SFPvs SFP+ vs QSFP: What's the difference?

What do SFP, SFP+, and QSFP represent respectively?

Optical transceivers are nowadays widely used in networking hardware installations in virtually all sectors. According to the Transparency Market Research, the optical transceiver market is expected to dominate the transceiver market with a revenue of US$ 36.8 billion by the end of 2027. Their growth is mostly visible in electronics, particularly electronic warfare systems and in IT.
Due to their popularity, they are believed to be one the simplest pieces of hardware in a network, but that is not the case. There are a great number of transceivers and possible configurations, and their quality and reliability can change from brand to brand. Choosing the wrong transceiver or ignoring any quality verification means that at the end of the day, system administrators might have to deal with unexpected issues caused by poor quality transceivers. So, what are the three main categories of transceivers and how are they best used in different applications?
 

FORMS	STANDARD	DATA RATE	WAVELENGTH	FIBER TYPE	MAX DISTANCE	TYPICAL CONNECTOR	DOM	SIZE	POWER CONSUMPTION	APPLICATION	PRICE
SFP	SFP MSA	155M 622M 1.25G 2.125G 2.5G 3G 4.25G 6G	850nm 1310nm 1550nm CWDM DWDM BiDi Copper	MMF SMF	180km	LC RJ-45	Yes/No	Smallest	Low	Ethernet Fiber Channel CPRI	$
SFP+	SFP+ MSA	8.5G 10G	850nm 1310nm 1550nm CWDM DWDM BiDi Copper	OM3 OM4 SMF	120km	LC RJ-45	Yes	Similar to SFP	Slightly bigger than SFP	Ethernet Fiber Channel CPRI Datacenter	$$
QSFP+	IEEE 802.3ba QSFP+ MSA SFF-8436 SFF-8636 Infiniband 40G QDR	40G 56G	850nm 1310nm 832-918nm	OM3 OM4 SMF	80km	LC MTP/MPO-12	Yes	2x bigger than SFP	Bigger than SFP+	Datacenter Cloud computing	$$

 

SFP vs SFP+

Same size with different speed and compatibility. SFP+ is used in 10-Gigabit Ethernet applications while SFP is for 100BASE or 1000BASE applications. SFP complies with standards of IEEE802.3 and SFF-8472 while SFP+ is based on SFF-8431. SFP+ ports can accept SFP optics but at a reduced speed of 1 Gbit/s. And an SFP+ transceiver can not be plugged into an SFP port, otherwise, the product or port may be damaged. Normally, SFP+ is more expensive than SFP.

SFP+ vs QSFP+

The primary difference between QSFP and SFP is the quad form. QSFP+ is an evolution of QSFP to support four 10 Gbit/s channels carrying 10-Gigabit Ethernet, 10G Fiber Channel, or InfiniBand, which allows for 4X10G cables and stackable networking designs that achieve better throughput. QSFP+ can replace 4 standard SFP+ transceivers, resulting in greater port density and overall system cost savings over SFP+.
 

How to Choose SFP Transceivers?

In addition to SFP vs SFP+ vs QSFP, you’ll also need to consider the application. SFP transceivers are available in different types depending on what they will be used for, for example single-mode vs multimode SFP. Single-mode SFP transceivers work with single-mode fibre, whereas multimode SFPs are compatible with multimode fibre. Additionally, there are long-reach WDM SFP transceivers for multiplexing, simplex SFPs for single fibre applications, video SFP transceivers for transmission of high-definition video, and PON SFP transceivers for fibre-based access networks. SFPs are available in commercial and extended operating temperature ranges, with or without extended diagnostics capabilities.

What is an SFP Transceiver?

SFP+ (small form-factor pluggable plus) is an enhanced version of the SFP. It supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. SFP+ also introduces direct attach for linking two SFP+ ports without additional fiber transceivers, including DAC (direct attach cable) and AOC (active optical cable), which are quite brilliant solutions for the short-distance direct connection between two adjacent network switches.
An SFP, or small form factor pluggable, is a compact, hot-swappable transceiver designed to support 100/1000Mbps Ethernet, Fibre Channel and SONET, among other communication standards. SFP transceivers support speeds up to 4.25Gbps and are commonly used in telecommunications and data communications applications. SFP ports are found in a range of devices, from Ethernet switches to routers, NIC cards and firewalls. Small form factor pluggable specification is based on IEEE802.3 and SFF-8472.

What is an SFP+ Transceiver?

Compared to SFP transceivers, SFP+ transceivers are a more advanced version of the technology. SFP+ transceivers are most typically offered at 8Gbps, 10Gbps, or 16Gbps. They have the exact dimensions of SFPs, making it simple to integrate them into existing infrastructure. SFP+ transceiver is one of the most popular data center cabling applications.

What is a QSFP+ Transceiver?

QSFP+ is an evolution of QSFP (quad small form-factor pluggable). QSFP can carry 4 channels simultaneously and each channel can handle 1 Gbit/s data rate- hence the name Quad SFP. Unlike QSFP, QSFP+ supports 4x 10 Gbit/s channels. And the 4 channels can be combined into a single 40 Gigabit Ethernet link. The QSFP+ transceiver can replace 4 standard SFP+ transceivers, resulting in greater port density and overall system cost savings over traditional SFP+ products.

QSFP, or quad small form factor pluggable, is another type of compact, hot-swappable transceiver. It supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. QSFP modules are commonly available in several different types: 4x1Gbps QSFP, 4x10Gbps QSFP+, 4x28Gbps QSFP28.
QSFP+ and QSFP28 are the most recent versions, which support numerous 40Gbps and 100Gbps applications. Both QSFP+ and QSFP28 modules integrate 4 transmit and 4 receiver channels. While QSFP+ supports 4x10Gbps or 1x40Gbps, QSFP28 can do 4x25Gbps, 2x50Gbps or 1x100Gbps, depending on the transceiver used. The specifications for QSFP are based on SFF-8436.

SFP Compatibility

Small form factor pluggable specifications are published in the SFP Multi-Source Agreement, which enables you to mix and match components from different vendors. However, some IT equipment manufacturers sell network devices that support only vendor specific SFPs. To ensure compatibility, review the vendor’s optics testing centre or ask your vendor to verify compatibility.

Summary

Currently, 400 Gbps is the highest rate available in commercially available products, although work is underway to develop standards and products that support 800 Gbps. SFP technology has demonstrated the ability to evolve as demands increase and will likely continue to evolve to support higher rates. Small form factor pluggable specifications are published in the SFP Multi-Source Agreement, which enables you to mix and match components from different vendors. However, some IT equipment manufacturers sell network devices that support only vendor specific SFPs. To ensure compatibility, review the vendor’s optics testing report or ask your vendor to provide compatibility information. Which SFP transceiver you choose depends on the cable type and application and required optical range for the network and the desired data transmission rate.