RE: AD review of draft-ietf-rddp-sctp-04

Lars Eggert wrote:

> 
> 
> Section 6.1., paragraph 2:
> 
>  >    The Payload Data Chunks for a given session, when sequenced by
>  their >    DDP-SSN, MUST follow one of the patterns defined in
> this section.
> 
>    The sequence patterns in the remainder of this section don't
>    include any DDP-SSNs? How can compliance thus be established?   
> (See next comment.) 
> 
> 

All SCTP Data Chunks generated by the DDP/SCTP Adaptation have a
DDP-SSN.
Therefore all messages specified in this draft have DDP-SSNs.
 
> Section 6.2., paragraph 3:
> 
>  >       Passive Side sends a DDP Stream Session Accept message.
> 
>    Text above says this section describes a valid message exchange
>    based on DDP-SSNs. I'd thus have expected this section to talk
>    about DDP-SSNs, e.g., saying "active Side sends a DDP
> Stream Session
>    Initiate message with DDP-SSN zero", "passive Side sends a
> DDP Stream
>    Session Accept message with DDP-SSN zero" and so on. Am I
> making sense?
>    (Same for Sections 6.3, 6.4 and 6.5.)
>

The rules for formulating the DDP-SSN are already clear. The
fact that the messsages are sequenced clearly mandates what
the DDP-SSNs would be.

Since implementations are not likely to generate the DDP-SSNs
at the layer discussed in these sequence sections, I do not
see the value of repeating this information here.
 
> 
> Section 6.2., paragraph 4:
> 
>  >       Each side may then send zero or more DDP Segments with
>  increasing >       DDP-SSNs, subject to various layers of flow
> control. 
> 
>    What does "various layers of flow control" mean? What happens
>    when the DDP-SSN wraps? It's no longer increasing then.
>

will be changed to "subject to whatever flow control imposed by
other protocol layers".

As specified earlier, the DDP-SSN has the same semantics that
the SCTP SSN would have had if the stream had been SCTP ordered.
It is hard to imagine a wire protocol where a field labeled as
a "sequence number" did not have wraparound semantics, so I believe
the "Same as the SCTP SSN would have been" is sufficiently clear.