As demand grows for higher speed networks, migration from 10GbE to 40GbE is becoming increasingly commonplace in data centers. However, the widely available parallel-optic QSFP+ transceiver used in 40G networks requires us to replacing or redesigning the existing 10G data center fiber infrastructure. In this case, the QSFP-40G-UNIV transceiver is introduced as a perfect solution to resolve this problem as it allows the same cables to be used for 10G connections to 40G connections.
Also named 40GBASE-UNIV or 40G QSFP+ universal transceiver, the QSFP-40G-UNIV is an industry-standard pluggable optical transceiver with a duplex LC optics interface. It has four 10G optical transmit channels and 10G receive channels that are multiplexed inside the transceiver module to transmit and receive an aggregated 40G signal over one single duplex LC fiber cable. Unlike other 40G QSFP+ transceivers, the QSFP-40G-UNIV transceiver can work with both duplex multimode and single-mode fiber cables without any changes to the transceiver or any additional hardware in the network. 40GBASE-UNIV transceivers can reach up to 150 m via OM3/OM4 multimode fiber and 500 m to 2 km (vary from different vendors) via 40G single mode fiber. Besides QSFP-40G-UNIV transceivers, JNP-QSFP-40G-LX4 and FTL4C2QE1C 40G LM4 transceivers are also introduced to support 40 Gigabit Ethernet links over LC-duplex fiber pair instead of MTP parallel cabling.
Except for the above-mentioned QSFP-40G-UNIV transceiver, the 40G BiDi QSFP+ transceiver is also designed with a duplex LC interface and allows reuse of the existing 10G duplex multimode fiber pair for 40G connection. However, the BiDi transceiver employs only two wavelengths (typically 850 nm and 900 nm) transmitting in the same fiber in opposite directions, with an actual bit rate of 20 Gbps. In addition, 40G BiDi QSFP+ transceivers are used only in OM3 or OM4 multimode cabling with distance up to 150 m.
Since QSFP-40G-UNIV transceivers have the same duplex LC optics interface as 10G transceivers and their transmission distances range from 100 m to 2 km, migrating from 10GbE to 40GbE becomes much easier and simpler: apart from the hardware replacement, users only need to replace existing 10G transceivers with 40GBASE-UNIV QSFP+ modules. In addition, there are more benefits listed below.
It is known that 40G short-reach transceivers such as 40GBASE-SR4 and 40GBASE-XSR4 transceivers often require 12-fiber parallel MTP OM3/OM4 cables to achieve 40GbE transmission per link. This is four times more fiber per link than is needed for a 10G short-reach link. QSFP-40G-UNIV transceivers operate over the same duplex fiber system as 10GBASE-SR modules, avoiding the need for expensive 40GbE migration cassettes and an additional MTP fiber infrastructure deployment.
QSFP-40G-UNIV transceiver enables operation on both SMF and MMF, allowing customers to consolidate their optics and use QSFP-40G-UNIV QSFP+ transceivers in their network irrespective of the fiber type. In addition, QSFP-40G-UNIV can interoperate with QSFP-40G-LR4 and QSFP-40G-LR4L which avoiding the transition process of moving from multi-mode to single-mode fiber cabling, further simplifying data center cabling.
As we know, OM3/OM4 multimode fiber cables have limited transmission distance in the future 100G or even 400G network. Therefore there is a strong desire for the data center to move to single mode fiber cabling for cost-effectiveness migration. But the price of 40G long-range single mode transceivers is too high. The 40GBASE-UNIV transceiver is an ideal choice for 40G single mode fiber infrastructure for distances from 500 m to 2 km.
How does QSFP-40G-UNIV 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 MTP connectors. 40GBASE-UNIV transceiver has LC connectors and works on both SMF and MMF fibers.
Is 40G QSFP-40G-UNIV QSFP+ interoperable with other QSFP transceivers?
The QSFP-40G-UNIV transceiver is based on the IEEE 40G-LR4 standard that is compliant to IEEE 802.3ba. So it can interoperate with any 40GBASE-LR4 standard transceivers and 40GBASE-LRL4 transceivers. Besides, a 40G QSFP-40G-UNIV transceiver can be plugged into any QSFP+ slot. However, as 40G QSFP-40G-UNIV transceiver uses a single pair of fibers, it fails to interoperate with parallel optics like the 40GBASE-SR4 transceiver.
Can the QSFP-40G-UNIV transceiver be used to break out 4x10G connections?
No. Only 40G transceivers that use MTP parallel fiber cables are available for applications requiring four 10GbE ports from a single QSFP interface. QSFP-40G-UNIV and all other 40G duplex modules are not capable of being broken into 4x10G.