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115 Cards in this Set

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YR-Phone Invented
1876
YR-First trans-continental and transatlantic phone connections
1915
YR-Rotary Phones
1919
YR-Microwave trunk lines
1948
YR-Telstar (telecommunications via satellite), Fax services, Digital transmission
1962
YR-Picurefone
1969
YR-Packet-switched data communications
1976
YR-Cellular Phone
1984
YR-Batch Processing
1950s
YR-Data communication over phone lines becomes common
1960s
YR-Online realtime transaction oriented systems (replace batch processing, DBMSs become common
1970s
YR-PC revolution
1980s
YR-PC Lans become common
1990s
YR-Networks everywhere
2000s
YR-ARPANET began
1969
YR-ARPANET splits into Milnet and internet
1983
YR-NSFNet created as US Internet backbone
1986
YR-Commercial access to the Internet begins
1990
YR-Gove funding of the backbone ends
1994
Over 240 million servers and 400 million users
2001
LAN
Local Area Network, for room, building - to link a group of PCs that share a circuit
BN
Backbone Network, less than a few km, links LANs at various locations
MAN
Metropolitan Area Network - < few 10 kms; connects LANs and BNs
WAN
Wide Area Network - >few 10 kms; same as MAN but on a wider scale
Network Models
Open Systems Interconnections (OSI)Model & Internet Model
OSI Model
Created by ISO (1984) - 7 layers
OSI Model - 7 layers
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer
Internet Model
Created by Darpa (1970s) - based on TCP/IP - 5 layers
Internet Model - 5 layers
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Application Layer
Function-Application Layer
Set of utilities used by application programs
Function-Presentation Layer
Formats data for presentation to the user; provides data interfaces, data compression and translation between different data formats
Function-Session Layer
Initiates, maintains and terminates each logical session between sender and receiver
Function-Transport Layer
Deals with end-to-end issues such as segmenting the message for network transport and maintaining the logical connections between sender and receiver
Function-Network Layer
Responsible for making rouing decisions
Function-Data Link Layer
Deals with message delineation, error control and network medium access control
Function-Physical Layer
Defines how individual bits are formatted to be transmitted through the network
ISO
International Organization for Standardization
ITU
International Telecommunications Union
ANSI
Americal National Standards Institute
IEEE
Institute for Electrical and Electronic Engineers
IETF
International Engineering Task Force
Application Architectures
Host-based (server performs almost all functionqs); Client-based (Client performs most functions); Client-Server (Functions shared between client and server
Problems with Host-based
Processing bottleneck; Upgrades Expensive and Jumpy
Problems with Client-based
Data must travel back and forth between server and client, makes for poor performance
Advantages/Disadvantages of Client-Server
(ADV)More efficient because of distributed processing, different hardware vendors can be used together; (DIS) Difficulty getting software to work together, may require middleware
Multi-tier Architectures
2-tier; 3-tier; N-tier
Multi-tier advantages/dis-advantages
(ADV) Better load balancing, more scalable; (DIS) More processing/exchanges, difficult to program and test due to complexity.
Criteria for choosing Architecture
Infrastructure cost; Development Cost; Scalability
HTTP
Hyper-Text Transfer Protocol
SMTP
Simple Mail Transfer Protocol
POP
Post Office Protocol
IMAP
Internet Mail Access Protocol
MIME
Multipurpose Internet Mail Extension (for multimedia files)
FTP
File Transfer Protocol
Telnet
Allows one computer to log into other computers
IM
Instant Messaging
Videoconferencing
Real time trasmission of video and audio signals
HTML
Hyper-Text Markup Language (used to format webpages)
Types of Data Transmitted
Analog or Digital Data
Analog Transmissions
Produced by tleephones, sound waves that vary continuously over time
Digital Transmissions
Can only take on 0s or 1s; Made of square waves with a clear beginning and ending
Communication Media
Guided (UTP, coaxial, fiber optic) OR Wireless (flows thru air - radio, infrared)
MAC
Media Access Control - the need to control when computers transmit
Controlled Acess
X-ON/X-OFF; Polling
Contention
Check then sends whenever they have data to send
Examples of Contention
CDMA/CD - Carrier Sense Multiple Access with Collision Detection; CDMA/CA - Carrier Sense Multiple Access with Collision Avoidance
Sources of Errors
Line outages, white noise, impulse noise, corss-talk, echo, attenuation, intermodulation noise, jitter, harmonic distortion
Types of error detection
Parity Checking; Longtitudinal Redundancy Checking; Polynomial Checking
Transmission Modes
Parallel(used for shorter distances) and Serial (used over longer distances, bits stay in the order they were sent)
Different sound modulations
Frequency(#), Amplitude(height), and Phase (distance from crest to trough) modulation.
