Vlan Stacking Packet Drop Precedence; Enabling Drop Eligibility; Honoring The Incoming Dei Value - Dell S4048–ON Configuration Manual

Network Position Incoming Packet
TPID
double-tag
0xUVWX
Egress Access Point untagged
double-tag
0xUVWX

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 82. Drop Eligibility Behavior
Ingress
Normal Port
Trunk Port
Access Port
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, you must explicitly map the DEI bit to an Dell Networking OS drop precedence.
Precedence can have one of three colors.
780
Service Provider Bridging
System TPID
0xUVWX
0xUVYZ
0xQRST
0xUVWX
0xUVWX
0xUVYZ
0xQRST
Egress
Normal Port
Trunk Port
Trunk Port
Match Type Pre-Version 8.2.1.0
double-tag match switch to VLAN
double-tag first- switch to VLAN
byte match
double-tag switch to default
mismatch VLAN
— switch to default
VLAN
double-tag match switch to VLAN
double-tag first- switch to VLAN
byte match
double-tag switch to default
mismatch VLAN
DEI Disabled
Retain CFI
Retain inner tag CFI
Retain outer tag CFI
Retain inner tag CFI
Set outer tag CFI to 0
Version 8.2.1.0+
switch to VLAN
switch to default
VLAN
switch to default
VLAN
switch to default
VLAN
switch to VLAN
switch to default
VLAN
switch to default
VLAN
DEI Enabled
Set CFI to 0.
Retain inner tag CFI.
Set outer tag CFI to 0.
Retain inner tag CFI
Set outer tag CFI to 0