962 | Service Provider Bridging
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Table 46-2 details the outcome of matched and mismatched TPIDs in a VLAN-stacking network with the 
C-Series and S-Series.
VLAN Stacking Packet Drop Precedence
VLAN Stacking Packet Drop Precedence is available only on platform: c s
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.
Table 46-2.  C-Series and S-Series Behaviors for Mis-matched TPID
Network
Position
Incoming
Packet TPID
System
TPID Match Type Pre-8.2.1.0 8.2.1.0+
Ingress Access Point untagged 0xUVWX — switch to default 
VLAN
switch to default 
VLAN
single-tag (0x8100) 0xUVWX single-tag 
mismatch
switch to default 
VLAN
switch to default 
VLAN
0x8100 single-tag match switch to VLAN switch to VLAN
0x81XY single-tag first-byte 
match
switch to VLAN switch to default 
VLAN
Core untagged 0xUVWX — switch to default 
VLAN
switch to default 
VLAN
double-tag 
0xUVWX
0xUVWX double-tag match switch to VLAN switch to VLAN
0xUVYZ double-tag 
first-byte match
switch to VLAN switch to default 
VLAN
0xQRST double-tag 
mismatch
switch to default 
VLAN
switch to default 
VLAN
Egress Access Point untagged 0xUVWX — switch to default 
VLAN
switch to default 
VLAN
double-tag 
0xUVWX
0xUVWX double-tag match switch to VLAN switch to VLAN
0xUVYZ double-tag 
first-byte match
switch to VLAN switch to default 
VLAN
0xQRST double-tag 
mismatch
switch to default 
VLAN
switch to default 
VLAN