[c-nsp] experiences or success stories related to XENPAK-10GB-ZR

[Emanuel Popa]

Hi Dale,

The attenuation is maximum 21dB for a longer distance link of 102km
and dispersion is between 16 and 18 ps/nm x km. We have no
measurements of ORL.

There is one more question i've got for you because you mentioned FEC.
I'm not quite sure I understood, but here it is:

- on other 10GE links over DWDM network with XENPAK-10GB-LW at both
ends, we experience an average of 1 interface flap per day
- the interface flapping does not really affect the traffic, beacuse
we have redundant links; the customers did not complain
- however, we tried to troubleshoot the interface flapping with our
carrier and they said there is nothing wrong with their network
- during several months of endless discussions with their NOC, there
were four or five times when the flapping became so dense that it
disturbed network traffic and we escalated the problem
- all this time we are convinced that cisco XENPAKs are flawless and
WS-X6704-10GB are also flawless
- one of the escalation methods was to interrupt traffic for 48 hours
and to measure the full circuit end-to-end, including optical patches
- after the measurement, results are: 3 errored seconds of SEF
(Severely Errored Frame) and 1 error of LSS (Loss of Sequence
Synchronization)
- the errored seconds are at different timestamps and might be related
with our interface flapping
- but with only 4 errored seconds during the 48 hours test, the
carrier said the line is ok and has no problems

now, i'm asking you:
- is it possible that the lack of FEC for the XENPAK may cause the
interface flapping when SEF or LSS alarms appear on the line?

have a nice day,
emanuel popa


On 7/5/07, Dale W. Carder <dwcarder at doit.wisc.edu> wrote:
>
> On Jul 5, 2007, at 6:58 AM, Emanuel Popa wrote:
> > now, examining the business case we would like to go further with the
> > second solution: tengigabit directly over the fiber. the problem is
> > that the distance between different points of presence is somewhere
> > between 50 - 80 km. the only XENPAK that can offer connectivity over
> > this distance is the XENPAK-10GB-ZR:
> > http://www.cisco.com/en/US/customer/products/hw/modules/ps4835/
> > products_data_sheet09186a008007cd00.html
>
> Do you know the exact type of fiber you're on or has it been measured
> for attenuation, ORL, and dispersion?  You probably want to know
> at least those parameters before proceeding, particularly for the
> longer spans.  Also, since you don't have any FEC on the xenpak,
> leave yourself some headroom.
>
> The ZR xenpak says it will tolerate up to 1600 ps/nm with a 3dB penalty.
> If so, that could be really cool, because worst-case hopefully you
> won't see much worse than 18 ps/nm/km.
>
> I mention optical return loss because if you are going through a lot
> of jumpers/patch panels to get to your metro fiber you could get
> burned (and all you will see on your 7600 is link-flap errdisable).
> Use only quality -40dB ORL or better jumpers.
>
> Dale
>