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Drop Every 2 nd Packet – Why Not?. Jon Crowcroft http://www.cl.cam.ac.uk/~jac22 http://www.turing.ac.uk. Remember. The power of 2 random choices Lots of packets Phase of arrival/flow effectively random Random Drop >> Tail or Head
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Drop Every 2nd Packet – Why Not? Jon Crowcroft http://www.cl.cam.ac.uk/~jac22 http://www.turing.ac.uk
Remember • The power of 2 random choices • Lots of packets • Phase of arrival/flow effectively random • Random Drop >> Tail or Head http://www.eecs.harvard.edu/~michaelm/postscripts/handbook2001.pdf
Easy to try • Normal drop from tail of FIFO • Can lead to synchronisation effects • Means queue is full • Drop from head = oldest • At least queue might not be full • Can lead to synchronisation effects • Random Drop may be fairer • Random Early Drop – needs mark • So drop 2nd with VQ estimator should work • Easier to track 2nd packet
Now only buffer 2 packets • Answers complicated question in this Stanford thesis • “Sizing Router Buffers”: • http://tiny-tera.stanford.edu/~nickm/papers/guido-thesis.pdf • Much more simply…. • Assumes a lot of flows • Or only 2...of course
Needs 30 mins of some NS3 hack • Exercise for the reader…. • Why different from drop from head? • Answers on a postcard
Meanwhile, the TAO of Netos • Lots of useful socio-tech advice https://www.cl.cam.ac.uk/research/srg/netos/culture.html + supervising ug courses is good for you. • Also Masters courses of interest, eg http://www.cl.cam.ac.uk/teaching/1617/R02/ Ask lecturer…