Re: [TIProtocol-askcisco] ECHO packets [CTMS TIP]

[Oren B. <or...@av...>]

Hi Nathan,
Thanks for the info.
Can you tell what is the reason that sending ECHO packets is not handled by the TIP library (like feedback packets)?

Thanks,
Oren.

From: Nathan Buckles (nbuckles) [mailto:nbu...@ci...]
Sent: Monday, July 30, 2012 12:26 PM
To: Oren Bakshe
Cc: David Benham (dbenham); Eyal Sayar; Balaji Villupuram (bvillupu); Murthy Atmakuri (muatmaku); Vijay Triplicane (vtriplic); ask-tip(mailer list); tip...@li...
Subject: Re: ECHO packets [CTMS TIP]

hi oren,

the TIP library does not send ECHO packets, but it does automatically respond to received ECHO packets.  this is handled automatically as part of the CTip::ReceivePacket(...) api.  anytime an ECHO is received the library will send back an ECHO response.  if you enable RECV and XMIT logging in the library you should see the packets coming in/out.

nathan.

On Jul 29, 2012, at 7:54 AM, Oren Bakshe wrote:


Hi David,
I can do it but I don't think it's a CTMS issue...
CTMS doesn't get any RTCP packets and disconnects the call.
While debugging this problem I saw we are not sending ECHO packets at all (Even when all other RTCP packets are sent and received OK).
My question is how does the TIP Library sends these ECHO packets? Which API handles sending them?

Thanks,
Oren.

From: David Benham (dbenham) [mailto:db...@ci...]
Sent: Friday, July 27, 2012 8:43 AM
To: Oren Bakshe; Eyal Sayar
Cc: Balaji Villupuram (bvillupu); Murthy Atmakuri (muatmaku); Vijay Triplicane (vtriplic); Nathan Buckles (nbuckles); ask-tip(mailer list)
Subject: RE: ECHO packets [CTMS TIP]

Oren
Can you repeat this and get a pcap for us to look at, as well as the CTMS log for the same time period?    Please post those at an ftp server of yours we can get to or post to one of
those (free) file transfer services (eg, dropbox.com<http://dropbox.com>).


> CTMS "An endpoint's VIDEO channel is detected not responding with 5 ECHO request".

From: Oren Bakshe [mailto:or...@av...]
Sent: Thursday, July 26, 2012 4:57 AM
To: David Benham (dbenham)
Cc: Murthy Atmakuri (muatmaku); Vijay Triplicane (vtriplic); Nathan Buckles (nbuckles); ask-tip(mailer list); tip...@li...<mailto:tip...@li...>; Eyal Sayar
Subject: RE: ECHO packets [CTMS TIP]
Importance: High

Hi David,
Can you please explain how does the Tip Library sends these ECHO packets? I saw how the ECHO ACKs are being sent, but could not find how the Library send requests.
Is there an API to send ECHO packets or is it done internally?

Our CTMS version is 1.8.3

Thanks,
Oren.

From: David Benham (dbenham) [mailto:db...@ci...]
Sent: Monday, July 23, 2012 7:50 PM
To: Oren Bakshe; Eyal Sayar
Cc: Murthy Atmakuri (muatmaku); Vijay Triplicane (vtriplic); Nathan Buckles (nbuckles); ask-tip(mailer list)
Subject: RE: ECHO packets [CTMS TIP]

Oren, Eyal

First, you all should send e-mail to, or at least always copy, either as...@ci...<mailto:as...@ci...> or tip...@li...<mailto:tip...@li...>(use the latter e-mail address for questions about the open source TIP library).   Please include one of these mail lists above rather than e-mailing only to individuals at Cisco.

Second, the best practice (per TIP spec) is to transmit an ECHO packet once per second during a call on each UDP channel, and measure average latency over 10 second periods.  Keep track of average latency changes can be useful for encoders and congestion avoidance algorithms.

Finally, historically, CTMS' expect responses to ECHO packets are expecting to respond to ECHO requests initiating by its attached TIP peers.  Remind us what software version of CTMS you used?


From: Oren Bakshe [mailto:or...@av...]
Sent: Monday, July 23, 2012 7:14 AM
To: Steve Fry (sfry)
Cc: Eyal Sayar; David Benham (dbenham)
Subject: ECHO packets

Hi Steve,
while debugging a problem with CTMS I saw in its log the following: "An endpoint's VIDEO channel is detected not responding with 5 ECHO request". (Call disconnects afterwards)
After checking this, I realized we don't send ECHO packets at all. We send ACK on received echo packets but do not initiate an echo request.
I thought the Tip library should be responsible for that, but did not find any relevant method.

Is it mandatory to send these echo packets? How can I trigger them?
Can you explain the CTMS behavior when one participant (Out of 3 for example) disconnects?

Many thanks,
Oren.