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New Member

Input errors on a DWDM link with good signal (-15.6) dBm

I was hoping someone might be able to point me in the right direction.  I just added an ECWDM solutoin with a 10 gig DWDM link which is X-2 on both sides.  On my remote side I'm seeing input and CRC errors but with a good light level.  I've changed out the amps, the X-2 taking errors, the DWDM mux so far.  The near side isn't taking any errrors and the 2 CWDM circuits on this ring are not taking errors.  Everything I read says this is a great signal for these optics.  Any ideas?

                                 Optical   Optical

           Temperature  Voltage  Tx Power  Rx Power

Port       (Celsius)    (Volts)  (dBm)     (dBm)

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

Te1/6        25.8        N/A       1.7     -15.6

TenGigabitEthernet1/6 is up, line protocol is up (connected)

  Hardware is Ten Gigabit Ethernet Port, address is e05f.b952.da45 (bia e05f.b952.da45)

  Description: DWDM 59.79 (CRH) to cws2-nnd3-nno <Te6/5>

  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 10Gb/s, link type is auto, media type is 10G-DWDM-59.79

  input flow-control is on, output flow-control is off

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:00:01, output never, output hang never

  Last clearing of "show interface" counters 00:16:22

  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 6380000 bits/sec, 1643 packets/sec

  5 minute output rate 0 bits/sec, 0 packets/sec

     1603189 packets input, 780652652 bytes, 0 no buffer

     Received 1600548 broadcasts (1524877 multicasts)

     0 runts, 0 giants, 0 throttles

     56 input errors, 56 CRC, 0 frame, 0 overrun, 0 ignored

     0 input packets with dribble condition detected

     49 packets output, 9456 bytes, 0 underruns

     0 output errors, 0 collisions, 0 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

Everyone's tags (2)
8 REPLIES
Cisco Employee

Re: Input errors on a DWDM link with good signal (-15.6) dBm

Hi Josh,

DWDM is passive here right?

also you mentioned 2 other CDWDM circuit are running fine.

can we check if this third 10Gig which you added on MUX is properly balanced,

means on input of MUX all wavelength should have almost same power level.

so to start with, you can note down Tx of other two 10Gig from device interface and let us know.

so as we are getting CRC only on one side, so we should check power level between Tx------RxMUX at far end.

Wavelength of both interfaces have to be equal, can be verified from serial number of SFP/XFP.

check type of patchcord or cable.

also what is the distance between two nodes.

also what kind of device is this, can we get sh run only for interfaces from both ends and serial number of XFP (from sh inventory)

show controllers ethernet-controller tenGigabitEthernet 3/1/1

New Member

Re: Input errors on a DWDM link with good signal (-15.6) dBm

Hi Sunil,

This setup is currently active with an amplifers but I have taken them out of the mix (this pushes the signal down to ~-22dBm.  I'll check to see if the MUX is properly balanced.

I have a little better signal on my local side, but it's not seeing much traffic so that might be why I'm only seeing errors on one side.    These are both the same DWDM and yes they're going into the right DWDM port on the MUX, I checked that.  Attached is a picture of the simple ring setup I'm running.

NNO side (6500)

NAME: "Transceiver Te6/5", DESCR: "X2 Transceiver DWDM-59.79 Te6/5"

PID: DWDM-X2-59.79     ,                     VID: V02 , SN: FLJ1621W007

Te6/5         32.1        N/A      97.4 --    1.3    -12.3

WCH side (4900) (errrors here)

NAME: "TenGigabitEthernet1/6", DESCR: "DWDM-59.79"

PID: DWDM-X2-59.79     , VID: V02  , SN: FLJ1621W006

Te1/6        25.8        N/A       1.8     -16.1

Cisco Employee

Re: Input errors on a DWDM link with good signal (-15.6) dBm

maybe try loopbacks with 10dB attenuator on interfaces to check if XFPs are good.

New Member

Re: Input errors on a DWDM link with good signal (-15.6) dBm

I've already swithced out both XFP's.  I've got some the same setup running on my desk (with 20db of attenuators to simulate a longer run) and I can't get them to take any errors, even with a worse signal.

