VPI(s) to be used for the VC switching (VCC). It should always contain VPI 0 for VC switching. All VC switching VPI have similar valid VCI range which is determined by 'vpi-vci-range' attribute. Rest of the VPIs will be used for the VP switching. The user needs to understand that adding a VPI in a list of VC switching VPI will allocate more VCCs for this port. The user needs to make sure that VCCs for the other ports have been reduced to accommodate increase in VCC for this port because system can support only 32k VCCs on all trunk ports combined. If vci-range is 4k and VPI 0 is the only VPI doing VC switching for this port than this port occupies 4k VCCs. If user adds VPI 1 to the list of VPIs to do VCC then total 8k VCCs are occupied for this port. System will reject the configuration if user tries to use more than 32k VCCs for all trunk ports combined. ANY CHANGES IN A LIST OF VPIs WILL BE EFFECTIVE IMMEDIATLY. IN ORDER TO DO THAT ALL CONNECTIONS WITHIN THIS SYSTEM WILL BE DROPPED AND REESTABLISHED.