Two Simplest Ways to Get 40G to 40G Connection

Technologies revolving around virtualization, cloud computing and big data are requiring more throughput capabilities than ever before, and 10G Ethernet is just not enough to deliver these resources. This is where administrators may run into the challenge of upgrading from 10G to 40G and beyond. This post will introduce how to get 40G to 40G connection through two simplest ways: MTP trunk cable and QSFP+ DAC.

MTP Trunk Cable and QSFP+ DAC Overview

Terminated with MTP fiber connector at both ends, MTP trunk cable is used to connect MTP port modules for high density backbone cabling in data centers and other high dense degree environments. 12-fiber and 24-fiber MTP trunk cables are commonly used in networking applications: 12-fiber MTP trunk cable is normally for 40G Ethernet network, while 24-fiber MTP trunk cable is normally for 100G Ethernet network as shown below.

12-fiber and 24-fiber MTP trunk cable for 40G Ethernet

QSFP+ DAC as shown below is a copper 40GBase twinax cable that comes in either active or passive twinax cable assembly and connects directly into QSFP+ modules, which are permanently attached to both ends of the cable. These QSFP+ connectors are not real modules, since they are without expensive optical lasers. That’s why QSFP+ DAC cables are much more cheaper than fiber optic cables.


40G to 40G Connection With MTP Trunk Cable

In this scenario, you can simply use 12-fiber MTP MPO trunk cable and 40GBase-SR4/40GBase-CSR4/40GBase-PLR4/40GBase-PLRL4 QSFP+ transceivers to accomplish a quick connection between two 40G switches as shown below. 40GBase-SR4 and 40GBase-CSR4 are used for 40G transmission in short distances up to 150 m or 400 m over OM4 fibers, respectively. The 40GBase-PLRL4 and 40GBase-PLR4 can support transmission distance over single-mode fiber up to 1.4 km and 10 km respectively. All of these QSFP+ modules can deliver 40G over 4 lanes fibers at 10Gbps per lane. When they deployed with a 12-fiber MTP trunk cable, only 8 fibers will be used (4 for transmit and 4 for receive), leaving the other 4 fibers unused. All these modules can be purchased from FS.COM, and you can choose the right one according to the distance between your two switches.


40G to 40G Connection With QSFP+ DAC

QSFP+ DAC and QSFP+ AOC cables are recommended when the distance between the two 40G switches is very short, normally 10 meters. Unlike the first solution, in this scenario, no QSFP+ modules are required. We just need to plug the QSFP+ connectors into the two QSFP+ interfaced switches within the same racks or across adjacent racks as shown below, and it can work, which is more easy to handle, especially for someone who is new to 40G deployment. FS.COM also provides QSFP+ DAC in active or passive versions (active for link length up to 7, 10 meters, and passive for 1, 3, 5 meters). You can choose the proper one up to your requirement.

40G to 40G connection with QSFP+ DAC


Data center migration to 40G Ethernet is imperative. If you are familiar with network deployment, and has bright budget, you can choose MTP trunk cable to get the 40G connection. If you are a new to 40G, you’d better choose 40G QSFP+ DAC for easy installation and lower investment. Of course, this is just personal suggestion, you can choose the right one according to your practical application.


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