Cisco GLC-SX-MMD
1000BASE-SX SFP transceiver module, MMF, 850nm, DOM, Original Cisco
Product Highlights
Managing Gigabit Ethernet connectivity across campus buildings, data centers, and wiring closets demands optics you can trust — modules that deliver consistent performance, real-time diagnostics, and broad platform compatibility without surprises.
The Cisco GLC-SX-MMD is an original Cisco 1000BASE-SX SFP transceiver module engineered for multimode fiber (MMF) deployments. Operating at an 850nm wavelength with a VCSEL transmitter, it supports data rates up to 1.25 Gbps and reaches up to 550 meters over standard OM2 50µm multimode fiber, up to 275m over OM1 62.5µm fiber, and up to 1 km over laser-optimized OM3/OM4/OM5 fiber. The "D" in the part number denotes built-in Digital Optical Monitoring (DOM), giving network administrators real-time insight into critical parameters such as optical TX/RX power levels, temperature, supply voltage, and laser bias current — enabling proactive fault detection before users are impacted.
Designed as a hot-swappable, plug-and-play module with a duplex LC/PC connector, the GLC-SX-MMD is compliant with IEEE 802.3z and the SFP Multi-Source Agreement (MSA). It is supported across a vast range of Cisco platforms — from Catalyst access switches to ASR routers and Nexus data center switches — making it one of the most versatile and widely deployed Gigabit SFP modules in the Cisco portfolio. Whether you're refreshing aging GLC-SX-MM inventory or expanding your fiber plant, the GLC-SX-MMD delivers the reliability and visibility modern networks require.
Features & Benefits
Digital Optical Monitoring (DOM)
The GLC-SX-MMD supports DOM per the SFF-8472 MSA standard, providing real-time monitoring of optical transmit power, receive power, temperature, laser bias current, and supply voltage. This enables network teams to detect signal degradation and diagnose link issues remotely — reducing truck rolls and accelerating mean time to resolution.
Flexible Multimode Fiber Reach
Engineered for 850nm short-wavelength transmission, this SFP supports distances up to 275m on OM1 (62.5µm), 550m on OM2 (50µm), and up to 1 km on laser-optimized OM3/OM4/OM5 fiber. This range of reach options makes it ideal for intra-building risers, data center row-to-row links, and campus backbone connections without requiring single-mode optics.
Hot-Swappable & Plug-and-Play
The SFP form factor allows the GLC-SX-MMD to be inserted or removed from a compatible port without powering down the host device. This hot-swappable design minimizes downtime during upgrades or replacements and supports a pay-as-you-populate deployment model — you only invest in optics as ports are activated.
Broad Cisco Platform Compatibility
The GLC-SX-MMD is supported across an extensive range of Cisco platforms including Catalyst 2960, 3560, 3750, 3850, 4500, 6500, and 9000 series switches, ISR and ASR routers, Nexus data center switches, and ASA security appliances. This broad compatibility simplifies procurement and standardizes your optics inventory across the enterprise.
Extended Operating Temperature
With an extended operating temperature range of -5°C to 85°C, the GLC-SX-MMD is built to perform reliably in environments beyond standard office conditions — including warm wiring closets, rooftop enclosures, and facilities with limited climate control.
Deployment Scenarios
Enterprise Campus Access & Distribution Layer
Deploy the GLC-SX-MMD in Catalyst access and distribution switches to provide Gigabit Ethernet uplinks over multimode fiber between floors, buildings, and IDFs. DOM support enables centralized monitoring of link health across hundreds of access ports from a single management platform.
Data Center Top-of-Rack Connectivity
Use the GLC-SX-MMD for 1 Gbps server-to-switch connections within data center racks and rows. The short-reach 850nm optics are perfectly suited for the typical distances involved, and hot-swap capability allows optics to be replaced during maintenance windows without disrupting adjacent ports.
Co-Location & Multi-Tenant Facilities
In co-location environments where intra-building multimode fiber links connect customer cages to meet-me rooms, the GLC-SX-MMD provides a cost-effective, standards-compliant Gigabit handoff. DOM diagnostics help facility operators and tenants independently verify link quality.
Legacy Network Refresh & GLC-SX-MM Migration
Organizations replacing end-of-life GLC-SX-MM modules can migrate directly to the GLC-SX-MMD as a drop-in replacement. The modules are optically interoperable on the same link, with the added benefit of DOM diagnostics on the upgraded side.
General
Performance
Reach by Fiber Type
Physical
Environmental
Compliance
Compatibility Notes
The Cisco GLC-SX-MMD is supported on a wide range of Cisco platforms, including but not limited to:
- Catalyst Switches: 2350, 2360, 2900, 2940, 2950, 2960 (incl. Plus, C, S, SF, X), 3560, 3750, 3850, 4500, 6500, 9200, 9300, 9400, 9500 series
- Routers: ISR series, ASR 901, 903, 1000, 9000 series
- Data Center: Nexus series switches
- Security: ASA 5500 series appliances
The module requires a host device with a standard 1G SFP port. It uses multimode fiber only with a duplex LC/PC patch cord. Do not use single-mode fiber — this is a physical-layer mismatch that cannot be corrected via software. The spare-part PID is GLC-SX-MMD=. Always verify compatibility with the Cisco Transceiver Compatibility Matrix for your specific platform and IOS/NX-OS version.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| GLC-SX-MM | Cisco 1000BASE-SX SFP (Legacy, No DOM) | Predecessor to GLC-SX-MMD — same optical specs but lacks Digital Optical Monitoring (DOM). End-of-Sale; replaced by GLC-SX-MMD. |
| SFP-GE-S | Cisco 1000BASE-SX SFP (Extended Temp, DOM) | Newer Cisco 1000BASE-SX SFP with DOM and extended temperature range (-5°C to 85°C). Positioned as the next-generation replacement across newer Cisco platforms. |
| GLC-SX-MM-RGD | Cisco 1000BASE-SX SFP (Industrial Temp) | Industrial-grade variant rated for -40°C to 85°C. Designed for harsh environments like factory automation and outdoor deployments. Higher cost than GLC-SX-MMD. |
| GLC-LH-SMD | Cisco 1000BASE-LX/LH SFP (Single-Mode, DOM) | Single-mode fiber SFP for longer reach (up to 10 km at 1310nm). Choose this when your fiber plant is single-mode or distances exceed 1 km. |
