StarTech.com Cisco QSFP-H40G-ACU7M Compatible 7m 40G QSFP+ to QSFP+ Direct Attach Cable Twinax - 40GbE QSFP+ Copper DAC 40 Gbps Low Power Active Transceiver Module DAC Firepower ASR1000 ASR9000

Product Overview

AI-generated summary

For £99.65 ex-VAT for a 7m 40G QSFP+ to QSFP+ DAC, this is one of those “cheap enough to be painless, but only if it’s a perfect fit” cables. Active DACs at this length can be great value versus fibre in real deployments—especially for short-reach links between racks where you don’t want the faff (and cost) of transceivers plus optics. If you’re connecting compatible Cisco-style gear in the same data hall/rack row, this kind of twinax tends to “just work” and gives you predictable performance without using extra cooling/complexity.

That said, I’d be a bit cautious about buying it solely as a “Cisco-compatible” blanket replacement. In practice, DACs are where quirky compatibility issues show up—things like switch/QSFP+ implementation, optics diagnostics support, and strict reach/port profiles. If your ASR/Firepower/related platform is known to accept third-party 40G DACs and you’ve got a confirmed part match from your vendor/community, it’s a good buy. If you don’t have that confidence, don’t gamble—buy from a channel that will back compatibility, or go fibre where interoperability is more forgiving. For most teams, this is a “buy when you know the ports/cabling rules” product; for anyone uncertain, it’s a “might save money today, costs time later” risk.