Contents

Introduction

Problem

Solution

Recommended Reading

Introduction

This document clarifies the confusion around polling of  "pethMainPseConsumptionPower" OID to get the usage power on an interface of a Cisco Switch from Network Management System (NMS).

Problem

Simple Network Management Protocol (SNMP) Object Identifier (OID) - 1.3.6.1.2.1.105.1.3.1.1.4 (pethMainPseConsumptionPower), when polled to get "usage power" in Watts returns value that does not match with the Command Line Interpreter (CLI) generally used on the Cisco switch.

Example:

NMS> snmpwalk -c public -v2c 10.106.36.239 1.3.6.1.2.1.105.1.3.1.1.4

SNMPv2-SMI::mib-2.105.1.3.1.1.2.1 = Gauge32: 370

SNMPv2-SMI::mib-2.105.1.3.1.1.3.1 = INTEGER: 1

SNMPv2-SMI::mib-2.105.1.3.1.1.4.1 = Gauge32: 121

SNMPv2-SMI::mib-2.105.1.3.1.1.5.1 = INTEGER: 0

Switch# Show power inline

Available:370.0(w)  Used:279.9(w)  Remaining:90.1(w)

Interface Admin  Oper       Power   Device              Class Max

(Watts)

--------- ------ ---------- ------- ------------------- ----- ----

Fa0/1     auto   off        0.0     n/a                 n/a   15.4

Fa0/2     auto   off        0.0     n/a                 n/a   15.4

Fa0/3     auto   off        0.0     n/a                 n/a   15.4

Fa0/4     auto   off        0.0     n/a                 n/a   15.4

Fa0/5     auto   on         3.3     IP Phone 7821       1     15.4

Fa0/6     auto   off        0.0     n/a                 n/a   15.4

Fa0/7     auto   off        0.0     n/a                 n/a   15.4

Fa0/8     auto   off        0.0     n/a                 n/a   15.4

Fa0/9     auto   on         3.3     IP Phone 7821       1     15.4

Fa0/10    auto   off        0.0     n/a                 n/a   15.4

Fa0/11    auto   off        0.0     n/a                 n/a   15.4

Fa0/12    auto   off        0.0     n/a                 n/a   15.4

Fa0/13    auto   on         3.3     IP Phone 7821       1     15.4

Fa0/14    auto   on         13.7    IP Phone DX650      4     15.4

Fa0/15    auto   on         3.3     IP Phone 7821       1     15.4

The above behavior is seen on below hardware software versions:

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 52    WS-C2960+48PST-S   15.0(2)SE6            C2960-LANLITEK9-M

--

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 26    WS-C2960+24PC-S    15.0(2)SE6            C2960-LANLITEK9-M

--

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 52    WS-C2960S-48LPS-L  15.0(2)EX5            C2960S-UNIVERSALK9-M

2 52    WS-C2960S-48LPS-L  15.0(2)EX5            C2960S-UNIVERSALK9-M

Solution

"pethMainPseConsumptionPower" returns power consumed by Power over Ethernet (PoE) for an interface. For switches like 2960 which has power sensing and policing capability, this object identifier will give actual power consumed by PoE devices. We can see this using the CLI "show power inline police" which gives "actual power" consumed, along with the port individual consumption (under "Oper Power" and also "Totals" at the end).

NMS> snmpwalk -v 2c -c public 10.106.36.239 1.3.6.1.2.1.105.1.3.1.1

SNMPv2-SMI::mib-2.105.1.3.1.1.2.1 = Gauge32: 462

SNMPv2-SMI::mib-2.105.1.3.1.1.3.1 = INTEGER: 1

SNMPv2-SMI::mib-2.105.1.3.1.1.4.1 = Gauge32: 23

SNMPv2-SMI::mib-2.105.1.3.1.1.5.1 = INTEGER: 0

Switch#show power inline police

Available:462.0(w)  Used:43.6(w)  Remaining:418.4(w)

