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What is the correct fiber cable to use between a 6807-XL 40G module and a Nexus 6K 40G module?




We've got a Cisco Catalyst 6807-XL with a 40G fiber module (CFP-40G-SR4) and Nexus 6K with a QSFP+40G transceiver module.  We've tried the straight aqua fiber trunk cables and the crossover (flip pair) aqua fiber trunk cables from black box but we cannot get the link to come up at all.  Even if I plug the cable into the other 40G module on the 6807-XL or the directly between two Nexus 6K's. 


Does anybody know the correct cable to use to get the link to come up?  Or is there some special command to activate these?  


7 Replies 7

Reza Sharifi
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Hi John,

Are you trying to connect the 2 devices via a 40gig QSFP/cable?

If yes,

See table-2 in this link for different length:



No, looking for a fiber trunk cable (MTP).  Just found this document that may provide what I need:


It looks like “type b” is the ticket? Am I looking at the right thing?


Appendix C: Twelve-Fiber MTP-MTP Assembly

The 12-fiber assembly uses a pinless MTP connector on both ends to interface with the QSFP switch ports (reference in this document as product G). The polarity of the assembly complies with a TIA/EIA 568C.3 Type-B array patch cord. This standard states that ribbon fiber must be installed in consecutive order on one end, and installed in reverse consecutive order on the other end of the assembly. In other words, fiber 1 (blue fiber) is installed in position 1 on one end and in position 12 on the other end. This positioning is required for transmission and reception. Figure 26 shows this assembly, and Table 11 provides part numbers.    


What is the distance?

If it is short (up to 10 meters) you can use a cable suggested in the link I provided.


See table-2


Thanks Reza, 

The length is fine, we only need 3 meters.  But I don't think that will work with the CFP-40G-SR4 module on the 6807-XL.  We'll need to the actual fiber trunk cable.  I believe this is the one:  


I have used the cable I mentioned above between 6ks and it works fine but not between 6k and 6800 series. If the 6807 uses a standard QSFP, it should also work.

Anyway, the cable you provided in that link will work fine too.

Good luck


Thanks.  This is the module we have on the 6807, so no, it doesn't use standard QSFP... I'm not sure if there is another module that does or not.

We'll try the corning cable above and update with the result. 


It turns out that this is the correct optical cable:

It must be Type-B Polarity.  OM3 or OM4 will work.  

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