Re: [tsvwg] comments draft-tuexen-tsvwg-sctp-prpolicies-01

[Jamal Hadi Salim <[e-mail]>]

Hi Michael,

On Wed, Jul 10, 2013 at 3:42 AM, Michael Tuexen <[e-mail]>wrote:

>
> Assume the sender sends a user message which is approximately of size
> 3*MTU.
> So SCTP will fragment it into 3 DATA chunk and send them. If the user
> has specified that the number of retransmissions is limited to 0 and
> the last fragment gets lost in the network, the sender will increment
> sprstat_abandoned_sent.
>

Ok,  so the last fragment essentially doesnt get acknowledged before we
abandon ship. And the other stat indicates we abandoned while we still had
some
sitting locally. Is the intersection of the two (some are sent but not
acked and
some are still sitting locally) implying both stats will be incremented?

Other than the perceived ambiguity -  why do i care to know about the
two types of abandoned messages in a user app? I  will have to sum
those two, so why not just give me one stat?

BTW: the doc will benefit from such a small description as you gave me
above.

What will happen at the receiver side if you assume that the first two
> fragments have been received. If partial delivery was started, you will
> get a SCTP_PARTIAL_DELIVERY_EVENT event indicating
> SCTP_PARTIAL_DELIVERY_ABORTED.
> Without partial delivery being started, the receiver could also drop the
> first part of the message.
>
>
You answered the essence of my question.
Silly follow up: I am assuming that event will come with an EOR?
To use your example (at receiver):
EPOLLIN, recvmsg chunk1, chunk2, EAGAIN
EPOLLIN, recvmsg SCTP_PARTIAL_DELIVERY_EVENT, EOR

cheers,
jamal