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10G SFP+ to 25G SFP28 or 10G SFP+ to 40G QSFP, Which to Choose?

Author Derek

Date 11/06/2021

The existing 10G networks are in saturation with increasing bandwidth requirements between the server and switches in recent years, so it is urgent to upgrade the 10G network to a higher speed. Today’s data center network trends are 100G/200G/400G. Now comes the question, which is the better transition plan among 40G QSFP+ transceivers and 25G SFP28 transceivers to upgrade to 100G and beyond. This article will tell.

25G Ethernet vs 40G Ethernet


25G Ethernet standard is an incremental update from 10G, and has the smallest pluggable form factor referred to as SFP28, which is similar to SFP+. The 25G SFP28 transceivers are backward compatible with SFP+ ports and existing data center infrastructure while seamlessly upgrading to 100G and beyond. SFP28 has a single lane at 25G, which supports efficient upgrading to 100G server connections at 4x25G configuration. The 25G Ethernet is generally applied in data center interconnects for storage, serves, switches, and 5G fronthaul.


See how to choose a 25G SFP28 Transceiver here.


40G Ethernet was the only upgrade transition path to higher speed 100G connectivity before the 25G Ethernet standard was issued. QSFP+ is the mainstream form factor type for 40G Ethernet transceiver, which provides four transmit and four receive lanes to support 40 Gigabit Ethernet applications. 40G Ethernet is mainly generally applied in the connection between data center switches to help break the bottleneck of the connection between access switches and distribution switches.



Upgrade Path of 10G SFP-40G QSFP-100G QSF28 vs 10G SFP-25G SFP28-100G QSFP28


10G-40G-100G vs 10G-25G-100G upgrade path

Fig. 1 - 10G-40G-100G vs 10G-25G-100G upgrade path


1. 10G SFP+ to 40G QSFP+ to 100G QSFP28 Upgrade Path

10G-40G-100G upgrade path supports 40G Ethernet at 4x10G parallel lanes and supports 100G Ethernet at 10x10G parallel lanes. Based on the single lane of 10G, the upgrade path is space-efficient and costly in cabling deployments. Besides, the underlying technology for 40G Ethernet is simply four lanes at 10G speed, which does not provide the advantages of power consumption, server rack density, and compatibility to widespread speed transition.


2. 10G SFP+ to 25G SFP28 to 100G QSFP28 Upgrade Path


The 10G-25G-100G upgrade path provides 2.5x higher bandwidth connectivity of the 10G in 25G Ethernet with only slightly increased cost. The upgrade path achieves 100G Ethernet by 4x25G based on 25G switch infrastructure without having to re-plan or change server per rack density, which saves a large number of fiber resources also. Moreover, the power consumption of the 4x25Gbit/s configuration is much lower than the 10x10Gbit/s configuration.



Why Choose 10G SFP+ to 25G SFP28 rather than 10G SFP+ to 40G QSFP


25G SFP28 is Back Compatible with 10G SFP+


25G SFP28 has a similar form factor to the existing 10G SFP+, it’s backward compatible with 10G SFP+. Also, the 25G switch has higher compatibility than the 40G switch. The majority of 25G switches and NICs (Network Interface Cards) enable backward compatibility to 10G and provide higher flexibility to manage a gradual upgrade to higher data rate servers and match port speeds.


Higher Bandwidth of 10G SFP+ with Dense 25G SFP28 Port Density


25G SFP28 transceiver enables network equipment manufacturers to provide 2.5x higher bandwidth connectivity of the 10G at approximately the same power, which is much lower than 40G. Besides, the 25G SFP28 module allows higher port density configurations than the 40G QSFP module.


25G SFP28 is Better Matched to 50G/100G Upgrading


25G Ethernet use single-lane 25G serializer-deserializer (SerDes) technology while 40G Ethernet consists of four lanes of 10G, thus 25G SFP28 modules can be used to build 50G Ethernet with 2x25G configuration and 100G Ethernet with 4x25G configuration without having to re-plan or change server per rack density, as shown in Fig.2.


25G SFP28 is better matched to 50G and 100G upgrading

Fig. 2 - 25G SFP28 is better matched to 50G and 100G upgrading

25G-100G Upgrade Path is More Cost-effective than 40G-100G Path


Upgrading from 25G to 100G can be achieved by 4x25G, the CapEx(Capital Expenditures) and OpEx (Operational Expenditures) saved by utilizing the existing cabling infrastructure and high backward compatibility. On the whole, the 25G to 100G upgrade path reduces the cost per gigabit significantly by fully utilizing switch port capability.





As cutting-edge technologies emerges and business needs grow, your 10G network infrastructure faces the challenge of upgrading to higher data rates. 10G SFP+ to 25G SFP28 and 10G SFP+ to 40G QSFP+ are two solutions to transit the transformation to 100G Ethernet. While considering backward compatibility, power consumption, port density, adaptability to legacy 2x 25G and 4x 25 configuration, and cost-efficiency, 25G SFP28 provides a future-proofing method to upgrade to 100G access. With the trends of enterprise server access gradually changing from 1G-10G to 10-25G, the number of 25G SFP28 port shipments will continue to grow in the next few years.


QSFPTEK provides widely compatible and quality assured 25G SFP28 transceivers at the best price based on mature 25G SFP28 production techniques. You can ask any questions about SFP28 via sales@qsfptek.com.



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