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Stacked VLAN frame format
VLAN stacking means that a frame contains two VLAN tags. An example of a stacked VLAN frame format is
shown in the following illustration:
Destination
Source
MAC Address
MAC Address
6
6
An S-tag can be distinguished from a C-tag as follows:
The value of the TPID field of an S-tag is set to 0x88a8.
An S-tag contains a DEI (Drop Eligible Indicator) field instead of a CFI field.
E-DOC-CTC-20080229-0001 v1.0
Service Provider
Customer
VLAN tag
VLAN tag
= S-tag
= C-tag
TPID
TCI
TPID
TCI
2
2
2
Priority DEI
VID
3
1
12
bits
2|
Length/
Data/LLC
Type
2
2
0 .. 1500
Min. 46 bytes - Max. 1500 bytes
Min. 72 bytes - Max. 1526 bytes
VLAN Overview
Pad
FCS
46 .. 0
4
bytes
7
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