GLC-SX-MMD - Cisco SFP Module 1000BASE-SX short wave with DOM

Cisco GLC-SX-MMD — 1000BASE-SX SFP Fiber Transceiver (with DOM)

What it is

GLC-SX-MMD is a Cisco SFP (Small Form-Factor Pluggable) fiber transceiver that supports 1 Gbps (1000BASE-SX) over multimode fiber. It includes DOM (Digital Optical Monitoring) for live link diagnostics, and is designed for use in switches, routers, and industrial gear with SFP ports.

Why buyers pick GLC-SX-MMD (plain English)

Gigabit fiber connectivity: Provides reliable 1 GbE fiber connections for uplinks or distribution links in campus, data center, or industrial networks.

Short-wave (SX) for multimode fiber: Works with multimode fiber (MMF) for connections up to typical campus distances without the cost of single-mode optics.

DOM support: Digital Optical Monitoring lets you see real-time signal metrics (like optical power) for troubleshooting and health monitoring.

Standard SFP form factor: Plugs into any standard SFP slot on Cisco and many third-party devices.

60-second spec box (GLC-SX-MMD)

Form factor

• SFP (Small Form-Factor Pluggable)

Speed / protocol

• 1000BASE-SX (1 Gbps over fiber)

Fiber type

• Multimode fiber (MMF)

Wavelength

• Short-wave 850 nm

DOM

• Digital Optical Monitoring supported (real-time signal metrics)

Connector

• LC duplex

Distance

• Typical reach depends on MMF type (e.g., 550 m on OM4)

Where it fits (and when to choose something else)

Perfect for:

• Gigabit fiber uplinks on campus or enterprise networks

• Short-reach fiber between switches/racks

• Environments where optical diagnostics (DOM) help with management

Choose something else if:

• You need longer distances → 1000BASE-LX or DWDM optics

• You need higher speeds → 10G/25G SFP+ / SFP28 modules

• You need copper → 1G copper SFP or RJ-45 ports

TL;DR

GLC-SX-MMD is a Cisco 1000BASE-SX multimode SFP with DOM — a Gigabit fiber transceiver with diagnostics for short-reach multimode fiber links.