>> However these are with a very high address-sharing ratio (several >> thousands users per address). Using a sparser density (<= 64 users per >> address) is likely to show much less dramatic user impacts. > > I think you have the numbers off, he started with 1000 users sharing > the same IP, since you can only do 62k sessions or so
These numbers were not off. From page 19: "...we should assign at least 1000 [..] ports per customer to assure good performance of IPv4 applications" "At least 1000 ports per customers" is roughly the same than "less than 64 users per address" as I stated above. Btw, 90% of subscribers have less than 100 active connections at any time, if I read these tiny graphs correctly: http://www.wand.net.nz/~salcock/pam2009_final.pdf > and with a "normal" timeout on those sessions you ran into issues quickly. Agreed for UDP, but most of these sessions are TCP, which arguably time out rather rapidly after a FIN and an extra hold time. Normal duration of a TCP session is usually under a few seconds. This study saw an average connection time of 8 seconds for DSL, but it's from 2004. http://www.google.com/#q=A+Comparative+Study+of+TCP/IP+Traffic+Behavior+in+Broadband+Access+Networks /JF