Re: [STDS-802-16] CS Parameter Encodings for the DSC Request

[Joël Demarty <joel@SEQUANS.COM>]

Title:

Hi Dinesh,

The spec states that the DSC-REQ message shall contain the Service Flow Parameters and points to the Service Flow Encodings section (§11.13).
As the CS Specific Service Flow Encoding is a sub-TLV ([145/146].cst) of the Service Flow Encodings ([145/146]), you're allowed to include CS Specific Encodings in the DSC-REQ. IMO, this should solve your issue.

Anyway, this is an ambiguity in the spec as all other DSx messages state explicitely when the CS Specific Service Flow Encoding is required or allowed and it may worth unifying all DSx messages in the corrigenda.

This ambiguity takes its roots from DOCSIS where Classifiers & PHS were encoded as separate TLVs from Service Flow Parameter TLV and this explains why the CS Encoding is almost allways mentioned in the DSX MAC message (§6.3.2.3) although it is implicetly refered to by the Service Flow Encoding.

This change from DOCSIS raises another ambiguity:
As the CS Specific Encoding is now a sub-TLV of the Service Flow Encoding and the DSx message can contain multiple Service Flow Encodings  TLVs (admitted, active, provisioned), how shall a station handle the case where multiple CS are encoded under multiple Service Flow Encodings in the same MAC management message. My understanding is that there is no such thing as an admitted or provisionned CS but the spec should be clear about that and require that CS is encoded in one and only one Service Flow Parameter TLV.

I although searched the spec and did not find the exact definition of the "QoS Parameter Set". Unfortunately the term "QoS Parameter Set" is often used in lieu of the term "Service Flow Parameters" (and vice versa...) , which adds to the confusion.

-- Joël


Dinesh Nambisan wrote:

I've run into an issue with the 802.16R5/D4 standard; either it is a obvious
missing element in the standard or I've missed some place where they have
specified it.

Now, the DSC-Request is intended for changing the Service Flow parameters,
my question is around whether those can include the classification rules
associated with it.
The CS Specific Service Flow Encodings Section (11.13.19) has a TLV
specification "Classifier DSC Action" (11.13.19.3.2) which seems to indicate
that you can add/delete/change the classifier rules associated with a DSC.
However, the DSC-Request itself (6.3.2.3.13) does not seem to have an option
for the CS Parameter Encodings, the only TLVs specified within are the
Service Flow Attributes and the HMAC Tuple (11.13 & 11.12).  This does not
make sense to me. Also, the DSC-RESP message has the CS encodings.

My guess is that the CS Parameter Encodings was inadvertently omitted, can
someone confirm/clarify? Thanks in advance,

Dinesh Nambisan,
Proxim.