Huawei quidway s7700 Configuration Manual page 467

Quidway S7700 Smart Routing Switch
Configuration Guide - VPN
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The sub-interfaces can be dotlq sub-interfaces, QinQ sub-interfaces, VLAN mapping sub-
interfaces, or VLAN stacking sub-interfaces.
When XGE, GE, Ethernet, or Eth-Trunk interfaces are used as AC interfaces, the outer tags
carried in the packets sent from the AC to the PW are C tags (inserted by customer devices,
which are meaningless to the SP) by default.
When sub-interfaces or VLANIF interfaces are used as AC interfaces, the outer tags carried in
the packets sent from the AC to the PW are S tags (inserted by SP devices, which are usually
used to differentiate user traffic) by default.
For details on how to access the VLL through a sub-interface, see Connecting Sub-interfaces to
a VLL Network in the Quidway S7700 Smart Routing Switch Configuration Guide -
Ethernet.
Processing Tags Carried in Packets by the VLL
The system process packets according to the AC interface type and PW encapsulation type.
The PW encapsulation types can be classified into Ethernet encapsulation and VLAN
encapsulation.
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Table 5-1 Processing VLAN tags carried in packets from the AC by the PW
PW Encapsulation Type
VLAN encapsulation
Ethernet encapsulation
Issue 01 (2011-07-15)
Eth-Trunk sub-interfaces
VLANIF interfaces
NOTE
l Only VLANIF interfaces can function as the AC interfaces for VLL connections in CCC mode.
l By default, physical interfaces on the S7700 are Layer 2 interfaces. When using XGE, GE, Ethernet,
or Eth-Trunk interfaces on the S7700 as AC interfaces, you need to run the undo portswitch command
to switch Layer 2 interfaces to Layer 3 interfaces.
l When using GE, XGE, Ethernet, or Eth-Trunk interfaces as AC interfaces, ensure that these interfaces
do not contain any sub-interfaces.
When VLANIF interfaces or sub-interfaces function as AC interfaces, the VLAN
encapsulation is adopted by default.
When Ethernet, GE, XGE, or Eth-Trunk interfaces function as AC interfaces, the Ethernet
encapsulation is adopted by default.
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Processing of the VLAN Tag
Do not process the S tag carried in a packet.
If an S tag is carried in a packet, delete the S
tag from the packet.
If no S tag is carried in a packet, do not
process the packet.
5 VLL Configuration
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