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

[Walter Keen]

Based on the following, you might have too much light.

 From : 
http://www.cisco.com/en/US/prod/collateral/modules/ps5455/product_bulletin_c25-530836.html

Notes for LX4:

1. In some cases, customers might experience that a link would be 
operating properly over OM2 fiber type without MCP.

2. Some customers may be tempted to connect 10GBASE-LX4 devices over MMF 
jumper cables without MCP cables. This includes the case of links over 
OM3 cable for which the MCP should not be used. There is a risk to 
overload and saturate the adjacent receiver causing high bit error rate, 
link flaps and eventually irreversible damage. In such cases, a 5-dB 
attenuator for 1300nm should be used and plugged at the transmitter of 
the optical module on each side of the link.

3. Another alternative for short reaches within the same location is to 
use a single-mode patch cable. There will be no saturation over 
single-mode fiber. Please note the 10GBASE-LX4 devices can reach up to 
10km over single-mode fiber as per compliance to IEEE.



On 08/04/2010 02:11 PM, 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.
>
>
> 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).
>
> Regards,
> Dirk-Jan van Helmond
>
>
>
>
>
> 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
>>> _______________________________________________
>>> cisco-nsp mailing list  cisco-nsp at puck.nether.net
>>> https://puck.nether.net/mailman/listinfo/cisco-nsp
>>> archive at http://puck.nether.net/pipermail/cisco-nsp/
>>>
>>>   _______________________________________________
>>>        
>> cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/cisco-nsp
>> archive at http://puck.nether.net/pipermail/cisco-nsp/
>>
>>      
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>