What Is 25 Gigabit Ethernet & Why Is It in Demand?

Posted on by FS.COM

25GbEThough the migration from 10 GbE (Gigabit Ethernet) to 40/100 GbE is widely recognized as the Ethernet speed upgrade path and greatly satisfies the increasing demands for higher bandwidth and speed, people still keep pursuing a better solution to replace the existing “10GbE-40GbE-100GbE” path. New deployments, such as 10GbE—25GbE—100GbE or 10GbE—25GbE—50GbE—100GbE are underway which are announced to better satisfy the data center and cloud network. Thus, what is 25 GbE and why is it in demand?

What Is 25 GbE?

25GbE, namely 25 Gigabit Ethernet, is a proposed standard for Ethernet connectivity in a datacenter environment. It is driven by an industry consortium, also called 25 Gigabit Ethernet Consortium. Now, the 25 Gigabit Ethernet Consortium includes many famous companies like Microsoft, Google, Broadcom, Mellanox, Arista, and Brocade etc. that make contributions to pushing for 25 GbE. Their specification recommends a single-lane 25 GbE and dual-lane 50 GbE link protocols. 25 GbE is in the process of becoming a standard and has passed the first hurdle in the IEEE standards body with a successful Call for Interest (CFI) in July, 2014. The industry expects that 25GbE hardware will be available as early as 2015 with the standard finalized by 2016.

Why Is 25 GbE in Demand?

As we know, in the high-density data center, using multiple 10 GbE would require twice as many Ethernet switches with their associated space, power, and cooling costs. Deploying 25GbE networks enables organizations to significantly decrease capital and operating expenses by reducing the required number of switches and cables to solve these issues, compared to 10GbE and 40GbE (4×10 GbE) technology. Additionally, fewer network components also reduce ongoing management and maintenance costs.

For instance, if we use the 10GbE—40GbE—100GbE path, we will have 10 GbE single, 40 GbE quads and 100 GbE ten lanes in production. But when we turn to 25 GbE, we just need 25 GbE single, 50 GbE dual and 100 GbE quads in production. Obviously, 25GbE enables us to have 2.5X the performance of 10Gb Ethernet, making it a cost-effective upgrade to the 10GbE infrastructure. While compared to 40GbE, which is actually four 10GbE lanes, 25GbE is delivered across a single lane which provides greater switch port density and network scalability. Moreover, using multiple 25GbE lanes, it is easy to upgrade of 50GbE and 100GbE networks. It is a cost-effective solution for datacenter upgrade and cloud-scale network expansion. This is why 25 GbE is favoured and highly recommended by those famous consortium.

100 GbE block diagram

SFP28 & QSFP28 Assemblies

QSFP28The SFP28 (25G Small Form-Factor Pluggable) and QSFP28 (25G Quad Small Form-Factor Pluggable) transceivers and interconnect cables are high-density, high-speed product solution designed for 25GbE and 100GbE applications in the telecommunications, data center and cloud-scale networks. The emergence of these two form-factors pluggable certainly reflect the trend in the industry to aggressively bring 100GE density up and costs down.

Based on the SFP+ MSA form-factor, SFP28 assembly solution enables a new generation of high-density 25G Ethernet switches and NIC cards, facilitating server connectivity in data centers, and a conventional and cost-effective upgrade path for enterprises deploying 10G Ethernet links today in the ubiquitous SFP+ form factor.

QSFP28 transceiver, as a new type of 100G transceivers, offers four channels of high-speed differential signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. According to IEEE 802.3bm, the 100GBASE-SR4 QSFP28 is designed for multimode application and support maximum link length of 100 m over OM4 Fiber. The 100BASE-LR4 QSFP28 is designed for single-mode application which support maximum link length of 10 km over SMF. QSFP28 has the same footprint and faceplate density as QSFP+ and is just slightly smaller than CFP4. Theoretically, QSFP28 seems to have the density advantage over CFP4, but CFP4’s higher maximum power consumption gives it the advantage on longer reach optical distances. As the two main types of 100GbE transceivers, each of them has its own merits. Only time will tell how this all plays out.

Conclusion

No matter which Ethernet speed upgrade path will become the winner in this race, there is only one purpose that is to get higher bandwidth and speed with lower cost. Obviously, 25 GbE solution is more suitable for the high-density data center. But at present, for long distance transmission, the existing 40/100GbE solution—QSFP/QSFP+ and CFP family (CFP, CFP2, CFP4) seems to be better. Fiberstore offers a comprehensive solution of fiber optic transceivers and cable assemblies. For data center, we offer a full product line of basic transceiver optics, such as 1000BASE-SX, 1000BASE-LX/LH SFPs, 10GBASE-LR SFP+ etc. We also offer high-density interconnection solution by launching whole series of 40GBASE QSFP+ optics and 100GBASE-LR4 CFP2 and CFP4 optics as well as the cable assemblies. Welcome to contact us over sales@fs.com and get detailed information about more cost-effective fiber optic solutions.

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