Reference Guide

Simple Network Management Protocol | 1003
• the next 5 bits represent the slot number
• the next 1 bit is 0 for a physical interface and 1 for a logical interface
• the next 1 bit is unused
For example, the index 72925242 is 100010110001100000000111010 in binary. The binary interface index
for GigabitEthernet 1/21 of a 48-port 10/100/1000Base-T line card with RJ-45 interface is shown in
Figure 48-27. Notice that the physical/logical bit and the final, unused bit are not given. The interface is
physical, so this must be represented by a 0 bit, and the unused bit is always 0. These two bits are not given
because they are the most significant bits, and leading zeros are often omitted.
Figure 48-27. Binary Representation of Interface Index
For interface indexing, slot and port numbering begins with the binary one. If the Dell Networking system
begins slot and port numbering from 0, then the binary 1 represents slot and port 0. For example, the index
number in Figure 48-27 gives the binary 2 for the slot number, though interface GigabitEthernet 1/21
belongs to Slot 1. This is because the port for this example is on an E-Series which begins numbering slots
from 0. You must subtract 1 from the slot number 2, which yields 1, the correct slot number for interface 1/
21.
Note that the interface index does not change if the interface reloads or fails over. On the S-Series, if the
unit is renumbered (for any reason) the interface index will change during a reload.
10 0010110 0011 00000000111010
Card
Type
Interface
Type
Port
Number
Slot
Number
14 bits
4 bits
7 bits2 bits