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Re: [SCTP-Discussion] Number of miss indications


Chronological Thread 
  • From: Michael Tuexen <Michael.Tuexen AT micmac.franken.de>
  • To: Randall Stewart <rrs AT cisco.com>
  • Cc: Hendrik Land <mail AT hendrik-land.de>, discussion AT sctp.de, tsvwg AT ietf.org
  • Subject: Re: [SCTP-Discussion] Number of miss indications
  • Date: Wed Aug 30 18:02:02 2006
  • List-id: SCTP Discussions <discussion.sctp.de>

Comment in-line.

Best regards
Michael

On Aug 30, 2006, at 5:37 PM, Randall Stewart wrote:

Michael Tuexen wrote:
Hi Hendrik,
this is a question regarding IETF documents, not regarding the sctplib implementation.
These questions are discussed at the tsvwg mailing list. I'm CCing it therefore.
Comments in-line.
Best regards
Michael
On Aug 30, 2006, at 11:16 AM, Hendrik Land wrote:
Hi,

I have a question regarding the number of miss indications before SCTP enters
Fast Retransmit/Recovery. The information in RFC4460 and
draft-ietf-tsvwg-2960bis-02 seems to be different.

draft-ietf-tsvwg-2960bis-02 states in the second paragraph of 7.2.4

"Whenever an endpoint receives a SACK that indicates that some TSNs
are missing, it SHOULD wait for 2 further miss indications (via
subsequent SACKs for a total of 3 missing reports) on the same TSNs
before taking action with regard to Fast Retransmit."

The same document states in the end of 7.2.4

"The counter increments for each
consecutive SACK reporting the TSN hole. After reaching 4 and
starting the fast retransmit procedure, the counter resets to 0."
This is an error in draft-ietf-tsvwg-2960bis-02 and Randall will fix this,
I guess... Thanks for catching it.

Yep.. good catch.. I missed this one :-0


And RFC 4460 states on p22

"Whenever an endpoint receives a SACK that indicates that some TSNs
are missing, it SHOULD wait for 3 further miss indications (via
subsequent SACKs) on the same TSN(s) before taking action with
regard to Fast Retransmit."


This text is overwritten in section 2.52 of RFC 4460. The new text reads:
Whenever an endpoint receives a SACK that indicates some TSN(s)
missing, it SHOULD wait for 3 further miss indications (via
subsequent SACK's) on the same TSN(s) before taking action with
regard to Fast Retransmit.
What is the latest word on this, 3 or 4 missing reports before a fast
retransmit?

Arghhhh I copied the "old text". The "next text" says:

Whenever an endpoint receives a SACK that indicates that some
TSNs are missing, it SHOULD wait for 2 further miss indications
(via subsequent SACKs for a total of 3 missing reports) on the
same TSNs before taking action with regard to Fast Retransmit.

It was my copy and past error in the mail...
This is a mix up.. we should wait for a total of 3 missing reports.. so
the above text should say "wait for 2 further miss indications" not 3.

I will fix this as well :-)

R

3

Thanks

Hendrik



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Randall Stewart
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