The primary objective of QoS Mapping is to allow 802.1p tags to persist across non-802.1p compliant links (for example, WAN links) by mapping them to corresponding DSCP tags before sending across the WAN link, and then mapping from DSCP back to 802.1p upon arriving at the other side, as shown below.
Mapping does not occur until you assign Map as an action of the QoS view of
For example, according to the default table, an 802.1p tag with a value of 2 is outbound mapped to a DSCP value of 16, while a DSCP tag of 43 is inbound mapped to an 802.1 value of 5.
Each of these mappings can be reconfigured. For more information, refer to Configuring QoS Marking.