Subject: Re: [lmap] Comments on draft-schulzrinne-lmap-requirements-00 - conflict resolution

From: Henning Schulzrinne <[email-masked]>
Date: Mon, 5 Nov 2012 01:18:55 +0000

4) The draft also doesn't discuss how conflict resolution among tests requested to be scheduled will be performed. Specifically, is the client allowed to decide, on its own, how to deconflict two tests that may have been scheduled at/near the same time? If so, how? Presumably a single algorithm could be used for conflict resolution at either the measurement controller or the client-end ... or, both ... Likewise, if a measurement controller has asked a client to perform a test, but the client is unable to do so because of a conflict, then it should report that to the measurement controller so the controller can: stop asking the client to do the test, re-schedule it at a different time or take some other action, e.g.: select a wholly different client.

Indeed, that is clearly one of the error cases that need to be handled. A common case is that the in-home client is busy doing "real" work and doesn't want to do a measurement and often cannot do so without either interfering with the non-measurement traffic or being affected by it. Generally, given that the client is the only entity that knows the local traffic, it seems to need to make the decision - after all, practically speaking, it's in control. If it doesn't "want to" do measurements, all the pleading of the controller can be ignored by the client and there's nothing the controller can do about it. I think it would be useful to discuss whether, say, a privileged controller (the ISP?) can tell the client to stop a running measurement, either because it's causing network harm or because the ISP needs to run a diagnostic test.

Thanks,

-shane
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