With the research and development of 25G by famous enterprises in Google, Microsoft and other industries and the recognition of 25G by industry suppliers, more and more people begin to support the use of 25G.  The emergence of 25G has made the upgrade path of 10G-100G more excellent. Compared with 40G, 25G has the advantages of high density and low cost.  Nowadays, 25G products are constantly emerging in the market, including 25G optical network cards. Do you know what 25G optical network cards are?  This article will focus on this product for you.

What is a 25G optical network card?
Optical fiber network card (NIC), also known as server network card, is a printed circuit board that can provide network communication functions for computers. It is usually used as a separate network adapter inserted into the motherboard slot of the server.  The 25G optical network card generally works in the physical layer or the data link layer and has a unique physical address (MAC address).  In addition, the side plates of 25G optical fiber network cards are provided with ports (as shown in the following figure), which are mainly used for inserting optical modules to connect switches. Generally, 25G optical fiber network cards are provided with one port, but there are also 25G optical fiber network cards with two or more ports.  As we all know, 40G is in the transition period of the network. As the bandwidth of 40G optical network card is too large for the server and the cost is relatively high, 25G optical network card is more in line with the requirements of the server than 40G optical network card.  ?

Why do we need 25G optical network card?
25G Ethernet has developed rapidly with impressive high performance and low cost.  The popularization of 25G server connection has promoted the strong development of 25G optical network card.  Compared with the previous 10G, 25G allows more bandwidth to be transmitted over single-core copper wire or optical fiber. Therefore, 25G can upgrade 100G network only through four channels (10G needs to realize 100G through ten channels), effectively saving a lot of space and cost.  At the same time, the bandwidth of 25G is 2.5 times that of 10G, while the price of 25G optical network card is less than 2.5 times that of 10G optical network card. Therefore, 25G optical network card is more cost effective.  The larger bandwidth of 25G optical network card can meet the network requirements of high-performance computing clusters. 25G optical network card will be one of the indispensable infrastructures in the network upgrade of 100G or higher rate.

Connection Scheme of 25G Optical Network Card between ToR Switch and Server
Compared with 10G-40G-100G, the application of 25G optical network card in server can effectively increase the connection cost between 10G-25G-100G or 10G-25G-50G-100G switch and server.When using 25G Ethernet, the connection between switches and servers in the cabinet often adopts ToR architecture.  In ToR architecture, 25G ToR switches are placed at the top of each cabinet and are directly connected to 25G servers in the cabinet through point-to-point cabling, while 25G fiber network cards are commonly used in 25G servers for signal transmission.  The connection between 25G server and 25G switch can be realized through 25G high-speed cable (DAC) or active optical cable (AOC) or 25G optical module and fiber jumper.  GRT 25G optical fiber network card can provide a faster, higher performance and backward compatible connection scheme for 25G Ethernet.

How to Select 25G Optical Network Card?
At present, some well-known manufacturers (such as Dell, Intel, etc.) have launched fierce competition in this field. Of course, Guangruntong is no exception. In order to meet the demanding requirements of the current data center environment and to reserve space for future network expansion, Guangruntong can provide you with a 25G optical network card with high flexibility and strong expandability.  As we all know, 25G optical network card is mainly used for the connection between servers and switches. For servers that operate frequently, it is necessary to select a higher quality 25G optical network card and invest more money in it.  When selecting a 25G optical network card, you can focus on the following three aspects:

1．Number of Ports of 25G Optical Network Card

The ports on 25G optical fiber network cards are generally connected to communication media (i.e. network communication lines), i.e. common SFP28 optical modules or SFP28 high-speed cables (DAC), which are used for accessing the Internet, storage and management. Currently, there are 1/2/4/6 ports of 25G optical fiber network cards on the market. You can select the appropriate 25G optical fiber network cards according to actual applications.

2．Interface Type of 25G Optical Network Card

The interface type of 25G optical network card is also the most important factor to consider when selecting 25G optical network card.  Compared with ISA (industry standard architecture), PCIe (high speed serial computer expansion bus standard) has the greatest advantage in high data transmission rate, so PCIe is the most ideal interface solution for 25G optical network card.  After continuous innovation, PCIe has successively released several versions of PCIe 1.0, PCIe 2.0, PCIe 3.0, PCIe 4.0, etc. Among them, PCIe 3.0× 8 (the x number indicates the physical size of PCIE, x16 is the maximum number, x1 is the minimum number) is welcomed by major manufacturers in the application of 25G optical fiber network cards.  Compared with PCIe 1.0 and PCIe 2.0, PCIe 3.0 can support 984.625 MB/s of maximum bandwidth per channel.  Before purchasing, you must clearly understand that if you want to choose a PCIe 3.0×8 25G optical network card, the server must support PCIe 3.0 and have a PCIe x8 slot.  Therefore, when purchasing, you must consider whether the servers you currently own or will purchase meet the standards.

3．Chip of 25G Optical Network Card

If you want to give full play to the function of 25G optical network card, its chip is especially important, which determines the quality, stability and speed of 25G optical network card.  Some large manufacturers usually choose Intel chips in order to ensure the high quality, high stability and high compatibility of 25G fiber optic network cards.  Guangruntong 25G optical network card is based on Intel® XXV710 chipset, compatible with PCIe x16 slot, with high flexibility and scalability, and meets the requirements of running mission-critical applications in virtualized and unified storage environments.

Summary
Nowadays, the vast majority of server vendors choose 25G optical network card as the I/O solution for servers. The network adopting this method has the advantages of higher speed, cost performance and backward compatibility, which can help large data centers reduce the total cost of ownership (TCO) of 100G network upgrade.  GRT has fully prepared for the upgrade of the 100G network. besides providing you with a 25G optical network card with high flexibility and expansibility, GRT has also introduced a series of 25G products, including optical modules, switches, high-speed cables and active optical cables.