Overview of Priority Mapping

Priority mapping implements conversion between priorities, for example, DSCP to 802.1P, and DSCP to drop priority.

Packets carry different types of precedence field depending on the network type. For example, packets carry the 802.1p field in a VLAN and the DSCP field on an IP network. Packet priorities must be retained when packets traverse different types of networks. Therefore, the devices connecting the networks must be configured with mappings between the priority fields. When packets arrive at a device connecting different networks, the device maps external priority fields (DSCP and IP precedence) of the packets to 802.1p priorities and then to internal priorities based on 802.1p priorities. The device performs queuing and scheduling for the packets based on internal priorities.