Optical virtual concatenation (OVC) is a promising technique for data-intensive, latency-sensitive and large-scale applications. In this paper, we present an OVC-based network architecture and key technologies for achieving virtual bulk-data transmission with a group of wavelengths. To offset the relative delay-difference among the grouped optical channels (wavelengths), a dynamic detection and compensation mechanism based on 40-Gb/s/ch OTN physical-layer multiframe architecture is proposed and discussed in detail. Using recently developed OVC hardware, 40-Gb/s/ch parallel transmission is demonstrated for the first time, and system performance is evaluated.