Intro to Data Communications - CH 1 (EXAM 1) Flashcards
client
user device to access network and receive data from a server
compter (client) –> server
server
device that stores and transmits data to client
computer –> upload files –> server
circuit
connection between client and server
why are networks important?
efficient data transmission, real-time communication, web
what are the 4 network types?
LAN
BN
MAN
WANs
What is a LAN?
Local Area Network
room, building, group of PC’s sharing network
What is a BN?
Backbone networks
less than a few km’s
high-speed backbone linking together LAN’s at various locations
What is a MAN?
Metropolitan area networks
more than a few kms
connects LAN’s and BN’s across locations
uses lease lines to transmit data
What is a WAN?
Wide area network
more than 10 kms
greater scale than MAN
What are the 2 types of networks?
intranet and extranet
What is the intranet?
network (LAN) that shares information IN an organization
What is the extranet?
a network that shares information BETWEEN organizations
invited users outside the org.
access through the internet
What are network models?
divide communication functions into layers
What are the 2 types of network models?
OSI model
Internet model
What is the OSI model?
7 layers
physcial, DL, network, transport, session, presentation, application
What is the Internet model?
5 layers
based on TCP/IP
physical, link, network, transport, application
What is a protocol?
defines the language of transmission and specifies rules, function, and messages for the communication at a layer
What is a protocol data unit (PDU)?
contains layer SPECIFIC information for a message to be transmitted through a network
encapsulation occurs when a higher level PDU is placed in a lower PDU
Application layer
user’s access to network
software to perform work
protocols: HTTP, SMTP, DNS, FTP, DHCP, IMAP, POP, SSL
PDU: packet (data)
Transport layer
end to end management
links application layer to network, segment and track, flow control
protocols: TCP and UDP
PDU: segment
Network layer
decides where the message goes (address and route)
protocols: IP and ICMP
PDU: packet
Data Link layer
moves a message from one device to next
controls hardware, formats message, error checking
protocols: ethernet, T1, frame relay
PDU: frame
Physical layer
transmits a message through a circuit
protocols: 100BASE-T, 802.11n, category 5 cable
What are the advantages of layers?
easy to troubleshoot
app developers can worry about the app layer in programs
What are the disadvantages of layers?
encapsulation and decapsulation at each layer before processing
encapsulation in PDU increases overhead at each layer
What are network standards?
ensures hardware and software from different vendors can work together and “speak the same language”
What are the de jure standards?
formalized by industry or government body
CIA, FBI
HTTP, IEEE, 802.3, 802.11n
What are de facto standards?
widely accepted, not normalized
MS windows
What is the de jure standardization process?
specification, choice identification, acceptance
What is specification?
identifying problems to be addressed
What is the identification of choices?
identify solutions and choose optimum solutions
What is acceptance?
defining a solution and recognized by industry
