[Planetlab-users] Bandwidth

[Robert P Ricci]

Thus spake Alex Sherman on Thu, Sep 28, 2006 at 11:55:48AM -0400:
> does BWLIMIT specify the cap for the physical machine or for each
> individual sliver on that machine ?

It's a cap for the whole machine. For individual slivers, there is a
'maximum average daily rate' - if your sliver sends too much data for
too long, it will get capped to a very low rate. If this happens, you
should get mail, and in practice, I find I don't run into it often. (The
maximum rate is higher for Internet2 paths.)

> If BWLIMIT is for the whole machine is that shared evenly by all
> slivers on that machine ?

Yes, PlanetLab uses a 'hierarchical token bucket' mechanism to share
bandwidth fairly between slivers. This page:
http://www.planet-lab.org/doc/BandwidthLimits.php
... describes how this mechanism works, as well as other details of
bandwidth limits on PlanetLab.

> Is there some way that I can get the value of the cap for my sliver or
> there is no such thing ?

I have seen mention of such a thing, but never any details. I believe
that it only exists if you set it yourself (which I don't know how to
do), or if you get capped for using too much bandwidth (see above).

-- 
/-----------------------------------------------------------
| Robert P Ricci <ricci at cs.utah.edu> | <ricci at flux.utah.edu>
| Research Associate, University of Utah Flux Group
| www.flux.utah.edu | www.emulab.net
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