This article focuses on frequently asked questions about optical transceivers!
The image above provides a comprehensive comparison chart of various transceiver types. Based on that, let’s discuss some common module comparisons:
SFP vs. SFP+
- SFP+ is an enhanced version of SFP, featuring the same physical dimensions but with differences in speed and compatibility.
- SFP complies with IEEE802.3 and SFF-8472 standards, whereas SFP+ follows the SFF-8431 standard.
- An SFP+ port can accept SFP modules, but the speed will be downgraded to 1 Gbit/s.
- SFP+ modules cannot be plugged into SFP ports, as this may damage the module or port.
- Typically, SFP+ modules are more expensive than SFP.
SFP+ vs. SFP28
- SFP+ is primarily used for 10G connections, while SFP28 is designed for 25G, though both share the same form factor and connector type.
- SFP28 modules are backward compatible with SFP+ ports but will operate at 10 Gbit/s when used in such ports.
SFP+ vs. QSFP+
- QSFP+ is an upgraded version of QSFP.
- QSFP+ can replace four standard SFP+ transceivers.
- Compared to SFP+, it provides higher port density and reduces overall cost.
SFP28 vs. QSFP28
- SFP28 and QSFP28 differ in size and working mechanisms.
- SFP28 supports a single 25 Gbit/s channel, while QSFP28 supports four individual channels.
- Both are used in 100G networks.
QSFP+ vs. QSFP28
- Both have four transmit and four receive channels, and share the same physical form factor.
- QSFP+ supports 1×40 Gbit/s.
- QSFP28 supports 100 Gbit/s transmission.
- QSFP28 modules generally cannot be split into four 10G links.
- If the switch supports it, QSFP28 can be configured as 4×10G, similar to a QSFP+ module.
FAQs on Various Transceiver Types:
- Can I use SFP or SFP+ modules in an SFP28 port?
Yes, SFP modules can be used in SFP28 ports. However, SFP+ modules are generally not compatible unless your switch allows configuring the port to 10G. SFP28 ports are backward compatible with SFP, but using a 10G SFP+ module in a 25G SFP28 port requires the switch to support speed configuration. In that case, the SFP28 port will function as a 10G SFP+ port. - Can I use an SFP28 module in an SFP+ port?
Yes. SFP28 modules are backward compatible with SFP+ ports. Just make sure the SFP28 module supports both 10G and 25G dual rates. - Can SFP+ be used with QSFP28?
Yes. Newer generation transceivers are generally backward compatible. SFP+ ports can accept SFP modules. Also, SFP+ modules can be inserted into SFP28 ports to operate at 10G speed. - What is the maximum transmission distance of SFP+ modules?
It varies depending on the module and speed. For example, many manufacturers offer 10G SFP+ modules with maximum transmission distances of up to 80km. - Is QSFP56 compatible with QSFP28?
Yes, they are compatible. Both use the QSFP form factor. - Does QSFP28 support 10G?
Yes. QSFP28 modules support 4×10GbE channels for 10G connectivity. Traditional QSFP modules also support 4×10GbE channels to achieve 40G. - Can SFP+ modules be connected with XFP modules?
Yes, provided they match in data rate and wavelength. If they don’t, the link may fail to establish. - Is QSFP-DD more suitable for 400G deployments?
Absolutely. QSFP-DD is the preferred form factor for 400G deployments. With the introduction of the QSFP-DD800 specification, the industry trend is shifting toward using QSFP-DD for 800G networks as well.