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10G-40G Migration: Saving With 40G SMF&MMF QSFP Transceiver

Posted on By FS.COM

The compelling demand for high-bandwidth application pushes data center to greater capacity—from legacy 10G Ethernet to more dense 40G Ethernet network. However, one challenge facing 10G-40G migration is the reduced reach of OM3/OM4 cable: OM4 can reach up to 400 m on 10GBASE-SR transceiver, but for 40G QSFP SR module, the link distance is decreased to 150 m. So we have to re-design or modify the data center to extend the reach. In this case, 40GBASE-UNIV SMF&MMF QSFP transceiver emerges as a perfect fit to solve this problem.

What is 40GBASE-UNIV SMF&MMF QSFP Transceiver?

SMF&MMF 40G transceiver, mostly refer to as 40GBASE-UNIV module, can operate on both 40G single mode fiber (SMF) and multimode fiber (MMF) without any change to the transceiver module or network. 40G SMF&MMF QSFP module is defined by IEEE 40GBASE LR4 spec: terminated with a duplex LC connector, it can reach up to 150 m via OM3/OM4 multimode fiber and 500m-2km (vary from different vendors) via 40G single-mode fiber. This universal 40G transceiver operates on four 10G optical signals at different channels (1270, 1290, 1310, and 1330 nm), then multiplexing these 10G links to transmit and receive an aggregated 40G signal over a single duplex LC fiber cable.

40gbase-univ QSFP-40G-UNIV

A host of vendors today supplies SMF&MMF QSFP transceiver, such as Cisco, Arista, Extreme and Huawei, etc. Let’s take a look at two commonly installed modules: Arista QSFP-40G-UNIV and Juniper JNP-QSFP-40G-LX4 specification.

Connector Type
Cable Type
Core Size
Modal Bandwidth (MHz*Km)
Operating Distance(m)
1270,1290, 1310,1330
2000(OM3) 4700 (OM4)
1270,1290, 1310,1330
1264.5-1277.5 1284.5-1297.5 1304.5-1317.5
2000(OM3) 4700 (OM4)
100m(OM3) 150m (OM4)
1264.5-1277.5 1284.5-1297.5 1304.5-1317.5 1324.5-1337.5

Highlights of 40GBASE-UNIV SMF&MMF QSFP Transceiver

SMF&MMF 40G transceiver enables zero-cost network upgrade by seamlessly integrating the current 10G MMF cabling plant to 40G connectivity, without making any changes to the fiber infrastructure. More benefits of using 40G SMF&MMF transceiver in 10G to 40G transition are listed below.

2-Fiber vs. 8-Fiber: No Additional Fiber Needed

Short-reach 40G QSFP transceivers like QSFP 40G SR4 module and QSFP+XSR4 module (X for extended reach) leverages four independent 10G transmitters and four 10G receivers (8 fibers in total) to deliver aggregated 40G link. When used in 10G-40G migration, these 40G multimode transceivers require parallel OM3/OM4 cables with a 12-fiber MTP/MPO connector to achieve 40GbE transmission. This is four times more fiber than required in 10G short-reach links. While 40G SMF&MMF QSFP transceiver can operate over the same duplex fiber system as 10GBASE-SR module with a duplex LC connector (seen in the below picture). Therefore avoiding the need to add additional fiber patch cables and patch panel infrastructure.


Prepare for Single-mode Fiber Transition

As data rate keeps accelerating, multimode fiber cabling is unable to support existing distance, IT managers are preparing their data centers for 100G and 400G migration with simpler single-mode fibers. 40G SMF&MMF QSFP transceiver reuses 10G fiber infrastructure, but with an extended reach capacity (500m-2km), which makes itself an ideal choice for 40G single-mode fiber infrastructure.

Simplify Cabling with a Mix of MMF and SMF

SMF&MMF 40G QSFP transceiver enables operation on both SMF and MMF, allowing customers to consolidate their optics and use SMF&MMF QSFP transceivers in their network irrespective of the fiber type. Hence one can make full use of the existing cabling systems, and to reap great reward from reduced cost and simplified deployment.

Common Questions On 40G SMF&MMF QSFP Transceiver

How Does SMF&MMF QSFP Transceiver Differ from Other Short-Reach QSFP Transceivers?

Short-reach 40G transceivers include QSFP-40G-SR4 module (100m over OM3 fiber) and QSFP-40G-XSR4 module (300m over OM3 fiber), which are based on the IEEE 40GBASE SR4 standards and operate over parallel MMF with an MPO-12 connector. Thus new fiber is needed to deploy MTP/MPO infrastructure. 40GBASE-UNIV transceiver like Arista 40G-QSFP-UNIV has LC connectors and works on existing OM3 and OM4 duplex multimode fiber infrastructure, eliminating any modification when expending to 40G network.

Is 40G SMF&MMF QSFP+ Interoperable With Other QSFP Transceivers?

40G SMF&MMF transceiver is based on the IEEE 40G-LR4 standard that compliant to IEEE 802.3ba. So it can interoperate with any 40GBASE-LR4 standard transceivers and 40GBASE-LRL4 transceivers, reaching up to 500m over SMF (Distance may differ from vendors). Besides, 40G SMF&MMF transceiver can be plugged into any QSFP+ slot. However, as 40G SMF&MMF transceiver uses a single pair of fibers, it fails to compatible with parallel optics like 40GBASE-SR4 transceiver, which demands MMF to operate on.

Arista QSFP-40G-UNIV vs. Juniper JNP-QSFP-40G-LX4: What Is the Difference?

There are many vendors supplying SMF&MMF QSFP transceiver, but the specific parameters may vary. For example, Arista QSFP-40G-UNIV and Juniper JNP-QSFP-40G-LX4, they have different operating wavelength and distance: Arista QSFP-40G-UNIV can reach up to 500 m on 40G single-mode fiber. While for Juniper JNP-QSFP-40G-LX4 module certificated in 40GBASE-LX4 standard, its reaching distance is further extended to 2 km. So when purchasing a 40GBASE-UNIV QSFP+ transceiver, always refer to the datasheet to know every detail of it.

What Is the Cost Difference Between Using SMF&MMF QSFP Transceiver and Other QSFP Transceivers?

Unlike 40G QSFP SR4 or QSFP LR4 transceiver that utilizes 8 fibers to achieve the transmission, 40G SMF&MMF module only adopts 2 fibers operating over a LC duplex connector, reducing the fibers by four times. This renders to over 75% saving on the cabling equipment alone. 40G SMF&MMF transceiver also enables seamless integration with legacy 10G cabling, so even more significant saving is available. Significant cost reduction is possible.

Where to a Find a Reliable Vendor for SMF&MMF QSFP 40G Transceiver?

The prosperous market has driven more optical transceiver vendors participating to design and provide SMF&MMF transceiver. FS.COM stands out of the competition by providing high-quality 40G SMF&MMF transceiver that fully compatible with Arista QSFP-40G-UNIV, Juniper QSFP-40G-LX4 and other 40GBASE-UNIV module from major vendors. Each optical transceiver is tested on brand-based switch in real environment to ensure performance and reliability. Besides, our global shipping system and adequate product storage enable us to deliver transceiver modules in volume, significantly shorten your waiting time.


40G SMF&MMF QSFP transceivers are ramping up in data centers to facilitate seamless 10G-40G transition, which address significantly cost reduction, simplified cabling and enhanced performance. Get a SMF&MMF 40GBASE-UNIV transceiver today, and prepares your network for tomorrow.