[Standards] RTT: no negotiation of the feature

Kurt Zeilenga Kurt.Zeilenga at Isode.COM
Fri Jun 24 15:18:49 UTC 2011


On Jun 24, 2011, at 8:00 AM, Mark Rejhon wrote:

> On Fri, Jun 24, 2011 at 10:51 AM, Kurt Zeilenga <Kurt.Zeilenga at isode.com> wrote:
> I should note that we'll kill this one way or the other, even if there's no negotiation.  I just rather kill it by disrupting the negotiation.
> 
> I just think it's really bad form to have non-negoiated extensions.
> 
> It's not a 100% non-negotiated extension.

It's used before negotiated.  That's bad form.

> Negotiation is simply optional, and not documented in the specification. Accept is done by continuing RTT by replying to event='start' with an event='start'.

This means that you have to implement the extension to stop it, as opposed to simply not advertising (or disrupting the advertisement) of the extension for it not to be used.

> Reject be done by rejecting an attempted event='start' with an event='stop' from the other end.
> 
> I also must point out that at least one 911 systems integrator is already testing XMPP RTT, as a long-term replacement for deaf TDD/TTY, as a companion to RFC4103 / T.140 which is also considered for this use too as well.  Thus, servers are encouraged to stick to server policy (i.e. bandwidth rate-limiting algorithms) rather than blocking the extension.

Rate-limits kick in too late, the damage would already have been done.  We need to stop the originator from putting the traffic onto the network.

-- Kurt


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