pppxStatsSubIndex 1.3.6.1.4.1.800.2.17.3.1.1.5

A unique value which identifies the sub-element of the WSM submodule port that this PPP link is running on. For Serial ports this will always return 0. For ISDN BRI ports, this will return 1 or 2 for B1 or B2 channel respectively.