|
|
Master-Slave Combinations/ Network Change Possibilities
eGroups Messages :
The Master-slave topology can cause some problems , here is an example of a
scenario and their answers Note: There can be just one master in a
piconet, further a communication is always initiated by the master.
Scenario:
3 Masters X,Y,Z are within the same room(within 10 meters)...theoretically we
have 3 active piconet and 21 potential active slaves within this room.
Event:
Device S comes in...and wants to become a slave to the masters X,Y,Z,
Solution:
- A
- If the new device S wishes to take a pro-active role in joining the
piconet, it can issue a page/inquiry to master X (actually all master would
receive the page/inquiry, which master responds first is irrelevant, let us
assume master X responds first) , and ask for a communication, the master X will
respond as slave and then S and X can switch their roles as master & slave
so that S has now joined X's piconet. After this is done the above procedure
will be repeated for Y and Z. The AM_ADDR's of all devices will be updated after
each network change.
-
- B
- If the new slave wishes to take a re-active role, if can go into the
inquiry scan state or page scan state. The page scan state would only be entered
if device S believed that one of the master had encountered S before and was now
seeking to page S again.The length of the scan state (Inquiry/Page) would
depend on the priority of the desired connection. I.e if device S required to be
contacted as soon as possible, it could stay in inquiry scan mode for as long as
it deemed necessary . Eventually one of the master would contact device S , and
it would join the piconet. After a while device S, should become a slave to all
3 masters.
Conclusion:
Which approach to take obviously depends on the urgency of the device, and
the situation of the networks. If speed and control is needed, solution A would
be preferable. If simplicity and a non-critical application are the features of
the device S, solution B might be better.
|
