How to Connect 40G QSFP+ SR4 Transceivers to Network

40G network is gradually being applied in today’s backbone transmission network, during which long distance transmission is required. 40G QSFP+ SR4 fiber optic transceiver is being widely applied for 40G transmission in short distances. Generally, 40G QSFP+ SR4, working on wavelength of 850 nm, can support 40G fiber optic transmission a distance up to 150 m over OM4 multimode optical fiber. Inserted in switch, QSFP+ SR4 module utilizes a MTP/MPO interface for dual way transmission. There are a lot of methods to connect QSFP+ SR4 transceivers with other devices for different applications, by using different connectivity products. In addition, the cabling for 40G is relatively more difficult than that of 10G network, which requires more cables and spaces. The following will introduce several high density QSFP+ SR4 transceiver cabling methods.QSFP+ SR4 40G to 40G Applications

40G to 40G transmission is needed in a 40G fiber optic network. The following picture simply illustrates how 40G to 40G multimode transmission is being achieved by QSFP+ SR4 transceivers. Two QSFP+ SR4 modules are separately inserted in two 40G switches. Then the two transceiver are connected by a length of multimode MTP trunk cable. This is the simplest way to use QSFP+ SR4 transceiver.

In some cases, there are lot of 40G connections required at the same time and same places, which means the increasing of both cable count and cabling difficulty. For better cable management and higher density cabling, a 48-port 1U rack mount MTP fiber patch enclosure can be used as shown in the following picture. Up to four 12-port MTP fiber adapter panels can be deployed in this standard 1U rack mount enclosure. With the help of this 48-port MTP fiber enclosure, cable management for 40G connections could be easier.

QSFP+ SR4 40G to 10G Applications

QSFP+ SR4 is a parallel fiber optic transceiver which means it uses four fibers for transmitting and four fibers for receiving at the same time. The 40G fiber optic signal can be separated into four 10G signals to meet the 40G to 10G transferring requirements. The fiber optic cable count will be increased at the 10G distribution end. Usually a breakout MTP-8LC harness cable is used. For better cable management, a 1U 96-fiber enclosure is recommended, which includes four HD MTP cassettes transferring MTP front the 40G end to LC at the 10G end. Four 10G-SR SFP+ modules, inserted in 10G switch/ports, can be connected to the corresponding LC ports on this fiber enclosure to achieve the duplex transmission between 40G and 10G.

For higher cabling density, the above mentioned 48-port 1U rack mount MTP fiber patch enclosure is still being recommended, which can provide high density 40G MTP cabling environment. And additional MTP-8LC harness cables should be used for transferring signals between 40G and 10G (shown in the following picture).

Conclusion

Depending on its parallel transmission mode, QSFP+ SR4 modules can meet a variety of cabling applications with great flexibility. The above methods is just several commonly used ones, detailed cabling methods for QSFP+ SR4 modules are depended on the practical applications and cabling environments. Related products for the above mentioned methods are listed in the following tables.