My current plan is to scope and clean every link on this path, run an OTDR test to see if there are any odd relfections and if that doesn't work a local telecom has an opictal spectrum analyizer I'll have to borrow and test the specific wavelenghts.  I'll be sure to report my findings.

Cisco Employee

Re: Input errors on a DWDM link with good signal (-15.6) dBm

ok and if there is any tunable XFP with you, than you can try switching on another wavelength.

Hall of Fame Super Gold

Re: Input errors on a DWDM link with good signal (-15.6) dBm

Can you post the output to the command "sh counter interface Ten 1/6" and "sh idp interface Ten 1/6 det"?

New Member

Input errors on a DWDM link with good signal (-15.6) dBm

Right now these are the only DWDM optics I have on hand.

Leo, the 4900M doesn't support that command (just like the controller command sunil mentioned above), but I think this is similar.

csw1-comm-crh#show int te 1/6 counters all

Port                InBytes       InUcastPkts      InMcastPkts       InBcastPkts

Te1/6           27313185218            168240         51647298           2343690

Port               OutBytes      OutUcastPkts     OutMcastPkts      OutBcastPkts

Te1/6                337653                 0             1727                 0

Port              InPkts 64        OutPkts 64    InPkts 65-127    OutPkts 65-127

Te1/6                  1150              1152          6525179                 0

Port         InPkts 128-255   OutPkts 128-255   InPkts 256-511   OutPkts 256-511

Te1/6               3760097                 0         35515121               575

Port        InPkts 512-1023  OutPkts 512-1023

Te1/6               1184452                 0

Port       InPkts 1024-1518 OutPkts 1024-1518 InPkts 1519-1548 OutPkts 1519-1548

Te1/6                696964                 0          6478202                 0

Port       InPkts 1549-9216 OutPkts 1549-9216

Te1/6                     0                 0

Port       Tx-Bytes-Queue-1  Tx-Bytes-Queue-2 Tx-Bytes-Queue-3  Tx-Bytes-Queue-4

Te1/6                337653                 0                0                 0

Port       Tx-Bytes-Queue-5  Tx-Bytes-Queue-6 Tx-Bytes-Queue-7  Tx-Bytes-Queue-8

Te1/6                     0                 0                0                 0

Port       Tx-Drops-Queue-1  Tx-Drops-Queue-2 Tx-Drops-Queue-3  Tx-Drops-Queue-4

Te1/6                     0                 0                0                 0

Port       Tx-Drops-Queue-5  Tx-Drops-Queue-6 Tx-Drops-Queue-7  Tx-Drops-Queue-8

Te1/6                     0                 0                0                 0

Port         Rx-No-Pkt-Buff     RxPauseFrames    TxPauseFrames   PauseFramesDrop

Te1/6                     0                 0                0                 0

Port       UnsupOpcodePause

Te1/6                     0

Port           CrcAlign-Err  Dropped-Bad-Pkts       Collisions        Symbol-Err

Te1/6                  1926                 0                0            708866

Port              Undersize          Oversize        Fragments           Jabbers

Te1/6                     0                 0                0                17

Port             Single-Col         Multi-Col         Late-Col        Excess-Col

Te1/6                     0                 0                0                 0

Port           Deferred-Col         False-Car        Carri-Sen      Sequence-Err

Te1/6                     0                 0                0               296

Port         RxIslTagFrames    TxIslTagFrames RxDot1qTagFrames  TxDot1qTagFrames

Te1/6                     0                 0         54157484                 0

Hall of Fame Super Gold

Re: Input errors on a DWDM link with good signal (-15.6) dBm

Thanks for the output.  It helps alot.

Line errors are in the bottom part of the output, starting with CRC/Alignment Errors.  This means it's a RECEIVE error.

It's not a congestion error but a Layer 1 error.   Be prepared to consider the following:

1.  Change the fibre optic patch cable at both sides;

2.  Observe;

3.  Change the X2 at both sides;

4.  Observe;

5.  Move the X2 modules to a different ASIC; and

6.  Observe.

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