[SIPForum-discussion] Post Dialing Delay (PDD)

[Hadriel Kaplan]

I'm not sure I understand what you mean?  Which part of the "network" do you mean, and what type of "health"?
PDD isn't really useful for network health checks in my opinion, although some people use it for determining peer provider "quality", just as they use ASR.  It's a very coarse way of determining this, because obviously the PDD or ASR is unique per called destination and even time of day, not per next-domain, so it has to be carefully "averaged" over long periods of time with a large data set to make smart decisions about the relative quality among multiple peers.  Many SIP systems have that ability.
If you mean measuring the PDD for a specific UA endpoint from the provider, there are ways of doing that too - for example using PRACKs for the provisional response.
If you mean accurate measurement of end-end network layer health for media, RTP and RTCP quality measurements are often employed, and obviously SBC's have been measuring that for ages.

But anyway, if you feel something else is needed for SIP layer measurements that isn't specified in draft-ietf-pmol-sip-perf-metrics-00.txt, then I encourage you join the PMOL WG mailing list and email your comments there so that they can be discussed and included in the draft. (to join go to https://www1.ietf.org/mailman/listinfo/pmol)

-hadriel

________________________________
From: Halit Sakca [mailto:sakcahalit at hotmail.com]
Sent: Friday, April 18, 2008 1:36 PM
To: Hadriel Kaplan; mario.baron at ericsson.com; discussion at sipforum.org
Subject: RE: [SIPForum-discussion] Post Dialing Delay (PDD)

you are right for far end perspective we don't need a mirrored port. BUT what about network health check I mean this measurement should be done from whole elements that will use 180 Ringing anyway.

Selamlar,
Halit Sakca

________________________________
From: HKaplan at acmepacket.com
To: sakcahalit at hotmail.com; mario.baron at ericsson.com; discussion at sipforum.org
Date: Fri, 18 Apr 2008 12:35:53 -0400
Subject: RE: [SIPForum-discussion] Post Dialing Delay (PDD)


________________________________
From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Halit Sakca
Sent: Friday, April 18, 2008 11:43 AM

> Can Anyone help me how we can measure and verify that the PDD is under
> a certain value?
>
> Is there any ITU-T value for the PDD to take as a reference?
>
> Our NGN provides the IP connetivity to IP carriers through Acmepacket SBCs.

For doing that mentioned above you will need a mirror port on switch anyway.
If you can not set the time of all components same via NTP and trace separately.

No, you don't need to do that with mirroring - most SBC's measure that time already and report it, as do other SIP device types.  PDD can typically be fully measured at one spot, although it may not represent the user's perceived PDD if it's not measured at the originating provider.
Also, you don't really need NTP, because the number is a differential value measured by the same entity that sends the INVITE request.  Thus the local view of global time does not really matter. (it does matter for reporting/determining when calls are made, but not for their delays or durations)

-hadriel

________________________________
Pahalı telefon faturaları? Windows Live Messenger'dan ücretsiz ve sınırsız bilgisayardan bilgisayara aramalar - buradan ÜCRETSİZ yükleyin! Buraya tıkla!<http://get.live.com/messenger/overview>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sipforum.org/pipermail/discussion/attachments/20080418/e5060b9a/attachment-0002.html>