Computer networks Flashcards
LAN
Local Area Network
MAN
Metropolitan Area Network
WAN
Wide Area Network
PAN
Personal Area Network
client-server model
Distributed application structure that partitions workloads and tasks between the providers of a resource or service (server) and service requesters (client).
peer to peer (P2P)
P2P computing or networking is a distributed application architecture that partitions tasks and workloads between equipotent participants (peers). E.g. torrent.
circuit switching
A method of implementing a telecommunication network in which two network nodes establish a dedicated communications channel (circuit).
packet-switching
A type of network in which relatively small units of data (packets) are routed through a network based on the destination address contained within each packet. (connectionless communication)
ISO OSI layers
application,
presentation,
session,
transport,
network,
datalink,
physical
application
supporting network applications: ftp, smtp, http
transport
-reliable end-to-end communication
-creates the abstraction of an error-controlled, dlow controlled and multiplexed end-to-end link
TCP: error-control, flow control, multiplexing
UDP: only multiplexing
network
-logically concatenates a set of links to form the
abstraction of an end-to-end link
-routing of datagrams from source to destination: ip, routing protocols
-provide unique network-wide addresses
-both in end-systems and intermediate systems
link
-the first layer of software
-usually in a bundle with the physical layer in the hardware
-data transfer between neighbouring network elements: ppp, ethernet
Internet
-network layer is provided by the Internet Protocol (IP)
-found in all end-systems and intermediate systems
-provides abstraction of end-to-end link
-packet-fowarding, routing, scheduling
-unique IP-address
error control
GOAL:
-message reaches its destination despite packet loss, duplication and corruption
ACTION:
-retransmits lost packets
-detect, discard and retransmit corrupted packets
-detect and discard duplicated packets
flow control
Match transmission rate to the rate sustainable on the path to destination and at the destination.
twisted pair cable
Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.
-two conductors, each with plastic insulation
-two types: shielded (STP), unshielded (UTP)
RJ
A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier.
-the most common UTP connector
-RJ45 male and RJ45 female
Coaxial cable
Coaxial cable is a type of electrical cable consisting of an inner conductor surronded by dielectric insulator and a concentric conducting shield.
-many have an outer protective plastic jacket/sheath
BNC connector
Bayone-Neill-Concelman connector
-the most common type of connector for coaxial cables
-types: BNC connector, BNC T connector, BNC terminator
-applications: TV cables, traditional LANs
optical fibre
Optical fibre is a transparent fibre made of silica. It’s mostly used for fibre-optic communications because they allow electromagnetic waves to travel long distances with small loss and interference.
-a dielectric waveguide that trasmits light along its axis due to internal refraction
parts:
-glass or plastic core
-cladding
-plastic buffer
-coating
-outer jacket
multimode fibre
-designed for small distances of transmission: LAN-systems, video surveillance
single mode fibre
-designed for larger distances of transmission: long distance telephony, multichannel television broadcast systems
unguided media
Unguided media (wireless communication) is the transport of electromagnetic waves without using a soild physical conductor.
The section of the electromagnetic spectrum called the radio communication is divided into 8 ranges (bands).
ground propagation
Radio waves travel through the lowest portion of the atmosphere. These emitted waves emanate in all directions from the transmitting antenna following the curvature of the earth.
sky propagation
Higher-frequency radio waves radiate upwards into the ionosphere and are reflected back to Earth. This type of transmission allows higher frequencies with lower power output.
line-of-sight propagation
Very high-frequency signals are transmitted in a straight line from antenna to antenna.
Consumer IR
CIR refers to a wide variety of devices employing the infrared electromagnetic spectrum for wireless communication.
IrDA
Infrared Data Association; an industry-driven founded in 1993 by 50 companies. IrDA provides specifications for a complete set of protocols for wireless infrared communications.
star topology
-central hub through which all traffic flows
-the hub is a central point of failure
-used in all LAN networks
-simple to implement, easy to monitor all connected devices
bus topology
-all devices in the network are connected by a single cable
-any break in the cable renders the system inoperable
ring topology
-normally associated with Token Rings and FDDI environments
-can use dual counter-rotating rings that tolerate a single break
-expensive to implement
-the access protocols are more complex, the devices more intelligent
