What and where to use 25G SFP28 Optical Transceivers and Cables?
What is SFP28 transceiver? What and where to use 25G SFP28 Optical Transceivers and Cables?
SFP28 stands for Small Form-Factor Pluggable 28. It is the third generation of the SFP interconnect systems designed for 25G performance per the IEEE 802.3by specification (25GBASE-CR). The SFP28 is an enhanced version of SFP+ and is designed for 25G signal transmission. The SFP28 has the same common form factor as the SFP+, and supports 25Gbps electrical interfaces per channel.
It provides high bandwidth and transmission rates over short distances and offers a cost-effective way to connect within racks and across adjacent racks. It has the characteristics of low power consumption, small volume and high speed, which is beneficial to increase capacity of data center, improve port density and reduce power consumption. Mainly used in Ethernet, Data center internal network, data center interconnection and other environments and the 5G installations.
What is the difference between SFP28 and 25G SFP?
They are actually the same.
The “SFP” form factor was originally defined for speeds lower than 10G. When it was adopted for 10G, the name became SFP+ to denote the higher aggregate performance. The same SFP form factor was later adopted for 25G with the electrical interface operating at 25Gbps. The electrical interface is designed to work up to 28Gbps, hence the engineering and industry name is SFP28.
Can I use SFP28 Transceivers in an normal SFP+ ports?
The answer is yes, because SFP28 is backward compatible with 10G SFP+ ports and can be fully functional. SFP+ optical modules and SFP+ cables can be plugged into the SFP28 port, it will not supports 25Gb / s data rate if the switch port doesn’t support 25Gb only 10Gb.
25G SFP28 come in several of different products/setups:
25GBase SFP28 comes in following solutions: Multi-mode Transceivers, Single-mode Transceivers, BIDI, CWDM, DWDM and LWDM. Direct Attached Cables (DAC) and Active Optical Cables (AOC).
The 25GBase SFP28 SR module underpins associations of up to 100 meters over multi-mode fiber and utilization MPO connectors. The frequency is 850nm and can reach up to 100M on OM3/4 MMF. The short reach (SR) module is the most economic answer for move up to a 25G organization.
10/25GBASE-CSR Module supports a link length of up to 300/400m over OM3/OM4. It also supports link lengths of 82m over OM2 at 10G, and up to 70m over OM2 at 25G.
10/25GBASE-LR Module supports a link length of 10 kilometres on standard Single-Mode Fiber (SMF) G.652 at both 10G and 25G.
10/25GBASE-LR Module supports a link length of 10 km on standard Single-Mode Fiber (SMF) G.652 at both 10G and 25G. This module has an industrial temperature range -40~ 85°C. This module also supports CPRI datarates options 7, 8, 9 and 10.
25G SFP28 CWDM optical transceivers comes in 10km or 40km with FEC function (30km without FEC) and are compatible with IEEE802.3by&CC, SFF-8472 and other standards. They have the wavelengths of 1270nm, 1290nm, 1310nm, 1330nm, 1350nm and 1370nm
25G SFP28 DWDM optical transceivers are 10KM and from Channel 17-61, and are compatible with IEEE802.3by&CC, SFF-8472 and other standards
25G LWDM SFP28 40km Optical Transceivers with wavelengths of 1286.66nm, 1291.10nm, 1295.56nm, 1300.05nm, 1304.58nm and 1309.14nm.
The 25GBase SFP28 Bidi transceiver upholds associations of 10km and 40km over single-mode fiber (SMF) and utilizations LC connectors. The frequencies are 1330TX/1270RX and1270TX/1330RX.
25G SFP28 DAC Passive Cable is a hot-swappable passive direct attach copper cable assembly (also known as Twinax Cable or DAC) with SFP28 modules at both ends. It is developed specifically as a cost-effective and lower-power alternative to 25Gb SFP28 optics and Active Optical Cables (AOC), to meet the increasing needs of higher bandwidth in data centers.
The 25G SFP28 DAC cable fully complies with SFP28 Multi-Source Agreement (MSA) standards SFF-8402 and SFF-8432 specifications. It is designed for very short reach links in 25Gbps high-speed I/O interconnect applications such as high-performance computing (HPC) and high-density data center.
25G SFP28 Passive Direct Attach Copper Twinax Cable DAC, the uninvolved copper link for distance from 0 to 5 meters.
25G SFP28 to SFP28 Active Optical Cables are direct-attach fiber assemblies with SFP connectors. It provides high bandwidth and transmission rates over short distances and offers a cost-effective way to connect within racks and across adjacent racks. They are used for longer distance , up to 70 meters.
When is FEC needed?
FEC decreases the BER to 10-12. For 25G, RS-FEC is used when the pre-FEC BER is above 5×10-5 and FC-FEC is used when the pre-FEC BER is above 10-8. Additional details can be found in IEEE802.3 Clause 74 for FC-FEC and Clause 91 for RS-FEC.
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