Fiber-Optic Cabling Connectivity for 40Gbps QSFP+
The data center is one of the most critical and dynamic operations in any business. As companies produce, collect, analyze and store more data, IT infrastructures need to grow as well to keep up with the demand. The speed of data center now is increasing to 40 Gbps and eventually to 100 Gbps. Thus, new optical technologies and cabling infrastructure are required. Now let's see some commonly used fiber cabling connectivity options for 40Gbps QSFP+ optics.
40G QSFP+ Optical Modules
As we know, fiber optical transceiver is an electronic device that receives an electrical signal, converts it into a light signal, and launches the signal into a fiber. It also receives the light signal, from another transceiver, and converts it into an electrical signal. Optical transceivers are becoming smaller, but more powerful, which makes them an important piece in server technology. It is the key component in fiber optic transmission. The basic interface of 40G QSFP+ transceiver modules are 40GBASE-LR4 and 40GBASE-SR4 in QSFP+ form factor.
40G QSFP+ Transceiver
40GBASE-LR4 QSFP+: 40GBASE-LR4 transceiver support with a link length up to 10 kilometers over 1310 nm single mode fiber, LC Connector. It is most commonly deployed between data-center or IXP sites with single mode fiber.
40GBASE-SR4 QSFP+: 40GBASE-SR4 transceivers are used in data centers to interconnect two Ethernet switches with 8 fiber parallel multimode fiber OM3/OM4 cables. It can support the transmission distance up to 100 m with OM3 fiber and 150 m with OM4 fiber. The optical interface of 40GBASE-SR4 QSFP+ is MPO/MTP.
40GBASE-LR4 PSM QSFP+: 40G LR4 Parallel Single Mode (PSM) transceivers which are used to provide support for up to four 10Gbps Ethernet connections on a QSFP+ port over single mode fiber at distances up to 10 km.
40GBASE Extended SR4 QSFP+: Designed with optimized VCSEL with better performance of RMS spectral width compared with QSFP+ SR4. QSFP+ extended SR4 transceivers can support transmission distance up to 300 m with OM3 fiber and 400 m with OM4.
Passive & Active DAC
The QSFP+ passive or active direct attach copper cables are designed with twinax copper cable and terminated with QSFP+ connectors. The main difference between passive QSFP+ DAC and active QSFP+ DAC is that the passive one is without the active component. They provide short distance (same shelf) inexpensive connectivity at up to 40Gbps rates and operate 4 independent 10G channels using the QSFP connector footprint. Each of the four channels can operate at multi-rate speeds Gigabit to 10Gbps.
Active Optical Cable (AOC) Assemblies
Active optical cable, namely AOC brings a more flexible cabling than direct attach copper cables with the advantages of lighter weigth, longer transmission distance and higher performance for anti-EMI. Now, 40G AOC assemblies are popular with users.
In addition, don't forget there are some typical cabling components you will require when building 40G cabling, such as MTP fiber cables, MPO cables, MTP cassettes, LC to MTP jumpers and so on. The existing MTP-LC modules that were used in the two-fiber serial transmission would be replaced with MTP conversion modules for parallel optics. 40G optical modules and cabling components are some of the little things that definitely can make a big difference in cabling connectivity.
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