Q1: What are the types of 25G SFP28 optical transceivers?
There are three types of 25G SFP28 transceivers: 25G SFP28 standard transceivers (SR, LR, ER), 25G BiDi SFP28 transceivers, and 25G WDM SFP28 transceivers (CWDM, DWDM, LWDM).
Q2: What is the maximum transmission distance of the 25G SFP28 transceiver?
At present, the transmission distance can reach 40KM.
Q3: Can SFP28 optical modules support backward compatibility?
It can support backward compatibility with 10G speed.
Q4: Can SFP28 ports be interconnected with QSFP28 ports?
Yes, they can be connected to each other using modules+jumpers or branch cables.
Module+jumper: The 25G end is a 25G SR module, the 100G end is a 100G SR4 module, and there is a multi-mode MTP/MPO-4xlC harness branch cable in the middle.
Branch cables: Use 100G to 4x25G branch AOC/DAC cables for interconnection.
Q5: Can the 25G SFP28 port support 10G modules?
Generally speaking, the 25G port of a device can support multiple speeds, such as 1G/10G/25G, which can meet the needs of 1G, 10G, and 25G speed modules.
Q6: What is the maximum transmission distance between 25G DAC and AOC?
The maximum transmission distance of DAC is 5 meters, while the maximum transmission distance of AOC can reach 100 meters.
Q7: Do I need to enable FEC function when using 25G SFP28 transceiver module?
FEC can reduce the BER (bit error rate) of modules to 10-12. For the 25G module, RS-FEC is enabled when the current FEC error rate is higher than 5 × 10-5, and FC-FEC is enabled when the current FEC error rate is higher than 10-8. Refer to Section 74 FC-FEC and Section 91 RS-FEC of IEEE802.3 for details.
Q8: Do I need to enable FEC function when using 25G DAC?
According to the IEEE 802.3by protocol specification, FEC does not need to be enabled when the transmission distance of 25G DAC is 1, 2, or 3 meters. When the transmission distance is 5 meters, RS-FEC needs to be enabled.
Q9: What is a 25G dual rate module?
Dual rate representation supports two types of rates. The 25G dual rate module supports 10G and 25G, and can switch rates on the supported device ports.
Q10: What are the application scenarios of different 25G SFP28 transceiver modules?
25G SFP28 traditional optical modules (SR, LR, ER, and BIDI) are mainly used for interconnecting servers, switches, and routers in data centers.
The 25G CWDM SFP28 optical module is a single-mode duplex CWDM module with a maximum speed of 25.78125Gbps and a transmission distance of up to 40 kilometers through single-mode fiber. It is mainly used in 25G Ethernet switches, routers, network interface cards (NICs), and storage network devices. It can effectively solve the current problem of 5G millimeter wave advancement.
The 25G DWDM SFP28 optical module is mainly used to meet the requirements of 5G pre transmission services. The device adopts the EML+APD scheme, with a maximum speed of 25.78125Gbps and a transmission distance of up to 10 kilometers through single-mode fiber. It is widely used in CPRI/eCPRI links on 25G Ethernet and single-mode SMF, tightly squeezing wavelengths together to increase the bandwidth of existing fiber optic networks.
The 25G LWDM SFP28 optical module uses high-performance and low-cost DML lasers to provide 12 wave multiplexing, which is more advantageous than other similar 25G fronthaul products in 5G fronthaul applications, making up for the problems of large dispersion in 25G CWDM modules and high laser cost in 25G DWDM optical SFP modules. On the premise of ensuring stable transmission, it can save 5G fronthaul, making it a stable and economical solution in 5G fronthaul networks.
