[c-nsp] 10GBase-LX4 and OM2 fibre -- MCP?

[Justin M. Streiner]

On Wed, 4 Aug 2010, Cisco NSP wrote:

> Thanks for all the responses.
>
> Unfortunately there is no single-mode fiber between the buildings. I'm much
> more familiar with 10GBase-SR and  10GBase-LR and I would have liked to use
> it instead. But we have to work with the current cabling.
>
> I've checked the orientation of the TX/RX both ways and both didn't work. I
> can try to clean the faces again, but the 1.9dB attenuation seems a good
> indication  to me that the fibre itself is ok.

Yes, it does sound like the plant fiber itself is ok, but a test with a 
power meter only tells you about attenuation.  On long multimode runs, 
dispersion can be a big issue.  Also, did you run that power meter test 
through all of the same jumpers that you're trying to use in the actual
link, to rule out the possibility of a bad jumper?

Are you sure the X2s themselves are OK, and don't have dirty connectors?

> Mack, I'm not aware that the X2-LX4 interface was not supported on the 6500.
> Do you have an url confirming this? FWIW, the optic is placed in a
> VS-S720-10G-3C supervisor (port Te5/4).

I found the following link, but it's only for XENPAKs, not X2s.  I could 
not find an X2-LX4 end of sale notice on Cisco's website.

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/eol_c51_599855.html

Also, regarding mode-conditioning patch cords, I've seen them for a lot 
less than $800 USD (assuming the price you originally mentioned was in 
USD).

jms

> On Wed, Aug 4, 2010 at 6:40 PM, Justin M. Streiner
> <streiner at cluebyfour.org>wrote:
>
>> On Wed, 4 Aug 2010, Cisco NSP wrote:
>>
>>  Hi all,
>>>
>>> I'm not very fibre-savvy, so if anybody could help me, I'd very much
>>> appreciate it!
>>>
>>> I have two Cisco 6500s about 250 meters apart in two separate buildings.
>>> Between those two buildings I have OM2 grade fibre. and both Cisco have an
>>> 10GBase-LX4 X2 interface.
>>>
>>
>>  From what I recall, the recommended maximum distance on 10GBASE-LX4 on
>>>
>> <OM3 fiber is 300 meters.
>>
>>
>>  When I measure the fibre end-to-end it has about 1,9dB attenuation in the
>>> 1300nm spectrum but when I connect the fibre to the interface, I don't get
>>> link-up.
>>>
>>
>> That is well within the published link budget for the LX4 spec.  Are you
>> sure that 1. both X2 modules are functional and 2. all of your jumpers and
>> connectors are in good shape (clean end faces, no kinks/micro-bends), etc?
>>
>>
>>  A little troubleshooting pointed me to mode conditioning patches (a piece
>>> of
>>> SM and MM welded together) but I find it very hard to believe that this
>>> patch will solve my problem.
>>>
>>
>> A mode-conditioning patch can extend the distance and reduce the dispersion
>> penalty you pay on multimode fiber by admitting only one mode of light into
>> the fiber from the transmit side of the optics at each end.
>>
>> Do you have any singlemode fiber between the buildings, or do you just have
>> OM2 grade multimode?
>>
>> jms
>>
>>
>>>
>>> Before I invest 800$ for 2 patch-fibers, Is this the way I should go, or
>>> am
>>> I overlooking anything?
>>>
>>>
>>> Thanks in advance,
>>> Dirk-Jan van Helmond
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