Traffic classification identifies a traffic flow and maps the packets belonging to that flow to a preset forwarding class, so that the flow can receive the required special treatment. Up to eight forwarding classes are supported for traffic classification. Refer to Table: Default Forwarding Classes for a list of these forwarding classes.
For TDM channel groups, all of the traffic is mapped to a single forwarding class. Similarly, for ATM VCs, each VC is linked to one forwarding class. On Ethernet ports and VLANs, up to eight forwarding classes can be configured based on 802.1p (dot1p) bits or DSCP bits classification. On PPP/MLPPP, FR (for Ipipes), or cHDLC SAPs, up to eight forwarding classes can be configured based on DSCP bits classification. FR (for Fpipes) and HDLC SAPs are mapped to one forwarding class.
If an Ethernet port is set to null encapsulation, the dot1p value has no meaning and cannot be used for classification purposes.
If a port or SAP is set to qinq encapsulation, use the match-qinq-dot1p top | bottom command to indicate which qtag contains the dot1p bits that are used for classification purposes. The match-qinq-dot1p command is found under the config>service context. Refer to the 7705 SAR Services Guide, ‟VLL Services Command Reference”, for details.
Once the classification takes place, forwarding classes are mapped to queues as described in the sections that follow.