Re: [tsvwg] WGLC Announcement for draft-ietf-tsvwg-sctp-sack-immediately-02: 19th March 2013

[Michael Tuexen <[e-mail]>]

On Apr 2, 2013, at 8:09 PM, Yoshifumi Nishida wrote:

> Hi Michael,
> 
> On Tue, Apr 2, 2013 at 12:27 AM, Michael Tuexen
> <[e-mail]> wrote:
>> On Apr 2, 2013, at 8:29 AM, Yoshifumi Nishida wrote:
> 
>>> 2: Because this rule will be checked on every packet transmission, I
>>> would like to know if the draft suggests to set I-bit everytime we
>>> have a chance or there might be a case where we shouldn't.
>> The sender could do it to switch off delayed SACK. However, this
>> might not be useful. Therefore, as stated, the sender should set it,
>> when he is waiting for an SACK.
> 
> OK. I just wanted to mention that in ideal equilibrium state, we might
> need to set I-bit every packet since you'll get an ACK for 1 MSS,
> which opens 1 MSS in cwnd.
> But, as far as I can think this won't be a problem as the receiver has
> a freedom to ignore it if it's necessary. (e.g. too much overhead)
That is a possibility. On the other hand, the receiver could set the
SACK frequency to 1 or the delay to 0 to get the same.
> 
> BTW, we might want to set I-bit when we find there's no more packet to
> send in buffer after sending a packet, even though
> SCTP_SACK_IMMEDIATELY is not used.
Why? It would definitely be possible...
> Do you have any comment on this?
Without the reason, I have only a general comment: The list provided
to indicate conditions to set the I-bit is not exhaustive. I expect
optimizations coming over time...

Best regards
Michael
> 
> Thanks,
> --
> Yoshifumi
>