Checking RX and TX light levels on the Cisco ASR platform

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It’s been quite a while since my last post and I thought I would post this little snippet of information that I found while deploying the ASR platform into my employers network.

The optics I am using are standard Cisco branded 10GBASE-LR

RP/0/RSP0/CPU0:cr01.the-lon#show controllers tenGigE 0/2/0/0
Sat Apr 14 21:03:18.509 UTC
Operational data for interface TenGigE0/2/0/0:

State:
    Administrative state: enabled
    Operational state: Up
    LED state: Green On

Phy:
    Media type: R fiber over 1310nm optics
    Optics:
        Vendor: CISCO-OPNEXT
        Part number: TRF5015FN-CA030
        Serial number: ONT1521113E

MAC address information:
    Operational address: 4055.3931.8940
    Burnt-in address: 4055.3931.8940
    No unicast addresses in filter
    No multicast addresses in filter

Autonegotiation disabled.

Operational values:
    Speed: 10Gbps
    Duplex: Full Duplex
    Flowcontrol: None
    Loopback: None (or external)
    MTU: 1526
    MRU: 1526
    Inter-packet gap: standard (12)

Now, I would have expected to see the RX and TX levels within this output but sadly, no.

To see the light levels, you need to look at the dwdm controller (counter-intuitive I know, as its not dwdm optics you are using).

RP/0/RSP0/CPU0:cr01.the-lon#show controllers dwdm 0/2/0/0
Sat Apr 14 21:06:16.583 UTC

Port dwdm0/2/0/0

Controller State: up

Transport Admin State: Out of Service

Loopback: None

G709 Status

         G709 Disabled
Connectivity Info

                Network Port ID:  Not Configured
                Network Connection ID:  Not Configured

Optics Status

         Optics Type:  10GBASE-LR, 10GE-FC-1200-SM-LL-L,
         Wavelength Info: C-Band, MSA ITU Channel= N/A, Frequency=228THz, Wavelength=1310nm
         TX Power = -2.68 dBm
         RX Power = -4.26 dBm
TDC Info

TDC Not Supported on the Plim

Network SRLG values:

Not Configured

Hope this is of help to people looking to find light level readings on the ASR platform.

Nick

Since posting this @aakso pointed out that the following can also be ran:-

“sh controllers te0/0/0/0 phy”

19 thoughts on “Checking RX and TX light levels on the Cisco ASR platform”

    • You can view the TX/RX levels on XR gig interfaces using a slightly different command. It is as follows:

      sho controller gi0/6/0/20 phy

      You can also use the | include function to specify dBm as to weed out all the other info:

      sho contorller gi0/6/0/20 phy | i dBm

      Here is an example of that. What you see first are the thresholds for alarming purposes, then the actually values:

      RP/0/RSP0/CPU0:MACNGAYQ91A-P-CI-9010-01#sho controller gi0/6/0/20 phy | i dBm
      Thu Oct 15 05:18:44.653 EDT
      Transmit Power: 0.63100 mW (-1.99971 dBm) 0.63100 mW (-1.99971 dBm) 0.07940 mW (-11.00179 dBm) 0.06680 mW (-11.75224 dBm)
      Receive Power: 1.25890 mW (0.99991 dBm) 0.79430 mW (-1.00015 dBm) 0.01580 mW (-18.01343 dBm) 0.01000 mW (-20.00000 dBm)
      Tx Power: 0.34540 mW (-4.61678 dBm)
      Rx Power: 0.26850 mW (-5.71056 dBm)

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      • Yes, actually. I use both platforms daily with my job as a systems technician for one of the large Cellphone service providers.

        For XE the command to view all stats would be:

        sho hw-module subslot 0/0 transceiver 0

        Generally, I use the | include function to view just the dbm readings:

        show hw-module subslot 0/0 transceiver 0 | i dBm

        Obviously you’d need to substitute “0/0” and “transceiver 0” with whatever card slot and transceiver position you’d be looking to view.

        Here’s an example output of both:

        CSR-0617-01#sho hw-mod sub 0/0 tran 0 sta
        The Transceiver in slot 0 subslot 0 port 0 is enabled.
        Module temperature = +18.972 C
        Transceiver Tx supply voltage = 3291.8 mVolts
        Transceiver Tx bias current = 4638 uAmps
        Transceiver Tx power = -5.5 dBm
        Transceiver Rx optical power = -6.1 dBm
        CSR-0617-01#sho hw-mod sub 0/0 tran 0 sta | i dBm
        Transceiver Tx power = -5.5 dBm
        Transceiver Rx optical power = -6.1 dBm

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  5. – 4 – 6 is acceptable when it comes to light levels , if your are seeing double digit figures you have some issues on the fiber connector or the path. the Closer to 0 a value is the better.

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    • Also, you can be too hot. There’s a happy medium that should be listed in the SFP manufacturers documentation. “Closer to 0” is not always good. -1, generally speaking, is getting into range of being too hot. The ASR9K gives the thresholds when yiu run the full command without the modifier (| include) but I don’t believe the 1k does. If a signal is coming in too hot you will have to use a dB pad online to reduce the signal or replace the sfp with one that’s better calibrated.

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      Reply ↓

      • Also, you can be too hot. There’s a happy medium that should be listed in the SFP manufacturers documentation. “Closer to 0” is not always good. -1, generally speaking, is getting into range of being too hot. The ASR9K gives the thresholds when you run the full command without the modifier (| include) but I don’t believe the 1k does. If a signal is coming in too hot you will have to use a dB pad inline to reduce the signal or replace the sfp with one that’s better calibrated.

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    • Hi Joyal. Yes they only apply to SFP’s that support DOM. IF they dont, i dont think there is anyway to get the light levels apart from pulling the cables out and using a light meter.

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