[c-nsp] XENPAK packet loss

[FF]

I thought Chromatic Dispersion is distance related. This is supposed
to be SMF-28 DSF, the optics are supposed to be 80km (XENPAK DWDM 1600
ps dispersion tolerance). Do you need a DCU even when operating within
that range? One of the links is only about 40-50km.

Is there a Cisco command to pull up the BER the optic is seeing?

Thanks.


On Tue, Jun 16, 2009 at 2:22 AM, Mikael Abrahamsson<swmike at swm.pp.se> wrote:
> On Mon, 15 Jun 2009, FF wrote:
>
>> On a longer span (140km) link, I have the same setup, with two EDFAs. The
>> input power comes in right around -24dbm. It tests clean mostly, but drops 2
>> packets out of 10,000 when empty. More traffic, more drops.  I figured it
>> was a strength problem (-24dbm is right at the edge). So went in with a some
>> fiber cleaners and rejumpered everything. Got it down to -22dbm which should
>> be well within the tolerances. If anything the problem got worse, not
>> better.
>
> Is this link dispersion compensated? Otherwise that is most likely your
> problem, 1GE rarely get chromatic dispersion (CD) problems, 10GE much more
> so.
>
>> So now I have two spans, of drastically different lengths, both dropping
>> packets directly related to the amount of traffic moving over them. Only BGP
>> and static routes are on these. All are 6500/SUP32 or SUP720s running
>> 12.22-33SXH5 or SXHI1.
>
> Which indicates a constant BER (bit error rate) which is consistant with CD
> induced BER.
>
> --
> Mikael Abrahamsson    email: swmike at swm.pp.se
>



-- 
FF