The interconnections capable of providing a wide bandwidth will be increasingly important in the near future. The workloads related toartificial intelligence et al machine learningin particular, have significantly raised the minimum requirements to handle large volumes of data. PCIe 6.0 It is the sixth generation of the PCI Express interface, widely used to connect components such as CPUs, GPUs and accelerators. New motherboards and hardware solutions have been starting to support PCIe 5.0 in scope for some time now mainstream while the PCIe 6.0 specifications, approved in January 2022, are still far from mass use.
However, just to support modern applications, two companies have announced the first demonstration of the technology PCI Express 6.0 on connection optics. It’s about Cloud Communicationsa provider of high-density, low-latency optical interconnects, and Alphawave Semi, a global leader in the development of high-speed communications technologies. The new frontier, which is arousing great interest, is called PCIe over Optics.
PCIe over Optics: First single-lane 64 GT/s PCIe 6.0 optical link
Nubis and Alphawave have announced that they are capable of moving 64 GT/s per single lane over a PCIe 6.0 optical link. Using fiber optics instead of copper cables allows you to extend the distance between components.
Service providers in the area data center In fact, they are exploring the use of PCIe over optical links to greatly expand the scope and flexibility of interconnection for memory, CPU, GPU and custom accelerators. The goal is to create more scalable clusters and energy efficient for AI/ML architectures.
The two companies use a PCIe subsystem made by Alphawave Semi with PiCORE IP controller and PipeCORE PHY, which “drives” and receives PCIe 6.0 traffic through a Nubis XT1600 linear optical engine. This optical engine supports up to 16 lanes of high-density PCIe Gen 6.0 optical connectivity or 100 Gbps Ethernet per lane, without the use of retainers (devices that restore the signal).
Il linear optical engine (linear optical engine, in English) is an optical component designed to transmit optical signals in a linear manner, without applying modulation processes or conversion of the signal into other formats. This feature is essential for computing and artificial intelligence applications, where accuracy and signal integrity are critical.
What does 64 GT/s mean
The reference to 64 GT/s means that the data transfer speed on each single lane of the PCIe 6.0 link is equal to 64 gigatransfers per second.
This is a rather common unit of measurement in communication systems. The choice to use “GT/s” instead of “Gbps” (gigabits per second) is linked to the nature of the PCIe communication protocol (Peripheral Component Interconnect Express) and its data transmission architecture.
In PCIe, the term “GT/s” is commonly used to refer to transfer rate as it refers to transfers of symbols or state information, not directly to the amount of data actually transferred. A symbol in PCIe can represent more than one bit in the past, due for example to the use of coding techniques. Therefore, the unit of measurement “GT/s” is often considered more accurate and relevant.
Since one symbol in PCIe 6.0 can represent 2 bits of data (due to the coding technique PAM4, Pulse Amplitude Modulation 4), the effective transfer rate will be 128 Gbps for each lane. In 16-line configurations (x16) of PCIe 6.0 we are talking about 2,048 Gbps or 256 GB/s bidirectional.