Tag Type
Name
Value
S-VLAN Tag
802.1q Service Tag Type
Customizable
NOTE
The IEEE 802.1ad specifies the TPID of the S-VLAN to 0x88a8. In actual application, the setting of TPID
for the S-VLAN tag varies according to the equipment manufacturer. To ensure compatibility between
interconnected equipment, it is recommended that you set the TPIDs of the S-VLAN tags of the
interconnected equipment to the same value within 0X600-FFFF.
l
TCI structure
The TCI structure of the S-TAG is basically the same as the TCI structure of the C-TAG. VLAN
ID (VID) field consists of 12 bits and ranges from 0 to 4095. The difference is that the TCI of
the S-TAG contains the drop eligible (DE) indication and works with the priority code point
(PCP) to indicate the priority of the S-TAG frame.
The TCI structures of the C-TAG and S-TAG are shown in
Figure 4-9
TCI structure of the C-TAG
Octets:
Bits:
PCP
CFI
VID
1
2
8
6
5
4
1
8
1
VID
The TCI field of the C-TAG consists of the following bytes:
l
PCP: three bits
l
CFI: one bit
Figure 4-10
TCI structure of the S-TAG
VID
Octets:
Bits:
PCP
DE
VID
1
2
8
6
5
4
1
8
1
The TCI field of the S-TAG consists of the following bytes:
l
PCP: three bits
l
DE: one bit
l
VID: 12 bits
4 Configuring Ethernet Services
OptiX OSN 550 Multi-Service CPE Optical Transmission
System
Configuration Guide
4-10
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Issue 02 (2011-06-30)