Re: [AVTCORE] Comments on draft-ietf-avtcore-rfc5764-mux-fixes-03.txt

Paul Kyzivat <pkyzivat@alum.mit.edu> Tue, 20 October 2015 16:11 UTC

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From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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Date: Tue, 20 Oct 2015 12:09:51 -0400
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Subject: Re: [AVTCORE] Comments on draft-ietf-avtcore-rfc5764-mux-fixes-03.txt
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On 10/20/15 6:49 AM, Magnus Westerlund wrote:

> 3.  Section 1.4:
>
> I still don't see how what is written in this section results in any
> improvement. You authors have assumptions of how this needs to be
> implemented that isn't written down. Looking on this problem of
> demultiplexing I would build a table driven solution based on the
> ranges, where the packet is sent to the relevant protocol based on the
> table-lookup. If that protocol don't use that value, that will be the
> end of the road for that packet as invalid, rather than giving it to any
> other protocol. I get the impression that you want one to send the
> packet for testing by the protocols one after each other according to
> the order the protocols are listed. I still don't see that
> implementations will do that.

This has been my concern as well.

Look at it this way:

A natural implementation of this is via a switch statement. Each 
disjoint range of values is one case. (Detailed syntax varies by 
language.) A simple implementation of this may be implemented as a 
sequence of comparisons - a series of if/then/else such as you describe. 
a more time-optimal implementation uses a table lookup.

You shouldn't be mandating how this be implemented - only what the 
result is.

	Thanks,
	Paul