10G Infrastructure for 40G Ethernet With 40G BiDi Optics

During migration from 10G to 40G, one of the most headache problem is that the 10G infrastructure is different from 40G. For example, 40GASE-SR4 QSFP+ transceiver is the most popular solution for 40G transmission in short distances. It uses four 10G lanes to support 40G through a 12-fiber MTP/MPO interface, with four for receiving and four for transmitting and the rest fibers are not in use. However, in traditional 10G transmission, a duplex fiber optic patch cable is enough, with one fiber for receiving and the other for transmitting. This difference requires the change of infrastructure when upgrading 10G network to 40G network. If the 40G QSFP+ transceiver for short distance also using the duplex transmission mode, things would be much easier. That’s why we have 40GBASE-SR BiDi QSFP transceiver. This 40G BiDi optics targeting on 40G Ethernet can finish both the transmitting and receiving via a duplex LC patch cords.

LC-LC patch cords

How Does 40GBASE-SR BiDi QSFP Work?

The secret of this 40G BiDi transceiver for short distance is based on the wavelengths. Instead of using four different lanes, this 40G BiDi QSFP uses two duplex 20G transmission mode on two fibers. In simple, each fiber optic should carry two 20G signals over two different wavelengths (usually 850nm and 900nm) respectively. The signal is sent to a target device via 850 nm on one fiber. The signal from the target device is sent via 850 nm on the other fiber. This also works for signals on 900 nm, as shown in the following picture.

40G BiDi QSFP optics

This is why 40GBASE-SR BiDi QSFP transceivers can support 40G Ethernet by using a duplex LC patch cords. Compare with the traditional 40G connection for short distance, 40GBASE-SR BiDi QSFP transceivers is straightforward. Replace the 10G optics by 40G BiDi QSFP optics and no additional cassettes are needed, you can have 40G Ethernet.

40GBASE-SR BiDi QSFP, Just Easier 40G Migration?

The power of 40GBASE-SR BiDi QSFP is definitely not limited to offering easier 40G migration path. 40G BiDi QSFP can also largely decrease the cost for 40G cabling. The traditional 40G short distance links usually pre-terminated 12-fiber MTP/MPO trunk cables with OM3/OM4 fibers, which are expensive than LC multimode patch cords. In additon, for nearly 95% of our data center links are no longer than 200 meters. The 40G BiDi optics can support 40G Ethernet up to 100 meters (OM3) and 150 meter (OM4). That means 40GBASE-SR BiDi QSFP can cover a wide range of using in data center. With LC patch cords being used, more space can be saved. And data center can have better cooling.

40GBASE-SR BiDi QSFP and Cabling Solution

Without changing the 10G cabling infrastructure, you can have 40G Ethernet by using 40GBASE-SR BiDi QSFP transceivers and duplex LC patch cords. The following table offers the 40GBASE-SR BiDi QSFP related products. To meet the high density trend in data center, a new version of LC patch cords with push-pull tab is also provided.

QSFP-BD-40G40GBASE-SR Bi-Directional QSFP Module
850/900nm,100m(OM3)/150m(OM4) LC Transceiver for MMF
LC/LC OM3 Patch CordsLC UPC to LC UPC 50/125 OM4 Duplex Multimode Fiber Patch Cable
LC/LC OM4 Patch CordsLC UPC to LC UPC 50/125 OM4 Duplex Multimode Fiber Patch Cable
Push-Pull Tab LC/LC OM3 Patch CordsLC-HD to LC-HD Duplex OM3 Multimode Push-Pull Tab Fiber Patch Cable
Push-Pull Tab LC/LC OM4 Patch CordsLC-HD to LC-HD Duplex OM4 Multimode Push-Pull Tab Fiber Patch Cable
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