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Calculating of entPhysicalIndex in the Entity MIB

The inventory in the switch system can be accessed through a MIB browser. These devices are indexed (entPhysicalIndex) using three layers:

  1. Module layer—includes modules located on system (e.g., cables, fan, power supply, and so forth). See the module type breakdown table for more details.
  2. Device layer—a number identifying the specific device that is associated with the module (e.g., ASIC on a leaf, fan on the management board, and so forth).
  3. Sensor layer—a number identifying the specific sensor that is associated with the device (e.g., fan sensors, temperature sensors, power sensors, and so forth).

Each layer is assigned a fixed position in the SNMP index number that represent it.

The physical entities in the system (other than port modules) use the following index schema:

Mod. Type ID

Module Index

Device Identifier

Sensor Type and Index

1

2

3

4

5

6

7

8

9

Layer 1

Layer 2

Layer 3

Spectrum-2 systems and above use the following index schema for port modules and port module sensors:

Mod. Type ID

Port Module Identifier

Port module Sensor index
TX sensors in range 1..39
RX sensors in range 41..79

1

2

3

4

5

6

7

8

9

10

Layer 1

Layer 2

Layer 3

Spectrum systems use the following index schema for port modules and port module sensors:

Mod. Type ID

Port Module Identifier

Port Module Sensor Type
0 for TX 
1 for RX

Sensor index

1

2

3

4

5

6

7

8

9

Layer 1

Layer 2

Layer 3


Module type breakdown:

Number

Description

1

Chassis

2

Management

3

Spine

4

Leaf

5

Fan

6

Power supply

7

BBU

8

x86 CPU

9

Port module

Physical entities—10 digits representation
1Port module



Port module 9 digits representation is kept for backwards compatibility.

Examples

  • entPhysicalIndex with value 401191311
    • 9 digits representation.
    • Layer 1 is “401”—“4” indicates a leaf (see module type breakdown table) and “01” indicates leaf at index #1 (i.e., leaf 01)
    • Layer 2 is “1913”—this is the identifier for one of the QSFP-ASIC in the system
    • Layer 3 is “11”—this is the identifier for temperature sensor #1
    • The description for this physical entity (appears in entPhysicalDescr column of the MIB) would be: L01/QSFP-ASIC-1/T1
  • entPhysicalIndex with value 501020021
    • 9 digits representation.
    • Layer 1 is “501”—“5” indicates a fan (see module type breakdown table) and “01” indicates fan at index #1 (i.e., fan 01)
    • Layer 2 is “0200”—this is the identifier for general fan in the system
    • Layer 3 is “21”—this is the identifier for fan sensor #1
    • The description for this physical entity (appears in entPhysicalDescr column of the MIB) would be: FAN1/FAN/F1
  • For entPhysicalIndex with value 1000012700
    • 10 digits representation.
    • Layer 1 is “1”—port module (see module type breakdown table).
    • Layer 2 is “127”—port identifier
    • Layer 3 is “00”—no sensors for this port module
  • For entPhysicalIndex with value 1000012742
    • 10 digits representation.
    • Layer 1 is “1”—port module (see module type breakdown table).
    • Layer 2 is “127”—port identifier
    • Layer 3 is “42”—sensor in the range 41..79 indicts an RX sensor