You can modify or remove any VLANs on the modules in your system. Review the following guidelines before you modify or remove VLANs:

• When you modify VLAN information for a VLAN interface on your module, you have the option to change VLAN characteristics such as the member bridge ports, protocol type, and form of explicit tagging.

• When you modify or remove a VLAN interface, you must specify a VLAN interface index to identify the VLAN interface. The Default VLAN always uses the VLAN interface index of 1. (The VLAN interface index is not the VID.)

• You cannot delete a VLAN for which you have defined a routing interface.

• If you add ports to a specific VLAN, you are permitting additional traffic through that port. If you remove ports from a specific VLAN and the Default VLAN is intact, those ports come under jurisdiction of the Default VLAN (unspecified protocol type, and no explicit or implicit tagging).

• Verify that each bridge port is associated with at least one VLAN in order to handle traffic.

• If you modify the Default VLAN to remove certain ports, verify that those ports are included in another VLAN. If the VLAN is in allClosed mode, those ports are not able to pass data if they are not part of another VLAN. See "Modifying the Default VLAN" earlier in this chapter for more information about the Default VLAN.

• If you remove the Default VLAN (and you have no other VLANs defined for the module), your ports may not be able to forward data until you create a VLAN for them (for example, if you are using allClosed mode).

• If you remove the Default VLAN, the system can no longer recognize any ports on a newly installed module, even if you delete the Default VLAN and then redefine it on the modules in the system.

• If you delete the Default VLAN, you must use the reserved VID of 1 if you redefine it.