The MIB module to contains configuration
and connection state information the VISM.
        
For VoIP(Voice over IP) support, VISM needs one
active AAL5 bearer PVC and one active AAL5
control PVC between the VISM card and the PXM.
The redundant PVC feature is supported for AAL5
PVCs. Each redundant PVC pair has one active
PVC and one standby PVC. There can be one AAL5
bearer redundant PVC pair and one AAL5 
control redundant PVC pair. 
        
All PVCs are added on the ATM virtual port=1.
        
For the AAL2 trunking application, there can
be multiple AAL2 bearer PVCs. Also, AAL2 bearer
PVC in this case, is between the two media
gateways, instead of just between the VISM and
the PXM. Up to 64 AAL2 bearer PVCs are supported
for this application.
        
Terminologies Used:
        
    PVC - Permanent Virtual Circuit OR
          Permanent Virtual Connection.
        
    SPVC - Soft Permanent Virtual Circuits.
           This is a PVC controlled by PNNI 
           Controller.
        
    AAL  - ATM Adaption Layer.
        
    PXM  - Processor Switch Module.
        
    VC   - Virtual Channel.
        
    CAC  - Connection Admission Control.
        
    LCN  - Logical Channel Number.
        
    VCI  - Virtual Channel Identifier.