Re: [Discuss-gnuradio] Calculating the delay of TCP link.

[Marcus D. Leech]

On 04/30/2013 03:40 PM, Sajjad Safdar wrote:

Hi,

Is it any way to calculate using the MTU size of TCP packet and the sampling rate, like a mathematical approach using formulas.

Best Regards,

SAJJAD SAFDAR

Well, no, because you have to actually *measure* the delay.

Any real IP network has a number of components, each of which introduces time-varying latencies.

It's a meaningless question to ask "what is the delay of a typical TCP channel".  Because, well, there's no such thing.

Is your TCP channel across the room on a piece of wire?  Does it go through switches/routers?  How many of them?

Are all the elements running at the same notional bit-rate?

What is the current latency of packets from userland, through the kernel, until they "hit the wire"?  That varies both with system
  architecture and current system loading factors.

You could probably boil it all down to several different delay contributions, assign them variables and weighting, and come up with an equation.
  But without estimates for the likely ranges of each parameter, it won't tell you anything useful, compared to actually measuring the channel.
  Frequently.

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org