The distance that a QSFP+ (Quad Small Form-Factor Pluggable Plus) transceiver can cover depends on the type of optics used. QSFP+ modules support various optical and copper interfaces, each with its own maximum reach. Here are the common QSFP+ optics and their associated distance specifications:

1. SR4 (Short Range 4):

• QSFP+ SR4 modules use multi-mode fiber (MMF).

• Typically supports distances up to 100 meters.

2. LR4 (Long Range 4):

• QSFP+ LR4 modules use single-mode fiber (SMF).

• Typically supports distances up to 10 kilometers.

3. ER4 (Extended Range 4):

• QSFP+ ER4 modules use single-mode fiber.

• Typically supports distances up to 40 kilometers.

4. CR4 (Copper 4):

• QSFP+ CR4 modules use copper cables (DAC - Direct Attach Copper) for short-range connections.

• Typically supports distances up to 5 meters.

5. AOC (Active Optical Cable):

• QSFP+ AOC modules use fiber optics within a cable assembly.

• Distances can vary but often support ranges from 10 meters to 100 meters or more.

It's important to note that these are general distance guidelines, and the actual reach can depend on factors such as the quality of the optical components, the type and quality of the fiber or cable used, and environmental conditions. Additionally, advancements in technology may lead to modules with improved performance and longer reach. Always refer to the specific datasheet or documentation for the QSFP+ module in question for accurate distance specifications.

SFP: SFP was first introduced in 2001, and built to replace the larger form factor GBIC and support data rates of up to 1G data rate. But with the demands for higher bandwidths like 5G applications or IoT, 1G SFP modules nowadays are estimated to be out of the market in the future, although they still have some market share.

SFP+: 2006 saw the introduction of SFP+, an enhanced version of SFP with a higher data rate of up to 10 Gbps. SFP+ module is now still a dominant industry format transceiver module. Data transmission is available at 8Gbps, 10Gbps, and 16Gbps. Transmission distances cover from 30m to 120km and SFP+ transceivers are available with several different connector types such as LC Duplex, LC Simplex, and RJ45.

SFP28: With the same physical dimensions as the SFP and SFP+, the SFP28 fiber transceiver type was launched in 2014 and designed for up to 25Gbps transmission rate. Mainly used for 25G Ethernet and 100G (4x25Gbps) Ethernet.

QSFP+: Launched in 2012, QSFP+ (Enhanced Quad Small Form-factor Pluggable) is composed of 4 channels of 10Gb/s rate that support LC duplex and MPO-12 fiber connectors.

QSFP28: QSFP28 was also introduced in 2014 and shares the same physical dimensions as QSFP+, but uses 4 lanes of 25Gbps. QSFP28 is now the standard interface of choice for 100G applications.

More specifications of SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28 are listed in the following Table 1.