Chapter 21
| VLAN Commands
Configuring VLAN Translation
– 603 –
Command Mode
Interface Configuration (Ethernet)
Command Usage
â—† If the next switch upstream does not support QinQ tunneling, then use this
command to map the customer’s VLAN ID to the service provider’s VLAN ID for
the upstream port. Similarly, if the next switch downstream does not support
QinQ tunneling, then use this command to map the service provider’s VLAN ID
to the customer’s VLAN ID for the downstream port. Note that one command
maps both the original-vlan to new-vlan for ingress traffic and the new-vlan to
original-vlan for egress traffic on the specified port.
For example, assume that the upstream switch does not support QinQ
tunneling. If the command switchport vlan-translation 10 100 is used to map
VLAN 10 to VLAN 100 for upstream traffic entering port 1, and VLAN 100 to
VLAN 10 for downstream traffic leaving port 1, then the VLAN IDs will be
swapped as shown below.
Figure 8: Configuring VLAN Translation
â—† The maximum number of VLAN translation entries is 8 per port, and up to 96 for
the system. However, note that configuring a large number of entries may
degrade the performance of other processes that also use the TCAM, such as IP
Source Guard filter rules, Quality of Service (QoS) processes, QinQ, MAC-based
VLANs, VLAN translation, or traps.
â—† If VLAN translation is set on an interface with this command, and the same
interface is also configured as a QinQ access port with the switchport
dot1q-tunnel mode command, VLAN tag assignments will be determined by
the QinQ process, not by VLAN translation.
Example
This example configures VLAN translation for Port 1 as described in the Command
Usage section above.
Console(config)#vlan database
Console(config-vlan)#vlan 10 media ethernet state active
Console(config-vlan)#vlan 100 media ethernet state active
Console(config-vlan)#exit
Console(config)#interface ethernet 1/1,2
Console(config-if)#switchport allowed vlan add 10 tagged
Console(config-if)#switchport allowed vlan add 100 tagged
Console(config-if)#interface ethernet 1/1
Console(config-if)#switchport vlan-translation 10 100
Console(config-if)#end
Console#show vlan-translation
Interface Old VID New VID
--------- ------- -------
Eth 1/ 1 10 100
12
(VLAN 10) (VLAN 100)
(VLAN 100)
(VLAN 10)
upstream
downstream
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