Subject: Re: [Fecframe] Fecframe Digest, Vol 25, Issue 9

From: Colin Perkins <[email-masked]>
Date: Mon, 10 Mar 2008 19:38:42 +0000

On 26 Feb 2008, at 20:06, Rajiv Asati (rajiva) wrote:
> I would like to request a timeslot (15mins) to present the 'FECframe
> Config signaling' draft.
>
> http://tools.ietf.org/html/draft-asati-fecframe-config-signaling-00

SAP is problematic, because its long inter-packet interval interacts  
poorly with many multicast routing protocols. Have you given any  
consideration to these problems? This was the reason for the  
(stalled) IMG work in MMUSIC.

Cheers,
Colin [by email, since the jabber doesn't seem to be in use]
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Fecframe mailing list
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https://www.ietf.org/mailman/listinfo/fecframe

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From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Mon, 10 Mar 2008 15:56:53 -0400

Hi Colin,

Thanks for the feedback. Could you please provide more context ? 

Cheers,
Rajiv 

> -----Original Message-----
> From: Colin Perkins [mailto:[email-masked]] 
> Sent: Monday, March 10, 2008 3:39 PM
> To: Rajiv Asati (rajiva)
> Cc: Greg Shepherd; [email-masked]
> Subject: Re: [Fecframe] Fecframe Digest, Vol 25, Issue 9
>

---

From: Marshall Eubanks <[email-masked]>
Date: Mon, 10 Mar 2008 16:05:32 -0400

> Thanks for the feedback. Could you please provide more context ?

 From the jabber logs

Colin : SAP is problematic, because its long inter-packet interval  
interacts
poorly with many multicast routing protocols. Have you given any
consideration to these problems? This was the reason for the
(stalled) IMG work in MMUSIC.

Colin : internet-media guides

Colin : Problem is that multicast state times about, because SAP  
sends so infrequently.

[he means "times out"]

Regards
Marshall

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From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Mon, 10 Mar 2008 16:15:50 -0400

Thanks for expanding it, Marshall. 

The cited problem is one of the reasons why section 4.1.1 of the
draft-asati-fecframe-config-signaling-00 includes simpler interval
definition so as to avoid having SAP to calculate the interval in an
adaptive manner.

~~~~~~~~~~~~~
4.1.1. Sender Procedure 

	....

   The sender must periodically send the 'SAP announcement' message. 
   This is required so that the receiver doesn't purge the cached 
   entry(s) from the database and doesn't trigger the deletion of FEC 
   Framework configuration information. While the time interval between 
   repetitions of an announcement can be calculated as per the very 
   sophisticated but complex formula explained in RFC2974, the preferred

   and simpler mean is to let the user specify the time interval from 
   the range of 1-60 mins with suggested default being 10 mins. The 
   implementation of signaling protocol should provide the flexibility 
   to the operator to choose the complex method over the simpler method 
   of determining the SAP announcement time interval. 
 ~~~~~~~~~~~~~~~

Cheers,
Rajiv

> From: Marshall Eubanks [mailto:[email-masked]] 
> Sent: Monday, March 10, 2008 4:06 PM
> To: Rajiv Asati (rajiva)
> Cc: Colin Perkins; [email-masked]

---

From: Colin Perkins <[email-masked]>
Date: Mon, 10 Mar 2008 20:36:09 +0000

Rajiv,

There were issues with the inter-packet interval in SAP being larger  
than one of the time-out values used in the multicast routing  
protocol (either PIM-SM or MSDP, I forget which), resulting in SAP  
being deterministically lost.

Colin

---

From: Colin Perkins <[email-masked]>
Date: Tue, 11 Mar 2008 10:33:38 +0000

Rajiv,

The problem isn't the adaptation, it's the length of the interval.
Colin

-- 
Colin Perkins
http://csperkins.org/

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From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Tue, 11 Mar 2008 11:44:48 -0400

Hi Colin,

Agreed. Perhaps, the default interval (in the draft) should be changed
to 2 mins (or less than 3 mins, which is the default timeout for an
mroute on a router) to better handle it.

Cheers,
Rajiv 

> Sent: Tuesday, March 11, 2008 6:34 AM
> To: Rajiv Asati (rajiva)
> Cc: Marshall Eubanks; [email-masked]

---

From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Tue, 11 Mar 2008 14:32:26 -0400

Hi Colin,

Thanks for the clarification.
I will update the draft with the default inteval=2mins in the next
version.

Cheers,
Rajiv 

> Sent: Monday, March 10, 2008 4:36 PM
> To: Rajiv Asati (rajiva)
> Cc: [email-masked]