Hi,

On Mon, Mar 3, 2008 at 7:55 PM, Bruce Lowekamp <[EMAIL PROTECTED]> wrote:
>  On Mar 3, 2008, at 1:23 PM, Henry Sinnreich wrote:
>
>  > Ted,
>  >
>  >> The overlay ends up being a path of last resort
>  >
>  > Having the media go over 5-10 hops, some of which may pass via several
>  > continents due to the hashing in the DHT makes such real time media
>  > worthless due to the delay and cut-offs.
>  >
>  > Bruce: Can you comment on this? Reload-03 has no clear text on
>  > symmetric
>  > routing for media.
>  >
>
>  I think that's because we assume a TURN server will be used, if
>  necessary.  I'm somewhat in Ted's camp of "it will be used as a last
>  resort, regardless of what the draft says" although I think some of
>  my fellow authors would like to require that implementors explicitly
>  prevent it from happening.

I don't want to take part in the discussion about media routing across
the overlay, I think this is out of scope for now. As far as I see, we
are defining a signaling protocol (control plane), but we are keeping
in mind that it will have implications for other planes (media,
management), this is why we assume a TURN server will be used.

Anyway, I fully agree with Ted: "Not all media, and not even all
SIP-arranged media, are necessarily real time". For example:
- overlay may need to store (and replicate) user's profile, user's
(public) keys, and so on
- IMHO, offline message delivery is a desired feature. We may need to
replicate such information within the overlay

By the way, when talking about real-time media, are you considering
p2p media? (e.g. chunk-based multisource media delivery)

>  I think Henry's point that geography comes into play is very
>  important here.  Henning has proposed that AS number be included in
>  selection of a TURN server.

I'd use other term rather than geography. Some kind of performance
diagnose may be used to to decide which server/relay to use in which
context.

Thank you,
-- 
Victor Pascual Ávila
Research Engineer
Tel.  +34 93 542 2906
Fax. +34 93 542 2517

Research Group on Network Technologies and Strategies (NeTS)
Universitat Pompeu Fabra (UPF)
Pg. de Circumval·lació, 8
Office 358
08003 Barcelona (Spain)
http://nets.upf.edu/
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