25G SFP28 transceivers: Quo Vadis?

25G SFP28 transceivers: Quo Vadis?

Nielsen’s Law of Internet Bandwidth states that users’ bandwidth grows by 50% per year, and this law has held true for a period of 37 years, all the way back to 1983.

Figure 1. Internet connectivity (bits per second)

It is always interesting to ask – which will be these traffic-hungry applications that will keep this law in check? Sometimes it is hard to imagine them through today’s lens, but let’s give it a try. It is estimated that a self-driving car will have more than 100 sensors and it will generate 10 GB of data per 1 kilometer, AR (Augmented Reality) and VR (Virtual Reality) headset for a 360-degree digital experience will generate about 11 GB of data an hour, targeting retail, entertainment, health and gaming industry, holographic 3D teleconferencing, holographic avatars (multi-dimensional information replicas of a true scene or real objects), telesurgery, remote patient monitoring, all these are just a few examples of data intensive applications which we might meet in the future. We will eventually approach the point where the line between virtual and real aspects of communications will begin to blur.

If we look at 25G SFP28, it looks like a small piece in this big puzzle, but it is an important piece as technologies are developing gradually, and all things are interconnected. For applications to have a fertile soil, there should be an infrastructure in place. As traffic is growing, this gives great pressure to Network Architects who need to design their networks optimally, so that the choices made today look wise and solid as well as tomorrow.

25G SFP28 is an important milestone in the path to 100G-200G-400G Ethernet and towards 5G Mobile Networks. Let’s take a closer look at how 25G SFP28 will transform the 3 most typical networking scenarios: Ethernet, Mobile Networks, and Datacenter SAN (Storage Area Networks).

The 10G-25G-100G Path in Ethernet Networks

Figure 2. Upgrade Path Comparison between 10G – 40G and 25G – 100G

25G Ethernet is the perfect path towards 100G and beyond. The key reason for that is 25G SFP28 helps to achieve a 2.5 times increase in speed, in the same size shell as 10G SFP+ (thus same front panel space on the switches), and uses the same cabling infrastructure as 1G/10G networks operators have now. The good news doesn’t even end there: 25G SFP28 is backward compatible with 10G SFP+ ports, is a future-proof solution towards 100G (100G consists of 4 parallel 25G channels), and uses the same power levels as predecessor 10G SFP+ modules.

An important aspect to mention is that a 25G data rate is the maximum data rate that we can achieve on 1 lane with NRZ modulation (by flashing light on and off). All the higher data rates 100G-200G-400G-800G are delivered either by adding more parallel transmission lanes or by changing modulation PAM4 (Pulse Amplitude Modulation) or by doing both at the same time. The main players for the 25G Ethernet are existing well-known vendors such as Cisco, Huawei, Juniper, Nokia/Alcatel, HP, Intel, Mellanox, and Dell.

25G SFP28 in 5G Mobile Fronthaul

People with a crystal ball in the mobile industry see massive growth and investments towards 5G Mobile Networks from 2020 to 2025. Key things 5G promises to bring are higher bandwidth, lower latency, and higher reliability. With the help of these 3 things, 5G Networks would actually make the infrastructure in place to help reshape traditional industries (and potentially make new ones we can’t even imagine) so that one day we would wake up in a completely new reality. For example, in the world where Transportation industry has vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) Intelligent Transport Systems, driverless cars, connected drones, Health industry has robotic surgery using VR, AR, Marketing/Sales use Virtual Reality (VR) and Augmented Reality (AR), we live in Smart cities and our businesses run using indus-trial automation and robotics and to make picture more complete we could add on top of that Artificial Intelligence (AI).

From a technical standpoint, 5G uses much higher radio frequency bands (mmWave), Massive MIMO and Beamforming technologies, which require bringing the Remote Radio Unit (RRU) closer to the end users and therefore a much denser RRU distribution. Additionally, enhanced Common Public Radio Interface (eC-PRI) is introduced, and 5G sets new speed requirements for Baseband to the Antenna connection, which are at 24.33 Gbps (CPRI Option 10), and this is where 25G SFP28 comes into play. 25G SFP28 optical transceivers will be among the many building blocks for the 5G Mobile Fronthaul to help interconnect BBU with RRU. The top wireless infrastructure companies for the 5G era remain: Huawei, Ericsson, Nokia, ZTE, and Samsung. Each of these brands requires specific EEPROM coding in the 25G SFP28 optical transceivers to make them compatible and usable in the base station.

32G SFP28 Fiber Channel in SAN

Figure 3. SAN component layers

We experience exponential growth of unstructured data, and requirements for fast, reliable, low-latency interconnections between computer data storage and servers keep growing. Fiber Channel (FC) is one of the leading protocols that can meet all the above and is favored by many Data Centers and large-scale industrial and commercial enterprise networks.

Evolution path of Fiber Channel data rates

32GFC uses the same SFP28 form factor as 25G Ethernet (25.78 Gbps), but its data rate from a software and hardware perspective is tweaked to 28.05 Gbps.

Leading equipment vendors specializing in Fiber Channel switches are: Broadcom (Brocade), HP, and Cisco, where the main vendors specializing in Fiber Channel HBAs (Host Bus Adapters) are Marvel (QLogic) and Broadcom (Emulex).

Afterwords

25G SFP28 has all the preconditions to transform how we build Next Generation Ethernet, 5G and Storage Area Networks and we expect that this form factor and data rate will have a dominant role in our industry and will be mainstream. We highly appreciate the time You spent reading this and if You have any questions or comments, feel free to reach us by e-mail sales@edgeoptic.com or by giving us a call at +371 22084457.