Measuring transmission time

Hi folks,

I'm looking for a way to know the time required by a wireless

interface to push out a certain number of packets (with a certain

size, at a certain rate, on a certain channel (hence interference)).

What I've been doing so far, is setting a fake arp table entry and use

ICMP (ping) to get this time ... BUT... what is exactly ICMP

measuring?

Another point is that I would like to cut off the retransmission

mechanism AND timeout.. but I can't act directly at the MAC layer, so

I thought to send broadcast packets... which points out the second

question:

What can I use in place of ICMP (as I need broadcast)?... I was

thinking to develop a simple UDP socket application, but I don't

really know how to measure the timings (what to probe for..)... I've

seen a previous post where people were trying to use queue_xmit or

something like that, and get direct access to the outgoing interface..

assuming that transmission would start right away, there would still

be a queue in the middle... hence I

Is there any fast solution aside using tcpdump ?

Re: Measuring transmission time

InuY4sha <inuy4sha@gmail.com> wrote:[color=blue]

>

>Hi folks,

>I'm looking for a way to know the time required by a wireless

>interface to push out a certain number of packets (with a certain

>size, at a certain rate, on a certain channel (hence interference)).[/color]

Are you hoping to compute the elapsed time after the transfer happens, or

are you hoping to get a number you can use to predict future transfers?

I suspect you're after prediction, but I'm not convinced that is reliably

computable from user mode. Further, because wireless is so wildly

variable, as soon as you got a number, it wouldn't be applicable any more.

--

Tim Roberts, [email]timr@probo.com[/email]

Providenza & Boekelheide, Inc.