Every Cisco 10G Ethernet SFP+ module is rated for a specific distance, and that number is the single most important spec when choosing one. Pick based on speed alone and you risk a module that can’t physically reach the other end of your link — or one that costs far more than your run needs. Here’s the full distance range of Cisco’s 10G SFP+ lineup, from 300 meters on multimode fiber to roughly 80 kilometers on single-mode.
Why Distance Varies So Much Within One Speed
All these modules carry the same 10 Gigabit Ethernet signal, but three things change the achievable reach:
- Fiber type. Multimode fiber (MMF) scatters light more as it travels, capping usable distance. Single-mode fiber (SMF) carries a tighter beam and supports much longer runs.
- Fiber grade. OM1 and OM2 (legacy-grade) multimode support shorter 10G distances than OM3 and OM4 (laser-optimized).
- Laser wavelength. Short-reach modules use 850nm VCSELs; long-reach modules use 1310nm or 1550nm lasers, which behave differently over single-mode distance.
Once you know your fiber type, grade, and required distance, the right module is usually obvious.
The Full Distance Spectrum
| Module | Fiber Type | Reach | Wavelength |
| SFP-10G-SR / SR-S | Multimode (OM3) | Up to 300 m | 850 nm |
| SFP-10G-SR / SR-S | Multimode (OM4) | Up to 400 m | 850 nm |
| SFP-10G-SR-X | Multimode (OM3/OM4) | Up to 300 m / 400 m | 850 nm |
| FET-10G | Multimode (OM3/OM4) | Up to 100 m | 850 nm |
| SFP-10G-LRM | Legacy multimode (OM1/OM2) | Up to 220 m | 1310 nm |
| SFP-10G-T | Copper | Up to 30 m | — |
| SFP-10G-LR / LR-S | Single-mode | Up to 10 km | 1310 nm |
| SFP-10G-ER | Single-mode | Up to 40 km | 1550 nm |
| SFP-10G-ZR | Single-mode | Up to ~80 km | ~1550 nm |
Reading the Distance Numbers Correctly
300 m / 400 m — standard multimode (SR / SR-S). The most common Cisco 10G SFP module for in-building links. The jump from 300m to 400m is purely fiber grade — OM3 gets 300m, OM4 extends to 400m, with the same module.
220 m — legacy multimode (LRM). Built for sites still on older FDDI-grade, OM1, or OM2 fiber. A mode-conditioning patch cord is required on OM1/OM2; not needed on OM3/OM4.
100 m — FET-10G. Restricted to Fabric Extender links between Nexus 2000 hardware and its parent switch; not sold standalone.
30 m — copper (SFP-10G-T). The shortest reach, over twisted-pair cabling via RJ-45 rather than fiber.
10 km — single-mode (LR / LR-S). Crossing from multimode to single-mode jumps reach dramatically. LR is the default choice for building crossings and modest campus links.
40 km — single-mode (ER). For links that outgrow LR’s 10km range.
~80 km — single-mode (ZR). The longest reach in Cisco’s standard 10G lineup. Note: 10GBASE-ZR isn’t part of the official IEEE standard — it’s Cisco’s own specification — though it’s widely deployed.
Matching Distance to Your Actual Link
Measure before you order. Don’t estimate — include patch panel runs and cable slack, not just straight-line distance.
Don’t default to the longest option “to be safe.” ER and ZR cost meaningfully more than LR, and a 2km link gains nothing from 40 or 80km of headroom.
Check fiber grade before assuming SR’s maximum reach. The 400m figure only applies on OM4. Older or OM3 cabling means shorter achievable distance.
Remember single-mode and multimode aren’t interchangeable, regardless of how close the stated distances might seem.
Sourcing Cisco 10G SFP+ Modules
NextGen Networks stocks the full Cisco 10G Ethernet SFP+ lineup across every distance tier covered here — from short-reach multimode to 80km single-mode — and can help confirm the right part for your measured link distance and fiber type before you order.
Conclusion
Distance is the first filter to apply when choosing a Cisco 10G SFP+ module, before features or price. Multimode fiber keeps you in the 100m–400m range depending on grade; single-mode opens up 10km, 40km, or roughly 80km depending on the module. Measure your actual link, match it to the shortest module that comfortably covers it, and confirm fiber grade before ordering.
Frequently Asked Questions
What is the shortest-reach Cisco 10G SFP+ module? SFP-10G-T, the copper variant, tops out at 30 meters. Among fiber modules, FET-10G is shortest at 100m, though it’s restricted to Nexus 2000 fabric links.
What is the longest-reach Cisco 10G Ethernet SFP module? SFP-10G-ZR, reaching approximately 80 kilometers over single-mode fiber.
Why does SFP-10G-SR reach 300m on one fiber and 400m on another? The module is the same — the difference comes from fiber grade. OM3 multimode fiber supports 300m; OM4 supports 400m.
What’s the maximum distance for a multimode 10G link? 400 meters, achievable with SFP-10G-SR or SR-S over OM4 fiber.
Can I extend a 10G multimode link past 400m without going single-mode? Not meaningfully within Cisco’s standard lineup — beyond multimode’s practical reach, the correct move is switching to single-mode fiber and an LR, ER, or ZR module.
Do I need a mode-conditioning patch cord for every multimode module? No. Only SFP-10G-LRM requires one, and only when run over legacy OM1 or OM2 fiber. It isn’t needed over OM3/OM4, and isn’t relevant at all for standard SR modules.
Which module should I use for a 25 km link? SFP-10G-ER, which covers up to 40 kilometers over single-mode fiber — LR’s 10km maximum falls short at that distance.
