How Much Do You Know About SONET/SDH SFP Module?

Updated on Mar 7, 2018 by

Over the past decades, Ethernet has been the ubiquitous standard of choice for Local Area Networks (LAN). Traditional SONET/SDH standard seems to be gradually migrating to Ethernet. Could it be said that the SONET/SDH is outdated? Absolutely not. With the expansion of packet-based network traffic in the service provider’s network, SONET/SDH is the dominant technology deployed in most metro and long distance networks. The next generation of SONET/SDH equipment continues to be well accepted by Internet service providers (ISPs). Therefore, SONET/SDH SFP module becomes the most commonly used connection methods to enhance the performance of telecommunications networks based on optical fibers.



SONET/SDH SFP module is compatible with the SONET/SDH and ATM standard. Both SONET and SDH have a basic unit of transmission: the basic unit of framing in SDH is a STM-1, which operates at 155.520 Mbit/s; the SONET is STS-1 or OC-1, operating at 51.84 Mbit/s. According to the hierarchy of signaling speeds, an STM-1 frame can be carried in an OC-3 signal. As a result, OC-3 and STM-1 have the same high-level functionality, frame size, and bit-rate. They are also combined to express the same data rate in a SONET/SDH SFP transceiver, such as Cisco ONS-SI-155-SR-MM OC-3/STM-1 SR-0 SFP module. Generally, SONET/SDH SFP transceiver modules cover the standard range of data rates extending from OC-3/STM-1 (155 Mbps) to OC-48/STM-16 (2488 Gbps) for multimode (MM), short-reach (SR), intermediate-reach (IR1), and long-reach (LR1/LR2) applications. For this reason, SONET/SDH SFP module is also called multi-rate SFP module. The following table lists the hierarchy of the most common SONET/SDH data rates:

SONET Optical Level SONET Electrical Level Line Rate (Mbps) Payload Rate (Mbps) Overhead Rate (Mbps) SDH Equivalent
OC-1 STS-1 51.840 50.112 1.728 STM-0
OC-3 STS-3 155.520 150.336 5.184 STM-1
OC-12 STS-12 622.080 601.344 20.736 STM-4
OC-48 STS-48 2488.320 2405.376 82.944 STM-16
OC-192 STS-192 9953.280 9621.504 331.776 STM-64
OC-768 STS-768 39813.120 38486.016 1327.104 STM-256

What’s the Difference Between SONET/SDH SFP and Ethernet SFP?

SONET/SDH and Ethernet are two different protocols. Ethernet was designed for data transport and SONET/SDH for voice, so each SFP module is inherently superior to the other for certain applications.


The Ethernet SFP transceiver is usually plugged into a Gigabit Ethernet port on the Ethernet switch, router, fiber media converter or similar device. However, the SONET/SDH SFP module is used to connect with SONET/SDH devices, such as SONET/SDH core switches, Multiservice Transport Platforms (MSTPs), Optical Edge Devices (OEDs) and OC-3/OC-12/OC-48 add/drop multiplexer. It provides a modular interface between a port on an interface card and the external fiber-optic cabling. This kind of transceiver module carries E1, T1, E3, T3, and Ethernet multiplexed signals within an optical SONET/SDH structure.

SONET SDH SFP Module Application

Data Rate

The fast Ethernet SFP optical module operates up to 155Mbps, and Gigabit Ethernet SFP supports data rate up to 1000Mbps. However, SONET/SDH SFP module supports three data rates:155 Mbps, 622 Mbps, and 2488 Gbps. So SONET/SDH SFP module performs at extremely high speeds, which makes it more competitive than Ethernet SFP transceiver module.


Ethernet SFP module can be divided into several different categories: 1000BASE-T SFP, 1000BASE-SX multimode SFP, 1000BASE-LX/LH SFP, 1000BASE-ZX single-mode SFP, 1000BASE-EX SFP, 1000BASE-BX10 SFP, CWDM and DWDM SFP. Whereas, SONET/SDH SFP optical transceiver only supports OC-3/STM-1, OC-12/STM-4, and OC-48/STM-16 for multimode, short-reach, intermediate-reach, and long-reach.


As SONET/SDH network is designed to carry large volumes of traffic over relatively long distances on fiber optic cabling, SONET/SDH SFP module supports 155Mbps data rate over multimode fiber up to 2km at the base distance level. The max distance is up to 80km over the single mode fiber. Besides, they have fixed length for short, intermediate and long reach in 2km, 15km, 40km/80km respectively. But for Ethernet SFP, the max cabling distance is 550m over MMF patch cable, and it can transmit up to 160 km over single mode fiber.

For more knowledge about Ethernet SFP module, you can refer to this article: SFP Module: What’s It and How to Choose It?

How to Choose SONET/SDH SFP?

As above mentioned, SONET/SDH SFP module can be divided into OC-3/STM-1 SFP, OC-12/STM-4 SFP, and OC-48/STM-16 SFP. They all support short reach (2km), intermediate reach (15km) and long reach (80km). Take Cisco SONET/SDH SFP module as an example, they have well-defined product IDs, making it easy for you to order the appropriate module. The product ID is structured as follows: ONS-AB-CCC-DD. The variables in the ID include:

- For the A variable: S stands for SFP, G for GBIC, X for XFP, and SB+ for SFP+.

- For the B variable: C stands for commercial temperature (0 to 70°C), E for extended temperature (-10 to 85°C), and I for industrial temperature (-40 to 85°C).

- The CCC variable indicates the supported bit-rate or signal type, such as 155Mbps for OC-12/STM-1 signal or 2GF for a tri-rate Gigabit Ethernet, Fibre Channel, and 2G Fibre Channel signal support.

- The DD variable indicates the supported reach, such as S1 for short-reach or intra-office 1310nm interface or SX for Ethernet.

Item Type Distance Fiber Type Transmitter Wavelength Range (nm)
OC-3/STM-1 SFP Multimode 2km MMF 1270 to 1380
Short Reach 2km SMF 1260 to 1360
Intermediate Reach 15km SMF 1261 to 1360
Long Reach 40 km/80 km SMF 1263 to 1360/ 1480 to 1580
OC-12/STM-4 SFP Multimode 2km MMF 1270 to 1380
Short Reach 2km SMF 1261 to 1360
Intermediate Reach 15km SMF 1293 to1334
Long Reach 40 km/80 km SMF 1280 to 1335/ 1480 to 1580
OC-48/STM-16 SFP Short Reach 2km SMF 1266 to 1360
Intermediate Reach 15km SMF 1260 to 1360
Long Reach 80 km SMF 1500 to 1580

Before buying a SONET/SDH SFP, you need have a clear understanding of these parameters. Another important consideration is the price. Compared with original brand SONET/SDH SFP modules, third-party SONET/SDH SFP optical transceivers are more cost-effective. Users can choose the right compatible SONET/SDH SFP optical modules from a reliable vendor according to their need with a cheap price.

FS.com SONET/SDH SFP Solution

FS.com offers a range of SONET/SDH SFP modules, including OC3/STM-1(155Mbps), OC12/STM-4 (622 Mbps), and OC48/ STM-16(2488 Gbps) SFPs for short reach, intermediate reach, long reach applications. All of the modules are interchangeable with the major brands, such as Cisco, Juniper, Extreme etc. In addition, we can also provide customized services of SONET/SDH SFP modules according to your requirements.

Related Article: How Many Types of SFP Transceivers Do You Know

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