As the conventional switch chip decodes the Virtual Local Area Network(VLAN) packet in fixed hardware
so that it is not possible to alter the processing flow
this paper presents a network processor-based programmable pipeline scheme.It studies the processing mechanism of the pipeline
analyzes the principle of VLAN mapping and describes in detail the implementation of the VLAN module.Test results indicate that this software operates stably and is significant to the development of the QinQ software.