[Standards] Fwd: Re: [Simple] MSRP congestion control issue when using relays

[Peter Saint-Andre]

Dave Cridland wrote:
> Hiya folks (and copying Rémi who wrote this).
> 
> This comes from a thread on the SIMPLE WG mailing list, relating to MSRP
> over relays. Rémi's post described the issue very cearly, much clearer
> than I can, hence the reason I've simply attached his post verbatim.

Do you mean this post?

http://www1.ietf.org/mail-archive/web/simple/current/msg07579.html

> I'm wondering if people think that a similar thing might affect XMPP, if
> you change "relay" to "XMPP Server". Is it possible, potentially, for
> Calin and Donald, by exchanging sufficient data sufficiently slowly, to
> choke up an XMPP s2s link? And if so, what do we do about it?

Theoretically this *might* be a problem with in-band bytestreams
(XEP-0047), which in a way is similar to MSRP. But you could send
"large" stanzas using plain old XMPP, too, so I don't think it is
(theoretically) limited to IBB. However, whether this theoretical
problem has any practical significance is another question.

In particular, using Rémi's options, I think that if an XMPP server were
in this situation it:

1. would not put the s2s connection on hold -- that's crazy!

2. would not discard the stanza, especially not for IQ stanzas but
probably not for message stanzas either

3. would not queue the stanza for later delivery since the recipient is
online and has an available resource

4. would return an error to the sender (e.g., <recipient-unavailable/>)

> And perhaps more importantly, has anyone ever seen this in the wild?

I have not seen this in the wild.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/


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