Lecture 8: Internetworking Flashcards
What three things are needed to allow computers to communicate with each other?
A physical connection between the two, agreed data representation and a set of rules for coordinating the exchange.
What is a computer network?
A collection of computers that use one or more network protocols to exchange with each over of a network medium.
What does a network protocol define?
What extra information needs to be sent, meaning of each bit in a data transmission and how to send it (when and how fast).
What are the 7 layers of the OSI model? Describe them.
Application layer: defines what message to send.
Presentation Layer: defines the format of the message.
Session Layer: defines when the message can be sent.
Transport Layer: sends entire message across network.
Network Layer: sends data packet across network.
Data-link Layer: sends data packt across connected devices.
Physical Layer: sends individual bits across connected devices.
What is encapsulation?
Encapsulating a message with extra data as to make it readable by another device.
What is the physical layer resposible for?
Physical characteristics of interfaces/connectors, representation of bits, synchronisation of bits, data rate, line config, physical topology, transmission mode.
Difference between serial and parallel transmission?
Serial transmission: one bit at a time.
Parallel transmission: one byte/word at at time (faster).
What is a data rate measured in?
Bits/sec.
Name and describe four delays measured by latency.
Propagation delay: time taken for signal to go from source to destination.
Transmission delay: time taken for entire message to cross given point along transmission path.
Access delay: time taken to access network.
Routing delay: time taken for message to be processed by network devices like routers.
What are the two forms of transmission media? Describe them and give examples.
Guided: medium has a conductor that restricts path. Eg, optical fibre.
Unguided: does not restrict path and travels all directions or in a general direction. Eg, microwave radar, satellite, radio waves, or infrared.
Two forms of unguided transmission:
Omnidirectional: all directions, multipoint.
Directional: general direction, point-to-point.
Name the five network topologies:
Ring, star, mesh, tree, bus.
What purpose do multipoint routers/network switches serve?
They permit multiple connections to be made between a number of computers at once.
What are the three categories of networks?
Local Area (LAN), Metropolitan Area (MAN), Wide Area (WAN).
What is an internetwork?
A network between different types of networks.
