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In a typical deployment of VLAN mapping, you want service provider to provide a transparent switching infrastructure that
includes customers’ switches at the remote location as a part of local site. This allows customers to use the same VLAN ID
space and run Layer 2 control protocols seamlessly across the provider network. In such scenarios, we recommend that service
providers do not impose their VLAN IDs on their customers.
One way to establish translated VLAN IDs (S-VLANs) is to map customer VLANs to VLANs (called VLAN ID translation) on trunk
ports that are connected to a customer network. Packets entering the port are mapped to service provider VLAN (S-VLAN) based
on the port number and the packet’s original customer VLAN-ID (C-VLAN).
Service providers’ internal assignments might conflict with a customer’s VLAN. To isolate customer traffic, a service provider
decides to map a specific VLAN into another one while the traffic is in its cloud.
Deployment Example
In the figure, the service provider provides Layer 2 VPN service to two different customers, A and B. The service provider separates the
data and control traffic between the two customers and from the providers’ own control traffic. The service provider network
must also be transparent to the customer edge devices.
Figure 1. Example of a Service Provider with Layer 2 VPN Service
All forwarding operations on Catalyst 9000 series switch are performed using S-VLAN and not C-VLAN information because the
VLAN ID is mapped to the S-VLAN on ingress.
Note
When you configure features on a port for VLAN mapping, you always use the S-VLAN rather than C-VLAN.
On an interface configured for VLAN mapping, the specified C-VLAN packets are mapped to the specified S-VLAN when they enter
the port. Symmetrical mapping to the customer C-VLAN occurs when packets exit the port.
The switch supports these types of VLAN mapping on trunk ports:
One-to-one VLAN mapping.
Selective QinQ.
QinQ on a trunk port.
Figure 2. Mapping Customer VLANs to Service-Provider VLANs
Figure shows a topology where a customer uses the same VLANs in multiple sites on different sides of a service-provider network.
The C-VLAN IDs is mapped to service-provider VLAN IDs for packet travel across the service-provider backbone. The C-VLAN IDs
are retrieved at the other side of the service-provider backbone for use in the other customer site. Configure the same set
of VLAN mappings at a customer-connected port on each side of the service-provider network.
One-to-One VLAN Mapping
One-to-one VLAN mapping occurs at the ingress and egress of the port and maps the customer C-VLAN ID in the 802.1Q tag to
the service-provider S-VLAN ID. Packets with VLAN IDs other than the ones with configured VLAN mapping are forwarded as normal
traffic.
Selective Q-in-Q
Selective QinQ maps the specified customer VLANs entering the UNI to the specified S-VLAN ID. The S-VLAN ID is added to the
incoming unmodified C-VLAN and the packet travels the service provider network double-tagged. At the egress, the S-VLAN ID
is removed and the customer VLAN-ID is retained on the packet. By default, packets that do not match the specified customer
VLANs are dropped.
Q-in-Q on a Trunk Port
QinQ on a trunk port maps all the customer VLANs entering the UNI to the specified S-VLAN ID. Similar to Selective QinQ, the
packet is double-tagged and at the egress, the S-VLAN ID is removed.
Configuration Guidelines for VLAN Mapping
Note
By default, no VLAN mapping is configured.
Guidelines include the following:
If the VLAN mapping is enabled on an EtherChannel, the configuration does not apply to all member ports of the EtherChannel
bundle and applies only to the EtherChannel interface.
If VLAN mapping is enabled on an EtherChannel and a conflicting mapping translation is enabled on a member port, the configuration
is rejected on the member port.
If a port with VLAN mapping is configured as a part of EtherChannel with a conflicting mapping translation, the port cannot
be a member of the port-channel.
The member port of an EtherChannel is suspended from the EtherChannel bundle if the mode of the port is changed to anything
other than ‘trunk’ mode.
To process control traffic consistently, either enable Layer 2 protocol tunneling (recommended), as follows:
Default native VLANs, user-configured native VLANs, and reserved VLANs (range 1002-1005) cannot be used for VLAN mapping.
The S-VLAN used for VLAN mapping cannot be a part of any other Layer 3 configurations like EVPN or LISP.
PVLAN support is not available when VLAN mapping is configured.
Configuration Guidelines for One-to-One VLAN Mapping
One-to-One VLAN mapping can be configured only on trunk ports and not on dynamic trunk.
One-to-One VLAN mapping should be identical on both ports.
