Administrator Guide

SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.3.1000.0.1.232.6.149.172.1 = INTEGER: 1
SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.4.1000.0.1.232.6.149.172.1 = INTEGER: 1
Deriving Interface Indices
The Dell Networking OS assigns an interface index to each (configured and unconfigured) physical or logical interface, and
displays it in the output of the show interface command.
The interface index is a binary number with bits that indicate the slot number, port number, interface type, and card type of the
interface. The system converts this binary index number to decimal, and displays it in the show command output.
Figure 136. Example of Assigning Interface Index Numbers
Starting from the least significant bit (LSB) in the preceding figure:
● The first 14 bits represent the card type of a physical interface or the interface number of a logical interface.
● The next 4 bits represent the interface type.
● The next 12 bits represent the slot and port numbers.
● The next bit is 0 for a physical interface and 1 for a logical interface.
● The last next is unused.
The Slot-Port Number value is derived from the slotId and portId parameters as follows: slotPortNum = ((slotId +1) *
IFM_IFINDEX_MAX_PORTS_PER_SLOT + portId).
The IFM_IFINDEX_MAX_PORTS_PER_SLOT value is 192 (10G). For backward compatibility, the
IFM_IFINDEX_MAX_PORTS_PER_SLOT value is 128 on other Dell Networking switches.
The slotId value is derived as follows: slotId = (slotPortNum / IFM_IFINDEX_MAX_PORTS_PER_SLOT) -1.
The portId value is derived as follows: portId = slotPortNum % IFM_IFINDEX_MAX_PORTS_PER_SLOT.
For example, the interface index 51528196 for the FortyGigE 0/4 port is 0000 0011 0001 0010 0100 0010 0000 0100 in binary
format as shown in the following figure.
Figure 137. Interface Index Number Assigned to FortyGigE 0/4 Port
In this example, if you start from the least significant bit on the right:
● The first 14 bits (00001000000010) identify a line card.
● The next 4 bits (1001) identify a 40-Gigabit Ethernet interface.
● The next 12 bits (000011000100) identify slot 0 and port 4.
● The next bit (0) identifies a physical interface.
● The last bit is always 0, which means that it is unused.
NOTE: The interface index does not change if the interface reloads or fails over.
942 Simple Network Management Protocol (SNMP)