Re: [dccp] Review of DCCP specification

[Magnus Westerlund <magnus.westerlund@ericsson.com>]

Hi,

I have one further comment that I think need discussion, namely 
deployment. I think this is one of major problems with DCCP or rather 
for any new transport protocol. To my understanding DCCP will not work 
in a NATed environment until these NATs has functionality to handle 
DCCP, i.e. do port translation also for DCCP. Some questions that should 
addressed are:

- Will an old NAT block any unknown protocol? If that is the case there 
will be very hard to get DCCP going at all. The upgrade of all these 
home NATs will be a big problem.

- What will be the incentive for a NAT manufacturer to support DCCP. To 
my understanding many of the applications that DCCP intend to be used 
for will be used by home users behind one or more NATs. Due to this fact 
there is any economic counter incentive to deploy DCCP. As any product 
still needs to be able to use UDP as a fallback solution there seem to 
be a catch 22 here for deployment.

- One can actually question if the current DCCP design is at all 
suitable to be deployable. Rosenberg suggested to me to build DCCP on 
top of UDP, instead of a its own protocol identifier, which would be 
much more deployable.

- To my understanding the DCCP authors has thought somewhat over 
deployment. Could they please shed some more light on how they see 
deployment will happen. Or are they simply relying on that Microsoft 
will implement DCCP so it will become available in all newer windows 
versions?

comments please!

Best Regards

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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Ericsson AB                | Phone +46 8 4048287
Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: magnus.westerlund@ericsson.com


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