25G become the best data center solutions

            With the rise of cloud computing, big data, mobile Internet and smart cities, the data traffic of the Internet is under explosive growth. Operators urgently need to upgrade their existing data centers to cloud data
centers to provide more flexible services and applications . Today's data centers are primarily based on 10G Ethernet architectures and in order to be able to handle the increasing data load, these data centers must scale with increased bandwidth capabilities
parallel to existing infrastructures. Interestingly, operators are now preferring evolution paths from 10Gbit / s to 25Gbit / s to 100Gbit / s, compared with the well-known 10Gbit / s → 40Gbit / s → 100Gbit / s upgrade path. Why 25G can replace 40G as a 10G
relay baton?

          Looking back at the evolution of the Ethernet standard, the 40G and 100G standards have long been known as "Beads and Jade" before and after 2010. The 25G standard until only gradually matured in recent years. In 2014,
the IEEE (Institute of Electrical and Electronics Engineers) established the IEEE802.3by working group. In July 2016, the IEEE formally announced its adoption of 100Gbit / s (4-channel 25Gbit / s) Ethernet technology as defined by IEEE802.3bj and defined Up
to 100m multimode fiber 25Gbit / s Ethernet transmission specifications, but also introduced a single-mode fiber 25Gbit / s Ethernet specification. From the IEEE following the 40G and 100G after the launch of the 25G standard this phenomenon, we can infer
that 25GbE technology is bound to have a unique "charm."



As long as the 25G and 40G standards for a simple comparison, we can also draw 25G evolution path is better than the 40G upgrade route judgment. On the one hand, while 40G can be achieved by aggregating four 10GbE physical channels
or 10 10GbE channels can be aggregated to operate at 100G speeds, these solutions are more expensive and consume more power than 25G. On the other hand, the 25G solution offers the advantages of increased compute and storage efficiency over 10G, providing
higher bandwidth, faster connections and running two 25G lanes for 50G or running four lanes for 100G The transition to the next generation of networks, its capital and operating expenditures should be relatively balanced. More importantly, the 25GbE is backwards
compatible and can communicate with 10G, so adding a new server can still work with existing network equipment, helping network operators more easily expand their data center. Due to the above significant advantages, there is a great rationale for the 25G
solution to become the trend of 10G baton.

At present, the optical modules suitable for 25G Ethernet in the industry mainly have two kinds of package styles, namely SFP28 (1x25Gbps) and QSFP28 (4x25Gbps). Among them, SFP28 optical module is based on SFP + package, can provide 25Gb / s error-free transmission,
in the four types of multimode fiber transmission distance up to 100 meters, and can be applied to high-density 25G Ethernet switches and networks Road interface, thus providing operators with more cost-effective solutions for upgrading 10G Ethernet. The QSFP28
optical module, on the other hand, provides four 25Gbps high-speed signaling channels and is used in high-density 25G Ethernet switches and network interfaces to provide a smooth upgrade of the data center to 100Gbps Ethernet (4x25Gbps) evolution .



Figure 2:  SFP28 25G SR optical module



Figure 3:  SFP28 25G LR optical module