Interconnect Solutions for Arista QSFP-40G-PLRL4 and SFP-10G-LR

Usually for single-mode fiber optic transceivers, the interface will be designed as LC duplex type. And for these optical modules, it will be easy to achieve structured cabling by using single-mode LC duplex infrastructure. But for 40G QSFP+, some single-mode transceivers do not follow this common rule. For example, 40GBASE-PLRL4 is a single-mode module supporting a transmission distance up to 1 km, but it has to be connected with an MTP/MPO-12 UPC connector. When migrating from 10G to 40G network using 40GBASE-PLRL4 modules, both single-mode LC duplex cable and single-mode MTP/MPO cable will be used. This article will take Arista QSFP-40G-PLRL4 and SFP-10G-LR optical modules as examples to explain several interconnect solutions for them.

Specifications of Arista QSFP-40G-PLRL4 and SFP-10G-LR

Arista 40GBASE-PLRL4 QSFP+ module is designed with a single-mode parallel MTP/MPO port. It can support a maximum link distance of 1 km on single-mode fiber operating at 1310nm wavelength. Arista 10GBASE-LR SFP+ module also has a single-mode port but its interface is LC duplex type. This SFP-10G-LR transceiver supports a long transmission distance up to 10 km over single-mode fiber operating at 1310 nm. Both of them support digital and optical monitoring.

Interconnect Solutions for Arista QSFP-40G-PLRL4 and SFP-10G-LR

In the first solution, a breakout cassette is used to move one 40G signal to four individual 10G signals. A 40G MPO cable is used on the QSFP-40G-PLRL4 side and four LC uniboot cables are connected to four SFP+s. The MTP/MPO equipment we used in this solution and the solutions below are all aligned as polarity B type.

interconnect for single-mode QSFP+ and SFP+ with MPO-12 to LC cassette

Figure 1: interconnect for single-mode QSFP+ and SFP+ with MPO-12 to LC cassette.

The second connection is a very cost-effective solution for three QSFP-40G-PLRL4 to twelve SFP-10G-LR modules. Here the three breakout cables on the left are female MPO to 4xLC 8 fibers harness. Then by using two 6 LC duplex adapter panel, the three groups of 40G signals are divided into two groups that each has six 10G network devices. In this link, no fiber or port is wasted. Besides, it also allows flexible location of the QSFP+ modules, like in different chassis. By using customized bend insensitive single-mode LC duplex fiber patch cable, high performance transmission at longer lengths can be achieved.

 interconnect for single-mode QSFP+ and SFP+ with MPO-8 to LC harness cable

Figure 2: interconnect for single-mode QSFP+ and SFP+ with MPO-8 to LC harness cable.

The next solution illustrated in figure 3 is a bit similar to the previous example in figure 2. It is also for three 40G parallel and twelve 10G duplex single-mode optical transceivers. But it is an application of MTP conversion harness cable and breakout patch panel. Here we used 3×8 strand MTP (female) to 2×12 strand MTP (female) single-mode conversion harness cable to connect the three QSFP+ transceivers to the 96 fibers 12xMTP/MPO-8 (male) to LC single-mode 40G breakout patch panel. Twelve LC uniboot patch cables are connected to the SFP-10G-LR transceivers.

interconnect for single-mode QSFP+ and SFP+ with 2x3 24-fiber MTP conversion harness cable

Figure 3: interconnect for single-mode QSFP+ and SFP+ with 2×3 24-fiber MTP conversion harness cable.

The last interconnect solution is for two single-mode QSFP+ and eight SFP+ modules. Here another type of MTP conversion cable is used. It is a 2×12 strand MTP (female) to 1×24 strand MTP (female) single-mode conversion harness cable. A 24 fibers male MTP-24 to LC UPC duplex single-mode cassette is used to connect the MTP-24 connector and the eight LC duplex connectors. Low loss LC uniboot cables are again used for this high-density cabling.

interconnect for single-mode QSFP+ and SFP+ with 1x2 24-fiber MTP conversion harness cable

Figure 4: interconnect for single-mode QSFP+ and SFP+ with 1×2 24-fiber MTP conversion harness cable.

