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Re: RTCDataChannel characteristics and failures -API description -

From: Gunnar Hellstrom <gunnar.hellstrom@omnitor.se>
Date: Tue, 26 Aug 2014 23:38:04 +0200
Message-ID: <53FCFE3C.2070301@omnitor.se>
To: public-webrtc@w3.org
On 2014-08-26 22:46, Michael Tuexen wrote:
>> [GH] I cannot find your indicated "no limit". Please clarify where you found it.
>> >Instead, earlier mail discussions have indicated that the reliable channel SHOULD use the default parameters for SCTP streams specified in SCTP RFC 4960, which says:
>> >-----------------------------------------------copy from RFC 4960--------------------------------------------------------------------------------------"
>> >15.  Suggested SCTP Protocol Parameter Values
>> >
>> >    The following protocol parameters are RECOMMENDED:
>> >
>> >       RTO.Initial - 3 seconds
>> >       RTO.Min - 1 second
>> >       RTO.Max - 60 seconds
>> >       Max.Burst - 4
>> >       RTO.Alpha - 1/8
>> >       RTO.Beta - 1/4
>> >       Valid.Cookie.Life - 60 seconds
>> >       Association.Max.Retrans - 10 attempts
>> >       Path.Max.Retrans - 5 attempts (per destination address)
>> >       Max.Init.Retransmits - 8 attempts
>> >       HB.interval - 30 seconds
>> >       HB.Max.Burst - 1
>> >-----------end of copy from RFC 4690------------------------------------------------------"
>> >
>> >The Path.Max.Retrans=5 is supposed to be the default limit for the number of retransmissions on WebRTC reliable data channels, and these retransmissions will normally be spread over 15 seconds before the Association is aborted with error.
> Please note that
> http://tools.ietf.org/html/draft-ietf-tsvwg-sctp-dtls-encaps-05
> states in Section 6.1:
>     o  All SCTP associations are single-homed, because DTLS does not
>        expose any address management to its upper layer.  Therefore it is
>        RECOMMENDED to set the SCTP parameter path.max.retrans to
>        association.max.retrans.
> This means that you will have 10 retransmissions, not 5.
Thanks for the clarification.
These 10 retries will then be spread over about 500 seconds, but in a 
really bad network the watchdog will usually abort the Association well 
before that, right?

I think this characteristic needs to be explained somewhere.

Regards

Gunnar
Received on Tuesday, 26 August 2014 21:38:37 UTC

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