Posted on August 28, 2017 10:05 am
 |  Asked by Brent Hutchin
 |  3521 views
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Hi,

We were wanting to start monitoring the Tx and Rx power on some of our switchs via SNMP, but we haven’t been able to find which MIB includes the oid’s for this we think we have it down to .1.3.6.1.2.1.99.1.1.1.4.1003PORTNUMBER but we aren’t sure as to which of these values are for which key. Any help would be appreciated.

Cheers Brent

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Posted by Abilash
Answered on August 28, 2017 10:07 am

You can follow the below steps to retrieve and interpret Tx Power of a port (For example, Ethernet 20) via SNMP:

Step 1: First, we can poll 1.3.6.1.2.1.47.1.1.1.1.2 to find out the description of the specific sensor which we want to monitor.  Issue the command show snmp mib walk 1.3.6.1.2.1.47.1.1.1.1.2 | grep <Port-Number>.

boo(config)#show snmp mib walk 1.3.6.1.2.1.47.1.1.1.1.2 | grep Ethernet20
ENTITY-MIB::entPhysicalDescr[100100020] = STRING: Ethernet20
ENTITY-MIB::entPhysicalDescr[100320100] = STRING: Xcvr for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320201] = STRING: DOM Temperature Sensor for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320202] = STRING: DOM Voltage Sensor for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320210] = STRING: Lane 0 for Xcvr for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320211] = STRING: DOM TX Bias Sensor for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320212] = STRING: DOM TX Power Sensor for Ethernet20
ENTITY-MIB::entPhysicalDescr[100320213] = STRING: DOM RX Power Sensor for Ethernet20
Step 2: Now we can poll .1.3.6.1.2.1.99.1.1.1.4.100320212 to find the exact value of the sensor.
boo(config)#show snmp mib walk .1.3.6.1.2.1.99.1.1.1.4.100320212
ENTITY-SENSOR-MIB::entPhySensorValue[100320212] = INTEGER: 5998


Step 3: For interpreting this value, we need to poll the following:

boo(config)#show snmp mib walk .1.3.6.1.2.1.99.1.1.1.1.100320212
ENTITY-SENSOR-MIB::entPhySensorType[100320212] = INTEGER: watts(6)


This OID (entSensorType) gives the unit of measurement that the sensor is reporting. In this case, it’s watts.

boo(config)#show snmp mib walk .1.3.6.1.2.1.99.1.1.1.2.100320212
ENTITY-SENSOR-MIB::entPhySensorScale[100320212] = INTEGER: 
milli(8)


This OID (entPhySensorScale) gives the scale of the unit of measurement that the sensor is reporting. In this case, it’s Milli (i.e.) the sensor is reporting in milliwatts (mW).

boo(config)#show snmp mib walk .1.3.6.1.2.1.99.1.1.1.3.100320212
ENTITY-SENSOR-MIB::entPhySensorPrecision[100320212] = INTEGER: 4


This OID (entPhySensorPrecision) gives the number of decimal places of precision in the value that the sensor is reporting. In this case, it’s 4.
Now since the value reported by the sensor is 5976 with 4 points of precision, the actual value is 0.5976 mW. Converting it to dbM, the value becomes -2.23 dBm, which can be confirmed from the output of show interfaces transceiver detail.

boo(config)#show interfaces transceiver detail
mA: milliamperes, dBm: decibels (milliwatts), NA or N/A: not applicable.
++ : high alarm, +  : high warning, -  : low warning, -- : low alarm.
A2D readouts (if they differ), are reported in parentheses.
The threshold values are calibrated.​
                                     High Alarm  High Warn   Low Alarm   Low Warn
           Tx Power      Threshold   Threshold   Threshold   Threshold
Port       (dBm)         (dBm)       (dBm)       (dBm)       (dBm)
-------    ------------  ----------  ----------  ----------  ----------​
Et20       -2.23         -1.00       -1.30       -8.00       -7.50​

 

Thanks,

Abilash

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Posted by Harshita Rastogi
Answered on August 28, 2017 10:53 am

Hello Brent,

Using SNMP server, you can poll the TX/RX power of the transceivers using the below OID’s:

OID RX Power: .1.3.6.1.2.1.99.1.1.1.4.1003XX21Y (Y=3)
OID TX Power: .1.3.6.1.2.1.99.1.1.1.4.1003XX21Y (Y=2)

1003XX21Y

XX = Port Number.
Y = 1,2 & 3.
if, Y=1 means TX Bias Sensor for that port
    Y=2 means TX Power Sensor for that port
    Y=3 means RX Power Sensor for that port

 

For instance, to fetch TX  power for a interface ethernet5.

#sh snmp mib get 1.3.6.1.2.1.47.1.1.1.1.2.100305212

ENTITY-MIB::entPhysicalDescr[100305212] = STRING: DOM TX Power Sensor for Ethernet5

#sh snmp mib get 1.3.6.1.2.1.47.1.1.1.1.2.100305212

ENTITY-MIB::entPhysicalDescr[100305212] = STRING: DOM TX Power Sensor for Ethernet5

 

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