Cisco Nexus 40g-FET

[Mike Schultz]

I'm trying to select the correct cable to connect to a Cisco Nexus 40G-FET (on a Nexus 6004). I've seen on Cisco's website that says the FET transceiver has 12 fibers in it. Yet when breaking this out to connect to four 10G FETs on a FEX (2232TM-E), only 8 fibers would be used.

Sooo... What type of mpo connector do I purchase? A 12 fiber MPO or an 8 fiber MPO? Are they interchangeable? Could I use both an 8 or a 12 fiber MPO connector on my fan-out cable?

[Marvin Rhoads · Accepted solution]

Cisco uses 8 lit fibers although the standard MPO is 12 fibers. Please refer to Figure 23 here.

As noted further down in that document (figures 25 and 26) some vendors (Corning cited there) do offer an 8 fiber MPO and that can be used for interconnectivity as well.

[Mariya Telitsina]

I am trying to get ports UP with MPO - SC breakout cable with 8 fibers. It comes UP only from the MPO side. How is this possible and could the reason be with 8 fibers instead of 12?

regards,

Mariya

[viyuan700]

Hi michaelschultz2,

How far is the 2 40G (QSFP)conenction so if they are within 30ft then you can use these MTP to MTP means both are within the same room.

J757512TE8-NB010F	12-fiber jumper; MTP (F) to MTP (F); OM3 50/125; overall length of 10 ft
J757512TE8-NB020F	12-fiber jumper; MTP (F) to MTP (F); OM3 50/125; overall length of 20 ft
J757512TE8-NB030F	12-fiber jumper; MTP (F) to MTP (F); OM3 50/125; overall length of 30 ft

But if the distance is more (between floors/buildings) and you have old fiber cables between two location then you can use 12 Fiber MPO or 8 Fiber MPO. You can check the cost of both and with 8 Fiber MPO you are using all 8 fibers 

H757908QPH-KW010F	8-fiber harness; MTP (F) to (4) LC uniboot; OM3/4 and 50/125; 24-in. LC breakout and overall length of 10 ft
H757908QPH-KW020F	8-fiber harness; MTP (F) to (4) LC uniboot; OM3/4 and 50/125; 24-in. LC breakout and overall length of 20 ft
H757908QPH-KW030F	8-fiber harness; MTP (F) to (4) LC uniboot; OM3/4 and 50/125; 24-in. LC breakout and overall length of 30 ft

 Yes you cand use 8 Fiber/12 fiber MPO but will depend how are you connecting.

[Mariya Telitsina]

Hi viyuan700,

My connections are about 60 meters. And I was trying to connect with 

MPO/UPC (female) - SC/UPC multimode OM3/150 8 fibers Fanout/breakout cable. It never comes up.

Would it work if it's gonna be 12 fibers instead of 8?

[viyuan700]

Hi chattanooga ,

Dumb questions but can you check if you are following the vendor info about how they are paring the fiber. Below is from the link in this thread are you using same cable else check that vendor. 

As per this 1 is Rx and 12 is Tx on the other side 12 have to be Rx and 1 to be Tx. 

"The polarity of the assembly pairs the fibers from the MTP Connector from the outside to the inside; thus, fiber 1 and fiber 12 are a duplex pair, as are fiber 2 and fiber 11, etc. Figure 25 shows the assembly, and Table 10 provides part numbers"

To check all your fiber are fine. See if you can use both qsfp in same box (if possible)and see with proper wiring if the port comes up. If they don't comes up when you use 60 m away means there is problem with your 8 fibers.

[Mariya Telitsina]

Hi viyuan700 ,

thank you for you advice. It was the pairing indeed. The vendor didn't give any info of that.

So my MPO - SC 8 fibers MMF works fine for 40G-QSFP

[Mike Schultz]

We ended up purchasing ProLine cabling which has 12 fibers in the MPO connector, even though it only fans out to four duel-LC cables (total of 8 fibers). The 12-MPO connector works for us.

Make sure you TX and RX are correctly connected on the SC side. They should be labeled. 

[viyuan700]

8 fiber MPO which didn't work was from Cisco/Cisco Recommended or from some other vendor.