I am getting quotes for Structured Cabling and one guy is saying that I can use 40G MPO from my distribution switch up to a 40G MPO patch panel connection and across a 40G MPO trunk but then break it out to 4 x 10G LC ports which I agree with but then he says that I can use each of those four 10G LC duplex cables to connect to four separate physical machines. Is this possible with NX-OS?

I will be using a Cisco 5696Q with mostly QSFP line cards as my distribution switch and 6001T's as my ToR's and building out a total of 12 racks. So I will have one rack with my distribution switch gear and the other 11 will all have ToR 6001T. I am asking for patch panel quotes for all 12 racks.
I am new Cisco and NX-OS so please let me know if this is possible or not and if you need more info.

FOLLOW UP What is best practice in this case? 1. Should I not use breakouts but instead change some of the line cards from QSFP to 10G LC OR 2. Keep line cards 40G for higher density and use break out configuration when 10G is needed.

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5 Answers 5


A 1x40G QSFP port can be fanned-out to 4x10G SFP+ ports. You need to configure that 40G port as 4 Tengig ports in the switch. The break out cables on the other end can go to different hosts.

  • Totally. In fact, these 4x10G cables are totally physical independent ports.
    – KorXo
    Apr 6, 2016 at 8:22

The Cisco 5696Q supports this according to the Cisco datasheet. There are instructions on how to configure it.

These 4 ports will behave like individual ports but be aware that they are the same QSFP (and the same cable until the breakout happens). If it breaks all four of them break. This may sound silly but I've seen people expecting redundancy when connecting all ports of a system to one QSFP.

  • Great caveat, and thanks so much for the links. Based on the "how to" it looks like I have to do a minimum of 3 ports and then add sets of three more ports going forward.
    – Hobbit-42
    Apr 6, 2016 at 19:07
  • One more question. Lets say I take the QSFP to MPO in patch panel then across an MPO patch panel trunk to another rack and then break it out in the patch panel cassette at the top of this other rack. How then do I identify which 10G LC duplex cable matches up to my breakout configuration within the 5696 configs?
    – Hobbit-42
    Apr 6, 2016 at 19:14
  • @Hobbit-42 Normally the MPO breakout cables have numbers from 1-4 (or 0-3) on the LC breakouts which correspond to the ordering of the interfaces in the configuration. There are different types of MPO patches so you should know which one your panels use. belden.com/blog/datacenters/… has a lot of information, as there are 3 types (A,B,C). Apr 6, 2016 at 19:25
  • Thanks for the info. I have not yet seen a breakout cable in the flesh so this helps. I have read up on Method A, B & C as there were warnings about polarity but thanks you for pointing that out as well and the links.
    – Hobbit-42
    Apr 6, 2016 at 22:50
  • You're absolutely right. Here is a little more information from the docs: The command syntax for the Linecard Expansion Module (LEM) is the following: In 40G mode: switch(config)# interface ethernet slot/port In 10G mode: switch(config)# interface ethernet slot/QSFP-module/port Apr 7, 2016 at 7:45

40G QSFP+ cables can be divided into two types—40G QSFP+ to QSFP+ cable or 40G QSFP+ to 4SFP+ breakout cable. The 40G QSFP to 4SFP+ breakout cable Can be used in different hosts.


yes, you can choose the QSFP LR4 PSM type ,I have project for Brocade , and EMC storage ,the 2 buliding so far the 500M , We are use the type for install, something liek the QSFP SR 4 with Breakout cable. to 10G LR ,



A fan-out cable looks very simple. It takes one (large bandwidth) physical interface and breaks it out into several (smaller bandwidth) interfaces. This 4 x 10G breakout cable takes one 40G QSFP interface on one end and uses a fan-out cable to break it into four SFP+ interfaces one the other end. These four LC modules then go to different ports.

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