SNMP MIB Objects
E-4 3160-A2-GB21-80March 1999
Interface Group, MIB II
The Interfaces Group consists of an object indicating the number of interfaces
supported 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, the DTE Drop/Insert (DSX-1) interface, each of the synchronous data
ports (1, 2, or 4 depending on the model), the COM port, the AUX port, and the
MODEM port, if they apply. The following sections provide clarification for objects
contained in the Interface Group where it is not clear how the object definition in
MIB II is related to the DSU/CSU.
Interface Group – “ifNumber” Object (interfaces 1)
This variable contains the maximum number of MIB II supported interfaces
possible across the 31xx Series product line (9). This is different from the MIB
description, 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 other
MIBs also. The values of the ifIndex object do not vary between models even
though not all indexes are supported for a particular model. When an
unsupported index 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
6 – DCE port 1
7 – DCE port 2
8 – DCE port 3
9 – DCE port 4