Subject: [AVT] Duplicate RTP packets

From: "Jorge Canas" <[email-masked]>
Date: Thu, 22 Feb 2007 13:29:47 -0500

Hello,

I have searched RFC 3550, but can't find an answer to the following 
questions:

Are RTP stacks required to drop received RTP packets with the same RTP 
sequence number (duplicate RTP packets)?  If so, how much history (in number 
of packets) does the RTP stack need to maintain in order to detect 
duplicates? Or is it only required to detect duplicates arriving piggy 
backed?

If the RTP stack is not required to drop those packets, I guess the 
application is expected to deal with duplicates?

Regards,

Jorge

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From: Colin Perkins <[email-masked]>
Date: Fri, 23 Feb 2007 10:22:47 +0000

On 22 Feb 2007, at 18:29, Jorge Canas wrote:
> Are RTP stacks required to drop received RTP packets with the same  
> RTP sequence number (duplicate RTP packets)?  If so, how much  
> history (in number of packets) does the RTP stack need to maintain  
> in order to detect duplicates? Or is it only required to detect  
> duplicates arriving piggy backed?
>

The standards don't specify implementation details such as these. My  
RTP library passes duplicates to the application, but there are other  
implementations which suppress duplicates in the RTP layer. The  
boundary between the RTP layer and the application is intentionally  
fussy (see http://portal.acm.org/citation.cfm?doid=99508.99553)

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

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From: Colin Perkins <[email-masked]>
Date: Fri, 23 Feb 2007 22:00:16 +0000

On 23 Feb 2007, at 10:22, Colin Perkins wrote:
>> I have searched RFC 3550, but can't find an answer to the  
>> following questions:
>>
>> If the RTP stack is not required to drop those packets, I guess  
>> the application is expected to deal with duplicates?
>
> The standards don't specify implementation details such as these.  
> My RTP library passes duplicates to the application, but there are  
> other implementations which suppress duplicates in the RTP layer.  
> The boundary between the RTP layer and the application is  
> intentionally fussy (see http://portal.acm.org/citation.cfm? 
> doid=99508.99553)

s/fussy/fuzzy/ of course... *sigh*

Colin

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From: "Tom-PT Taylor" <[email-masked]>
Date: Sat, 24 Feb 2007 11:34:39 -0500

I just figured it was your Scottish accent on paper :-)