Topic 2 -Data transmission

broken uop into smaller parts, data packets,

header payload trialer

IP address of sending , receiving device and sequernce number of packet

actual data

method of identifying end of packet + some form of error checking

way of transmitting data. message broken up into number of packets that can be sent indipendently, at the destination they will be reassambled in correct order each packet will follow its own pathj based on traffic

determine which routye the packet needs to take, depends on n. of packets waiting to be processed at each node, shortes route always chosen

fast, efficient high data transmission rate is possible emails and text will work in a crisis or disaster different speeds devices can communicate

packets can be lost this method only good for some type of data there is a delay at destination (re-order)

transmitting bits from one device to another

less likely to do errors slower, less efficient6 long distance

quicker, very effiecient high error rate short distance

simplex= one direction half duplex= both directions but one at the time full duplex= both directions at the same time

universal serial bus, serial data transmission form (half and full duplex) 4 wires,2 for power, 2 for data transmission

standard in industry error-free data transmission easy to add more USB ports devicesplugged in automatically detected

max 5 metres may not be supported by older computers

interface problems data switching skewing of data power surges

extra bit added to ensure that n of bits is even or odd

additional digit at the end of a string to check for mistakes, can be calculated using modulo 10 system

block of data is sent alongside a calculated checksum value, receiving compoter calculates this value and the 2 values are compared to check fo error

message sent to the sender indacating if data has been received correctly tuime out= time allowed to elapse before an ackowlegmebnt is received