Cisco Nexus 7000 with NX6.2(2) shows wrong TX and RX DDM values

FLEXOPTIX 18. Sep 2014

Now Cisco! After Juniper moved the comma about two positions to the left side in EX4200 with JunOS 12.2R4 and R5 before the A/D value was converted, Cisco imitate the method on the Nexus platform.
Certainly they shifted the comma about two positions to the right side. The interface with NX OS 6.2.(2) looks like follows:

sh int et1/22 transceiver detail
Ethernet1/22
    transceiver is present
    type is 10Gbase-LR
...
           SFP Detail Diagnostics Information (internal calibration)
  ----------------------------------------------------------------------------
                Current              Alarms                  Warnings
                Measurement     High        Low         High          Low
  ----------------------------------------------------------------------------
  Temperature   32.36 C        90.00 C    -25.00 C     85.00 C      -20.00 C
  Voltage        3.28 V         3.59 V      3.00 V      3.50 V        3.04 V
  Current       18.40 mA       90.00 mA     2.00 mA    80.00 mA       3.00 mA
  Tx Power      18.80 dBm      22.50 dBm   12.99 dBm   21.49 dBm     14.00 dBm
  Rx Power      18.12 dBm      20.00 dBm    1.98 dBm   18.99 dBm      3.01 dBm

For example: a converted value of 18.80 dBm would be 75.8 mW. (This is the direct A/D value from the transciever and in that case the laser protection class 3B in DIN EN 60825-1/05.2008. The 3B laser protection class means an immediate strong damage for the eyes after a direct look into the laser beam.) If the comma is moved about two positions to the left side, the received value is 0.758 mW. That would be a converted value of -1.2 dBm which matches for transmit level of a LR SFP+. Anyway they consistently pulled the mistake through the whole time as they not only converted the Current Measurement wrong than also the alarm and warning thresholds. In this case you at least do not get alarms from the NX-OS. After the correct convertion of all values it should look like follows:

  ----------------------------------------------------------------------------
                Current              Alarms                  Warnings
                Measurement     High        Low         High          Low
  ----------------------------------------------------------------------------
  Temperature   32.36 C        90.00 C    -25.00 C     85.00 C      -20.00 C
  Voltage        3.28 V         3.59 V      3.00 V      3.50 V        3.04 V
  Current       18.40 mA       90.00 mA     2.00 mA    80.00 mA       3.00 mA
  Tx Power      -1.20 dBm       2.50 dBm   -7.00 dBm    1.50 dBm     -6.00 dBm
  Rx Power      -1.88 dBm       0.00 dBm  -18.00 dBm   -1.00 dBm    -17.00 dBm

Cisco make an update for NX-OS 6.2(5)FH(0.47), 6.2(5.56)S0, 6.2(6) and 6.2(0)HS(0.10) - reference CSCuj80663

1 comments

Peter Schückes March 23, 2018 at 11:27

Could be the same issue on an Extreme Switch X690-48x-2q-4c

show ports transceiver info | exclude not

Port Temp TxPower RxPower TxBiasCurrent Voltage-Aux1/ Voltage-Aux2
(Celsius) (dBm) (dBm) (mA) Vcc (Volts) (Volts)
================================================================================
1 0.35* -16.27* 6.14* 0.17* 0.02* N/A
3 0.37* -16.27* 3.56* 0.18* 0.02* N/A
4 0.49* -16.66* 3.56* 0.23* 0.02* N/A
7 0.43* -16.70* 6.14* 0.19* 0.02* N/A
9 0.43* -16.70* 6.14* 0.19* 0.02* N/A
10 0.49* -16.66* 3.56* 0.23* 0.02* N/A
11 0.49* -16.66* 3.56* 0.23* 0.02* N/A
12 0.31* -16.00* 6.14* 0.15* 0.02* N/A
13 0.31* -16.00* 6.14* 0.15* 0.02* N/A
14 0.31* -16.00* 6.14* 0.15* 0.02* N/A
16 0.31* -16.00* 6.14* 0.15* 0.02* N/A
17 3.77* 6.01* 478.77* 59.87* 3.39* N/A
18 0.43* -16.70* 6.14* 0.19* 0.02* N/A
25 0.35* -16.27* 6.14* 0.17* 0.02* N/A
26 0.35* -16.27* 6.14* 0.17* 0.02* N/A
27 0.35* -16.27* 6.14* 0.17* 0.02* N/A
28 0.35* -16.27* 6.14* 0.17* 0.02* N/A
47 0.35* -16.27* 6.14* 0.17* 0.02* N/A
48 0.29* -inf* 7.19* 0.14* 0.03* N/A