CTSmartTrunkIndex
Most of the tables in this MIB are indexed in whole or in part by 'ctTrunkIndex' - not by 'ifIndex'. Why is there a separate index? Traditionally, ifIndex values are chosen by agents, and are permitted to change across restarts. Using ifIndex to index ctTrunkConfigTable could complicate row creation and/or cause interoperability problems (if each agent had special restrictions on ifIndex). Having a separate index avoids these problems.