how many TCP connections at a time?

hegdeshashi · 01-04-2006, 12:36 AM

HI friends,

In a TCP stack, at a time how many TCP connections are possible ? Is there any limit?

regards,
hegdeshashi

uovgaz · 01-04-2006, 02:03 PM

I would say the maximum is 65536 simultaneous connections, given that there are that many ports available for use.

jcliburn · 01-04-2006, 07:50 PM

Each TCP socket needs a file descriptor (an integer), and there's a kernel limit on the maximum number of open file descriptors, though I don't know the kernel parameter name, nor it's default value. Additionally, each TCP socket needs a socket structure, which also consumes a small amount of memory. So as a practical matter, if you could theoretically set the max file descriptor parameter to infinity, the maximum number of TCP connections should be limited only by the quantity of available memory.

jcliburn · 01-04-2006, 08:04 PM

Looks like my kernel allows 101,285 file descriptors.

Code:

[jcliburn@osprey ~]# /sbin/sysctl fs.file-max
fs.file-max = 101285

stickman · 01-04-2006, 09:44 PM

Do quick Google search for "linux tcp tuning". You should find a few good articles on kernel and TCP tuning.

hegdeshashi · 01-05-2006, 11:19 PM

I am not able to find how many connections in the TCP stack in"TCP TUNING GUIDE ".

any idea regarding this one?