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Data center applications, networks, and optical transceivers are rapidly evolving, usually using port branching to deaggregate 40max 100G parallel optical transceivers into four 10ax 25G links. Branch parallel optical ports are beneficial for many applications, including the creation of large-scale Spine-and-leaf networks and the implementation of high-density 10max 25G networks, where the upgrade planning time for each data center varies depending on technical requirements, budget, size, and business priorities.

History of data Center change

Today's data center

At present, the transmission rate of many enterprise data centers is still 10Gbps, traditional 10G often uses SFP+ optical module, dual-core LC interface interconnection; 40G Ethernet specification requires 8-core interconnection, 4 transmit and 4 receive, using 12-core optical cable wiring solution, each channel has 4 dedicated transmitting fiber and 4 special receiving fiber, the middle 4 optical fiber remains idle.

The 100 Gigabit Ethernet common solution requires the use of 24 optical fibers, divided into two 12-core arrays, one array dedicated to transmitting and another array dedicated to receiving, with 10 fibers in the middle of each array for transmitting traffic and 2 fibers at both ends idle.

Transmission type

In traditional serial transmission, data is transmitted through a pair of optical fibers, one optical fiber transmitting (Tx) and one optical fiber receiving (Rx). At 1G and 10G transmission speeds, the choice of transceivers is not crucial because all transceivers operate in the same way and at the same wavelength. When the network speed gradually increased to 40amp 100G, different (proprietary) WDM technologies appeared on the market, and the choice of transceivers became more critical because some transceivers used two different wavelengths, while others used four different wavelengths, making them incompatible with the IEEE-approved SR4 protocol using parallel optical transmissions.

1. Parallel optical transmission

Parallel optical transmission uses parallel optical interfaces to transmit and receive data on multiple optical fibers at the same time, which is usually used in medium-and short-distance transmission. For parallel optical transmission, 40G and 100G Ethernet interfaces have 4 × 10G channels and 4 × 25G channels respectively, and four optical fibers are used in each transmission direction. In other words, for 40G applications, the back end of the QSFP transceiver is connected to four 10G electrical signals, while four discrete 10G optical signals are transmitted and received from the front end of the transceiver through eight optical fibers. This design enables a 40G transceiver to be used both as four discrete 10G links and as a 40G link.

two。 Wavelength division multiplexing (WDM)

Wavelength division multiplexing (WDM) transmission is a technology that uses different wavelengths of laser to transmit multiple optical signals on a single optical fiber. This technology can use a single optical fiber to achieve two-way communication, but also can achieve capacity superposition. WDM is usually used for long-distance transmission, so that the cost savings in cabling can offset some of the more expensive transceiver costs.

Note: the data lists the IEEE standard protocol of the American Institute of Electrical and Electronic Engineers as of 2017, which is applicable to Ethernet only. Fibre Channel and unlimited bandwidth are gradually adopting the same approach based on parallel optical / QSFP connections.

Network status wiring diagram

In cabling systems based on MPO connectors, it is very simple to upgrade from 1G to 10G, 40G, 100G or even 400G. Starting with 10G, deploy a MPO backbone cable between two 10G switches, and deploy a pre-end module or MPO panel to connect the LC jumper or MPO-to-LC branch jumper at one end of the switch.

40G/100G upgrade

When you need to upgrade the switch, simply replace the MPO/LC module box with the MPO adapter panel and use the MPO jumper to connect the 40G/100G switch to complete the upgrade.

Structured cabling Design of data Center

Parallel optical transceivers run on eight optical fibers, so it is critical to consider how to design structured cabling in the data center to support port branch applications. The recommended design includes the use of an 8-core-based MPO optical connectivity infrastructure solution to optimize fiber utilization and port mapping.

As you can see from figures a, b, and c, the link that deploys an 8-core MPO connector interface allows the port to be broken down into four LC duplex ports for wiring connections to 10G device ports using a simple optimization solution.

Recommended: 100g QSFP28 optical module

Figures an and b depict a structured cabling design in which a private cabling backbone is installed between devices with 40ax 100G and 10max 25G ports. Figure an is of practical significance, and the layout diagram in figure b is very helpful for the necessary structured cabling to connect the jumpers of different device ports in the cabinet when all 10max 25G ports are in one device unit. However, figure c provides the greatest flexibility for structured cabling in the data center, decomposing 40G (MPO) ports into LC duplex ports at cross-connect points. When cross-connecting in the central distribution area, any 10max 25G port obtained from the decomposition of the 40max 100G switch can be hopped to any device that requires the use of a 10Unix 25G link.

Yi Tianguang Communication, as a professional optical module manufacturer, can meet users'1G to 100G optical module solutions, thank you for your support!

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