Description: This object specifies the identity of the physical port and virtual ports whose state is to be monitored. Each port index is an ifIndex, if there are consecutive 4 or more ifIndex then they will be encoded like below. Encoding and decoding scheme is range based: Each range prefix with 0000 (2 octets) where 0000 is not valid ifIndex. Next 2 octets indicates lower range ifIndex, followed by 2 octets of higher range ifIndex. Individual(non range) ones will be displayed as it is. Ex: port list: 0001..0005 0015 0032..0047 Port list in PDU: 0000 0001 0005 000f 0000 0020 002f. If this object is configured then the Preference Level of this interface will be adjusted dynamically depending on the state of the Track Port. The interface's Preference Level is reduced by value of Preference Level parameter when the Track Port states first changes from UP to DOWN. When the Track Port next comes up the interface's Preference Level is increased by the amount specified by the Preference Level. The router VSRP physical track port membership.