Argus newbie

[Carter Bullard]

Hey George,
These types of questions are great for the list, and really are all about process,
so the conversation can get quite long.  Hopefully, you will keep the questions coming
and we'll capture a lot of the process of doing QoS measurement and analysis.

So, you're talking about doing end-to-end (E2E) QoS measurements for your VoIP
service.  So what are you most interested in?  Operations?  Performance? Security?

If Operations is the case then metrics for reachability and availability are really
important.  This is important especially with SIP based VoIP, since the service
is dependent on reachability/availability of the end system but also the SIP
service, which can be a complex distributed service all in its own right.

The presence support for SIP can have you trying lots of different destination
addresses and paths in order to place a call to a single individual, and so
there can be uncertainty as to why a call failed.  Things like call frequency,
call duration, percentage of successful calls, number of  interrupted calls, and
having cause indications for call failure etc ..... can be important.  Argus data
can help a lot with all of that, but we don't do SIP protocol specific processing,
so some of the cause stuff you'll have to do on your own.

For Performance, we become more interested in loss, jitter and one-way delay
as these have the biggest impact on call quality, and of course DSByte tracking
becomes important, when DiffServ is being used for voice calls. 

Sometimes its good to know just the # of calls with loss, rather than dealing
with the severity of the loss per call, as an example.  It really all depends on
what you want to know.

For Security, we interested in protocol conformance, access control, and for SIP,
we're interested in SIP server/client scanning.  We've just added the first round of
support for ZRTP encrypted voice tracking (not decrypting the call, but know that
encryption is being used), so if you have any ideas on what you
would like to know about these features, then, of course, send some mail.

So you mentioned bandwidth, end-to-end delay, loss and jitter.   So lets email
regarding each of these metrics, and I'll try to walk you through some approaches.
I think it will be easier if we keep the emails shorter, than longer.

Running argus on both asterisk servers will generate all the data you need to
do what you're after.  It's important to know what you want to know about your
service and then generate meaningful metrics that directly answer your questions.

You don't really need to worry about the "-R" option.  Argus now generates response
data regardless of the option, so the option is somewhat obsolete.

Yes, you can capture packets for say experimental runs, and then use argus afterwards
to generate stats.  That is a great way to proceed when you're just starting to build
out an infrastructure and have a lot of issues to deal with.  When you want to have
more of a real-time awareness, then running argus() somewhere along the path
becomes important.

With regard to ragraph().   The argus project is really all about the metrics, and so we
recommend using all and any types of graphing, processing, whatever, to get the answer
you need.  ragraph() is not bad for plotting some simple time series graphs of some metrics
in argus data, but there are lots of other strategies.  I would suggest that ragraph() be
your second or third tool at this point.

Carter


On Jul 15, 2010, at 9:22 AM, Pallis, Georgios wrote:

> Hello! Finished with setting up my Asterisk servers, so now it's time to move to Argus and performance measurements. You can see my topology in the attached image. VoIP calls (SIP & IAX2) are generated from Asterisk1 to Asterisk2 (upon connection a pre-recorded message is played in both directions). So what I want to do is measure bandwidth, end-to-end delay, jitter and packet loss in the packet flow between the two servers . I 've read the man pages of argus, ra and ragraph as well as the wiki and the documentation provided in the tar files, but I 'm still a bit confused. Mainly I 'm confused with ragraph and the way it generates graphics regarding the metrics I 'm interested in (I 've played a bit with a sample capture, but I did not succeed much). Apparently, I have to run argus with -R option, right? Also, is it the same if I capture data with something like wireshark and then process the pcap file with argus? Thank you for you time.
> 
> Kind regards,
> George Pallis
> <topology.jpg>


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