Chapter 1 Flashcards
What is the internet?
It is a combination of software and hardware.
Network infrastructure that provides services to different apps.
Hosts/end systems
any device connected to the internet
Communication Links consist of what?
Coax, copper wire, optical fibre, and radio spectrum
Transmission Rate
measured in bits/sec
Packets
segments of data with header
Packet switches
routers or link-layer switches
Distributed apps
involve multiple end systems that exchange data with each other
Internet Apps
run on end systems
API
specifies how a program on a end system asks internet infrastructure to deliver data to a specific destination program running on another end system
What is a protocol
It is a set of actions specified to define the format/order of messages exchanged between two or more communicating entities
Access Network
physically connects end systems to first router on a path from the end system to any other distant end systems
Home Access Exmaples
DSL, Cable, FTTH, Dial-up, Satellite
DSLAM
DSL access multiplexing- converts signal from digital to analog
Cable network
requires DSLAM from analog to digital and terminates at CMTS
Wifi
most prevalent in corporate, university, and home networks
3G/LTE
Uses a base station to connect phones
Physical media types
radio, satellite, cable
Example of unguided vs guided medium
Wifi-unguided, cable-guided
End to End Delay Example
N-Number of links
R-transmission rate
L-length of one packet
How does the router determine which link to forward to?
1) forwarding table: maps dest address to routers outbound links
2) end-to-end: asks directions
Circuit Vs Packet Switched networks
Circuit-resources are reserved for a duration of the session
Packet switched-resources are not reserved
FDM
Frequency is divided among established connections
TDM
Divides the time into frames of fixed duration and each frame is divided and has a fixed number of time slots
Does the ISP provide internet services?
No, Service provider does
