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Table 80. Behaviors for Mismatched TPID (continued)
Network Position Incoming Packet
TPID
System TPID Match Type 9.1(1.0)
Egress Access Point untagged 0xUVWX — switch to default VLAN
double-tag 0xUVWX 0xUVWX double-tag match switch to VLAN
0xUVYZ double-tag first-byte
match
switch to default VLAN
0xQRST double-tag mismatch switch to default VLAN
VLAN Stacking Packet Drop Precedence
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 81. 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.
Retain outer tag CFI Set outer tag CFI to 0.
Access Port Trunk Port Retain inner tag CFI Retain inner tag CFI
Set outer tag CFI to 0 Set outer tag CFI to 0
To enable drop eligibility globally, use the following command.
● Make packets eligible for dropping based on their DEI value.
CONFIGURATION mode
dei enable
By default, packets are colored green, and DEI is marked 0 on egress.
Honoring the Incoming DEI Value
To honor the incoming DEI value, explicitly map the DEI bit to a Dell Networking OS drop precedence.
Precedence can have one of three colors.
Precedence
Description
Green High-priority packets that are the least preferred to be dropped.
Yellow Lower-priority packets that are treated as best-effort.
Red Lowest-priority packets that are always dropped (regardless of congestion status).
● Honor the incoming DEI value by mapping it to a Dell Networking OS drop precedence.
INTERFACE mode
dei honor {0 | 1} {green | red | yellow}
Service Provider Bridging
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