1000BASE-SX, 1000BASE-LX, 1000BASE-ZX&BX SFP: A Simple Guide

Last updated: November 29, 2024

Gigabit Ethernet (GbE) has become very popular and is currently used in the backbone of many enterprise networks. It is defined by the Institute of Electrical and Electronics Engineers (IEEE) as 802.3z, 802.3ab, and 802.3ap. As a critical Ethernet physical layer standard, they specify a set of 1000BASE-X standards, including 1000BASE-T, 1000BASE-CX (Copper), 1000BASE-KX, 1000BASE-SX, 1000BASE-LX, 1000BASE-EX, 1000BASE-ZX, and 1000BASE-BX.

This post will focus on several standards for transmission over fiber optic media, especially for SFP modules, including the most commonly 1000BASE-X terms. The details are as follows:

Table of Contents

What is 1000BASE-SX?
What is 1000BASE-LX?
What is 1000BASE-LH?
What is 1000BASE-EX?
What is 1000BASE-ZX?
What is 1000BASE-EZX?
What is 1000BASE-BX?
Complete comparison
1000BASE-SX vs 1000BAS-LX SFP
FAQ
Conclusion

What is 1000BASE-SX?

1000BASE-SX is a gigabit Ethernet standard over fiber optic for short reach. It is used for operating on multimode fiber with a short wavelength of 770 to 860 nanometers (typically 850nm). The “SX” stands for short reach over multimode fiber.

1000BASE-SX defines a maximum length of 220 meters for 62.5μm fiber distributed data interface (FDDI) multimode fiber, 275 meters for 62.5μm/200MHz·km multimode fiber, and 550 meters for 50μm/500MHz·km multimode fiber. However, It supports a 1km distance over laser-optimized OM3, OM4, or OM5 multimode fiber.

This standard is widely used in large office buildings, co-location facilities, and carrier-neutral Internet exchanges.

What is 1000BASE-LX?

1000BASE-LX SFP is a gigabit Ethernet standard over fiber optics for long reach. It operates on single-mode fiber (SMF) or multimode fiber (MMF) with a long wavelength of 1270 to 1355 nanometers (typically 1310nm). The “LX” stands for long reach.

1000BASE-LX SFP supports 10km over single mode fiber. Some industry vendors also provide an extended distance of 20km, which is not defined in the standard.

When used with multimode fiber, it supports a maximum distance of 550 meters. Please note a specific conditioning patch cable may be required for link distances higher than 300 meters.

Due to the low cost and extended reach that meets most enterprise networks, 1000BASE-LX has become one of the most popular standards.

What is 1000BASE-LH?

It’s worth noting that while 1000BASE-LX is specified in the IEEE 802.3 standard, 1000BASE-LH is not. However, industry leaders commonly use the term to describe long-distance fiber optic connections. The “LH” in 1000BASE-LH stands for “long haul”. Its typical transmission distance is 20km or 40km.

For instance, some ethernet switch manufacturers refer to the 1000BASE-LH SFP as the 1G 1310nm 40km SFP transceiver, which indicates the module’s transmission distance and wavelength. Although 1000BASE-LH is not an IEEE standard, it is still a commonly used term in the industry, and it is crucial to understand its features and limitations when working with long-range fiber optic connections.

What is 1000BASE-EX?

1000BASE-EX is a non-standard but widely used industry term for Gigabit Ethernet fiber optic transmission. The letter “EX” means extended reach, which supports 40km over single mode fiber.

Like 1000BASE-LX, it uses the same long wavelength of 1310nm but provides a higher power budget to achieve more considerable distances. Sometimes, many manufacturers also call it 1000BASE-LH (Long Haul).

1000BASE-EX usually costs more for the optical components, so it is offered at a higher price than 1000BASE-SX and 1000BASE-LX.

What is 1000BASE-BX?

