Q: How to Dynamicaly change channel in Zigbee (Since we have large number of nodes communicating with each other) To avoid collision of data packets transmitted simultaneously, i want to ask if we partition nodes into groups communicating in same channel shall we change  channel dynamically so that whenever any node moves into another group should change its communication channel of that group.    
If dynamically channel change is not possible, suggest some other good alternative.

A: I believe ZigBee 2007 PRO includes provisions for a network dynamically changing channels.  This is something that should happen automatically in the core ZigBee stack provided by your vendor (Ember, Freescale, TI, etc.) and not something you need to worry about in your application-layer networking code.

A: There are two possibilities to force a remote device to change the channel.
In ZDP you could use the Mgmt_NWK_Update_req.
Or just use the Commissioning Cluster, set the desired channel mask and force to restart the device.
