Editing Random early detection (section)

{{Short description|Algorithm}}
[[Image:Random Early Detection algorithm en.svg|right|519px]]
'''Random early detection''' ('''RED'''), also known as '''random early discard''' or '''random early drop''', is a [[Active Queue Management|queuing discipline]] for a [[network scheduler]] suited for [[network congestion avoidance|congestion avoidance]].<ref>{{cite journal | last = Floyd | first = Sally |author2=Jacobson, Van  | title = Random Early Detection (RED) gateways for Congestion Avoidance | url = http://www.icir.org/floyd/papers/red/red.html | journal = IEEE/ACM Transactions on Networking | volume = 1 | issue = 4 |date=August 1993 | accessdate = 2008-03-16 | pages = 397–413 | doi = 10.1109/90.251892| citeseerx = 10.1.1.147.3833 | s2cid = 221977646 }}</ref>

In the conventional [[tail drop]] algorithm, a [[router (computing)|router]] or other [[Computer networking device|network component]] buffers as many packets as it can, and simply drops the ones it cannot buffer. If buffers are constantly full, the network is [[Network congestion|congested]]. Tail drop distributes buffer space unfairly among traffic flows. Tail drop can also lead to [[TCP global synchronization]] as all [[Transmission Control Protocol|TCP]] connections "hold back" simultaneously, and then step forward simultaneously. Networks become under-utilized and flooded—alternately, in waves. 

RED addresses these issues by pre-emptively dropping packets before the buffer becomes completely full. It uses predictive models to decide which packets to drop. It was invented in the early 1990s by [[Sally Floyd]] and [[Van Jacobson]].<ref>{{Cite news|url=https://www.nytimes.com/2019/09/04/science/sally-floyd-dead.html|title=Sally Floyd, Who Helped Things Run Smoothly Online, Dies at 69|first=Katie|last=Hafner|newspaper=The New York Times |date=September 4, 2019}}</ref>