Subject: [Fwd: RTP measuring]

From: Rafiq Shaikh <[email-masked]>
Date: Thu, 25 Nov 1999 10:15:48 +0530

Hi,
I think these questions can be better answered on this list.

Regards,
-Rafiq.

Subject: RTP measuring
From: "Bogdan Ghita" <[email-masked]>
To: <[email-masked]>
Date: Wed, 24 Nov 1999 17:30:09 -0000

Hello all,

I have three questions related to RTP/RTCP.
1. Are there any  tools for monitoring RTP/RTCP (free or commercial)? I am interested especially in RTP analysis, and not RTCP parsing. And, if there are, which are their capabilities?
In order to restrict the range of replies, I must mention that I've already found:
- Hammer VoIP Test System - analysing all the parameters (drop packets, jitter, delay) within a VoIP call
- HP Internet Advisor - similar
(for these two commercial packages, I couldn't get more information about what actually is monitored)
- rtpmon, which is free, but, in spite of its name, it is an RTCP monitor.

2. Can anybody explain me what is the structure of a compound RTCP packet? I know, from the RTP specification, that it looks like this:

if encrypted: random 32-bit integer
|
|[------- packet -------][----------- packet -----------][-packet-]
|
| receiver reports chunk chunk
V item item item item
--------------------------------------------------------------------
|R[SR|# sender #site#site][SDES|# CNAME PHONE |#CNAME LOC][BYE##why]
|R[  |# report #  1 #  2 ][    |#             |#         ][   ##   ]
|R[  |#        #    #    ][    |#             |#         ][   ##   ]
|R[  |#        #    #    ][    |#             |#         ][   ##   ]
--------------------------------------------------------------------
|<------------------ UDP packet (compound packet) --------------->|
#: SSRC/CSRC

The question is, as I couldn't understand the figure: how is the above figure packetised in UDP packets (is it 'line-by-line') ? 

3. Are there any standards for encrypting RTP/RTCP (in relation with H.323) ? Besides inserting the 32-bit integer in the RTCP packet and using DES there is nothing else specified.

Thank you very much
Best regards
Bogdan Ghita