IP traffic is predicted to grow 10 fold in less than 10 years. This fact alone speaks to why even incremental increases in Ethernet speeds are important. The ever-rising demand for data is driven by cloud services and already can be seen in early Internet of Things devices. This trend helped lead to development of the 25 Gigabit Ethernet data rates. Even though the technology is rather new, in the two years since the 25 Gigabit Ethernet Consortium was created, server and switch vendors have already launched devices into the market.
The rollout for 25 GbE is expected to be fairly rapid as the specification was driven heavily by the needs of hyper-scale and cloud-scale focused data centers. This quick rollout is also due to the fact that the 25 GbE specification leverages capabilities from the IEEE 802.3 40/100G project as well as capabilities from other data center solutions.
One example is the single lane solution, SFP28, the small form factor module already developed for 32G Fibre Channel. This port type is used either in stand-alone mode or in the data center environment via breakout from a QSFP28 to four SFP28 ports. This allows both users and equipment manufacturers to continue to use the same form factor on their ports, but provides a simple upgrade path for systems that can take advantage of a full 100 Gbps link.
Cost is another major factor behind a quick 25 GbE rollout. While 25 GbE brings the bandwidth up 2.5x from 10 GbE, the cost per port is likely to increase by a factor of 1.5x or less. This is a much higher value proposition than the upgrade to a 40 GbE port. With the anticipated growth in IP traffic, this type of scalability is crucial. Another major cost benefit is that 25 GbE can utilize existing optical plants -- depending on what was installed -- and increase the bandwidth without changing all of the physical infrastructure.
On the practical side, many current applications can easily exceed the 10 Gbps rate available on a 10 GbE interface, but may not need the full bandwidth of a 40 or 100 GbE device. For servers, the bandwidth on the PCIe bus is certainly more in alignment with 25 GbE than 10GbE. The 25 GbE interface offers a happy medium to take advantage a speed increase with minimal pain for early adopters.