Since 400G switches were entered the market in early 2019, they have been recognized by a growing number of users and have gained a lot of recognition. According to Dell’Oro, a market research firm, the number of 400G switch ports shipped will reach 15 million in 2023. In order to respond to the market development and meet the high performance requirements of 400G networks, most vendors have started to work on 400G network solutions, which include the development of 400G optical transceivers and MTP/MPO fiber patch cord products. This article will introduce 400G network solutions in detail.

400G Optical Module and MTP/MPO Fiber Patch Cable Overview

As we all know, optical transceivers and fiber optic cables are the most important infrastructure for network connectivity, and 400G network solutions are no exception.
Nowadays, with the maturation of 400G Ethernet technology, different types of 400G optical transceivers such as 400G SR8/DR4/FR4/FR8/LR8/SR16 are emerging, among which, 400G SR8/DR4/FR4 optical transceivers in QSFP-DD and OSFP packages have been frequently appeared in Optical Fiber Communication Exhibition and Seminar (OFC), and now Some suppliers have started to sell 400G SR8/DR4/FR4 optical transceivers in QSFP-DD or OSFP packages.

400G SR8 QSFP-DD/OSFP optical transceivers defined by the IEEE P802.3cm working group and designed for short-range transmission over 16 core MTP/MPO multimode fiber patch cable connections with a maximum distance of 100 meters.

400G DR4 QSFP-DD/OSFP optical module conforming to IEEE 802.3bs standard, designed for transmission up to 500 meters over 8-core or 12-core MTP/MPO single-mode fiber patch cable connections.

400G FR4 QSFP-DD/OSFP optical module meeting 100G Lambda MSA requirements, which differs from the above two types of 400G optical transceivers in that it uses only 4 lasers and achieves 2 km transmission via LC duplex singlemode fiber patch connection.

Simply put, 400G network transmission within 500 meters generally requires the use of MTP/MPO fiber optic cables, with the number of cores depending on the optical module model.

Typical 400G Network Solutions

The common 400G network connection methods are 400G-400G, 400G-4x100G, 400G-2x200G, 400G-5x80G. The following will focus on these four 400G network solutions.

400G-400G Direct Connection

400G direct connection is the simplest way to connect, just select the corresponding fiber patch cable to connect the 400G optical transceivers at both ends. Take 400G SR8 optical module as an example, 400G SR8 optical module uses 8 50Gbps channels, normally, 16 core MTP/MPO multimode fiber patch cable is used, and the connection is as shown below. This 400G network solution is expected to be used by hyperscale cloud service providers in China and North America.

As mentioned above, the 400G-DR4 optical module can be used with both 8 core MTP/MPO single-mode fiber patch cable and 12 core MTP/MPO single-mode fiber patch cable, it has the same 400G network solution as above, but it should be noted that when using 12 core MTP/MPO single-mode fiber patch cable, there will be 4 cores of fiber in idle state, because the 400G-DR4 optical module uses The 400G-DR4 optical module uses four 100Gbps channels, and only 2 cores are needed for one channel.

400G-2x200G Direct Connection

Compared with single-carrier 400G technology, dual-carrier 400G technology can reduce channel spacing, extend transmission distance and improve spectrum efficiency, so the 400G-2*200G direct connection method can effectively reduce the use of bandwidth resources and is more suitable for 400G backbone networks and more complex metro networks. The 400G network solution in this connection mode requires 16-core MTP/MPO branch fiber optic cables. One end of the branch fiber patch cable connects to a 400G optical module, and the other end of the two MTP fiber connectors connects to two 200G optical transceivers. The following figure shows the 400G SR8 optical module solution.

400G-4x100G Direct Connection

Take 400G DR4 optical module as an example. Since the connector interface of 400G DR4 optical module is MTP/MPO, and the connector interface of 100G DR optical module is LC duplex, so if you want to realize 400G-4x100G connection, you need to use 8 core MTP to 4 core LC duplex branch fiber patch cable, the MTP connector at one end connects to 400G DR4 optical module, and the 4 LC connectors at the other end connect to 4 100G DR optical transceivers on the other end. If you have ready-made 8-core MTP fiber patch cable and LC dual fiber patch cable can also achieve 400G-4*100G direct connection, as shown in the figure below, install the MTP-LC fiber patch box or branching patch box on the rack, and then use fiber patch cable to connect the two ends.

400G-8x50G Direct Connection

Although 50G Ethernet is currently less sought after in the market, as it can provide an expansion path for the upcoming 400G Ethernet (400Gbps transmission through eight 50Gbps channels), it will also drive the development of 50G Ethernet to a certain extent as 400G Ethernet develops rapidly.

The 400G-8x50G direct connection scheme is similar to the 400G-4*100G direct connection scheme mentioned above. Taking the 400G SR8 optical module as an example, one end uses a 16-core MTP fiber patch cable and the other end uses an LC duplex fiber patch cable to connect eight 50G optical transceivers, as shown below.

Summary

With the maturation and popularization of 400G Ethernet, MTP cabling solutions will become the mainstream solution for high-performance and high-density network construction in the future, such as large-scale data centers.

Related Resources:
400G Optical Transceiver Module Types
Typical Solutions for 400G Data Center
Typical Connection Solutions of 400G Optical Transceivers and Cables
The Next Station of Data Center Networks—200G vs 400G
400G Optical Module Application Scenarios
100G & 400G Optical Transceiver Marketing
400G Solutions Changes High-Bandwidth DCI Architecture
400G QSFP-DD FR4 vs 400G QSFP-DD FR8
A Beginner Guide: What is 400G Optical Module?
FAQs for 400G Transceivers and Cables