Administrator Guide

Figure 132. Single and Double-Tag TPID Mismatch
VLAN Stacking Packet Drop Precedence
VLAN stacking packet-drop precedence is supported on the switch.
The drop eligible indicator (DEI) bit in the S-Tag indicates to a service provider bridge which packets it should prefer to drop when
congested.
Enabling Drop Eligibility
Enable drop eligibility globally before you can honor or mark the DEI value.
When you enable drop eligibility, DEI mapping or marking takes place according to the defaults. In this case, the CFI is affected according
to the following table.
Table 106. Drop Eligibility Behavior
Ingress Egress DEI Disabled DEI Enabled
Normal Port Normal Port Retain CFI Set CFI to 0.
Trunk Port Trunk Port Retain inner tag CFI Retain inner tag CFI.
846 Service Provider Bridging