SNMP/MIB v.s. COPS/PIB

Hi, 

    I am trying to understand the differences between using SNMP/MIB
    for general network management and using COPS/PIB for QoS
    provisioning.  After reading through the RFCs and drafts, I am
    just getting more and more confused.  My question is "Isn't QoS
    provisioning is a case of network management?"  Some Cisco router
    does even have a QoS MIB, so why can't one use SNMP to manage a
    network device and therefore provide admission control?

    Thanks and best regards
    
Lihua

-- 
The man who finds his homeland sweet is still a tender beginner;
he to whom every soil is as his native one is already strong;

but he is perfect to whom the entire world is as a foreign land.