S-VLAN should be created and present in the allowed VLAN list of the trunk port where One-to-One VLAN mapping is configured.
When One-to-One VLAN mapping is configured, multiple C-VLANs cannot be mapped to the same S-VLAN.
Merging of C-VLAN and S-VLAN spanning-tree topology is not supported in case of one-to-one VLAN mapping.
Configuration Guidelines for Selective Q-in-Q
S-VLAN should be created and present in the allowed VLAN list of the trunk port where Selective Q-in-Q is configured.
When Selective Q-in-Q is configured, the device supports Layer 2 protocol tunneling for CDP, STP, LLDP, and VTP. For emulated
point-to-point network topologies, it also supports PAgP, LACP, and UDLD protocols.
IP routing is not supported on Selective Q-in-Q enabled ports.
IPSG is not supported on Selective Q-in-Q enabled ports.
The tagging of native VLAN̉ packets and selective QinQ ports is mutually exclusive and cannot be supported together on the
same port. If the native VLAN tagging global command is enabled on the switch, you should disable the tagging of native VLAN
packets on selective QinQ enabled ports using the command no switchport trunk native vlan tag command.
Configuration Guidelines for Q-in-Q on a Trunk Port
S-VLAN should be created and present in the allowed VLAN list of the trunk port where Q-in-Q on a trunk port is configured.
When Q-in-Q on a trunk port is configured, the device supports Layer 2 protocol tunneling for CDP, STP, LLDP, and VTP. For
emulated point-to-point network topologies, it also supports PAgP, LACP, and UDLD protocols.
Ingress and egress SPAN, and RSPAN are supported on trunk ports with QinQ enabled.
When QinQ is enabled, the SPAN filtering can be enabled to monitor only the traffic on the mapped VLAN, i.e. S-VLANs.
IGMP snooping is not supported on the C-VLAN.
The tagging of native VLAN̉ packets and QinQ on a trunk port are mutually exclusive and cannot be supported together on the
same port. If the native VLAN tagging global command is enabled on the switch, you should disable the tagging of native VLAN
packets on the QinQ enabled trunk ports using the command no switchport trunk native vlan tag command.
How to Configure VLAN Mapping
The following sections provide information about configuring VLAN mapping:
One-to-One VLAN Mapping
Note
VLAN Mapping is supported only with the network-advantage license level.
To configure one-to-one VLAN mapping to map a customer VLAN ID to a service-provider VLAN ID, perform this task:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3
interface interface-id
Example:
Device(config)# interface gigabitethernet1/0/1
Enters interface configuration mode for the interface that is connected to the service-provider network. You can enter a physical
interface or an EtherChannel port channel.
Step 4
switchport mode trunk
Example:
Device(config-if)# switchport mode trunk
Configures the interface as a trunk port.
Step 5
switchport vlan mappingvlan-id translated-id
Example:
Device(config-if)# switchport vlan mapping 2 102
Enters the VLAN IDs to be mapped:
vlan-id —the customer VLAN ID (C-VLAN) entering the switch from the customer network. The range is from 1 to 4094.
translated-id —the assigned service-provider VLAN ID (S-VLAN). The range is from 1 to 4094.
By default, the packets with VLAN IDs other than the ones with configured VLAN mapping are forwarded as normal traffic.
Step 6
exit
Example:
Device(config-if)# exit
Returns to global configuration mode.
Step 7
spanning-tree bpdufilter enable
Example:
Device(config)# spanning-tree bpdufilter enable
Inserts a BPDU filter for spanning tree.
Note
To process control traffic consistently, either enable Layer 2 protocol tunneling (recommended) or insert a BPDU filter for
spanning tree.
Step 8
end
Example:
Device(config)# end
Returns to privileged EXEC mode.
Step 9
show vlan mapping
Example:
Device# show vlan mapping
Verifies the configuration.
Step 10
copy running-config startup-config
Example:
Device# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
Example
Use no switchport vlan mapping command to remove the VLAN mapping information. Entering no switchport vlan mapping all command deletes all mapping configurations.
This example shows how to map VLAN IDs 2 to 6 in the customer network to VLANs 101 to 105 in the service-provider network
(Figure 3-5). You configure the same VLAN mapping commands for a port in Switch A and Switch B; the traffic on all other VLAN
IDs is forwarded as normal traffic.
