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Restrictions and guidelines
When you configure QinQ, follow these restrictions and guidelines:
• Before you configure QinQ on a port, you must remove all VLAN mappings on the port. After
you enable QinQ on the port, you can configure any VLAN mapping types except two-to-two
VLAN mapping on it. If QinQ and a VLAN mapping conflict, the VLAN mapping takes effect.
• The inner 802.1Q tag of QinQ frames is treated as part of the payload. As a best practice to
ensure correct transmission of QinQ frames, set the MTU to a minimum of 1504 bytes for each
port on the forwarding path of QinQ frames. This value is the sum of the default Ethernet
interface MTU (1500 bytes) and the length (4 bytes) of a VLAN tag.
Enabling QinQ
Enable QinQ on customer-side ports of PEs. A QinQ-enabled port tags an incoming frame with its
PVID.
To enable QinQ:
Step Command Remarks
1. Enter system view.
system-view
N/A
2. Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface
interface-type
interface-number
N/A
3. Enable QinQ.
qinq enable
By default, QinQ is disabled.
Configuring transparent transmission for VLANs
You can exclude traffic of a VLAN (for example, the management VLAN) from the QinQ tagging
action on a customer-side port. This VLAN is called a transparent VLAN.
To ensure successful transmission for a transparent VLAN, follow these configuration guidelines:
• Set the link type of the port to trunk or hybrid, and assign the port to its PVID and the transparent
VLAN.
• Do not configure any other VLAN manipulation actions for the VLAN on the port.
• Make sure all ports on the traffic path permit the VLAN to pass through.
To enable transparent transmission for a list of VLANs:
Step Command Remarks
1. Enter system view.
system-view
N/A
2. Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface
interface-type
interface-number
N/A
3. Configure the port link type.
port link-type
{
hybrid
|
trunk
}
By default, the link type of
ports is access.
4. Configure the port to allow
packets from its PVID and
the transparent VLANs to
pass through.
• For hybrid ports:
port hybrid vlan vlan-id-list
{ tagged | untagged }
• For trunk ports:
port trunk permit vlan
By default, trunk ports allow
only packets from VLAN 1 to
pass through. Hybrid ports
allow only packets from
VLAN 1 to pass through
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