Re: [rtcweb] Plan A, respun

[Harald Alvestrand <[e-mail]>]

On 05/16/2013 08:41 PM, Adam Roach wrote:
> On 5/16/13 13:26, Harald Alvestrand wrote:
>
>> I don't believe your comment (or the RFCs you cite) reflect currently 
>> deployed reality. 
>
> I'm not sure how much design we need to do to accommodate out-of-spec 
> implementations. I would be interested in knowing how pervasive this 
> behavior actually is in deployments, since the proper handling of 
> dynamic PTs has been well documented for nearly a decade.

Since an argument that has been made in favour of Plan A is that it is 
(supposedly) more compatible with deployed code, this interests me greatly.

Has dynamic allocation of sub-96 payload numbers ever been tested at a 
SIPit, for instance?

>
>> If the true limit at which one has to change allocation strategy were 
>> to become 96, not 32, it actually strengthens my "falling off a 
>> cliff" argument
>
> And, to be clear, it's not a cliff. For any given session (without 
> a=ssrc:), you have to allocate ceiling(streams/96) ports. It's not 
> like you go from using one port to using 97 ports when you add the 
> 97th stream. You go from one port to two, which will handle 192 streams.

Going from one port to two ports is a cliff.
We may have differing opinions on how tall it is.

>
> And that's okay. As you approach 100 streams, I seriously doubt that 
> port utilization is going to be the constraining factor in what your 
> network can support.
>
> /a