[c-nsp] XENPAK packet loss

[FF]

On Tue, Jun 16, 2009 at 10:19 AM, Mikael Abrahamsson<swmike at swm.pp.se> wrote:
> On Tue, 16 Jun 2009, FF wrote:
>
>> I thought Chromatic Dispersion is distance related. This is supposed
>
> Yes it is.
>
>> 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.
>
> Well, you didn't say the links were DC or not, and you didn't say how long
> the link was. At 40-50km, CD is most likely not the cause of your problems.

On the shorter link, we are seeing the same kind of problem, but not
the same problem. Any traffic-related issues at that distance that
could explain it?

>
> According to some info I found, SMF-28 DSF still has 17.1ps/nm/km, meaning
> your 1600ps dispersion tolerance only gets you 94km? I might be wrong
> though, I can't get the whole article, google only displays from its cache.


Well, that could explain the longer link, definitely. Is dispersion
something, say I'm +300 ps over my dispersion budget,
I get a -625 ps DCU on each side and I'm good? I'm trying to avoid
upsizing the amplifiers to compensate for the DCU's insertion loss.

>
>> Is there a Cisco command to pull up the BER the optic is seeing?
>
> No, on GE you can only see it by sending traffic and observing the error
> counters.
>

Thank you very much.


-- 
FF