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
