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77 Cards in this Set
- Front
- Back
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millions of connected computing devices network of networks Interconnected ISPs |
Internet |
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hosts= |
endsystems clients and servers |
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endsystems = |
hosts |
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fiber,copper, radio, satellite |
communicationlinks |
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transmission rate: |
bandwith |
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Packet switches |
forward packets (chunks of data)
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routers and |
switches |
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internet |
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______ control sending, receiving of msgs, e.g., TCP, IP, HTTP, Skype, 802.11 |
protocols |
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______ define format, order of msgs sent and received among network entities, and action taken on msg transmission, receipt
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protocols |
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protocols define ______ of msgs sent and received among network entities, and actions taken on msgtransmission, receipt |
format order |
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protocols define format, order of ______ among network entities, and actions taken on msg transmission, receipt
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msgs sent and received |
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protocols define format, order of msgs sent and received among network entities, and ______ on msg transmission, receipt
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actions taken |
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all communication activities in Internet are governed by the internet protocols
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network protocols
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computer network protocol |
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hosts: clients and servers servers often in data centers |
network edge |
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wired, wireless communication links |
access networks, physical media
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interconnected routers network of networks |
network core |
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different channels transmittedin different frequency bands
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frequency division multiplexing
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base station AKA |
access point |
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access point AKA |
base station |
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within building (100 ft)
802.11b/g (WiFi): 11, 54 Mbps transmission rate |
wireless LANs |
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provided by telco (cellular) operator, 10’s km between 1 and 10 Mbps
G, 4G: LTE |
wide-area wireless access |
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wireless LANs |
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wide-area wireless access |
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host takes application message
breaks into smaller chunks, known as packets, of length L bits transmits packet into access network at transmission rate R |
host sending function |
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host takes application message breaks into smaller chunks, known as ______ of length L bits |
packets |
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host takes application message breaks into smaller chunks, known as packets of length ___ bits |
L |
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host takes application message
breaks into smaller chunks, known as packets, of length L bits transmits packet into access network at ______ R |
transmission rate |
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host takes application message
breaks into smaller chunks, known as packets, of length L bits transmits packet into access network at transmission rate ___ |
R |
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link transmission rate AKA link capacity AKA |
link bandwidth |
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link bandwidth AKA link capacity AKA |
link transmission rate
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link transmission rate AKA link bandwidth AKA |
link capacity |
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Host sends packets of data |
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packet transmission delay |
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time needed to transmit L-bit packet into link |
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L (bits) |
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R (bits/sec) |
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propagates between transmitter/receiver pairs
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bit |
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what lies between transmitter & receiver
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physical link |
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signals propagate in solid media: copper, fiber, coax
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guided media |
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signals propagate freely, e.g., radio
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unguided media |
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two insulated copper wires
Category 5: 100 Mbps, 1 Gpbs Ethernet Category 6: 10Gbps |
twisted pair (TP) |
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two concentric copper conductors
bidirectional broadband: multiple channels on cable, HFC |
coaxial cable
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glass fiber carrying light pulses, each pulse a bit
high-speed operation: high-speed point-to-point transmission (e.g., 10’s-100’s Gpbs transmission rate) low error rate: repeaters spaced far apart immune to electromagnetic noise |
fiber optic cable
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twisted pair (TP) |
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coaxial cable
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fiber optic cable
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signal carried in electromagnetic spectrum no physical “wire” bidirectional |
radio |
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reflection obstruction by objects interference |
propagation environment effects
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terrestrial microwave LAN (e.g., WiFi) wide-area satellite |
radio link types
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e.g. up to 45 Mbps channels
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terrestrial microwave
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11Mbps, 54 Mbps
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LAN (e.g., WiFi)
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3G cellular: ~ few Mbps
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wide-area (e.g., cellular)
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Kbps to 45Mbps channel (or multiple smaller channels)
270 msec end-end delay geosynchronous versus low altitude |
satellite
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mesh of interconnected routers
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network core
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hosts break application-layer messages into packets
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packet-switching
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name of the colored part? (not grey) |
network core |
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store-and-forward
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entire packet must arrive at router before it can be transmitted on next link
through the process of transmission packet might suffer delay |
store and forward
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forward packets from one router to the next, across links on path from source to destination
each packet transmitted at full link capacity |
packet-switching
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queueing delay, loss
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If arrival rate (in bits) to link exceeds transmission rate of link for a period of time:
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packets will queue, wait to be transmitted on link and packets can be dropped (lost) if memory (buffer) fills up
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routing and forwarding |
key network-core functions
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move packets from router’s input to appropriate router output
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forwarding |
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determines source-destination route taken by packets |
routing |
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Two key network-core functions: routing and forwarding
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circuit switching |
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end-end resources allocated to, reserved for “call” between source & dest
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circuit switching |
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dedicated resources: no sharing circuit segment idle if not used by call (no sharing) Commonly used in traditional telephone networks |
circuitswitching |
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great for bursty data resource sharing simpler, no call setup |
packet switching |
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excessive congestion possible: packet delay and loss protocols needed for reliable data transfer, congestion control |
packet switching
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How to provide circuit-like behavior?
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bandwidth guarantees needed for audio/video apps
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End systems connect to Internet via ______
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access ISPs (Internet Service Providers) |
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Access ISPs in turn must be interconnected
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So that any two hosts can send packets to each other
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Evolution was driven by ______ and national policies
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economics |
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Evolution was driven by economics and ______
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national policies |
