0 Network Basic

7/30/2019 0 Network Basic

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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

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0 Network Basic