While different from any of the above terms, 1000BASE-BX is a gigabit Ethernet standard that operates over a single strand fiber optic cable. Unlike other names requiring two fibers, 1000BASE-BX uses WDM (wavelength division multiplexing) technology to enable Bidirectional (BiDi) transmission on a single fiber strand. That makes it a cost-effective solution for network connections with only a single fiber.

Simply put, it is achieved by employing two different wavelengths (1310nm-TX/1550nm-RX or 1310nm-TX/1490nm-RX) on both the transmitter and receiver sides, separated by a WDM optical filter. This innovative approach allows for the simultaneous transmission of both wavelengths on the same fiber, thereby enabling efficient use.

It’s essential to remember that BiDi transceivers must be paired with suitable wavelengths. For instance, if you’re using 1310nm-TX/1550nm-RX on one end, you should use 1550nm-TX/1310nm-RX on the other. Otherwise, the fiber link will fail.

1000BASE-BX Variants

Based on the maximum distance supported, 1000BASE-BX can be categorized into different variants: 1000BASE-BX10, 1000BASE-BX20, 1000BASE-BX40, and 1000BASE-BX80. Every variant stands for a different distance, like 10km, 20km, 40km, or 80km.

In addition to the above terms, 1000BASE-BX10-U usually refers to the upstream links of 10km, using 1310nm-TX/1550nm-RX or 1310nm-TX/1490nm-RX. On the other hand, 1000BASE-BX10-D commonly stands for downstream links of 10km, featuring 1550nm-TX/1310nm-RX or 1490nm-TX/1310nm-RX.

What is 1000BASE-ZX?

1000BASE-ZX is a non-standard but widely used industry term for 70km (43 miles) Gigabit Ethernet transmission. It uses a 1550 nm long wavelength over single mode fiber. The SFP vendors often provide 80km (50 miles) versions to replace the standard 1000BASE-ZX.

Some manufacturers offer 120 kilometers (75 miles) distance using single-mode fiber, defined as 1000BASE-EZX or 1000BASE-ZX120. Since the 1000BASE-EZX transceivers offer very high transmitter power and receiver sensitivity, you must add a proper fiber attenuator to avoid bit errors caused by overload.

What is 1000BASE-EZX?

1000BASE-EZX is a non-standard term for gigabit Ethernet. However, many networking vendors and users refer to it as ultra-long distances of 100km or 120km over single-mode fiber. The letter “EZX” means extend long reach. In this application, the SFP module adapts a wavelength of 1550nm for lower dispersion and loss. Some other vendors may have referred to it as 1000BASE-ZX100 or 1000BASE-ZX120, but it still represents the same term.

Comparison: 1000BASE-SX vs 1000BASE-LX, 1000BASE-EX, 1000BASE-ZX vs 1000BASE-BX

Name	Standard	Wavelength	Media	Interface	Distance	Transceiver Type	System Cost
1000BASE-SX	IEEE802.3z	850nm	MMF	Duplex LC/SC/ST	OM1: 220m, OM2: 550m, OM3: 1km	SFP, SFF, 1×9	Low
1000BASE-LX	IEEE802.3z	1310nm	MMF/SMF	Duplex LC/SC/ST	OS1/OS2: 10km, OM2: 550m, OM3: 550m	SFP, SFF, 1×9	Low
1000BASE-LH	proprietary (non IEEE)	1310nm	SMF	Duplex LC/SC/ST	20km or 40km	SFP, SFF, 1×9	Medium
1000BASE-EX	proprietary (non IEEE)	1310nm	SMF	Duplex LC/SC/ST	40km	SFP, SFF, 1×9	Medium
1000BASE-ZX	proprietary (non IEEE)	1550nm	SMF	Duplex LC/SC/ST	70km	SFP, SFF, 1×9	High
1000BASE-EZX	proprietary (non IEEE)	1550nm	SMF	Duplex LC/SC/ST	120km	SFP, SFF, 1×9	higher
1000BASE-ZX160	proprietary (non IEEE)	1550nm	SMF	Duplex LC/SC/ST	160km	SFP, SFF, 1×9	Highest
1000BASE-BX	802.3ah	1310/1490nm or 1310/1550nm	SMF	Simplex LC/SC/ST	10km, 20km, 40km, 80km, 120km	SFP, SFF, 1×9	Highest

Table 1: Gigabit Ethernet 1000BASE-SX, LX, EX, ZX, BX Comparison

1000BASE-SX vs 1000BASE-LX SFP: What is the difference?

