StarTech.com Cisco QSFP-40G-SR4 Compatible QSFP+ Transceiver Module - 40GBASE-SR4~Cisco QSFP-40G-SR4 Compatible QSFP+ Module - 40GBASE-SR4 - 40GbE Multimode Fiber MMF Optic Transceiver - 40GE Gigabit Ethernet QSFP+ - MPO 150m - 850nm - DDM Cisco Firepower, ASR1000, ASR9000

Product Overview

AI-generated summary

At ~£120 ex‑VAT, this StarTech QSFP+ SR4 optic looks like a sensible “keep-the-lights-on” buy for anyone running Cisco kit that accepts this form factor. In day-to-day use, the real question isn’t the brand name on the label—it’s whether your switches/routers *happily* negotiate link and whether you’ve got the right multimode fibre + MPO polarity already in place. If you’re replacing a failed SR4 in a data centre or wiring closet and your environment matches (and you have DDM/monitoring expected), this is the kind of part that usually just does the job without drama.

I’d only avoid it if you need tight reassurance around interoperability for a high-availability change window, or if your support contract/process is picky about “Cisco branded only.” Also note that optics are one of those areas where you can’t “make it work later”: wrong fibre type/length or a polarity/layout issue will make this feel flaky even when the module is fine. Who it suits best: UK B2B resellers/MSPs and infrastructure teams maintaining Cisco 40G links on multimode MPO with a known-good design, where cost control matters. For anything experimental, or where you can’t confirm compatibility up front, it’s safer to validate with your exact Cisco model and port behaviour before ordering.