Contents

Configuring QinQ·· 1

About QinQ·· 1

QinQ benefits· 1

How QinQ works· 1

QinQ implementations· 2

Protocols and standards· 2

Restrictions and guidelines: QinQ configuration· 3

Enabling QinQ·· 3

Configuring the TPID for VLAN tags· 3

About TPID·· 3

Restrictions and guidelines· 4

Configuring an interface-specific TPID value· 4

Setting the 802.1p priority in SVLAN tags· 5

About the 802.1p priority in SVLAN tags· 5

Tasks at a glance· 5

Creating a traffic class and configuring CVLAN match criteria· 5

Creating a traffic behavior and configuring a priority marking action for SVLAN tags· 5

Creating a QoS policy· 6

Applying the QoS policy· 6

Display and maintenance commands for QinQ·· 6

Configuring QinQ

This document uses the following terms:

·     CVLAN—Customer network VLANs, also called inner VLANs, refer to VLANs that a customer uses on the private network.

·     SVLAN—Service provider network VLANs, also called outer VLANs, refer to VLANs that a service provider uses to transmit VLAN tagged traffic for customers.

About QinQ

802.1Q-in-802.1Q (QinQ) adds an 802.1Q tag to 802.1Q tagged customer traffic. It enables a service provider to extend Layer 2 connections across an Ethernet network between customer sites.

QinQ benefits

QinQ provides the following benefits:

·     Enables a service provider to use a single SVLAN to convey multiple CVLANs for a customer.

·     Enables customers to plan CVLANs without conflicting with SVLANs.

·     Enables customers to keep their VLAN assignment schemes unchanged when the service provider changes its VLAN assignment scheme.

·     Allows different customers to use overlapping CVLAN IDs. Devices in the service provider network make forwarding decisions based on SVLAN IDs instead of CVLAN IDs.

How QinQ works

As shown in Figure 1, a QinQ frame transmitted over the service provider network carries the following tags:

·     CVLAN tag—Identifies the VLAN to which the frame belongs when it is transmitted in the customer network.

·     SVLAN tag—Identifies the VLAN to which the QinQ frame belongs when it is transmitted in the service provider network. The service provider allocates the SVLAN tag to the customer.

The devices in the service provider network forward a tagged frame according to its SVLAN tag only. The CVLAN tag is transmitted as part of the frame's payload.

Figure 1 Single-tagged Ethernet frame header and double-tagged Ethernet frame header

 

As shown in Figure 2, customer A has remote sites CE 1 and CE 4. Customer B has remote sites CE 2 and CE 3. The CVLANs of the two customers overlap. The service provider assigns SVLANs 3 and 4 to customers A and B, respectively.

When a tagged Ethernet frame from CE 1 arrives at PE 1, the PE tags the frame with SVLAN 3. The double-tagged Ethernet frame travels over the service provider network until it arrives at PE 2. PE 2 removes the SVLAN tag of the frame, and then sends the frame to CE 4.

Figure 2 Typical QinQ application scenario

 

QinQ implementations

QinQ is enabled on a per-port basis. The link type of a QinQ-enabled port can be access, hybrid, or trunk. The QinQ tagging behaviors are the same across these types of ports.

A QinQ-enabled port tags all incoming frames (tagged or untagged) with the PVID tag.

·     If an incoming frame already has one tag, it becomes a double-tagged frame.

·     If the frame does not have any 802.1Q tags, it becomes a frame tagged with the PVID.

QinQ provides the most basic VLAN manipulation method to tag all incoming frames (tagged or untagged) with the PVID tag. To perform advanced VLAN manipulations, use VLAN mappings or QoS policies as follows:

·     To use criteria other than the CVLAN ID to match packets for SVLAN tagging, use the QoS nest action. The QoS nest action can also be used with other actions in the same traffic behavior.

·     To set the 802.1p priority in SVLAN tags, use the priority marking action as described in "

·     Setting the 802.1p priority in SVLAN tags."

For more information about VLAN mappings, see "Configuring VLAN mapping." For more information about QoS, see ACL and QoS Configuration Guide.

Protocols and standards

·     IEEE 802.1Q, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local Area Networks

·     IEEE 802.1ad, IEEE Standard for Local and Metropolitan Area Networks-Virtual Bridged Local Area Networks-Amendment 4: Provider Bridges

Restrictions and guidelines: QinQ configuration

When you configure QinQ, follow these restrictions and guidelines:

·     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 their forwarding path. This value is the sum of the default Ethernet interface MTU (1500 bytes) and the length (4 bytes) of a VLAN tag.

·     You can use a QoS policy, a VLAN mapping, and QinQ on a port for VLAN tag manipulation. If their settings conflict, the QoS policy has the highest priority, the VLAN mapping has the medium priority, and QinQ has the lowest priority.

Enabling QinQ

About this task

Enable QinQ on customer-side ports of PEs. A QinQ-enabled port tags an incoming frame with its PVID.

Restrictions and guidelines

Before you enable or disable QinQ on a port, you must remove any VLAN mappings on the port. For more information about VLAN mapping, see Layer 2—LAN Switching Configuration Guide.

