2017-12-19

What Is 25G Gigabit Ethernet and Its Advantages

The well-known Ethernet upgrade path is 10G-40G-100G. However, a new research report shows that the latest server upgrade path will be 10G-25G-100G, and it can be upgraded to 400G in the future. But why is it 25G? Because it is a big jump from 10G to 40G, and the fact is that the incremental cost of upgrading from 10G to 25G are not high. We need to support this new Ethernet rate with upgraded cable and optical modules, which will undoubtedly drive the development of QSFP28 and SFP28 optical modules.

An Emerging Standard - 25GbE


In July 2014, 25G Gigabit Ethernet (25GbE) passed the first level of the IEEE agency and successfully completed the Intent Call (CFI). 25G Ethernet is a recommended new Ethernet standard for cloud computing and enterprise data centers. The 25GbE uses four optical fibers in parallel with paired copper cables to achieve a 100G Ethernet transfer rate over four 25-Gbit / s lanes.

Why to Select 25G Gigabit Ethernet?


Compared to the existing 40G standard, 25GbE technology value has been very clear. The 25GbE provides greater port density and lower unit costs for rack server bandwidth connections. For the applications requiring high end-of-line throughput, 25G uses two lanes to 50G compared to four lanes to achieve 40, which is a better choice both for connectivity and physical channel efficiency.

The 25GbE standard uses biaxial copper cables and provides up to 2.5x faster performance per SerDes channel over the existing 10G and 40G. The 50G Ethernet connection uses two switches or network card SerDes channels running at 25 Gb / s, delivering 25% more bandwidth than the 40G and using only four biaxial copper cables, half the 40G. With a single switch / network card SerDes channel, the 25GbE connection provides 2.5 times the 10GbE bandwidth using the same number of SFP + Direct Attach Cables (DAC).

The biggest benefit that 25GbE technology brings to data center operators is the ability to maximize bandwidth and port density with 1U of panel space. It can also implement 100GbE with 25Gb / s single physical layer technology.



25G Ethernet Drives the Development of QSFP28 and SFP28 Optical Modules


QSFP28 applies to 4x25GE access ports and SFP28 for a single 25GE access port. SFP28 module, based on SFP + package, supports 25G Ethernet standard. The SFP28 delivers 25Gb / s transmission with up to 100 meters in over four types of multimode fiber without error code and can be used in high-density 25G Ethernet switches and network interfaces to facilitate data center server connectivity. It applies the popular SFP+ form factor, offering enterprises a more cost-effective solution to upgrade 10G Ethernet connectivity.

QSFP28 (25G Quad Small Form-factor Pluggable) module and interconnect cable are high-density, high-speed product solutions, which is designed for optical communication, data center and networking market applications. It provides four high-rate signaling channels that can grow from 25Gbps to 40Gbps and will meet the 4X wireless bandwidth-enhanced data rate (EDR) requirements of 100 Gbps Ethernet (4x25 Gbps).

The below photo is the QSFP28 100GBASE-SR4 by Gigalight. The QSFP28 SR4 optical module is a vertically integrated solution that meets the IEEE802.3 standard and MSA requirements while power consumption is significantly lower than 2.5W. This module supports breakthrough applications of the 100GBASE-SR4 standard and IEEE 802.3bm.


 Conclusion


25G will be the dominant next-generation server connection speed standard because it offers mainstream customers a long-term cost advantage. Compared to the existing 40G standard, 25GbE technology value has been very clear. The 25GbE provides greater port density and lower unit costs for rack server bandwidth connections. For applications requiring high end-of-line throughput, 25G uses two lanes to 50G compared to four lanes to achieve 40, which is a better choice both for connectivity and physical channel efficiency.