Question about SFP breakout cables

[Zhomart Asken]

Hi everyone!

I' ve never had experience working with these type of cables and have a couple of questions.

As i understand they are mostly used for directly attaching several devices (such as servers) to one qsfp port. Do we need trancseivers on a server and switch side to connect them to a switch? Can we use this cables to connect to other fiber cables? For what applications they are mostly used?

Thank you!

[David Hild · Accepted solution]

Hi Zhomart.

The breakout cables are designed to split a single 40Gb QSFP+ interface into four (4) 10Gb SFP+ interfaces. The cable itself has a QSFP-shaped connector on one end and SFP-shaped connectors on the other end. These connectors plug directly into the NAD or server devices so there is no need for QSFP+ or SFP+ transceivers. However, it is strongly advised that you check the Compatibility Matrix because not every NAD supports the breakout cables. As for connecting other fiber cables to the breakout cables, this is not a supported use case. The primary use case for the breakout cable is to increase the 10Gb port density on the switch using available QSFP+ interfaces. For example, a 48-port N9K switch can be increased to a total of 72 10G ports by using breakout cables on all six QSFP+ interfaces.

I hope this is helpful.

[Zhomart Asken]

Thank you!

[luis.arias]

Good morning David,

I had the same question that Zhomart had, but after reading your answer, I think I understand how to use these new QSFP breakout cables. I just got one more question, though!
If we can add 24 extra 10GB ports to our N9K switches, does this means these 24 ports can be used as individual 10GB port? Can they be connected to separate devices?
I will give you a scenario to see if I can explain this better.
Say we got a core Cisco N7K Switch, which has two QSFP to Four SFP+ cable, and I have 8 N9K production switches. May I connect trunk cables from each N9K switch to one of the eight 10GB SFP connections on the two QSFP to SFP cables?

Ahead of time, thank you for your help and time you dedicate to read and answer my questions.

Sincerely,

Luis A.