XPO form factor: New optical modules from Arista with up to 12.8 Tbit/s

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The expansion of AI backend networks leads to significantly increasing demands on the bandwidth, port density, and energy efficiency of network hardware. For such application scenarios, Arista has released a new module approach with XPO (eXtra-dense Pluggable Optics), which enables higher packing density with a bandwidth of 12.8 Tbit/s.

Currently, Quad Small Form Factor Pluggable – Double Density (QSFP-DD) and Octal Small Form Factor Pluggable (OSFP) form factors are mostly used in AI data centers. They already achieve transmission rates of 400G and 800G. However, with the growing size of AI clusters, both power consumption and the demands on the physical packing density of the optics continue to increase.

As GPUs scale, the number of required network connections also grows significantly. The power consumption of optical modules also increases, making cooling of switch front panels more difficult. This creates new demands on optics form factors that must enable both higher port density and more efficient cooling.

Less space requirement, more performance

According to Arista, one XPO module will be able to replace eight OSFP transceivers in the future, thereby significantly increasing the throughput per rack unit. To achieve this, the module uses 64 communication channels (lanes).

The new module variant also increases port density on the switch front while reducing the total number of components in the network. In large AI infrastructures, this can help reduce the space requirement and complexity of the network architecture.

Liquid cooling for future network hardware

Another trend is the increasing use of liquid cooling in data centers. While GPUs and CPUs have primarily been liquid-cooled so far, this approach will become more relevant for network components and their accessories, such as optical modules in this case, in the future.

The XPO module design already takes this development into account by integrating cooling structures that can be connected to liquid cooling systems. This allows significantly higher power consumption of the modules to be handled while achieving lower operating temperatures.

In addition to higher integration density, new optics designs also aim for better energy efficiency and higher reliability. More efficient cooling reduces the operating temperatures of the components and can thus extend the lifespan of the modules. At the same time, a smaller number of individual components leads to fewer potential sources of error within the infrastructure.

Outlook

To ensure interoperability between manufacturers, a Multi-Source Agreement (MSA) for XPO is planned. This is an agreement between different manufacturers to define uniform standards for the form factor and electrical as well as optical interfaces of fiber optic transceivers (e.g., SFP, SFP+, QSFP). A list of participating manufacturers is expected to be available next week on the website set up for this purpose. Modules are then expected to be available from 2027, Arista explained when asked by the iX editorial team.

(axk)