Subject: [6tisch] [6TiSCH] return code in 6p response defined in sixtop draft

From: Tengfei Chang <[email-masked]>
Date: Fri, 23 Sep 2016 12:22:49 +0200

Dear all,

I have some question about the return code (mainly about the ERROR code) in
6p response packet define in the draft:
https://tools.ietf.org/html/draft-ietf-6tisch-6top-protocol-02

In figure 7:
https://tools.ietf.org/html/draft-ietf-6tisch-6top-protocol-02#section-4.2.4

 Return Code              Value          Description
   +--------------+------------------------+---------------------------+
   | RC_SUCCESS   | IANA_6TOP_RC_SUCCESS   | operation succeeded       |
   +--------------+------------------------+---------------------------+
   | RC_ERR_VER   | IANA_6TOP_RC_ERR_VER   | unsupported 6P version    |
   +--------------+------------------------+---------------------------+
   | RC_ERR_SFID  | IANA_6TOP_RC_ERR_SFID  | unsupported SFID          |
   +--------------+------------------------+---------------------------+
   | RC_ERR_GEN   | IANA_6TOP_RC_ERR_GEN   | schedule generation error |
   +--------------+------------------------+---------------------------+
   | RC_ERR_BUSY  | IANA_6TOP_RC_ERR_BUSY  | handling previous request |
   +--------------+------------------------+---------------------------+
   | RC_ERR_NORES | IANA_6TOP_RC_ERR_NORES | not enough resources      |
   +--------------+------------------------+---------------------------+
   | RC_ERR_RESET | IANA_6TOP_RC_ERR_RESET | abort 6P Transaction      |
   +--------------+------------------------+---------------------------+
   | RC_ERR       | IANA_6TOP_RC_ERR       | generic error             |
   +--------------+------------------------+---------------------------+
   | reserved     | TODO-0xf               |                           |
   +--------------+------------------------+---------------------------+

As it defined a lots of error return code and also it has generic error:
RC_ERR.

   - When should the nodes use the generic RC_ERROR? I assume it indicates
   the request cells are not available (the cell is occupied already when
   adding OR can't find the cell when deleting)?
   - Also, if the 6p response has multiple cases matched (for example, the
   candidate cells are occupied RC_ERROR and also no enough resource
   ERROR_NORES...), which one should the mote choose? (add priority for the
   error code? at least we need a decision)

Looking forward to talk to you during the meeting soon!

Tengfei

-- 
Chang Tengfei,
Pre-Postdoctoral Research Engineer, Inria

---

From: Xavier Vilajosana <[email-masked]>
Date: Sat, 1 Oct 2016 06:28:56 +0200

Hi Tengfei,

see inline

2016-09-23 12:22 GMT+02:00 Tengfei Chang <[email-masked]>:

> Dear all,
>
>
> I have some question about the return code (mainly about the ERROR code)
> in 6p response packet define in the draft:
> In figure 7: https://tools.ietf.org/html/draft-ietf-6tisch-6top-
> protocol-02#section-4.2.4
>

>
>
>    - When should the nodes use the generic RC_ERROR? I assume it
>    indicates the request cells are not available (the cell is occupied already
>    when adding OR can't find the cell when deleting)?
>
> If a node receives a 6P Request from a given neighbor before
   having sent the 6P Response to the previous 6P Request from that
   neighbor, it MUST send back a 6P Response with a return code of

   RC_ERR.

this is, a Node A has still not received from Node B the response of a
command while A issues again a command to B. In this case B responds with
RC_ERR.

>
>    - Also, if the 6p response has multiple cases matched (for example,
>    the candidate cells are occupied RC_ERROR and also no enough resource
that is a good point. The two options I see are, either returning the list
of error codes or defining priorities and returning the most important. We
should consider that in the next version of the draft.

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