Difference between sfp+ and sfp28

With the popularization and promotion of VR/AR, data centers, mobile devices, CDN, etc., there will be an increasing demand for network bandwidth in the future. The demand for network bandwidth is currently increasing at a geometric rate, which in turn leads to a large increase in the demand for high-bandwidth Ethernet ports, such as 100GbE, 200GbE, 400GbE, and even the future 800GbE, in ultra-large-scale data centers and cloud vendors. These high-bandwidth Ethernet ports help to meet the growing east-west data flow demand in data centers. At this time, a hot-pluggable network interface module that can be used to connect network switches and other network devices (such as servers or media converters) for data transmission is born, and SFP+ and SFP28 are different types of optical transceivers. So what are the differences between these different types of modules, such as SFP+ vs SFP28?

Understanding the Types of Optical Modules Before understanding the differences between these modules, we need to understand what SFP, SFP+, SFP28, QSFP, and QSFP28 modules are. The following will introduce these modules separately.

SFP+

SFP+ is an enhanced version of SFP, supporting 8Gbit/s fiber channels, 10G Ethernet, and OTU2 optical transmission network standards. In addition, SFP+ direct-attach cables (i.e., SFP+ DAC high-speed cables and AOC active optical cables) can connect two SFP+ ports without adding extra optical modules and cables (Ethernet cables or fiber patch cords), which is a good choice for direct connection between two nearby short-distance network switches. SFP+ is also an industry standard supported by major telecom equipment suppliers. The initial standard was mainly for applications on 8G fiber channels, 10G Ethernet, and 10G fiber channels, where the electrical interface on the motherboard is a standardized serial interface called SFI. These applications have been extended to include SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G fiber channel, and emerging 32G fiber channel applications.

SFP28

SFP28 is an enhanced version of SFP+, with the same size as SFP+, but it can support a single-channel 25Gb/s rate. SFP28 provides an efficient solution for the 10G-25G-100G network upgrade to meet the growing demand of the next-generation data center network. SFP28 transmission rate is a 25Gbps optical module, in compliance with multiple standards and specifications such as IEEE802.3, SFF-8472, SFF-8402, SFF-8432, and SFF-8431. It is mainly used for 25G Ethernet and 100G (4x25Gbps) Ethernet and supports data rates of 25G Ethernet and 28.05Gbps (for 32GFC). The SFP28 optical module is compatible with SFF-8432.

Similarities and Differences of SFP+, SFP28 After understanding what SFP+, SFP28 are, the specific similarities and differences between them will be introduced next.

Differences between SFP+ and SFP28:

Size SFP+ and SFP28 have the same size.

Transmission Rate SFP+ has a transmission rate of 10Gbit/s, while SFP28 has a transmission rate of 25Gbit/s.

Compatibility If an SFP+ optical module is inserted into an SFP28 port, the link transmission rate is 10Gbit/s.

Cable SFP28 direct attach copper cable has higher bandwidth and lower loss than SFP+ direct attach copper cable.

Extended Knowledge:

SFP28 vs SFP+: SFP28 optical modules can be used in SFP+ ports. As mentioned above, SFP28 is an upgraded version of SFP+, they have the same size, but different transmission rates. SFP+ has a transmission rate of 10Gbit/s, while SFP28 has a transmission rate of 25Gbit/s. If an SFP+ optical module is inserted into an SFP28 port, the link transmission rate is 10Gbit/s, and vice versa. In addition, SFP28 direct attach copper cable has higher bandwidth and lower loss than SFP+ direct attach copper cable.

SFP28 has the same structural definition and interface standards as SFP, only that SFP28's rate reaches 25Gbps, and its transmission efficiency is 2.5 times higher than that of SFP+. At present, the prices of 40G optical modules and 100G optical modules are too high and their power consumption is too large, while the rate of 10G optical modules cannot meet the network requirements. Therefore, the 25G SFP28 optical module perfectly fills the gap between these three. At the same time, in 5G communication, SFP28 modules will be widely used in front-haul networks.

SFP28 vs SFP+: Can I use SFP28 transceivers in SFP+ ports? The answer is affirmative. SFP28 is an upgraded version of SFP+, SFP28 has been upgraded to handle 25 Gbit/s per lane. They use the same form factor and the pinouts of SFP28 and SFP+ connectors are matching compatible. So SFP28 will work with SFP+ optical systems, but the speed will drop to 10 Gbit/s. If the SFP+ module's SFP28 port can be set to transmit at 10G, then the SFP+ module can work well with the SFP28 port on the network switch, otherwise the SFP+ module cannot work. In terms of copper cables, compared with the SFP+ version, SFP28 copper cables have a larger bandwidth and lower loss.

SFP28 vs QSFP28: They work on different principles even though there's a number "28" in their names. SFP28 and QSFP28 transceivers actually adopt different sizes and working principles. SFP28 only supports a 25Gbit/s channel, while QSFP28 supports four independent 25Gbit/s channels. They can both be used in 100G networks, but SFP28 is applied in the form of QSFP28 in SFP28 break-out cables.