Re: [p2pi] [tana] [tsv-area] TANA proposed charter

Roland Bless <> Wed, 22 October 2008 15:05 UTC

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Date: Wed, 22 Oct 2008 11:18:19 +0200
From: Roland Bless <>
Organization: Institute of Telematics, University of Karlsruhe
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To: Reinaldo Penno <>
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Subject: Re: [p2pi] [tana] [tsv-area] TANA proposed charter
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Hi Reinaldo,

Reinaldo Penno wrote:
> I'm not sure I'm reading the semantics of "Less than Best Effort" like other
> folks. 

Maybe RFC 3662 defines this more clearly.

> 'Best Effort' has a well-defined semantics in the scope of Diffserv,
> including a code point of its own. Less than best effort seems we are
> defining a code point for such applications. Are we? The charter talks about
> 'end-to-end Diffserv'.

See RFC 3662

> End-to-end diffserv is a challenge on its own given ISP policies, etc.
> If the link is not saturated, are such application also treated as 'less
> than best effort' by still being DSCP marked and treated differently within
> routers? 

Usually lower effort (LE) packets will go into a different queue
and served only if no other BE packets are waiting. So if
the BE queue is empty, LE packets will get the same treatment as BE
packets. Only in case of congestion, LE packets will be treated

> I would like if possible to decouple the 'less than best effort', as in
> diffserv, from the algorithm per se.
> Besides, there are ISPs that are worried about the effect that P2P have on
> other applications when the link is saturated, but otherwise they do not
> care. P2P would be treated like best effort in non-saturated situations (a
> more ECN type approach).

Yes, and that's exactly where LE helps: an ISP can be sure that
LE traffic will not harm other BE traffic at any time. In case
of congestion BE traffic will preempt LE traffic. If the
link is not saturated, LE will be treated like BE.


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