As usual, optical transceivers such as SFP or SFP+ use two fibres to transmit data between switches. One fibre is used to transmit data to the network equipment and the other fibre is utilised to receive the data. As to the transceiver modules of high speed data rate like QSFP-40G-SR4 and QSFP-40G-ESR4, they need more fibres. Is there any technology allowing transceivers to transmit and receive through one single optical fibre or two fibres for QSFP+? In fact, this can be achieved by Bidi transceivers.
What Is BiDi Transceiver?
The answer is yes. And that kind of transceiver is called BiDi transceiver. Bidi (Bi–Directional) transceiver is also known as WDM transceiver, because it applies wavelength division multiplexing (WDM) couplers, also called diplexers, which combine and separate data transmitted over a single fibre based on the wavelengths of the light.
Compared with traditional transceiver modules, BiDi transceivers can cut your cost on fibre cabling infrastructure by requiring fewer fibre cables, reducing the number of fibre patch panel ports and saving fibre cable management space. Based on the obvious advantages, you should deploy BiDi transceivers in your network. Here will recommend you several kinds of BiDi transceivers of 1Gbps, 10Gbps and 40Gbps.
BiDi SFP transceivers transmit and receive optical signal through a single fibre on the wavelengths of 1310 nm & 1490 nm, 1310 nm & 1550 nm, 1490nm & 1550 nm. BiDi SFPs include the supportable data rate of 100Mbps and 1000Mbps. Take the Cisco GLC-BX-U compatible 1000BASE-BX-U BiDi SFP as an example. The wavelengths of the BiDi SFP are 1310 nm and 1490 nm. It can support the link lengths of 10 km over LC simplex fibre patch cable. As shown in the following figure, a pair of Cisco GLC-BX-U compatible BiDi SFPs are linked via a single LC simplex fibre patch cable to build the direct connection of two Cisco Catalyst 4948E-F switches.
Bidi SFP+ transceiver is enhanced SFP designed to support 10Gbps data rate with link lengths up to 80 km over one fibre. It uses WDM technology sharing 1270 nm & 1330 nm. Take a look at the figure below. It’s about the direct connection for 10G BiDi SFP+ in room wiring. The two Cisco SFP-10G-BXU-I compatible 10GBASE-BX10-U SFP+ transceivers are plugged into Cisco Nexus 9396PX switches. The connection is achieved by using an LC simplex fibre patch cable. It’s a simplest and cost-effective way to build 10 Gigabit Ethernet connectivity for data centre.
40G BiDi QSFP+ transceiver is specially designed for high density data centre. With QSFP+ BiDi transceivers, you can get 40Gbps network over 10Gbps cable. In this way, you don’t need to replace all 10G two-fibre patch cables with 8-fibre MTP/MPO patch cable if you need network upgrade. In Figure 3, we use Cisco QSFP-40G-SR-BD compatible 40GBASE-SR BiDi transceivers for the direct connection of two switches. Instead of applying 40G MTP patch cable, we can just plug the common LC-LC fibre patch cable into the transceivers to get 40Gbps network. It saves you lots of costs.
Warm Tips: When you buy a BiDi transceiver, you may notice wavelengths are labeled on the BiDi transceivers like 1270nm-TX/1330nm-RX or 1270nm-RX/1330nm-TX. From this perspective, you can see this type of transceivers should be used in matched pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to.
BiDi transceivers may be more expensive than common transceiver modules, but they can save you the cost on fibre cables from the long run. FS offers BiDi transceivers of various data rates which are highly compatible with some famous brands. If you plan to purchase BiDi transceivers for building or upgrading your network, you can visit our site www.fs.com.
Related Article: A Brief Introduction of BiDi SFP Transceiver