Conclusion

This post introduced four interconnect solutions for single-mode parallel QSFP-40G-PLRL4 transceiver and single-mode duplex SFP-10G-LR transceiver. In order to meet different requirements, different equipment is deployed in different examples. Hope that these connections can be a guide for your single-mode network and can work well in specific applications.

MTP Specifications and Deployment for 40GBASE-PLRL4 QSFP+

Commonly, QSFP+ transceiver designed with LC interface works with single-mode fiber for long distance application, while QSFP+ transceiver with MTP/MPO interface is used over multimode fiber for short distance transmission. For instance, 40GBASE-ER4 QSFP+ is designed with LC duplex interface, and it supports maximum transmission length of 40 km over single-mode LC duplex fiber; 40GBASE-SR4 QSFP+ with MTP/MPO interface supports a transmission distance no more than 150m over multimode fiber. However, in order to meet user’s diverse needs in real applications, some 40G transceivers are designed not following this rule, like 40GBASE-PLRL4 (parallel LR4 Lite). This transceiver is with MTP/MPO interface design but is used over single-mode fiber for long distance transmission. This article will introduce the MTP/MPO specifications for this transceiver and its deployment cases.

40GBASE-PLRL4 transceiver

MTP Specifications for 40GBASE-PLRL4 QSFP+

QSFP-40G-PLRL4 transceiver uses MTP-12 interface to achieve parallel transmission, supporting maximum data links up to 1.4 km. The cable type required for 40GBASE-PLRL4 is an APC (angle polished connector) single-mode MTP-12 cable. The cable is similar to the 40G-SR MTP or MPO, with the only change being the use of single-mode fiber. UPC (ultra polished connector) is another type of connector for MTP-12 cables, but it is not suited for single-mode fiber in market. APC is the only available type for single-mode MTP-12 fiber. The MTP-12 connector plugged into the QSFP-40G-PLRL4 transceiver carries the 40G signal over only 8 of the 12 fibers, remaining four fibers unused, and these four can optionally be not presented in the cable for economic reason. The used 8 fibers are mapped as 4x10G Tx and Rx pairs. In addition, the MTP cables connected to QSFP-40G-PLRL4 transceiver can be either MTP trunk cables or MTP splitter cables.

Deployment of 40GBASE-PLRL4 QSFP+

The QSFP-40G-PLRL4 is optimized to guarantee interoperability with any IEEE 40GBASE-LR4 and 10GBASE-LR. So when the link for 40G network and 10G to 40G migration is less than 1.4 km, it will be very appropriate to use 40GBASE-PLRL4 QSFP+ transceiver with single-mode MTP cables.

In the first case, you can choose a MTP trunk cable together with the 40GBASE-PLRL4 QSFP+ module for direct 40G connection. The following picture shows two 40GBASE-PLRL4 QSFP+ transceivers connected by a single-mode 12-fiber MTP trunk cable.

40GBASE-PLRL4 QSFP+ for 40G connection

In the second case, you can simply use an 8-fiber MTP to 4xLC duplex harness cable with one 40GBASE-PLRL4 QSFP+ and four 10GBASE-LR SFP+ to achieve 10G to 40G.

40GBASE-PLRL4 QSFP+ for 10G to 40G migration

You can see in the above two cases, MTP cable plays an important role and due to the special requirements of 40GBASE-PLRL4 for single-mode MTP APC fiber, it is necessary to choose the right MTP products connected to this 40G QSFP+.

Conclusion

40GBASE-PLRL4 QSFP+ module has special interface design which can be only compatible with single-mode MTP connector. During the deployment of 40GBASE-PLRL4 QSFP+ module, selecting proper MTP assemblies are essential to successfully accomplish the link. FS.COM is a professional fiber optic transceiver vendor and MTP product manufacturer, supplying compatible 40GBASE-PLRL4 QSFP+ transceiver of different brands, such as Cisco, Arista, Brocade, Huawei, etc. Also other customized compatible brands are available for your requirements. MTP cables and assemblies are available for same-day shipping at low prices, including customized 8 fibers MTP/MPO trunk cable. You will be surprised to see how many kinds of network devices FS.COM can offer and you will get more than cost-effective products but also impressive service.