QinQ Packet Encapsulation Format
A QinQ packet has a fixed format, in which an 802.1Q tag is added outside the existing 802.1Q
tag of the packet. A QinQ packet has 4 more bytes than an 802.1Q packet.
Figure 4-1 802.1Q encapsulation
QinQ Encapsulation
QinQ encapsulation changes a single-tagged packet into a double-tagged packet.
QinQ encapsulation falls into basic QinQ and selective QinQ depending on the data
encapsulated. Basic QinQ refers to interface-based QinQ, and selective QinQ includes VLAN
ID-based QinQ and 802.1p priority-based QinQ.
l Interface-based QinQ encapsulation
This encapsulation mode is also called QinQ tunneling. It encapsulates packets arriving at
the same interface with the same outer VLAN tag, and therefore cannot distinguish users
and services at the same time.
l VLAN ID-based QinQ encapsulation
This encapsulation mode determines whether to add outer VLAN tags and which outer
VLAN tags to add based on data flows.
Traffic can be classified based on VLAN ID ranges if a customer uses different VLAN IDs
for different services. For example, PC users access the Internet through VLANs 101 to
200, IPTV users through VLANs 201 to 300, and VoIP users through VLANs 301 to 400.
When receiving service data, the underlayer provider edge (UPE) adds outer tag 100 to
packets from PCs, outer tag 300 to packets from IPTV users, and outer tag 500 to packets
from VoIP users.
l 802.1p priority-based QinQ encapsulation
This encapsulation mode determines whether to add outer VLAN tag and which outer
VLAN tags to add based on priorities of data flows.
For example, when different services of a user have different priorities, these services can
be transmitted over different data channels based on priorities.
QinQ Implementation
QinQ can be implemented in either of the following ways:
1. Basic QinQ
Basic QinQ is implemented based on interfaces. After basic QinQ is configured on an
interface, the device adds the default VLAN tag of this interface to all packets regardless
of whether the packets carry VLAN tags.
l If a single-tagged packet is received, the packet becomes a double-tagged packet.
l If an untagged packet is received, the packet is tagged with the default VLAN ID of the
local interface.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
4 QinQ Configuration
Issue 01 (2014-11-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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