Re: [tsvwg] SCTP question

[Michael Tuexen <[e-mail]>]

> On 22. Oct 2018, at 12:01, [e-mail] wrote:
> 
> Do other people agree?- especially Randall, as editor of RFC4960, and other people who've been involved a lot with SCTP?
I agree with the other people... I interpret it as a SHALL.

When doing conformance testing (which I do once in a while), I expect the INITs and COOKIE-ECHOs to be retransmitted
based on the timer rules (Start with RTO.Initial, double until reaching RTO.Max). If the peer is multihomed and this
is configured, one has to consider if the multiple address are used for retransmitting the INITs and COOKIE-ECHOs.

I know that the use of shall sometimes causes confusion and we will likely resolve this when working on RFC 4960bis.

You can forward my address to your colleague in case he has further questions. I wrote two implementations of the
ETSI conformance test suite for SCTP:
* https://github.com/nplab/ETSI-SCTP-Conformance-Testsuite
  This is based on an extended version of packetdrill and can be used to test socket based
  implementations like the FreeBSD or Linux kernel implementation. Working on Solaris support.
* https://github.com/nplab/sctp-tests
  This can be used for blackbox testing and is based on the SCTP Test Tool stt.

Best regards
Michael
> Thanks
> phil
> 
> 
> -----Original Message-----
> From: Proshin, Maksim [mailto:[e-mail]] 
> Sent: 17 October 2018 09:32
> To: Neil Horman <[e-mail]>; Eardley,PL,Philip,TUD1 R <[e-mail]>
> Cc: Wilks,PB,Perry,TLB35 R <[e-mail]>; [e-mail]
> Subject: RE: [tsvwg] SCTP question
> 
> Hi Neil,
> 
> In general it's not correct to say that "shall" is the same as SHALL. Thus RFC 8174 explains that "only UPPERCASE usage of the key words have the defined special meanings".
> Saying this anyway I think that RFC 4960 actually means SHALL/MUST in that note.  
> 
> BR, Maxim
> 
> 
> -----Original Message-----
> From: tsvwg [mailto:[e-mail]] On Behalf Of Neil Horman
> Sent: Tuesday, October 16, 2018 20:36
> To: [e-mail]
> Cc: [e-mail]; [e-mail]
> Subject: Re: [tsvwg] SCTP question
> 
> On Tue, Oct 16, 2018 at 02:42:05PM +0000, [e-mail] wrote:
>> A colleague of mine, Perry, has a couple of questions about SCTP RFC4960. He's in the BT design team on Signalling protocols and concerned about conformance testing amongst other issues.
>> 
>> The statement is on page 57 of RFC4960  (section on Association initialisation) "Note: T1-init timer and T1-cookie timer shall follow the same rules given in Section 6.3."
>> The question is: how should the "shall" be interpreted in this sentence? Does it mean that the S6.3 rules MUST be followed? Or does it mean that the S6.3 rules are optional - in which case, are there any thoughts about rules other than those in S6.3?
>> 
> The conventions section indicates that they keyword SHALL is goverened by RFC2119, which asserts SHALL is synonomous with the keywork MUST.  That is to say that the phrase above on page 57 of RFC4960 is an absolute requirement.  You have to have the T1-init and T1-cookie timer follow the same rules given in Section 6.3
> 
> Neil
> 
>> Thanks,
>> Best wishes,
>> Philip Eardley
>> Research and Innovation
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