Rambus Demonstrates Advancing Data Center Capabilities with CXL Over Optics

By _Rambus Blog

August 6, 2024

At Rambus, we are committed to pioneering advancements that meet the evolving demands of modern data centers. Today, we are showcasing advanced technology for high-speed data center interconnects: CXL 2.0 over optics.

What is CXL?

Compute Express Link (CXL) is an open interconnect standard that enhances communication between processors, memory expansion, and accelerators. Built on the robust PCI Express (PCIe) framework, CXL provides memory coherency between CPU memory and attached devices. This innovation enables efficient resource sharing, reduces software complexity, and lowers system costs—making it an essential component in the future of data center architecture.

Demonstrating the Future: CXL Over Optics

In this demonstration, Olivier Alexandre, Senior Manager of Validation Engineering at Rambus, shows a Rambus CXL endpoint device connected to a Viavi Xgig 6P4 Exerciser using Samtec Firefly optic cable technology, effectively creating a remote “CXL Memory Expansion” block.

Here are more details on the demo:

Device Setup: Our Device Under Test (DUT), incorporating a Rambus CXL 2.0 Controller, is configured in CXL 2.0 Type 2, operating at 16 GT/s on four lanes. The Viavi Xgig 6P4 emulates a Root Complex Device, and both devices are linked through a Samtec Firefly PCUO G4 cable, supporting speeds up to 16 GT/s.

Performance Insights: The DUT successfully maintains stability at Gen 4 speed by 4. We also conducted tests at varying speeds, confirming expected performance limits at earlier generations.

Device Discovery: During device discovery, the Rambus CXL device was correctly identified, highlighting our device’s capability and integration.

Compliance Success: Utilizing the Viavi exerciser, we conducted a CXL 2.0 compliance test over a 100-meter fiber optic connection. The test suite, taking approximately 20 minutes, confirmed that our DUT passed all compliance tests.

The Promise of CXL/PCIe Over Optics

This demonstration illustrates the potential of CXL/PCIe over optics as a key solution to meet the bandwidth demands of heterogenous distributed data center architectures. Optical interconnects offer significant advantages including extended reach, reduced latency, and efficient resource sharing across multiple servers.

Learn more about Rambus CXL IP solutions here.

About Samtec and Viavi

Samtec
Known for its high-performance interconnect solutions, Samtec provides leading-edge technology such as the Firefly optic cable, enabling high-speed data transmission with impressive range and low latency.

Viavi
A leader in network testing and measurement, Viavi Solutions offers products like the Xgig 6P4 Exerciser, which is crucial for ensuring compliance and performance in complex network environments.