CWDM question

Jared Mauch jared at
Fri Dec 13 01:15:40 UTC 2013

On Dec 12, 2013, at 8:11 PM, Keith <kwoody at> wrote:

> Hi.
> We are doing a fiber link between us and another SP using CWDM.
> There is traffic flowing just fine at the 1310 wave, and have recently added a
> 1471 wave.
> On the 1471 wave there are some problems with it. From our perspective, and we
> have packet captured this, we are transmitting data to them, but they say they
> are not seeing anything. We are receiving from them, and while we show that
> packets are leaving our interface to them, they are getting nothing at all.
> There are good light levels between the two locations and do not understand
> why they are not seeing traffic from us even though we are sending it. Our packet
> counters show we are transmitting to them and receiving from them.
> Is it possible to have RX and TX light and things appear to be ok, but have the
> RX on their side fubar in some way that it is not operating correctly in that our
> traffic is not reaching them?

Are you using fixed optics or tunables?  Are transponders involved for the CWDM side then you have “client optics” at 850nm or 1310?  Is there a filter involved?  Do you have a light meter?  What do the optics show for the various light levels and frequencies involved?

- Jared

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