Flashcards
Internet Communication
Cards in this deck (19)
- 1Circuit SwitchingA direct link is created between two devices for the duration of communication
Examples include the public telephone network - 2Circuit switching advantagesExclusive connection between the two devices
Data arrives in the right order - reassembly is easier - 3Circuit switching disadvantagesBandwidth wasted during periods of non-transmission
Data transfer rate of both devices must be identical
There may be electrical interference on the line (through parasitic capacitance) - 4Packet SwitchingData is broken into a series of packets, which can take several routes across a network
- 5Data packetsConstituent components of a piece of data that are sent across a network
Can vary between 500 and 1500 bytes
Can take different routes through a network, increasing overall transmission speed - 6Structure of a packetHeader - contains metadata for the packet including source and destination addresses, packet number (e.g. 2 of 8), protocol and a Time To Live (TTL) or hop limit.
Payload - Contains the section of data to be transferred
Trailer - If present, it will contain error-detecting code e.g. checksums or a Cyclical Redundancy Check (CRC) - 7Routing packets through a networkData is split into packets and sent through a network of routers
Each time a packet reaches a router, it is checked and requested again if its checksums don't match up
The next stage of the route is found and the packet is forwarded on
Each transfer between routers is known as a hop - 8Function of a routerStores data about the available routes to different destination nodes and uses this data to send packets on the fastest route
The fastest route can be found using a routing algorithm (e.g. Dijkstra's algorithm) or a routing table - 9GatewayActs as a barrier between networks using different protocols
When a packet reaches the network, its header data is removed and replaced with data in a new format
The packet is then sent on via standard routing procedures - 10Media Access Control (MAC) addressContained within and unique to the Network Interface Card (NIC)
Used as a unique 48-bit identifier for the device - 11ProtocolsStandards defining common methods of data communication
Ensures that all devices are equipped to communicate with each other - 12The TCP/IP Protocol StackSet of networking protocols working as 4 layers
- 13TCP/IP LayersApplication
Transport
Network
Link - 14Application Layer (TCP/IP)Highest level
Relates protocols for data transfer to the application and selects/uses high-level protocols
Displays received data to the user - 15Transport Layer (TCP/IP)Establishes an end-to-end connection between sender and receiver
Responsible for conversion of raw data into packets and vice versa
Also requests and acknowledges packets
Specifies the port on which data should be handled - 16Network Layer (TCP/IP)Also known as Internet or IP layer
Adds source and destination IP addresses to outgoing packets and removes them from incoming packets - 17Link layer (TCP/IP)Removes the current MAC address (if any) and adds the MAC address of the next router in the packet's route (if not the last stop)
- 18File Transfer Protocol (FTP)High-level protocol
Used to transfer files across a network
Operates in the Application layer
Uses a file management system so looks like an ordinary folder
Often requires a login but can be configured for anonymous use - 19Mail ServersStorage servers
Post Office Protocol v3 (POP3) - Deletes emails once they're received
Internet Message Access Protocol (IMAP) - Retains messages on the server for synchronising across devices
Transmission servers
Simple Mail Transfer Protocol (SMTP)
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- A level OCR A level Computer Science (Topic 5 - Networks and Web Technologies) Flashcards on Internet Communication, created by James Norman on 02/02/2020.
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- James Norman
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