Interface Admin  Oper       Admin      Oper       Cutoff Oper

State  State      Police     Police     Power  Power

--------- ------ ---------- ---------- ---------- ------ -----

Gi0/1     auto   on         none       n/a        n/a    5.7

Gi0/2     auto   on         none       n/a        n/a    3.9

Gi0/3     auto   on         none       n/a        n/a    5.2

Gi0/4     auto   on         none       n/a        n/a    8.7

Gi0/5     auto   off        none       n/a        n/a    n/a

Gi0/6     auto   off        none       n/a        n/a    n/a

Gi0/7     auto   off        none       n/a        n/a    n/a

Gi0/8     auto   off        none       n/a        n/a    n/a

Gi0/9     auto   off        none       n/a        n/a    n/a

Gi0/10    auto   off        none       n/a        n/a    n/a

Gi0/11    auto   off        none       n/a        n/a    n/a

Gi0/12    auto   off        none       n/a        n/a    n/a

Gi0/13    auto   off        none       n/a        n/a    n/a

Gi0/14    auto   off        none       n/a        n/a    n/a

Gi0/15    auto   off        none       n/a        n/a    n/a

Gi0/16    auto   off        none       n/a        n/a    n/a

Gi0/17    auto   off        none       n/a        n/a    n/a

Gi0/18    auto   off        none       n/a        n/a    n/a

Gi0/19    auto   off        none       n/a        n/a    n/a

Interface Admin  Oper       Admin      Oper       Cutoff Oper

State  State      Police     Police     Power  Power

--------- ------ ---------- ---------- ---------- ------ -----

Gi0/20    auto   off        none       n/a        n/a    n/a

Gi0/21    auto   off        none       n/a        n/a    n/a

Gi0/22    auto   off        none       n/a        n/a    n/a

Gi0/23    auto   off        none       n/a        n/a    n/a

Gi0/24    auto   off        none       n/a        n/a    n/a

Gi0/25    auto   off        none       n/a        n/a    n/a

Gi0/26    auto   off        none       n/a        n/a    n/a

Gi0/27    auto   off        none       n/a        n/a    n/a

Gi0/28    auto   off        none       n/a        n/a    n/a

Gi0/29    auto   off        none       n/a        n/a    n/a

Gi0/30    auto   off        none       n/a        n/a    n/a

Gi0/31    auto   off        none       n/a        n/a    n/a

Gi0/32    auto   off        none       n/a        n/a    n/a

Gi0/33    auto   off        none       n/a        n/a    n/a

Gi0/34    auto   off        none       n/a        n/a    n/a

Gi0/35    auto   off        none       n/a        n/a    n/a

Gi0/36    auto   off        none       n/a        n/a    n/a

Gi0/37    auto   off        none       n/a        n/a    n/a

Gi0/38    auto   off        none       n/a        n/a    n/a

Gi0/39    auto   off        none       n/a        n/a    n/a

Gi0/40    auto   off        none       n/a        n/a    n/a

Gi0/41    auto   off        none       n/a        n/a    n/a

Interface Admin  Oper       Admin      Oper       Cutoff Oper

State  State      Police     Police     Power  Power

--------- ------ ---------- ---------- ---------- ------ -----

Gi0/42    auto   off        none       n/a        n/a    n/a

Gi0/43    auto   off        none       n/a        n/a    n/a

Gi0/44    auto   off        none       n/a        n/a    n/a

Gi0/45    auto   off        none       n/a        n/a    n/a

Gi0/46    auto   off        none       n/a        n/a    n/a

Gi0/47    auto   off        none       n/a        n/a    n/a

Gi0/48    auto   off        none       n/a        n/a    n/a

--------- ------ ---------- ---------- ---------- ------ -----

Totals:                                                  23.4

The USED power column represent the amount of PoE allocated to ports..

The AVAILABLE power column  represents the total amount of PoE in the system.

The REMAINING power column  means (Available - Used)

Hence the correct command to be used to compare the output of SNMPWALK of "pethMainPseConsumptionPower" is “show power inline police”.

Recommended Reading

Configuring Power over Ethernet