1000BASE-SX and LX SFP are the most popular modules in the market. However, some readers still need clarification about them and help to choose. Now, let’s make a detailed comparison to help you understand them.

1. Transmission Distance

The 1000BASE-SX SFP only supports very short transmission distances. It can support 550m over OM2 fiber or 275m over OM1 fiber. The 1000BASE-LX SFP provides a much longer distance, typically transmitting for 10km or 20km by single-mode fiber. Therefore, if you need long connectivity over fiber, 1000BASE-LX will be the best choice.

2. Optical Wavelength

1000BASE-SX SFP only uses a short wavelength of 850nm and is usually equipped with the VCSEL transmitter and PIN receiver for a lower cost. Meanwhile, the 1000BASE-LX SFP uses a long wavelength of 1310 nm, a unitized FP or DFB laser, and a PIN receiver. The FP and DFB lasers provide higher optical power and are specifically suitable for single-mode fiber cabling.

3. Optical Fiber Type

The 1000BASE-SX SFP targets traditional multimode fiber, including OM1, OM2, OM3, and OM4 cables. In contrast, the 1000BASE-LX SFP operates primarily with single-mode fiber optimized for long-distance transmission.

4. Cost

The 1000BASE-SX SFP usually provides a lower cost, while the 1000BASE-LX costs a bit higher. However, they are equal in price in the real world because mass production decreases the cost impact.

5. Application

Based on the above difference, 1000BASE-SX SFP is ideal for local area networks (LANs), data centers, and enterprise or campus networks, especially for short-distance and low-cost optical connectivity.

In the meantime, the 1000BASE-LX SFP is ideal for long-distance optical connectivity like wide-area networks (WANs), metropolitan area networks (MANs), long-haul connections between different locations, or any single mode-based fiber systems.

FAQs

Q: What is a Gigabit Ethernet

Gigabit Ethernet (GbE) is a computer networking standard and protocol based on the Ethernet frame format. The Gigabit Ethernet standard can theoretically enable a maximum data throughput of one gigabit per second (1,000 Mbps) or 1 billion bits per second.

Q: What is 1000BASE-FX?

No standards define 1000BASE-FX, but some media converter vendors call it gigabit ethernet (1000BASE) over fiber (FX). So we can see 1000BASE-SX, 1000BASE-LX, 1000BASE-EX, and 1000BASE-ZX variants of 1000BASE-FX.

Q: Can I use a 1000BASE-LX SFP with multimode fiber?

Yes, but it is not recommended. Because the 1000BASE-LX SFP is designed for single mode fiber cabling, whereas multimode fiber is typically used with 1000BASE-SX. Therefore, you should add a mode conditioning patch cable when using a 1000Base-LX SFP for multimode fiber.

Conclusion

We know 1000BASE-SX is for multimode fiber cabling and provides ultra-low total cost, but it has a distance limit, so it is suitable for very short transmission. 1000BASE-LX, 1000BASE-EX, and 1000BASE-ZX are designed for single mode fiber cabling while providing much longer distances for backbone networks.

Remember, each standard has its unique features and limitations. So, take the time to learn and explore, and you’ll be well on your way to building a robust and reliable network infrastructure.

Reference:

https://www.lifewire.com/definition-of-gigabit-ethernet-816338

Read more:

Network Cabling, Optical Networking, Optical Transceiver