The present disclosure provides physical coding sublayer architectures that enable high-speed serial interfaces capable of operating at data rates ranging from 400 gigabits per second (Gbps) to 1 terabit per second (Tbps). A first embodiment relates to an architecture that provides an aggregated physical coding sublayer (PCS) that provides multiple virtual lanes. A second embodiment relates to an architecture that has a channel-based PCS and provides an aggregation layer above the PCS channels. A third embodiment relates to an architecture that, like the second embodiment, has a channel-based PCS and provides an aggregation layer above the PCS channels. However, each channel-based PCS in the third embodiment provides multiple virtual lanes. Other embodiments, aspects and features are also disclosed.