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Contents
Restrictions and guidelines: QinQ configuration
Configuring the TPID for VLAN tags
Configuring an interface-specific TPID value
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 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.
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 and QinQ on a port for VLAN tag manipulation. If their settings conflict, the QoS policy has higher priority than QinQ.
Enabling QinQ
About this task
Enable QinQ on customer-side ports of PEs. A QinQ-enabled port tags an incoming frame with its PVID.
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 | hybrid | trunk }
By default, the link type of a port is access.
¡ 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.
¡ Configure the hybrid port to send packets from its PVID untagged and send packets from the CVLANs tagged.
port hybrid vlan vlan-id-list { tagged | untagged }
By default, the hybrid port is an untagged member of the VLAN to which the port belongs when its link type is access.
port trunk permit vlan { vlan-id-list | all }
By default, a trunk port allows packets only from VLAN 1 to pass through.
4. 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
You can configure the TPID value in VLAN tags by using one of the following methods:
· In system view—The TPID value configuration made in system view takes effect on all ports of the device.
· In interface view—The TPID value configuration made in interface view takes effect only on the current interface. For a port, the TPID value configured in interface view has priority over that configured in system view. 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 { customer-tag | service-tag } hex-value
If the device supports global TPID configuration, the default interface-specific TPID value in the SVLAN and CVLAN tags is the same as the global TPID value.
If the device does not support global TPID configuration, the default TPID value is 0x8100 in both SVLAN and CVLAN tags.
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 ] |
QinQ configuration examples
Example: Configuring basic QinQ
Network configuration
As shown in Figure 3:
· The service provider assigns VLAN 100 to Company A's VLANs 10 through 70.
· The service provider assigns VLAN 200 to Company B's VLANs 30 through 90.
· The devices between PE 1 and PE 2 in the service provider network use a TPID value of 0x8200.
Configure QinQ on PE 1 and PE 2 to transmit traffic in VLANs 100 and 200 for Company A and Company B, respectively.
For the QinQ frames to be identified correctly, set the SVLAN TPID to 0x8200 on the service provider-side ports of PE 1 and PE 2.
Procedure
1. Configure PE 1:
# Configure GigabitEthernet 1/2/0/1 as a trunk port, and assign it to VLAN 100 and VLANs 10 through 70.
<PE1> system-view
[PE1] interface gigabitethernet 1/2/0/1
[PE1-GigabitEthernet1/2/0/1] port link-type trunk
[PE1-GigabitEthernet1/2/0/1] port trunk permit vlan 100 10 to 70
# Set the PVID of GigabitEthernet 1/2/0/1 to VLAN 100.
[PE1-GigabitEthernet1/2/0/1] port trunk pvid vlan 100
# Enable QinQ on GigabitEthernet 1/2/0/1.
[PE1-GigabitEthernet1/2/0/1] qinq enable
[PE1-GigabitEthernet1/2/0/1] quit
# Configure GigabitEthernet 1/2/0/2 as a trunk port, and assign it to VLANs 100 and 200.
[PE1] interface gigabitethernet 1/2/0/2
[PE1-GigabitEthernet1/2/0/2] port link-type trunk
[PE1-GigabitEthernet1/2/0/2] port trunk permit vlan 100 200
# Set the TPID value in the SVLAN tags to 0x9100 on GigabitEthernet 1/2/0/2.
[PE1-GigabitEthernet1/2/0/2] qinq ethernet-type service-tag 9100
[PE1-GigabitEthernet1/2/0/2] quit
# Configure GigabitEthernet 1/2/0/3 as a trunk port, and assign it to VLAN 200 and VLANs 30 through 90.
[PE1] interface gigabitethernet 1/2/0/3
[PE1-GigabitEthernet1/2/0/3] port link-type trunk
[PE1-GigabitEthernet1/2/0/3] port trunk permit vlan 200 30 to 90
# Set the PVID of GigabitEthernet 1/2/0/3 to VLAN 200.
[PE1-GigabitEthernet1/2/0/3] port trunk pvid vlan 200
# Enable QinQ on GigabitEthernet 1/2/0/3.
[PE1-GigabitEthernet1/2/0/3] qinq enable
[PE1-GigabitEthernet1/2/0/3] quit
2. Configure PE 2:
# Configure GigabitEthernet 1/2/0/1 as a trunk port, and assign it to VLAN 200 and VLANs 30 through 90.
<PE2> system-view
[PE2] interface gigabitethernet 1/2/0/1
[PE2-GigabitEthernet1/2/0/1] port link-type trunk
[PE2-GigabitEthernet1/2/0/1] port trunk permit vlan 200 30 to 90
# Set the PVID of GigabitEthernet 1/2/0/1 to VLAN 200.
[PE2-GigabitEthernet1/2/0/1] port trunk pvid vlan 200
# Enable QinQ on GigabitEthernet 1/2/0/1.
[PE2-GigabitEthernet1/2/0/1] qinq enable
[PE2-GigabitEthernet1/2/0/1] quit
# Configure GigabitEthernet 1/2/0/2 as a trunk port, and assign it to VLANs 100 and 200.
[PE2] interface gigabitethernet 1/2/0/2
[PE2-GigabitEthernet1/2/0/2] port link-type trunk
[PE2-GigabitEthernet1/2/0/2] port trunk permit vlan 100 200
# # Set the TPID value in the SVLAN tags to 0x9100 on GigabitEthernet 1/2/0/2.
[PE2-GigabitEthernet1/2/0/2] qinq ethernet-type service-tag 9100
[PE2-GigabitEthernet1/2/0/2] quit
# Configure GigabitEthernet 1/2/0/3 as a trunk port, and assign it to VLAN 100 and VLANs 10 through 70.
[PE2] interface gigabitethernet 1/2/0/3
[PE2-GigabitEthernet1/2/0/3] port link-type trunk
[PE2-GigabitEthernet1/2/0/3] port trunk permit vlan 100 10 to 70
# Set the PVID of GigabitEthernet 1/2/0/3 to VLAN 100.
[PE2-GigabitEthernet1/2/0/3] port trunk pvid vlan 100
# Enable QinQ on GigabitEthernet 1/2/0/3.
[PE2-GigabitEthernet1/2/0/3] qinq enable
[PE2-GigabitEthernet1/2/0/3] quit
3. Configure the devices between PE 1 and PE 2:
# Set the MTU to a minimum of 1504 bytes for each port on the path of QinQ frames. (Details not shown.)
# Configure all ports on the forwarding path to allow frames from VLANs 100 and 200 to pass through without removing the VLAN tag. (Details not shown.)
