What Are The Differences Between 25G SFP28 SR and 10/25G Dual-Rate SR?

25G Ethernet is gradually replacing 10G Ethernet as the preferred choice for enterprise networks and data centers as the bandwidth demand for network applications grows, especially with the popularity of high-bandwidth applications such as 5G, cloud computing, and AI. How to smoothly transition from a 10G network to a 25G network has become a challenge for everyone, especially for organizations with lower budgets. Whether to directly choose 25G SFP28 optical modules or 10/25G dual-rate optical modules has become a difficult decision. This article will guide you through the differences between these two modules to help you make an informed choice.

What is 25G SFP28 SR 

25G SFP28 SR module is a 25G module using SFP28 package, it uses 850nm VCSEL laser for transmission, and works with OM3/OM4 fiber, the maximum transmission distance is 100M, the module is compliant with the IEEE 802.3by and SFF-8402 standards, although 25G SFP28 SR module is backward compatible with 10G module, it can not be applied to SFP+ ports. 25G SFP28 SR module is usually used in data centers to connect switches and NICs. While the 25G SFP28 SR module is backward compatible with 10G modules, it is not available for SFP+ ports. 25G SFP28 SR modules are typically used in data centers to interconnect switches and NICs, and can also be used with branching cables to connect four 25G modules to one 100G module, allowing the network to move towards 100G Ethernet.

What is 10/25G SFP28 SR 

10/25G SFP28 SR module refers to the module that supports both 10Gbps and 25Gbps rates, it has auto-negotiation function and adopts SFP28 package, it has higher flexibility than 25G SFP28 SR fixed rate. It is compatible with both SFP28 and SFP+ port types, uses 850nm VCSEL lasers for transmission, and has a maximum distance of 400M using OM4 patch cables. 10/25G SFP28 SR modules can be used in 10G and 25G hybrid networks and can be smoothly upgraded from a 10G network to a 25G network later. Like the common 25G SR module, it can be connected with 100G SR4 module in 1:4, and it is also backward compatible with 10G, which can be used to realize network expansion in stages.

Difference Between 25G SFP28 SR and 10/25G SFP28 SR 

Although the 25G SR and 10/25G SR packages are the same, there is still a slight difference in their parameters, and I'll compare the parameters of the two to show you the difference more intuitively.

The main difference between the 25G SFP28 SR module and the 10/25G dual-rate SR module is their support for data rates and, in some cases, transmission distance. While both are packaged in SFP28, the 25G SFP28 SR module operates at only 25Gbps, while the 10/25G dual-rate module supports both 10Gbps and 25Gbps. 

Here is a detailed explanation: 

Data Rates

The 25G SFP28 SR module supports a single data rate of 25Gbps. 10/25G dual-rate modules can be used at both 10Gbps and 25Gbps. The 10/25G dual-rate optical modules are switchable between 10Gbps and 25Gbps, giving them the flexibility to be used to upgrade a network or connect different types of equipment.

Transmission Distance

The 10/25G dual-rate optical module enables greater transmission distance at 10G and 25G rates with the same fiber type (OM3/OM4) than the standard 25G SR optical module. For example, a 25G SFP28 SR can only transmit 100M using OM4, while a 10/25G dual-rate module can achieve a maximum distance of 400M.

Compatibility

10/25G dual-rate optical modules can be used with 10G SFP+ ports and 25G SFP28 ports, providing flexibility for network upgrades. The 25G SFP28 SR module is only compatible with SFP28 ports.

25G SFP28 SR and 10/25G SFP28 SR Application Scenario Comparison 

25G SFP28 SR 

25G SFP28 SR modules are generally used in 25G private networks to support high-rate applications.

In 25G private networks, 25G SR modules are typically used to directly connect 25G switches and server NICs for efficient intra-rack communications.

25G SR modules can also be used in 5G to support high-speed connections between base stations and distributed units to support low-latency, high-bandwidth 5G networks.

The 25G SR module also has a wide range of applications in large-scale virtualization and hyper-converged systems. Stable 25G connectivity can be achieved in platforms with high traffic throughput through bulk deployment.

The 25G SFP28 SR module can also be used to achieve seamless connectivity with 100G by branching patch cords to realize 1X 100G QSFP28 to 4X 25G SFP28, an application that is ideal for networks with high bandwidth requirements. Especially in high-density environments, data can be aggregated and processed through 1x4 connections, and it is also able to smoothly migrate to 100G networks.

10/25G SFP28 SR 

The 10/25G SFP28 SR Dual Rate Module offers broader compatibility with the 25G SFP28 SR Fixed Rate Module than the 25G SFP28 SR Fixed Rate Module for mixed 10G and 25G networks. In a network where 10G and 25G devices coexist, the 10G/25G SR can automatically negotiate the appropriate rate to seamlessly connect 10G and 25G devices, reducing the complexity of equipment replacement and cabling, and making it easier to maintain at a later stage.

The 10/25G SR module can also play a transitional role when upgrading from 10G to 25G networks. Because it supports both 10G and 25G devices, it is ideal for companies or organizations that want to upgrade their networks in stages, without having to pause the network to do so and without disrupting business.

The 10/25G SR module is also suitable for cost-sensitive networks. When the network moves from 10G to 25G, it can realize 25Gbps transmission without replacing the optical module, which reduces the cost of the upgrade.

Conclusion

25G SFP28 SR modules and 10/25G SFP28 SR modules have different application scenarios. If your network is a 25G network, then direct deployment of 25G modules is a good choice because they are more cost-effective. If you are using a 10G, 25G hybrid network and intend to migrate to a 25G network, then 10/25G dual-rate modules are more suitable.