At 5:10 AM -0800 3/1/08, [EMAIL PROTECTED] wrote:
>
> > a. Churn can break the return path. For a example a 95% probability
>> for success in the presence of churn over 10 hops each will result in a
>> total probability of success of 099^10=0.59, that is 59%. The media path
>> cannot work well if the two end points cannot see each other and there
>> is no solution given here for the media path. Perhaps another media
>> relay or using HIP? This is a missing item. In any case the media path
>> MUST NOT follow the symmetric search path since the delay will be
>> unacceptable over so many hops and unknown geographic locations that can
>> be anywhere on the Internet.
>>
>
>Most people believe that media should never be routed across the overlay
>regardless of the routing mode. TURN is assumed for deployments where a
>direct connection can't be established, like regular SIP.
I find statements like "media should never be routed across the overlay"
to be invitations to Murphy to muck things up. It's clear that the base
case should be that media should be routed directly between nodes where
possible. It's also clear that where a deployment provides adequate
infrastructure
(like TURN servers), using those is preferable to routing media over the
overlay.
But never? Sorry, I'm more pessimistic than that. The overlay ends up being
a path of last resort, and I have a strong suspicion that paths of last resort
always
get used sometime. The protocol document should be clear that it is a last
resort
and why, but I believe we need to provide guidance on how to use an
overlay as a media path. If we don't, it will get used in whatever way is
easiest, with whatever consequences that entails. After some of the recent
proposals, I can't even come up with a scenario I'm sure is parody. I
thought about suggesting TCP over DATA URIs, but I'm pretty sure Jonathan
has a draft on that in the works.....
Ted
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