Ruigu Electronic

1000Base-SX and 1000Base-LX are both physical layer standards for Gigabit Ethernet, defined by IEEE 802.3z. They enable 1Gbps (1000Mbps) data transmission over fiber optic media, with key differences in supported fiber types, transmission distances, and optical wavelengths. Below is a detailed overview:

1. Shared Characteristics

• Transmission Speed: Both support 1000Mbps in full-duplex mode, 10 times faster than early Fast Ethernet (100Mbps), meeting high-bandwidth needs in scenarios like enterprise LANs and data center interconnects.
• Encoding: Use 8B/10B encoding, converting 8-bit data into 10-bit transmission signals to ensure synchronization and error correction. The actual line rate is 1.25Gbps.
• Media Type: Both rely on fiber optics (unlike copper-based 1000Base-T), offering strong resistance to electromagnetic interference (EMI) and suitability for long-distance transmission.

2. Key Differences: SX vs. LX

Feature	1000Base-SX	1000Base-LX
Optical Wavelength	Short wavelength (850nm)	Long wavelength (1310nm)
Supported Fiber Types	Multimode Fiber (MMF), primarily OM1, OM2, OM3	Multimode Fiber (MMF) or Single-Mode Fiber (SMF)
Typical Transmission Distance	– OM1 (62.5μm): 275 meters – OM2 (50μm): 550 meters – OM3 (50μm, 10G MMF): 550 meters	– Multimode Fiber (OM1/OM2): 550 meters – Single-Mode Fiber (SMF): 5000 meters (5km)
Application Scenarios	Short-distance indoor connections (e.g., in-rack device links, inter-floor cabling)	Medium-to-long-distance transmission (e.g., campus building interconnects, cross-facility links)
Cost	Lower (cheaper short-wavelength transceivers and MMF)	Higher (more expensive long-wavelength transceivers and SMF)

3. Use Cases

• 1000Base-SX: Ideal for short-range, cost-effective gigabit transmission, such as connecting servers to switches within data centers or intra-office LAN 布线. It leverages multimode fiber for economical deployment.
• 1000Base-LX: Suited for longer distances, including inter-building links in enterprise campuses, backbone networks for universities, or outdoor communication spanning several kilometers, thanks to its support for single-mode fiber.

4. Relationship to Other Gigabit Standards

1000Base-SX/LX are fiber-based standards, contrasting with the copper-based 1000Base-T (using twisted-pair cables for 100-meter distances). Fiber standards (SX/LX) excel in longer-range and interference-prone environments, while 1000Base-T dominates short-distance indoor setups due to compatibility with existing twisted-pair infrastructure.

Together, these standards drove the adoption of Gigabit Ethernet, providing flexible solutions for modern high-bandwidth network demands.