Editing Exponential backoff (section)

==Truncated exponential backoff==
The 'truncated' variant of the algorithm introduces a limit on {{math|''c''}}. This simply means that after a certain number of increases, the exponentiation stops. Without a limit on {{math|''c''}}, the delay between transmissions may become undesirably long if a sender repeatedly observes adverse events, e.g. due to a degradation in network service. In a randomized system this may occur by chance, leading to unpredictable latency; longer delays due to unbounded increases in {{math|''c''}} are exponentially less probable, but they are effectively inevitable on a busy network due to the [[law of truly large numbers]]. Limiting {{math|''c''}} helps to reduce the possibility of unexpectedly long transmission latencies and improve recovery times after a transient outage.

For example, if the ceiling is set at {{math|1= ''i'' = 10}} in a truncated binary exponential backoff algorithm, (as it is in the [[IEEE 802.3]] CSMA/CD standard<ref name="IEEE_802_3">{{Cite web|title=IEEE Standard 802.3-2015|url=https://standards.ieee.org/ieee/802.3/6003/|publisher=IEEE|access-date=20 March 2022}} (purchase)</ref>), then the maximum delay is 1023 slot times, i.e. {{math|2<sup>10</sup> &minus; 1}}.

Selecting an appropriate backoff limit for a system involves striking a balance between collision probability and latency. By increasing the ceiling there is an exponential reduction in probability of collision on each transmission attempt. At the same time, increasing the limit also exponentially increases the range of possible latency times for a transmission, leading to less deterministic performance and an increase in the average latency. The optimal limit value for a system is specific to both the implementation and environment.<ref>{{harvnb|Tanenbaum|Wetherall|2010|chapter=4.3|page=285}}</ref>