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Old September 30th, 2009   #1
Task Group Member
Join Date: May 2009
Location: Gothenburg
Posts: 40
Default Figure 7-2: Device Discovery Process

Some time ago I noticed that this flowchart may lead to some problems if people use it as an implementation guide...

The flow chart does not handle ghosted UIDs very well.

For instance:
The flowchart says that if you get a single response and then no response on MUTE of that UID, then the current search interval is terminated.
Hence, if you get a ghosted UID due to collisions and the ghosted UID does not exist in the network, then it will not branch any further.
If I remember correctly this is handled in the pseudo code in the appendix (don't have the document right now), but I think it is quite serious if this is not noted in the discovery section flow chart (or at least as a note).

Also, the case with a ghosted UID of a device that is actually on the network is not handled since if implemented as the flowchart describes it it will get stuck in an endless loop. (As the some controllers seems to do.)

I guess the flowchart is intended just to give a basic idea of the binary search tree, but since we have seen controllers having problems with ghosted UIDs, then it might be necesarry to actually give this issue more space and focus.
Michael Karlsson
LumenRadio AB
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