Re: [6tisch] 6P and Sf0 issue: Examples of error handling

Hello Diego,

*For IANA_6TOP_CMD_ROLLBACK command: *

I think I understand what you are trying to solve. But using
IANA_6TOP_CMD_ROLLBACK
has another issue: how to decide when to send the command. I think this is
the same question for setting the value of 6P_TIMEOUT.
Also if a transaction timeout because of bad link quality or lost
connection, sending another packet is not a good idea.

*For Retry handling:*

First, I think whether retry or not is a decision made by scheduling
function. For 6P, it just forwards this message to upper layer (such as SF0)

If retries are required, I think it makes sense that retrying within a
transaction.

What do you think?

Tengfei

On Thu, Mar 3, 2016 at 9:41 PM, Prof. Diego Dujovne <
diego.dujovne@mail.udp.cl> wrote:

> Dear all,
>            One of the sections I would like to add to
> the SF0 draft is the examples of error handling.
>
> One example could be Timeout handling:
> When a transaction times out, either a packet is lost,
> the destination node lost connectivity or it is too busy
> to answer on time.
> Consequence: The transaction, in any stage, should
> be rolled back by both ends.
> Here, both nodes are expected to Timeout.
> Section 3.6.2 of the sublayer draft "Aborting a
> 6P transaction", cannot be used, since in this case
> there is no response.
> I propose to issue a rollback command such as
> "IANA_6TOP_CMD_ROLLBACK" to the destination
> node using the same token from the original transaction,
> and do not wait for an answer.
> This enables the source node to try a new transaction
> before the destination node times out, thus reducing
> delay.
>
> Would you agree in adding this command to reduce
> delay?
>
> Another issue should be Retry handling, in case of
> timeout.
> Do we allow retries within a transaction?
> If we allow retries, the maximum number of retries before
> considering a transaction failed should be configured on
> the SF.
>
> Thank you.
> Regards,
>
>                                     Diego Dujovne
>
>
> --
> DIEGO DUJOVNE
> Académico Escuela de Ingeniería en Informática y Telecomunicaciones
> Facultad de Ingeniería UDP
> www.ingenieria.udp.cl
> (56 2) 676 8125
>
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