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Re: CWDM question
From: Christopher Costa <ccosta () gaikai com>
Date: Thu, 12 Dec 2013 19:31:13 -0800

If you're also doing 1310 does that mean there's a splitter cable inline
with the passive mux? If so, some are cheap and don't filter well outside
of the 1550 band.
On Dec 12, 2013 10:23 PM, "Keith" <kwoody () citywest ca> wrote:

That is whats next. They took down the whole fiber instead of just the
1471 wave to test
which killed transit...grrr..

They say their tx/rx are within spec.

Next is jumpers and sfp swaps I guess.

On 12/12/2013 6:40 PM, Sam Roche wrote:

If you have a CWDM optical power meter and light source, see if you can
measure the power level on the receiving end and verify that it is within
the spec of the SFP. Maybe it is a bad jumper or port on the 1471 receive
on their end or send on your end.

If the two switches can be brought to the same location, you might also
want to connect them together using short jumpers, but make sure you have a
power meter to ensure you use the proper attenuators to avoid burning out
your optics. This would rule out your fiber and mux in case it an issue
with an appliance or SFP. I've had CWDM SFPs burn out for no apparent
reason twice now.

*From: *Keith
*Sent: *Thursday, December 12, 2013 8:11 PM
*To: *nanog () nanog org
*Subject: *CWDM question

CWDM question


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
are not seeing anything. We are receiving from them, and while we show
packets are leaving our interface to them, they are getting nothing at

There are good light levels between the two locations and do not
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?


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