If the switch is in VTP server or transparent mode (see the “How to Configure VTP” section), you can configure VLANs in global and config-vlan configuration modes. When you configure VLANs in global and config-vlan configuration modes, the VLAN configuration is saved in the vlan.dat files. To display the VLAN configuration, enter the
If the switch is in VLAN transparent mode, use the copy
command to save the VLAN configuration to the startup-config file. After you save the running configuration as the startup configuration, use the
commands to display the VLAN configuration.
When the switch boots, if the VTP domain name and the VTP mode in the startup-config file and vlan.dat files do not match, the switch uses the configuration in the vlan.dat file.
You can configure extended-range VLANs only in global configuration mode.
Supervisor engine redundancy does not support nondefault VLAN data file names or locations. Do not enter the
command on a switch that has a redundant supervisor engine.
Before installing a redundant supervisor engine, enter the
no vtp file
command to return to the default configuration.
A VLAN is a group of end stations with a common set of requirements, independent of physical location. VLANs have the same attributes as a physical LAN but allow you to group end stations even if they are not located physically on the same LAN segment.
VLANs are usually associated with IP subnetworks. For example, all the end stations in a particular IP subnet belong to the same VLAN. Traffic between VLANs must be routed. LAN port VLAN membership is assigned manually on an port-by-port basis.
Cisco IOS Release 15.1SY supports 4096 VLANs in accordance with the IEEE 802.1Q standard. These VLANs are organized into several ranges; you use each range slightly differently. Some of these VLANs are propagated to other switches in the network when you use the VLAN Trunking Protocol (VTP). The extended-range VLANs are not propagated, so you must configure extended-range VLANs manually on each network device.
For system use only. You cannot see or use these VLANs.
Cisco default. You can use this VLAN but you cannot delete it.
For Ethernet VLANs; you can create, use, and delete these VLANs.
Cisco defaults for FDDI and Token Ring. You cannot delete VLANs 1002–1005.
For Ethernet VLANs only.
The following information applies to VLAN ranges:
Layer 3 LAN ports, WAN interfaces and subinterfaces, and some software features use internal VLANs in the extended range. You cannot use an extended range VLAN that has been allocated for internal use.
To display the VLANs used internally, enter the
show vlan internal usage
command. With earlier releases, enter the
show vlan internal usage
show cwan vlans
You can configure ascending internal VLAN allocation (from 1006 and up) or descending internal VLAN allocation (from 4094 and down).
Except for the VLAN name, Ethernet VLANs 1006 through 4094 use only default values.
You can configure the VLAN name for Ethernet VLANs 1006 through 4094.
You can configure the following parameters for VLANs 2 through 1001:
VLAN type (Ethernet, FDDI, FDDI network entity title [NET], TrBRF, or TrCRF)
VLAN state (active or suspended)
Security Association Identifier (SAID)
Bridge identification number for TrBRF VLANs
Ring number for FDDI and TrCRF VLANs
Parent VLAN number for TrCRF VLANs
Spanning Tree Protocol (STP) type for TrCRF VLANs
The VLAN locking feature provides an extra level of verification to ensure that you have configured the intended VLAN. When VLAN locking is enabled, you need to specify the VLAN name when you change a port from one VLAN to another. This feature affects
commands (in interface configuration mode) that specify the VLANs or private VLANs for access and trunk ports.
By default, the VLAN locking is disabled. To enable VLAN locking, perform this task:
vlan port provisioning
Enables VLAN locking.
Creating or Modifying an Ethernet VLAN
User-configured VLANs have unique IDs from 1 to 4094, except for reserved VLANs (see Table 16-1). Enter the
command with an unused ID to create a VLAN. Enter the
command for an existing VLAN to modify the VLAN (you cannot modify an existing VLAN that is being used by a Layer 3 port or a software feature).
See the “Default Settings for VLANs” section for the list of default parameters that are assigned when you create a VLAN. If you do not specify the VLAN type with the
keyword, the VLAN is an Ethernet VLAN.
Creates or modifies an Ethernet VLAN, a range of Ethernet VLANs, or several Ethernet VLANs specified in a comma-separated list (do not enter space characters).
Updates the VLAN database and returns to privileged EXEC mode.
When you create or modify an Ethernet VLAN, note the following information:
Because Layer 3 ports and some software features require internal VLANs allocated from 1006 and up, configure extended-range VLANs starting with 4094.
You can configure extended-range VLANs only in global configuration mode. You cannot configure extended-range VLANs in VLAN database mode.
Layer 3 ports and some software features use extended-range VLANs. If the VLAN you are trying to create or modify is being used by a Layer 3 port or a software feature, the switch displays a message and does not modify the VLAN configuration.
When deleting VLANs, note the following information:
You cannot delete the default VLANs for the different media types: Ethernet VLAN 1 and FDDI or Token Ring VLANs 1002 to 1005.
When you delete a VLAN, any LAN ports configured as access ports assigned to that VLAN become inactive. The ports remain associated with the VLAN (and inactive) until you assign them to a new VLAN.
This example shows how to create an Ethernet VLAN in global configuration mode and verify the configuration:
Note • To avoid spanning tree loops, be careful not to misconfigure the VLAN translation feature.
On trunk ports, you can translate one VLAN number to another VLAN number, which transfers all traffic received in one VLAN to the other VLAN.
VLAN Translation Guidelines and Restrictions
When translating VLANs, follow these guidelines and restrictions:
A VLAN translation configuration is inactive if it is applied to ports that are not Layer 2 trunks.
Do not configure translation of ingress native VLAN traffic on an 802.1Q trunk. Because 802.1Q native VLAN traffic is untagged, it cannot be recognized for translation. You can translate traffic from other VLANs to the native VLAN of an 802.1Q trunk.
Do not remove the VLAN to which you are translating from the trunk.
The VLAN translation configuration applies to all ports in a port group. VLAN translation is disabled by default on all ports in a port group. Enable VLAN translation on ports as needed.
Cisco IOS Release 15.1SY supports only IEEE 802.1Q trunking.
Translates a VLAN to another VLAN. The valid range is 1 to 4094.
When you configure a VLAN mapping from the original VLAN to the translated VLAN on a port, traffic arriving on the original VLAN gets mapped or translated to the translated VLAN at the ingress of the switch port, and the traffic internally tagged with the translated VLAN gets mapped to the original VLAN before leaving the switch port. This method of VLAN mapping is a two-way mapping.
Exits configuration mode.
This example shows how to map VLAN 1649 to VLAN 755 Gigabit Ethernet port 5/2:
This example shows how to verify the configuration:
Router# show interface gigabitethernet 5/2 vlan mapping
Original VLAN Translated VLAN
Enabling VLAN Translation on Other Ports in a Port Group
To enable VLAN translation on other ports in a port group, perform this task:
Selects the LAN port to configure.
switchport vlan mapping enable
Enables VLAN translation.
Exits configuration mode.
This example shows how to enable VLAN translation on a port:
Router# configure terminal
Router(config)# interface gigabitethernet 5/2
Router(config-if)# switchport vlan mapping enable
Saving VLAN Information
The VLAN database is stored in the vlan.dat file. You should create a backup of the vlan.dat file in addition to backing up the running-config and startup-config files. If you replace the existing supervisor engine, copy the startup-config file as well as the vlan.dat file to restore the system. The vlan.dat file is read on bootup and you will have to reload the supervisor engine after uploading the file. To view the file location, use the dir vlan.dat command. To copy the file (binary), use the copy vlan.dat tftp command.
Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page: