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Wireshark-users: Re: [Wireshark-users] end-to-end delay calculation

From: "Fabiana moreno" <fvmoreno@xxxxxxxxx>
Date: Thu, 13 Mar 2008 19:30:52 +0000
Thanks for your reply! very helpful...But can you explain what do you exactly refer with merging the captures? sorry my first language isnt english. Thanks!

On 13/03/2008, Martin Mathieson <martin.r.mathieson@xxxxxxxxxxxxxx> wrote:
Then you can run a normal ping. Merge the captures, and, assuming that both journies took the same amount of time, you now know:
- the network latency (although note that ICMP may not be given the same priority as RTP./RTCP traffic)
- how much you might need to time-shift the second trace before merging to get them in the same time frame



On Thu, Mar 13, 2008 at 6:52 PM, Fabiana moreno <fvmoreno@xxxxxxxxx> wrote:
My receiver computer is running under windows and the one transmitting the video is running under linux.....How can i do this in this case???


On 13/03/2008, Rob MacKenzie <rmackenzie@xxxxxxx> wrote:

I looked at re-writing ping once to test time difference…  IF your endpoints are in the same building, consider running a wire between the parallel ports and code something to check the exact time when you flip a switch or something.  Then you would have a trigger time for both.

 


From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Martin Mathieson
Sent: March 13, 2008 12:13 PM


To: Community support list for Wireshark
Subject: Re: [Wireshark-users] end-to-end delay calculation

 

If you have console / command prompt of some type, most operating systems have a ping command that uses ICMP to test connectivity and routrip delay to a remote host and back.
But I don't know what OS or environment is running on your endpoints.

On Thu, Mar 13, 2008 at 4:05 PM, Fabiana moreno <fvmoreno@xxxxxxxxx> wrote:

how can do the ping? I dont know what this is

 

On 13/03/2008, Martin Mathieson <martin.r.mathieson@xxxxxxxxxxxxxx> wrote:

You could of course do a ping.  And see how close to the middle the far side sees something happen...

 

On Thu, Mar 13, 2008 at 2:49 PM, Fabiana moreno <fvmoreno@xxxxxxxxx> wrote:

Well i did this...but i dont know if it's ideal...i think it would work though....

I synchronized the two computers to a server on the internet before every capture so both have the exact same time.

i have my sniffer in the two computers, the one that sends and the ones that receive.

I created a function in matlab that calculates the difference between those two times...

I am being really carefull when i have a packet lost or things like that....

But probably this can work???? ...

 

On 13/03/2008, juan.wortley@xxxxxxx <juan.wortley@xxxxxxx> wrote:

Hi Fabiana,

 

the only way to do that is if you know the time difference between the machines.

It´s not so easy however if you use windows you could try synchronizing both endpoints by using:

w32tm /config /manualpeerlist:[IP to synchronize to] /update /syncfromflags:MANUAL

 

and then monitor the time difference with:

w32tm /stripchart /computer:[IP to synchronize to]

 

,you always can have a delay reference by pinging and dividing by 2 the RTT.

 

HTH

Juan

 

 


From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of ext Fabiana moreno
Sent: Miércoles, 12 de Marzo de 2008 09:38 a.m.
To: Community support list for Wireshark
Subject: Re: [Wireshark-users] end-to-end delay calculation

so ... it is not reliable if i substract the time i hav in the client minus the time i have in the server to get my end the end delay? 

On 12/03/2008, Hansang Bae <hbae@xxxxxxxxxx> wrote:

Fabiana moreno wrote:
> Hello there,
>
> I know wireshark is not able to calculate the end-to-end delay of a
> packet when streaming. I was just wondering if adjusting the clocks of
> my two computers(sender and receiver) to the network time protocol and
> having the sniffer at both ends i could calculate the end-to-end-delay
> tracing each packet. Does this sound logical?
>


It is within the limits of ntp.  Unless there is a WAN involved, the
packets are flying around at an order of magnitude faster than what ntp
can provide (ms resolution)

--

Thanks,
Hansang
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