For information, CUPS and CUPC are assigned to different vlan: CUPS is in Management vlan and CUPC is in data vlan and IP Phone is in voice vlan.
However it seem that there are very much delay between CUPS and CUPC like change status or even IM between CUPC.
But when I try change CUPC to be on the same vlan as CUPS (Management vlan), it work fine, no more delay.
I'm now using SW3750 to manage the vlan.
What could really be the cause?