RTP and UDP checksum=0

"Dan Wing" <dwing@cisco.com> Fri, 15 April 2011 15:26 UTC

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From: Dan Wing <dwing@cisco.com>
To: draft-ietf-6man-udpzero@tools.ietf.org, draft-ietf-6man-udpchecksums@tools.ietf.org, ipv6@ietf.org
Subject: RTP and UDP checksum=0
Date: Fri, 15 Apr 2011 08:26:40 -0700
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Observation:  tunneled packets have two elements actively 
deciding checksum=0 is okay.  Those elements are the 
tunnel encap and tunnel decap.

Question: Should non-tunneled UDP flows, *established with 
explicit signaling*, also be allowed to decide that checksum=0 
is okay?  For example, an RTP-over-UDP flow established 
with RTSP or SIP signaling.  Some RTP traffic includes its
own checksum at the application layer (e.g., SRTP authentication)
and gains little or no benefit to a UDP checksum.  Near as I
can discern, SIP-signaled flows meet all of the constraints
discussed in 
http://tools.ietf.org/html/draft-ietf-6man-udpzero-02#section-5.1

-d