4 Wiring Dci Solutions For 400g Optical Transceiver Modules

By Author: Ricky
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The continuous growth of global data traffic has promoted the development of data centers from 100G to faster, larger bandwidth and lower latency. 400G will be the direction of the next-generation backbone network upgrade and new construction, and will become an inevitable trend in the development of data centers.

Many service providers have begun to deploy 400G network construction plans, such as Cisco and Huawei. In the process of constructing a 400G network system, 400G optical modules play a vital role. You may be familiar with the 10G/40G/100G wiring method. This article will talk about the short-distance wiring method of 400G optical modules in the data center in the future.

Before discussing the wiring method of 400G optical modules, let's first understand the mainstream form factors of 400G optical transceiver modules: QSFP-DD and OSFP.

The full name of QSFP-DD is Quad Small Form Factor Pluggable-Double Density. This solution adds one row to the original 4-channel interface to 8 channels, the so-called double density. Support 25Gb/s (NRZ modulation) or 50Gb/s (PAM4 modulation), compatible with the ...
... previous QSFP+/QSFP28, with small size and high density, suitable for short-distance wiring in data centers; this solution is an extension of QSFP interface , Compatible with QSFP solution, which is one of its main advantages. The original QSFP28 module can still be used, just plug in another module.

OSFP stands for Octal Small Formfactor Pluggable. This standard is a new interface standard, which is not compatible with the existing optoelectronic interface. Its size is 100.4 * 22.58 * 13 mm ^ 3, which is slightly larger than the size of QSFP-DD. The size of OSFP is a bit larger than QSFP-DD. OSFP and QSFP-DD are backward compatible with QSFP+/QSFP28, but an additional OSFP is required. It can be realized by the transfer adapter to QSFP, it can support 800G backward, and it comes with a heat sink, which is suitable for the telecommunications market.

DCI Solution

MPO/MTP-8F fiber optic patch cords are used in SR4/DR4 connection solutions, and MPO/MTP-16F fiber optic patch cords are used in SR8 connection solutions.

Interconnection Solution between Two 400G DR4 QSFP-DD/OSFP Optical Transceiver

The 400G QSFP-DD/OSFP DR4 optical module connection scheme is to deploy an MPO/MTP pre-terminated backbone optical cable between two 400G switches, and deploy an 8-core MPO/MTP fiber jumper to connect the optical module at the 400G switch end. Deploy high-density optical fiber distribution boxes (including MPO adapters) between the terminated backbone optical cables and optical fiber jumpers for management.

Interconnection between Two 400G SR8 QSFP-DD/OSFP Optical Modules

Direct connection of 400G QSFP-DD/OSFP SR8 optical modules. Deploy an MPO/MTP pre-terminated backbone optical cable between two 400G switches, and deploy 16-core MPO/MTP-MPO/MTP fiber optic jumper connections on the 400G switch. For 400G optical modules, a high-density optical fiber distribution box (including MPO adapter) is deployed between the pre-terminated backbone optical cable and the optical fiber jumper for management.

Interconnection Solution between 400G SR8 QSFP-DD/OSFP and 200G QSFP56 SR4

For the connection between 400G QSFP-DD SR8 optical module and 200G QSFP56 SR4 optical module, deploy an MPO/MTP pre-terminated backbone optical cable between the two switches, and deploy 16-core MPO-2*MPO/MTP on the 400G switch end Fiber patch cords are connected to 400G optical modules, 8-core MPO/MTP fiber patch cords are deployed on the 200G switch end, and a high-density fiber optic distribution box (including MPO adapters) is deployed between the pre-terminated backbone optical cables and fiber patch cords for management .

The 400G SR8 optical module complies with the IEEE 802.3cm standard and meets the requirements of 70m OM3 and 100m OM4/OM5 transmission links. It uses 16-core multimode MPO connectors, 8 transmitters and 8 receivers, and each channel uses PAM4 modulation to carry 50Gbps signals. A Due to the use of VCSEL lasers, the VCSEL laser market is relatively mature, so it has a price advantage.

400G SR4.2 uses a dual-wavelength 25G VCSEL laser, but it needs to use a 2:1 Mux multiplexer and a 1:2 Demux splitter, which will increase the cost of the optical module.

The 400G DR4 optical module complies with the IEEE 802.3bs standard and meets the 500m transmission link requirements. It uses a 12-core MPO connector, 4 transmitters and 4 receivers, and each channel carries 100Gbps signals. The use of more expensive DML lasers or SiPh silicon photonics technology can reduce the power consumption and cost of optical modules, but because silicon photonics technology is currently in the early stages of industrial development, the shipment volume is low, and it cannot form a scale effect.

In the current 400G optical modules, 8 channels of 53Gbps PAM4 (400G-SR8, FR8, LR8) or 4 channels of 106Gbps PAM4 (400G-DR4, FR4, LR4) are mainly used on the optical port side to achieve 400G signal transmission, and used on the electrical port side 8 channels of 53Gbps PAM4 electrical signals, using OSFP or QSFP-DD package form. Both OSFP and QSFP-DD packages can provide 8 electrical signal interfaces.