Chapters 1 & 2 Flashcards
Computer Network
Any telecommunication connection that allows computers to electronically exchange data
Internet
Any set of (inter)connected networks
Intranet
Network that is not available to the outside world
The Internet
Global system of interconnected computer networks that uses TCP/IP protocol suite to link billions of computers worldwide
formed by connecting multiple packet switching networks
World Wide Web (WWW)
System of interlinked hypertext documents that are accessed via the Internet using the web browsers
Y/N All computer networks are internets
no
Y/N Any internet is a computer network
YEs
Y/N The internet is a computer network
Yes
Y/N The Internet is an internet
Yes
Y/N The WWW is a computer network
No, WWW does not connect computers, it connects files. It is an application, just like email.
message
information to be communicated
sender
device that sends the message
receiver
device that receives the message
medium
physical path from sender to receiver
protocol
set of rules that govern data communications
The Internet uses this protocol suite
TCP/IP
circuit switching
(dedicated line) method of implementing network communication in which two network nodes require a dedicated communications channel/wire (circuit) to communicate (like phone communication)
packet switching
(small packets travel independently) Data is divided into small “packets” and packets travel independently through the network to reach the recipient
Protocol layer
subset of specific aspects of communication
Each protocol should handle a part of communication that is not handled by other protocols
Layers
each layer implements a service
- via its own internal-layer actions and procedures
- relying on services provided by layer below
Each layer of protocol verifies that the messages arrive as expected
Why layering?
Helps deal with complex systems
- Provides a conceptual framework that can help us understand the system
- Easier maintenance or updating of system
Encapsulation
change of implementation of layer’s service is invisible to rest of system
Internet Layered Model (Protocol Stack)
Application
Transport
Internet
Link (network interface)
Physical
Application (Layer 5)
for network applications
ex)
- email exchange
- file transfer
- web browsing - HTTP & HTML protocols
- telephone services
Protocols: FTP, SMTP, HTTP
Transport (Layer 4)
Provide communication from an application program on one computer to an application program on another; controlling the maximum data rate a receiver can accept, how to avoid network congestion, techniques to ensure that all data is received in the correct order
process-process data transfer
Protocols: TCP, UDP
Internet (Layer 3)
Fundamental for the Internet; specify communication across the Internet (spanning multiple interconnected networks)
routing of datagrams from source to destination
Protocols: IP, routing protocols
Network Interface Layer; Link (Layer 2)
Specify details about communication between higher layers of protocols (implemented in software) and the underlying network (implemented in hardware): network addresses, maximum packet size that a network can support, how to access the underlying medium, hardware addressing
data transfer between neighboring computers
Ethernet, PPP, wireless
Physical (Layer 1)
How electrical and electromagnetic energy is used to carry information across wires, glass, or through the air
bits “on the wire”
Protocols: Manchester encoding, ASCII
header
To perform verification on packages
- each layer on the sender prepends extra information onto the packet
- The corresponding protocol layer on the receiver removes and uses the extra information
- Application layer doesn’t prepend information (up to down)
message
HTTP, FTP, DNS
segment
TCP or UDP
datagram
IP
frame
Ethernet
IP address
Each computer connected to the Internet is given a unique address
IP meaning
internet protocol
IPv4: series of four numbers separated by dots (147.53.6.172)
