Re: [rtcweb] Question about support for RFC 6520 DTLS heartbeat

On 15 Jan 2015, at 00:19, Harald Alvestrand <harald@alvestrand.no> wrote:
> 
> Den 14. jan. 2015 23:40, skrev Michael Tuexen:
>> On 14 Jan 2015, at 23:12, Harald Alvestrand <harald@alvestrand.no> wrote:
>>> 
>>> Den 14. jan. 2015 21:06, skrev Michael Tuexen:
>>>> On 14 Jan 2015, at 18:17, Martin Thomson <martin.thomson@gmail.com> wrote:
>>>>> 
>>>>> On 14 January 2015 at 00:49, Michael Tuexen
>>>>> <Michael.Tuexen@lurchi.franken.de> wrote:
>>>>>> * DTLS does the PMTUD using DTLS heartbeats
>>>>>> * SCTP does the PMTUD using SCTP HEARTBEAT and PADDING chunks
>>>>>> 
>>>>>> My understanding is the RTCWeb uses the second option as described in
>>>>>> http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-13#section-5
>>>>> 
>>>>> SGTM.  That means we don't need to reference the DTLS heartbleed extension.
>>>> It is not referenced in the RTCWeb documents, only in
>>>> https://tools.ietf.org/html/draft-ietf-tsvwg-sctp-dtls-encaps-07
>>>> which allows both options.
>>> 
>>> So which document should we put it in that we use the second option?
>>> -transport, or a post-last-call update of -datachannel?
>> Do we really need a change? We have in 
>> https://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-13#section-5
>>   Incoming ICMP or ICMPv6 messages can't be processed by the SCTP
>>   layer, since there is no way to identify the corresponding
>>   association.  Therefore SCTP MUST support performing Path MTU
>>   discovery without relying on ICMP or ICMPv6 as specified in [RFC4821]
>>   using probing messages specified in [RFC4820].  The initial Path MTU
>>   at the IP layer SHOULD NOT exceed 1200 bytes for IPv4 and 1280 for
>>   IPv6.
> 
> Good! I misunderstood what "it is not referenced" referred to above.
> 
>> 
>> In the next revision of
>> https://tools.ietf.org/html/draft-ietf-tsvwg-sctp-dtls-encaps-07#section-4
>> there will be the sentence:
>>   The path MTU discovery is performed by SCTP when SCTP over DTLS is
>>   used for data channels (see Section 4 of
>>   [I-D.ietf-rtcweb-data-channel]).
> 
> I think the section number is wrong - section 4 of data-channel is
> requirements. (unless revised).
That is correct. I guess Gorry (who suggested the text) had Req. 9 in mind.
But we can change the reference to Section 5 if you prefer.

Best regards
Michael
> 
> 
> 
>> 
>> Best regards
>> Michael
>>> 
>>>> 
>>>> Best regards
>>>> Michael
>>>>> 
>>>> 
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>>> 
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>>> 
>> 
> 
>