> Finding a network path efficient relay is very important for reducing

> latency in real-time media flows.

Yes, this is very true and interestingly enough seems to have been
solved by running auxiliary applications, mostly PING apps to measure
the following metrics for neighbors:

1. Latency,
2. Number of IP routing hops,
3. Bandwidth.

The DHT also plays a role. See <draft-baset-sipping-p2pcommon-00>

The impact of neighbor selection was a big topic in the DHT research
community, so I won't flood the list with more references  :-)

Henry

Henry

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Dean Willis
Sent: Friday, March 14, 2008 11:34 AM
To: [EMAIL PROTECTED]
Cc: [email protected]
Subject: Re: [P2PSIP] separate message for service lookup?


On Mar 14, 2008, at 11:28 AM, John Buford wrote:

> Regarding Henning's comment that DHT lookup seems sufficient
> for handling service lookups, there have been a number of
> papers which directly use the DHT for
> - serving DNS records
> - locating relay peers in an overlay, including discovery
>   by network position
> - location telephony feature serving peers in an overlay
> - locating servers for other service discovery mechanisms like SLP
>
> no modification to the DHT or overlay protocol was needed to
> support these cases.  as long as you can describe a service
> with a key that all participating peers understand, the DHT should
> work for service lookup.
>
> there are some cases where the service-related resource's
> availability is dynamic (e.g., relay load for admission control),
> which could be part of the advertisement.  then there is a
> tradeoff between updating the DHT-stored advertisement when
> the load changes or leaving it for service invocation time for
> the invoking peer to find out.

It is, however, more difficult to provide weighting and/or adaptive  
load balancing to services using a DHT lookup than it might be with  
other techniques.

It is also difficult to rank services on their network-path  
optimaility unless such a ranking is implicit in the underlying DHT.  
Finding a network path efficient relay is very important for reducing  
latency in real-time media flows.

--
Dean

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