Users Guide

The following table details the outcome of matched and mismatched TPIDs in a VLAN-stacking network.
Table 75. Behaviors for Mismatched TPID
Network Position Incoming Packet
TPID
System TPID Match Type 9.1(1.0)
Ingress Access Point untagged 0xUVWX — switch to default
VLAN
single-tag (0x8100) 0xUVWX single-tag
mismatch
switch to default
VLAN
0x8100 single-tag match switch to VLAN
0x81XY single-tag first-byte
match
switch to default
VLAN
Core 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
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.
Service Provider Bridging 962