CISCO AP 1830 Mobility Express CAPWAP master subordinate design

[PsyphonCat]

Hi,

We recently purchase 3 units of 1830 with mobility express.

We do not have wireless controller in our network.
I have tried looking at the CME User Guide for Release 8.1 before creating this post.

I like to enquire,

1) Can I set up all 3 APs as master ap with mobility express failsafe election function.

Or do I need to set up 1 AP and the other 2 as CAPWAP subordinate AP
Note: we have plans to increase this number to say 10 AP.

2) If we have to configure CAPWAP subordinate AP, which should be the right image/software combination?
Is it option A or option B?
Option A: 

AP Image Type: MOBILITY Express Image Software

AP Configuration: CAPWAP Lightweight AP

Option B:
AP Image Type: CAPWAP lightweight AP software 

[Ric Beeching]

1) You can setup all APs as Mobility Express and they will go through a master election process to determine who is the master at the time. If you change the subordinates to CAPWAP they can never take over as the master so leave all as ME.

2) Option A as the APs will still join the master and be 'normal' APs but in the event of an outage to the master, the elected secondary will take over.

Ric