What Are The Advantages Of QSFP28 Compared To QSFP+?

SFP and SFP+:

SFP28 and QSFP28:

QSFP and QSFP28:

SFP, SFP+, SFP28, QSFP+, and QSFP28 are optical module types that are well-known to professionals. These hot-pluggable modules can be used to connect network switches and other network devices such as servers or transceivers for data transmission. But do you understand the differences between these modules? Are QSFP28 and QSFP+ compatible? Can SFP28 modules be used in SFP+ slots?

Next, we will introduce the specific similarities and differences between each pair:

SFP and SFP+:

Same Size, Different Speeds and Compatibility SFP and SFP+ modules share the same physical dimensions, allowing equipment manufacturers to adopt the SFP physical design on switches with SFP+ ports. Due to the identical size, many customers mistakenly use SFP modules in SFP+ ports, which is feasible but will reduce the speed to 1Gbit/s. It's also important to note that SFP+ modules cannot be used in SFP slots, as this may result in damage to the port or module. Apart from compatibility differences, SFP and SFP+ also differ in transmission speeds and standards. SFP can transmit up to 4Gbit/s, while SFP+ can transmit up to 10Gbit/s; SFP is based on the SFF-8472 protocol, while SFP+ is based on the SFF-8431 and SFF-8432 protocols.

SFP28 and SFP+: SFP28 optical modules can be used in SFP+ ports. SFP28 is an upgraded version of SFP+, and both have the same size, but different transmission rates. The transmission rate of SFP+ is 10Gbit/s, while that of SFP28 is 25Gbit/s. If an SFP+ optical module is inserted into an SFP28 port, the link transmission rate becomes 10Gbit/s, and vice versa. Additionally, SFP28 direct-connect copper cables have higher bandwidth and lower loss compared to SFP+ direct-connect copper cables.

SFP28 and QSFP28:

Despite both SFP28 and QSFP28 carrying the number "28", they differ in size and protocol standards. SFP28 supports a single 25Gbit/s channel, while QSFP28 supports four 25Gbit/s channels. Both can be used in 100G networks, but their usage methods differ. QSFP28 can achieve 100G transmission through the three methods mentioned above, while SFP28 relies on QSFP28-to-SFP28 branching high-speed cables.

QSFP and QSFP28:

Different rates, different applications: QSFP+ and QSFP28 optical modules have the same size, with four integrated transmit and receive channels. In addition, although both QSFP+ and QSFP28 series products include optical modules and DAC/AOC high-speed cables, they have different rates. The QSFP+ module supports a single-channel rate of 40Gbit/s, and the QSFP+ DAC/AOC supports a transmission rate of 4×10Gbit/s. The QSFP28 module transmits data at a rate of 100Gbit/s, and the QSFP28 DAC/AOC supports 4×25Gbit/s or 2×50Gbit/s. It should be noted that the QSFP28 module cannot be used for 10G branch links. However, if the switch with QSFP28 ports supports QSFP+ modules, a QSFP+ module can be inserted into the QSFP28 port to achieve 4×10G branch links.

YXFiber has provided a detailed explanation of the differences between SFP and SFP+, SFP28 and SFP+, as well as QSFP+ and QSFP28 optical modules. Although some of them have similar dimensions, their operating speeds are not the same. It is not difficult to see from the comparison that the main driving force behind the development of optical modules lies in the pursuit of higher bandwidth while maintaining small size, as evidenced by the fact that QSFP28 and QSFP+ have the same size but offer higher bandwidth.