topic Re: Can DAC cables and optical fibers coexist in the same stack? in ExtremeSwitching (EOS)

Can DAC cables and optical fibers coexist in the same stack?

Aaron_wang — Tue, 15 Sep 2026 01:50:37 GMT

I currently have 4 Extreme switches 7520-48Y-8C-AC-F. Two of them are in one cabinet, and the other two are in another cabinet which is 1 kilometer away. I need to stack these four switches. I have configured two 100G-DACP-QSFPZ5M direct copper cables and four 100G-FR-QSFP2KM optical modules. Could this solution be feasible? Can the DAC straight cable and the optical fiber coexist in the same stack?

Re: Can DAC cables and optical fibers coexist in the same stack?

dariusmp — Tue, 15 Sep 2026 14:55:18 GMT

Yes, in principle that setup should be possible. Extreme’s documentation for the 7520:

“Up to eight systems can be stacked using qualified direct attach cables and/or optical transceivers.”

https://www.extremenetworks.com/products/switches/universal-switches/7520

So, as I understand it, there should be no problem mixing DAC cables and fiber links within the same stack. In this case, I would use the 100G DAC cables to connect the switches in the same cabinet, and the 100G-FR-QSFP2KM transceivers for the two 1 km links between cabinets, closing the stack ring.

Re: Can DAC cables and optical fibers coexist in the same stack?

Aaron_wang — Wed, 16 Sep 2026 13:06:25 GMT

Thank you very much for your confirmation. I think the same way.

Re: Can DAC cables and optical fibers coexist in the same stack?

danuta741 — Tue, 06 Oct 2026 10:04:28 GMT

This specific solution is partially unfeasible as configured because the 5-meter direct attach copper (DAC) cables are physically far too short to bridge the 1-kilometer distance between your two cabinets. However, mixing DAC cables (for the two switches inside the same cabinet) and the 100G-FR optical modules with single-mode fiber (for the 1km inter-cabinet link) in the same Extreme stack is fully supported, provided you configure a complete redundant ring. To make this work, you will need to replace the long-distance DAC requirement with additional optical modules and fiber links to bridge the 1-kilometer gap. Verify your stack topology using the show stack command in EXOS after cabling to ensure all four switches form a unified, healthy ring.