Re: [core] Request for clarification of NSTART and concurrent requests

[Carsten Bormann <[e-mail]>]

On 15. Aug 2022, at 21:03, Bryan Green <[e-mail]> wrote:
> 
> I'm looking for some clarification of NSTART, specifically this wording under "Congestion Control":
> 
>    An outstanding interaction is either a CON for which an ACK has not
>    yet been received but is still expected (message layer) or a request
>    for which neither a response nor an Acknowledgment message has yet
>    been received but is still expected (which may both occur at the same
>    time, counting as one outstanding interaction).
>  
> Does this wording imply that concurrent CON requests (ACK'ed, but for which a CON response is still expected) are acceptable if NSTART=1?  

Yes.

> If an empty ACK has been received for a CON request, may a new CON request be sent before a CON response has been received for the first request, without violating the NSTART=1 constraint?

Yes.

The idea is that the fact that the CON did receive an ACK (and the latency taken for that) indicates that the path is not heavily suggested, or that the necessary slow-down has been achieved (by the original RTT, and by wait times before retransmission).

The server will independently congestion-control their separate responses.

Grüße, Carsten