what is "IDLE" for TCP commections

[Vytautas Vysniauskas]

Regarding my previous question




what is difference between "IDLE" and "ESTABLISHED" for TCP connections (not UDP) ?
Does it mean that no traffic posted yet since three-way handshaking ? There also opinion that it could mean not bounded yet socket.

Thank you.

[sven verhaegen]

Hello

I have no notion of a socket state for TCP called IDLE in HP-UX , normally the states are LISTEN or ESTABLISHED , IDLE is a state for UDP as far as I know , usually meaning the socket is in a LISTENING state , the source code of LSOF might just use IDLE as indication for ESTABLISHED , 'LSOF' is not a standard supported tool by HP ( altough HP advised the use of it if needed) so it might not adhere to the common naming in HP_UX socket states , I don't have the code so I'm not sure about that

[Ceesjan van Hattum]

About idle tcp:
TCP congestion avoidance mechanisms are based on adjustments to the congestion-window size, triggered by the ACK clock. These mechanisms are not well matched to large but intermittent bursts of traffic, such as responses from a HTTP/1.1-based web server. Idle periods between bursts (web page replies) stop the ACK clock and hence disrupt even data flow.

The above tells that IDLE is used on TCP (not only UDP) as well.
See also: http://www.isi.edu/~johnh/PAPERS/Visweswaraiah97b.html

Regards,
Ceesjan