In the previous example, at the ingress of the service-provider network, VLAN IDs 2 to 6 in the customer network are mapped
to VLANs 101 to 105, in the service provider network. At the egress of the service provider network, VLANs 101 to 105 in the
service provider network are mapped to VLAN IDs 2 to 6, in the customer network.
Note
Packets with VLAN IDs other than the ones with configured VLAN Mapping are forwarded as normal traffic.
Use show vlan mapping command to view information about configured vlans.
Device> enable
Device# configure terminal
Device(config)# show vlan mapping
Total no of vlan mappings configured: 1
Interface Po5:
VLANs on wire Translated VLAN Operation
------------------------------ --------------- --------------
20 30 1-to-1
Selective Q-in-Q on a Trunk Port
To configure VLAN mapping for selective Q-in-Q on a trunk port, perform this task:
Note
You cannot configure one-to-one mapping and selective Q-in-Q on the same interface.
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3
interface interface-id
Example:
Device(config)# interface gigabitethernet1/0/1
Enters interface configuration mode for the interface that is connected to the service-provider network. You can enter a physical
interface or an EtherChannel port channel.
vlan-id —the customer VLAN ID (C-VLAN) entering the switch from the customer network. The range is from 1 to 4094. You can
enter a string of VLAN-IDs.
outer-vlan-id —The outer VLAN ID (S-VLAN) of the service provider network. The range is from 1 to 4094.
Use the no form of this command to remove the VLAN mapping configuration. Entering the no switchport vlan mapping all command deletes all mapping configurations.
Specifies that all unmapped packets on the port are forwarded with the specified S-VLAN.
By default, packets that do not match the mapped VLANs, are dropped.
Untagged traffic are forwarded without dropping.
Step 7
exit
Example:
Device(config-if)# exit
Returns to global configuration mode.
Step 8
spanning-tree bpdufilter enable
Example:
Device(config)# spanning-tree bpdufilter enable
Inserts a BPDU filter for spanning tree.
Note
To process control traffic consistently, either enable Layer 2 protocol tunneling (recommended) or insert a BPDU filter for
spanning tree.
Step 9
end
Example:
Device(config)# end
Returns to privileged EXEC mode.
Step 10
show interfaces interface-id vlan mapping
Example:
Device# show interfaces gigabitethernet1/0/1 vlan mapping
Verifies the configuration.
Step 11
copy running-config startup-config
Example:
Device# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
Example
This example shows how to configure selective QinQ mapping on the port so that traffic with a C-VLAN ID of 2 to 5 enters the
switch with an S-VLAN ID of 100. By default, the traffic of any other VLAN ID is dropped.
This example shows how to configure selective QinQ mapping on the port so that traffic with a C-VLAN ID of 2 to 5 enters the
switch with an S-VLAN ID of 100. The traffic of any other VLAN ID is forwarded with the S-VLAN ID of 200.
Device(config)# interface GigabiEthernet0/1
Device(config-if)# switchport vlan mapping 2-5 dot1q-tunnel 100
Device(config-if)# switchport vlan mapping default dot1q-tunnel 200
Device(config-if)# exit
Device# show vlan mapping
Total no of vlan mappings configured: 5
Interface Hu1/0/50:
VLANs on wire Translated VLAN Operation
------------------------------ --------------- --------------
2-5 100 selective QinQ
* 200 default QinQ
Q-in-Q on a Trunk Port
To configure VLAN mapping for Q-in-Q on a trunk port, perform this task:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configure terminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3
interface interface-id
Example:
Device(config)# interface gigabitethernet1/0/1
Enters interface configuration mode for the interface that is connected to the service-provider network. You can enter a physical
interface or an EtherChannel port channel.
This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
Release
Feature
Feature Information
Cisco IOS XE Gibraltar 16.11.1
One-to-One VLAN mapping
One-to-One VLAN mapping allows to map customer VLANs to service-provider VLANs on trunk ports that are connected to a customer
network.
Cisco IOS XE Gibraltar 16.11.1
Selective Q-in-Q
Support for selective Q-in-Q was introduced
Q-in-Q on a Trunk Port
Support for Q-in-Q on a trunk port was introduced
Cisco IOS XE Cupertino 17.7.1
One-to-One VLAN mapping
Support for this feature was introduced on Cisco Catalyst 9600 Series Supervisor 2 Module (C9600X-SUP-2)
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator,
go to http://www.cisco.com/go/cfn.
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