[Click] Measuring

[Giorgio Calarco]

just one thing: are you going to measure the
packet's delay/jitter inside your click configuration
or the global delay/jitter from the packet source to the
receiver ?

In the first case, the CycleCount elements can help you
(you can also modify the CycleCountAccum to collect the single delay of each
packet in a table - but that table cannot be too large,
bacause the kernel memory space is limited).

In the second case, you could
- sincronize the packet source and receiver with
some tool, but this could be helpful if you are interested
in an averaged measurement, usually this way doesn't
conduct to extreme precise measurements
- use the source as a receiver at the same time, inserting
a timestamp inside the packets, but...
you can't inject packets too fast, not only because the CPU
would be overloaded but also because your generated/received packets
would interfere with themselfs
(remember that the PCI bus and memory are shared structures).

If you are interested, I described an analysis of these problems
here:

http://www.read.cs.ucla.edu/click/publications

Software techniques for multiservice IP networks.
Giorgio Calarco. Ph.D. thesis, University of Bologna, Italy

at Chapter II.


ciao
giorgio


----- Original Message ----- 
From: "Beyers Cronje" <bcronje at gmail.com>
To: "Egi, Norbert" <n.egi at lancaster.ac.uk>
Cc: <click at pdos.csail.mit.edu>
Sent: Tuesday, March 06, 2007 7:52 AM
Subject: Re: [Click] Measuring


> You could also try:
>
> In click userlevel:
> http://www.read.cs.ucla.edu/click/elements/timestampaccum
>
> Or iperf:
> http://dast.nlanr.net/Projects/Iperf/
>
> Cheers
>
> Beyers
>
> On 3/5/07, Egi, Norbert <n.egi at lancaster.ac.uk> wrote:
>>
>> Hi,
>>
>> Is there any way to measure packet delay and jitter with Click?
>>
>> I'm using Click's FastUDPSource to generate packets on a machine, which
>> packets are forwarded through another machine and are counted on a third
>> with the AverageCounter element. This works quite good for measuring the
>> packet forwarding rate and loss of the system in the middle, but I would
>> also like to measure the delay and jitter of the packets. I guess to do 
>> that
>> the traffic should be generated and counted on the same machine, which 
>> isn't
>> a problem, but what elements could be used to do that? I found the
>> StoreTimestamp element, which stores the packet timestamps in packet 
>> data,
>> but couldn't find any element that is able to get this timestamp out of 
>> the
>> packet after it has been received.
>>
>> Any suggestion how to do it if it's possible at all?
>>
>> Many thanks,
>> Norbert
>>
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>>
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