25G Vs. 40G Ethernet: Who Is the Winner?

In recent years, the fast growth of data centers leads to increase in global data traffic, which give rise to the need for faster data transmission over a network. 25G Ethernet is the product of that condition. 25G Ethernet is regarded as an incremental update from 10G Ethernet, and it supports 100G Ethernet with single lane at 25Gbps. Due to the booming of 25G, some industry experts claimed that 40G Ethernet is dead, which is biased in some degree. Then 25G vs. 40G Ethernet, which is even better?

Advantages and Disadvantages of 25G and 40G Ethernet
Advantages of 25G Ethernet

Different from 40G and 100G, 25G is a single-lane variant for 25Gbps operation, and that allows a breakout of 100G, which fit the most popular form factors. Based on existing module form factors, such as SFP28 and QSFP28, 25G operations allow for a breakout connection that is configurable as either 25G per lane or the full 100G without changing the port on front of switches, bring more flexibility in the rack and front-panel connections. In addition, with the 25G Ethernet, network operators are no longer forced to use a 40G QSFP port to go from one individual device to another to achieve 100G throughput. The final advantage of 25G is that it can use existing optical plants (depending on what was installed) and increase the bandwidth by 2.5x without changing the physical infrastructure.

25g ethernet sfp28

Disadvantages of 25G Ethernet

As 25G Ethernet is just rising, the interoperability becomes an important factor to ensure wide market adoption and to offer higher speeds for future applications. Besides, compared with 10G 40G and 100G, there aren’t many products of 25G, which limit the development of 25G networks.

Advantages of 40G Ethernet

40G Ethernet is an Ethernet standard developed by the IEEE 802.3ba Task Force to support sending Ethernet frames at 40 gigabits per second. It also addresses physical layer specifications for communication across back planes, copper cabling, multimode fiber optic cable, and single mode fiber. And 40G Ethernet technology is more mature compared with 25G. In the market, there are various types of products for 40G applications, especially the MPO trunk cable assemblies, cassettes, and QSFP 40G optical modules, which offers the required bandwidth for different applications.

40G solution

Disadvantages of 40G Ethernet

At present, 40G is popular in data centers and no drawbacks found. If we have to say one, the utilization of fibers may be one. As we all know, 12-fiber cabling solution is common in 40G networks. But there are four fibers unused, resulting in fiber waste.

Comparison Between 25G and 40G Ethernet in Network

At present, 25G is mainly used for switch-to-server applications. While 40G is for switch-to-switch applications. In other words, no one is using 25G for switch-to-switch links right now. Even the industry giant like Cisco doesn’t offer 25G optical transceiver. But with the fast development of 25G Ethernet, 25G for switch-to-switch application maybe come into reality in the near future.

Switches Selection

Switches are important when comparing 25G and 40G Ethernet. Most switches are currently sold, like Cisco 93180YC-EX, Arista 7060CX-32S support both 10G and 25G, and the price is not higher than older 10G products with full backward compatibility. For example, each SFP28 port supports 1G, 10G or 25G, and each QSFP28 port supports 10G, 25G, 40G, 50G or 100G.

Cabling Options

Cabling options determine how far the two types of Ethernet go. It’s a big mistake to ignore cabling. In the market, there are several types of cabling options, and there are some big swings in price. Here is a simple comparison.

25g ethernet vs 40g ethernet


From the comparison above, we can draw a conclusion that 25G Ethernet can be used for data centers, but it doesn’t mean 40G is dead. Even though 25G Ethernet seems to have a brilliant future, under present conditions, 40G is a safe choice due to its mature market adoption. Perhaps in a few years, 25G connectivity will be a cheaper alternative.

Server Power Cords Applications in Different Cabling Systems

Each power supply has a separate power cord to support its work. Server power cord connecting the servers and PDU (power distribution unit) plays a critical role in this process. Since the power cords standard for connector types and voltage levels varies from country to country. It’s important to choose the most suitable one for network systems. This post intends to give a simple introduction to server power cords and their applications in different systems.

Power Cords Overview

Usually standard power cords or jumper power cords are available for connection to the server. Power cord consists of three necessary parts: plug, cord and receptacle. And there are many different types of power cords used all over the word. The most commonly seen types are the IEC60320 power cord and NEMA power cord. The former one is often used in US. While the latter is usually seen in North America and other countries that use the standards set by the NEMA.

Among these two types of power cords, the most popular one in some vendors like Dell, HP and IBM is the C13 to C14 power cord. And there are many kinds in this two types of power cords. Here is a simple table showing them.

C14-C13 5-15P – C13
14 to 13 power cord NEMA 15p-C13 power cord
C14-C15 5-15P – C15
C14 to C15 power cord 5-15P - C15 power cord
Applications in Different Cabling System
Cabling for Low Density System

It’s relatively easy to install cords for low density systems. Take servers in a tower configuration for an example. It needs to use a country-specific power cord for direct connection to a facility AC feed. However, server availability goals can require providing redundant AC power to the server in the form of a redundant AC bus or a UPS. The following figure shows two servers connected an UPS with a different types of server power cords. Server in picture A uses C13 to C14 power cord, and server in picture B uses NEMA 5-15P to C13 power cord.

server power cord 1

Note: Connection to a local AC outlet requires an optional country-specific power cord for each power supply. Just shown in picture A above.

Cabling for Medium Density System

Medium density system is a little complex than low density system. Therefore different types and other accessories are maybe needed to achieve an effective power connection. Just shown in the following picture, power connections are achieved using modular PDH, extension bars and C13 to C14 power cord assemblies.

server power cord 2

Note: some servers contain hot-pluggable fans accessible by sliding the chassis out on rails. This means the power cords or jumper cables connecting to the servers must have adequate length and slack to allow chassis movement while staying connected and powered up.

Cabling for High Density System

Compared with the application of power cords in the two systems mentioned above, power cords used in high density systems can be short since cable movement is of little. This following figure shows three kinds of methods to connect enclosures to AC power. The first one shown in the upper area of this figure is that the C13 to C14 power cord is used to connect a single-supply server to a vertical mount PDU, which is suitable for lower-density installations. The second shown in the central area of the figure is to use the C13 x4-to-C20 fixed cord extension bars, a method recommended for extreme-density installations using redundant power supplies. The last one shows the use of a C13 x2-to-C20 Y-cable assembly recommended for connecting a server with dual 1200-watt power supplies directly to a PDU core with C19 outlets.

server power cord 2

Note: Considering there are many cables used in high-density systems, color coding power cords are helpful in systems like that.


Power cords serve as an important bridge in the network device power supply system. FS.COM offers several varieties of IEC power cords, NEMA power cords, and jumper cords for server rack equipment in up to 12 colors with many different types and options for your data center power cords, including: IEC C14 to C13, C20 to C19, C14 to C15, etc. Welcome to visit our website www.fs.com for more information.