QinQ - Maipu Configurations

In last post, As we discussed about QinQ. Let’see in action, The same thing.Here we will see selective QinQ. Since this most used QinQ style.

For Basic no need to give any Vlan mapping. It will work by default with port pvid.Just you need to enable vlan dot1q tunnel under port. Then it will tag incoming vlan with port vlan and while going out of network. It will remove the Service provider vlan tag. 

Here we can see selective QinQ....

PE1 and PE2 are the operator’s network devices; Customer A, Customer B and Customer C are the user network devices.

Networking requirement: VLAN 10 packets of Customer A and VLAN 10 packets of Customer C are inter-communicated via VLAN 100 of the operator network. VLAN 20 packets of Customer B and VLAN 20 packets of Customer C are inter-communicated via VLAN 200 of the operator network.

Topology                          

PE1 configuration:

Command	Description
PE1(config-port-0/1)#port mode hybrid	Set the port as Hybrid port
PE1(config-port-0/1)#port hybrid untagged vlan 100	Add the port to VLAN 100
PE1(config-port-0/1)#vlan dot1q-tunnel enable	Enable the basic vlan dot1q-tunnel function on the port
PE1(config-port-0/1)#vlan dot1q-tunnel 10 100	The port configures flexible items and encapsulates outer Tag 100 for received VLAN 10 packets.
PE1(config-port-0/1)#vlan dot1q-tunnel drop	The port configuration only supports flexible items.
PE1(config-port-0/2)#port mode hybrid	Set the port as Hybrid port
PE1(config-port-0/2)#port hybrid untagged vlan 200	Add the port to VLAN 200
PE1(config-port-0/2)#vlan dot1q-tunnel enable	Enable the basic vlan dot1q-tunnel function on the port
PE1(config-port-0/2)#vlan dot1q-tunnel 20 200	The port configures flexible items and encapsulates outer Tag 200 for received VLAN 20 packets.
PE1(config-port-0/2)#vlan dot1q-tunnel drop	The port configuration only supports flexible items.
PE1(config-port-0/3)#port mode trunk	Set the port as Trunk port
PE1(config-port-0/3)#port trunk allowed vlan 100	Set port 0/3 to allow VLAN 100 to pass
PE1(config-port-0/3)#port trunk allowed vlan 200	Set port 0/3 to allow VLAN 200 to pass

PE2 configuration:

Command	Description
PE2(config-port-0/2)#port mode hybrid	Set the port as Hybrid port
PE2(config-port-0/2)#port hybrid untagged vlan 100	Add the port to VLAN 100
PE2(config-port-0/2)#port hybrid untagged vlan 200	Add the port to VLAN 200
PE2(config-port-0/2)#vlan dot1q-tunnel enable	Enable basic vlan dot1q-tunnel function on the port
PE2(config-port-0/2)#vlan dot1q-tunnel 10 100	The port configures flexible items and encapsulates outer Tag 100 for received VLAN 10 packets.
PE2(config-port-0/2)#vlan dot1q-tunnel 20 200	The port configures flexible items and encapsulates outer Tag 200 for received VLAN 20 packets.
PE2(config-port-0/2)#vlan dot1q-tunnel drop	The port configuration only supports flexible items.
PE2(config-port-0/3)#port mode trunk	Set the port as Trunk port
PE2(config-port-0/3)#port trunk allowed vlan 100	Set port 0/3 to allow VLAN 100 to pass
PE2(config-port-0/3)#port trunk allowed vlan 200	Set port 0/3 to allow VLAN 200 to pass

Note -

The user must ensure that the network devices between PE1 and PE2 can permit vlan dot1q tunnel packets to pass via configuration.

Monitoring Commands

Command	Description
show vlan dot1q-tunnel	View the information about the flexible vlan dot1q-tunnel items
show vlan dot1q-tunnel mapping	View the information about the flexible vlan dot1q-tunnel mapping items
show frame-tag tpid	View all port TPID information

Monitoring Command Output - show outputs are for reference , not actual*

switch#show vlan dot1q-tunnel

Displayed result:

switch#show vlan dot1q-tunnel

-------------------- ------------VLAN DOT1Q-TUNNEL-----------------------

Port                     Inner VlanId             Outer VlanId            

-------------------- --------------------- ----------------------------------------------

port 0/1                 totals:2

                                  10                              100                     

                                  15                              150                     

port 0/2                 totals:1

                                  20                              200                     

Description and analysis:

Port: port name

Inner VlanId: The VLAN ID of the Tag packets received by the port, that is, the inner VLAN ID of the packets after encapsulation.