Procedure

1.     Enter system view.

system-view

2.     Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.

interface interface-type interface-number

3.     Set the port link type.

port link-type access

By default, the link type of a port is access.

4.     Assign the access port to the specified VLAN.

port access vlan vlan-id

By default, all access ports belong to VLAN 1.

The PVID and CVLAN of an access port are the VLAN to which the port belongs. The port sends packets from the VLAN untagged.

5.     Enable QinQ on the port.

qinq enable

By default, QinQ is disabled on the port.

Configuring the TPID for VLAN tags

About TPID

TPID identifies a frame as an 802.1Q tagged frame. The TPID value varies by vendor. On an H3C device, the TPID in the 802.1Q tag added on a QinQ-enabled port is 0x8100 by default, in compliance with IEEE 802.1Q. In a multi-vendor network, make sure the TPID setting is the same between directly connected devices so 802.1Q tagged frames can be identified correctly.

TPID settings include CVLAN TPID and SVLAN TPID.

A QinQ-enabled port uses the CVLAN TPID to match incoming tagged frames. An incoming frame is handled as untagged if its TPID is different from the CVLAN TPID.

SVLAN TPIDs are configurable on a per-port basis. A service provider-side port uses the SVLAN TPID to replace the TPID in outgoing frames' SVLAN tags and match incoming tagged frames. An incoming frame is handled as untagged if the TPID in its outer VLAN tag is different from the SVLAN TPID.

For example, a PE device is connected to a customer device that uses the TPID 0x8200 and to a provider device that uses the TPID 0x9100. For correct packet processing, you must set the CVLAN TPID and SVLAN TPID to 0x8200 and 0x9100 on the PE, respectively.

The TPID field is at the same position as the EtherType field in an untagged Ethernet frame. To ensure correct packet type identification, do not set the TPID value to any of the values listed in Table 1.

Table 1 Reserved EtherType values

Protocol type	Value
ARP	0x0806
PUP	0x0200
RARP	0x8035
IP	0x0800
IPv6	0x86dd
PPPoE	0x8863/0x8864
MPLS	0x8847/0x8848
IPX/SPX	0x8137
IS-IS	0x8000
LACP	0x8809
LLDP	0x88cc
802.1X	0x888e
802.1ag	0x8902
Cluster	0x88a7
Reserved	0xfffd/0xfffe/0xffff

 

Restrictions and guidelines

The TPID value in VLAN tags is typically configured on the service provider-side ports of PEs.

Configuring an interface-specific TPID value

1.     Enter system view.

system-view

2.     Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.

interface interface-type interface-number

3.     Set the interface-specific CVLAN TPID or SVLAN TPID.

qinq ethernet-type service-tag hex-value

The default interface-specific TPID value in the SVLAN tag is 8100 in hexadecimal notation.

Setting the 802.1p priority in SVLAN tags

About the 802.1p priority in SVLAN tags

By default, the 802.1p priority in the SVLAN tag added by a QinQ-enabled port depends on the priority trust mode on the port. If the 802.1p priority in frames is trusted, the device copies the 802.1p priority in the CVLAN tag to the SVLAN tag.

For more information about QoS policies and priority trust mode, see ACL and QoS Configuration Guide.

Tasks at a glance

To use QoS policies to set the 802.1p priority in SVLAN tags, perform the following tasks:

1.     Creating a traffic class and configuring CVLAN match criteria

2.     Creating a traffic behavior and configuring a priority marking action for SVLAN tags

3.     Creating a QoS policy

4.     Applying the QoS policy

Creating a traffic class and configuring CVLAN match criteria

1.     Enter system view.

system-view

2.     Create a traffic class and enter its view.

traffic classifier classifier-name [ operator { and | or } ]

3.     Configure CVLAN match criteria.

Choose one option as needed:

¡     Match CVLAN IDs.

if-match customer-vlan-id vlan-id-list

¡     Match 802.1p priority.

if-match customer-dot1p dot1p-value&<1-8>

Creating a traffic behavior and configuring a priority marking action for SVLAN tags

1.     Enter system view.

system-view

2.     Create a traffic behavior and enter its view.

traffic behavior behavior-name

3.     Copy the 802.1p priority in the CVLAN tag to the SVLAN tag.

remark dot1p customer-dot1p-trust

By default, the device copies the 802.1p priority in the CVLAN tag to the SVLAN tag.

Creating a QoS policy

1.     Enter system view.

system-view

2.     Create a QoS policy and enter its view.

qos policy policy-name

3.     Specify the traffic behavior for the traffic class in the QoS policy.

classifier classifier-name behavior behavior-name

Applying the QoS policy

1.     Enter system view.

system-view

2.     Enter Layer 2 Ethernet interface view.

interface interface-type interface-number

3.     Apply the QoS policy to the inbound direction of the port.

qos apply policy policy-name inbound

Display and maintenance commands for QinQ

Execute display commands in any view.

 

Task	Command
Display QinQ-enabled ports.	display qinq [ interface interface-type interface-number ]