Users Guide
Figure 134. Example of Assigning Interface Index Numbers
Starting from the least signicant bit (LSB) in the preceding gure:
• The rst 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 gure.
Figure 135. Interface Index Number Assigned to FortyGigE 0/4 Port
In this example, if you start from the least signicant bit on the right:
• The rst 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) identies 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.
Simple Network Management Protocol (SNMP) 999