Bit
a unit of information
Baud
A unit of signaling speed
Baud rate
# of symbols tranmitted per second
Modem
Translates from Digital to Analog
Codec
Translates from Analog to Digital
PAM
Pulse Amplitude Modulation (Measures signal; Encodes signal as a binary data sample; takes samples of the data)
PCM
Pulse Code Modulation (Converts analog signals to digital data using PCM, similar to PAM)
DSL
Digital Line Subscriber
Parity Checking
A single bit added to each character (even parity vs odd parity)
LRC
Logitudinal Redundancy Checking - Adds an additional character (instead of a bit)-98% error detection
Polynomial Checking
Adds 1 or more characters to the end of message (based on a mathematical algorithm); Checksum & CRC (Cyclical Redundancy Check)l detects 100% of errors
Error Correction Techniques
ARQ (Automatic Repeat Request); Stop and Wait ARQ (waits for acknowledgements); Continuous ARQ (sliding window)
Datalink Protocols
Asynchronous vs Synchronous
Asynchronous Transmission
Start-Stop Transmission, uses idles to separate characters; uses stop-wait ARQ
Synchronous Transmission
Data sent in large blocks, including addressing information
SDLC
Synchronous Data Link Control
HDLC
High-Level Data Link Control
TCP/IP
Tranmission Control Protocol / Internet Protocol
IPv4 vs IPv6
IPv4 = 32 bit addresses; IPv6 = 128 but addressing (because we were running out of addresses)
X.25
Protocol to send packets; Widely used in Europe
Connection Oriented Messaging
Sets up a TCP connection (cirtual circuit) between the sender and receiver.
Connectionless Messaging
Each packet is treated separately and makes its own way through the network.
QoS
Quality of Service Routing; Different connections are assigned different priorities (#1=Videoconferencing; #10=emails)
IPX/SPX
Internet Packet Exchange/Sequenced Packet Exchange; routing protocol developed by Xerox, used to be used by Novell, now not so much
Internet Addresses
Managed by ICANN (Internet Corporation for Assigned Names and Numbers)
Subnet
Group of computers on the same LAN with IP numbers with the same prefix; additional bits added to length.
DHCP
Dynamic Host Control Protocol; develop in 1993
Address Resolution
Server Name Resolution (DSN-Domain Name Service); Data Link Layer Resolution
Routing
Determining the route or path through the netowrk
Types of Routing
Centralized routing; Static routing; Dynamic Routing
Centralized Routing
All routing decisions are made by one central computer or router
Static Routing
Routing table developed by network manager determines routing from one centralized computer
Dynamic Routing
Routing decisions are made in a decentralized mananer by individual computers
Routing Protcols (Def)
A protocol that is used to exhcnage information among computers to enable them to build and maintain their routing tables.
Types of Routing Protocols
RIP (Routing Information Protocol); OSPF (Open Shortest Path First); BGP (Border Gateway Protocol)
Why use a LAN ?
Information and Resource sharing
Types of Dedicated Servers
Web servers, e-mail servers, database servers, file servers, print servers, remote access servers
Peer-to-Peer Network
Requires no dedicated server; for small networks, lower cast, slower than dedicated server networks, difficulat to manage
NIC
Network Interface Cards (has datalink layer address-MAC Address)
Hubs
Acts as junction boxes, linking cables from several computers on a network
Network Profiles
Kept by servers; Specify resources available for use by other computers (includes data files, printers, etc.)
User Profiles
One profile for each user, used for security reasons; describes what each user on a LAN has access to; Includes access codes assigned to devices and users
Ethernet (IEEE 802.3)
Used by almost all LANs today, standardized
Types of Ethernets
Shared Thernet (uses Hubs) & Switched Ehternet (Uses switches)
Topology
Basic geometric layout of the network