Marvell announced the first networking chip with 802.3cd support, this model enables support for Ethernet bandwidth of up to 400Gbps. Samples of the Alaska C 88X7120 transceivers are currently shipping to customers for further testing. These chips are intended for top-of-rack switches:
The chips support 16 50Gbps ports, four 200Gbps ports, and two 400Gbps ports, using PAM4 signaling. They're aimed at top-of-rack switches with interfaces ranging from 25Gbps to 400Gbps.
PAM4 stands for pulse-amplitude modulation, a four-level signaling technique designed to replace the non-return to zero (NRZ) binary modulation. It has long been thought to be the way to get to 400Gbps throughput, and now Marvell says it can do it. Although PAM4 is a a newer protocol, devices using it will be backwards-compatible with NRZ hardware.