F. SNMP MIB ObjectsF-4 March 2001 3160-A2-GB24-10Interface Group, MIB IIThe Interfaces Group consists of an object indicating the number of interfacessupported by the unit and an interface table containing an entry for each interface.The DSU/CSU provides an entry in the interface table for the network interface, theDTE Drop/Insert (DSX-1) interface, each of the synchronous data ports (1, 2, or 4depending on the model), the COM port, the AUX port, and the MODEM port, ifthey apply. The following sections provide clarification for objects contained in theInterface Group where it is not clear how the object definition in MIB II is related tothe DSU/CSU.Interface Group – “ifNumber” Object (interfaces 1)This variable contains the maximum number of MIB II supported interfacespossible across the 31xx Series product line (9). This is different from the MIBdescription, which is defined as the number of interfaces on the particular device.This change allows the use of the same ifIndexes across all 31xx Series models.Interface Group – “ifIndex” Object (ifEntry 1)This object provides the index into the ifTable and typically into tables in otherMIBs also. The values of the ifIndex object do not vary between models eventhough not all indexes are supported for a particular model. When an unsupportedindex is accessed, “noSuchName” is returned.The following are the values of the ifIndexes for all DSU/CSU models: 1 – Net T1 2 – DTE T1 3 – COM port 4 – Modem port 5 – Auxiliary RS-232 port (Model 3164 only) 6 – DCE port 1 7 – DCE port 2 8 – DCE port 3 9 – DCE port 4
