy)
y 802.11 (1-2 Mbps)
y - -.
y 802.11a (54 Mbps - 22-28 Mbps realized)y 802.11g (54 Mbps - 32 Mbps realized)
y 802.11n (108 Mbps - 30-47 Mbps realized)
et ernet
Access Point
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Connectin to the Internety DOCSIS modem via cable TV service
y DSL router
y
Ethernet converted to ATM data streamy Up to 20 Mbps up to ~ 2 km.
y POTS limited to 300-3400 Hz
y DSL operates > 3500 Hz
y Data modulated over voice spectrum
(300-3400 Hz)
y Serial interface to endpoint
y V.92: 48 kbps downstream, near 56 kbps up
y Use PPP or SLIP to ri ge IP protoco