Outer VlanId: The outer VLAN ID encapsulated by the port, that is, the outer VLAN ID of the packets after encapsulation

The displayed result shows the flexible vlan dot1q-tunnel items configured on the port and the details.

switch#show vlan dot1q-tunnel mapping

Displayed result:

-------------------- -------VLAN DOT1Q-TUNNEL MAPPING--------------------

Port                     Former VlanId            Mapping VlanId           

-------------------- --------------------- ----------------------------------------------------

port 0/4                 totals:1

                                  40                                400                     

port 0/5                 totals:2

                                  40                                400                     

                                 50                                 500                     

port 0/6                totals:1

                                 40                                400 

Description and analysis:

Port: port name

Former VlanId: The VLAN ID of the Tag packets received by the port, that is, the VLAN ID of the Tag in the packet before replacing

Outer VlanId: The VLAN ID used by the port for replacing as per the flexible items, that is, the VLAN ID used to replace Tag

The displayed result shows the flexible vlan dot1q-tunnel mapping items configured on the port and the details.

Hope this configuration will help you for better understanding of QinQ functions.

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What is QinQ

In this section, we will see about Switching concept QinQ. In service provider networks, This is very important. Service provider use this Switching function to pass customer data from one end to other end with two vlan id’s in own switching network. 

Let’s see this concept in detail---

What is QinQ?

The QinQ technology is called VLAN dot1q tunnel, 802.1Q tunnel, VLAN Stacking technology. The standard comes from IEEE 802.1ad and it is the expansion of the 802.1Q protocol. QinQ adds one layer of 802.1Q tag (VLAN tag) based on the original 802.1Q packet head. With the double layers of tags, the VLAN quantity is increased to 802.1Q.

QinQ encapsulates the private network VLAN tag of the user in the public(service provider) network VLAN Tag to make the packet with double layers of VLAN Tags cross the backbone network (public network) of the operator. In the public network, the packet is passed according to the out layer of VLAN tag (that is the public network VLAN Tag) and the private network VLAN Tag of the user is shielded.

The formats of the common 802.1Q packet with one layer of VLAN TAG and the QinQ packet with two layers of VLAN TAGs are as follows:

The formats of common VLAN packet and QinQ packet

The formats of common VLAN packet and QinQ packet Two layers of VLAN tags can support 4K × 4K VLANs, meeting most of requirements ISP and overcoming limitation of VLANs.

QinQ features:

1. Provide one simple L2 VPN tunnel for the user.
2. Do not need the supporting of the protocol and signaling; be realized by the static configuration.

QinQ mainly solves the following problems:

1. Shield the VLAN ID of the user, so as to save the public network VLAN ID resource of the service provider.
2. The user can plan the private network VLAN ID, avoiding the confliction with the public network and other user VLAN IDs.
3. Provide the simple L2 VLAN solution.

QinQ in Action

The upstream packet of the CE1 switch carries one layer of VLAN tag. The packet reaches the QinQ port of the PE1 switch. According to the configuration of the QinQ port, add one out layer of VLAN TAG to the packet. The packet with two layers of VLAN tags is forwarded to PE2 via the public network. On the QinQ port of PE2, the out layer of VLAN TAG is deleted, and the packet recovers to have one layer of VLAN Tag and is forwarded to CE2.

Realizing Modes of QinQ

QinQ is divided to two kinds, including basic QinQ and selective QinQ.

Basic QinQ: 

When receiving the packet, the QinQ port adds the VLAN TAG of the default VLAN of the port to the packet no matter whether the packet has the VLAN TAG. Before the packet is forwarded out from the QinQ port, delete the out layer of TAG and then forward it. The disadvantage of the method is that the encapsulated out layer of VLAN cannot be selected according to the VLAN TAG of the packet

Selective QinQ: 

The selective QinQ solves the disadvantage of the basic QinQ. When receiving the packet, the QinQ port adds the specified out layer of VLAN TAG to the packet according to the VLAN TAG of the packet. If the encapsulated out layer of VLAN TAG is not specified, add the VLAN TAG of the default VLAN of the port to the packet.

QinQ expansion: Configure the mapping entries on the QinQ port to replace the VLAN TAG of the packet with the specified VLAN TAG to realize the conversion of the VLAN TAG. The function is called VLAN Mapping.

TPID (Tag Protocol Identifier): It is one field in VLAN TAG, used to indicate the protocol type of VLAN TAG. IEEE 802.1Q protocol defines the value of the field as 0x8100 The default value of the out layer of TPID of QinQ is 0x8100. The TPID of the out VLAN TAG of the device QinQ packet of some manufacturer is 0x9100 or 0x9200. The user can modify the TPID of the port at the public network to realize the intercommunication of the devices of different manufacturers.

In next post we will see about configuration of Maipu Switches for QinQ, For Cisco QinQ configuration - Click here 

Hope this post will help you for understanding concepts of QinQ.

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