Week 4: Session 8: Route tracing, collision avoidance, and scene setting Flashcards
backing off
In WiFi, backing off is a procedure for randomly allocating access to a radio channel to a single device out of all the ones waiting to transmit data. When a radio channel has been unused for a set length of time (the ‘check period’), devices with data to transmit count down from a random number. This is backing off. The first device to reach zero gains access to the radio channel.
check period
A fixed length of time for which a radio channel must be unused before backing off begins.
contention window
The period of time during which contending devices count down from a random number in order to determine which one will gain access to the radio channel. It’s the stage during which backing off occurs.
enterprise network
A network used in large-scale businesses and organisations. Enterprise networks use powerful, dedicated hardware, such as separate switches, routers, firewalls and DHCP servers, rather than a single device that does all this as would be found in a home network.
listen before transmit
A protocol (carrier-sense multiple access with collision avoidance, or CSMA/CA) to ensure that only one device at a time transmits data on a radio channel. The protocol governs all devices within range of each other that use the same radio channel, irrespective of whether the devices belong to the same network.
multiple access
Allowing many devices to use the same medium.
round-trip time (RTT)
The time it takes for a packet of data to reach a destination and be returned.
timeserver
An online clock that other devices consult to find the current date and time.
time to live (TTL)
The maximum number of hops an IP packet can make before it is discarded.
traceroute
A diagnostic tool for locating blockages on the route of an IP packet.
