StarTech.com Cisco QSFP-40G-SR4-S Compatible QSFP+ Module - 40GBASE-SR4 - 40GbE Multimode Fiber MMF Optic Transceiver - 40GE Gigabit Ethernet QSFP+ - MPO 100m - 850nm - DDM Cisco Firepower, ASR9000, ASR1000

Product Overview

AI-generated summary

At £31.45 ex‑VAT, this is the kind of optics you buy when you’ve got a pretty standard 40GbE multimode link and you don’t want to pay Cisco-brand “tax”. It’s aimed at QSFP+ ports on Cisco platforms like Firepower/ASR gear, and in a lot of real networks the compatibility angle is what matters most—assuming your ports are happy with third‑party optics (and your vendor tickets/rules don’t require branded modules). If your use case is short‑reach MMF (your typical data‑centre patching scenario), it’s a solid value play: cheap enough to keep spares, straightforward to deploy, and usually “it just works” as long as the optics and fibre are correctly matched.

That said, I wouldn’t treat “compatible” as “no worries.” The usual gotchas are monitoring/alarms (DDM behavior can vary), switch/policy compatibility on certain Cisco models, and the eternal fibre reality check: multimode link distance and polarity/connectivity matter more than the module name on the box. If you’re buying for anything mission-critical where optics changes trigger support escalations, or you don’t have a good handle on your fibre plant, then the risk isn’t worth the saving—go brand or standardize on whatever your network team already trusts. But for a practical, established 40GbE MMF environment, this is absolutely the right price-to-performance type of purchase.