Creating An Extended-Range Vlan - Cisco Catalyst 3550 series Software Configuration Manual

Chapter 12 Configuring VLANs
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Creating an Extended-Range VLAN

You create an extended-range VLAN in global configuration mode by entering the vlan global
configuration command with a VLAN ID from 1006 to 4094. This command accesses the config-vlan
mode. The extended-range VLAN has the default Ethernet VLAN characteristics (see
the MTU size is the only parameter you can change. Refer to the description of the vlan global
configuration command in the command reference for defaults of all parameters. If you enter an
extended-range VLAN ID when the switch is not in VTP transparent mode, an error message is
generated when you exit from config-vlan mode, and the extended-range VLAN is not created.
Extended-range VLANs are not saved in the VLAN database; they are saved in the switch running
configuration file. You can save the extended-range VLAN configuration in the switch startup
configuration file by using the copy running-config startup-config privileged EXEC command.
Before you create an extended-range VLAN, you can verify that the VLAN ID is not used internally by
Note
entering the show vlan internal usage privileged EXEC command. If the VLAN ID is used internally
and you want to free it up, go to
section on page 12-14
Beginning in privileged EXEC mode, follow these steps to create an extended-range VLAN:
Command
Step 1
configure terminal
Step 2
vtp mode transparent
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VLANs in the extended range are not supported by VQP. They cannot be configured by VMPS.
STP is enabled by default on extended-range VLANs, but you can disable it by using the no
spanning-tree vlan vlan-id global configuration command. When the maximum number of
spanning-tree instances(128) are on the switch, spanning tree is disabled on any newly created
VLANs. If the number of VLANs on the switch exceeds the maximum number of spanning tree
instances, we recommend that you configure the IEEE 802.1S Multiple STP (MSTP) on your switch
to map multiple VLANs to a single STP instance. For more information about MSTP, see
Chapter 17, "Configuring MSTP."
Each routed port on a Catalyst 3550 switch creates an internal VLAN for its use. These internal
VLANs use extended-range VLAN numbers, and the internal VLAN ID cannot be used for an
extended-range VLAN. If you try to create an extended-range VLAN with a VLAN ID that is
already allocated as an internal VLAN, an error message is generated, and the command is rejected.
– Because internal VLAN IDs are in the lower part of the extended range, we recommend that you
create extended-range VLANs beginning from the highest number (4094) and moving to the
lowest (1006) to reduce the possibility of using an internal VLAN ID.
Before configuring extended-range VLANs, enter the show vlan internal usage privileged
–
EXEC command to see which VLANs have been allocated as internal VLANs.
If necessary, you can shut down the routed port assigned to the internal VLAN, which frees up
–
the internal VLAN, and then create the extended-range VLAN and re-enable the port, which
then uses another VLAN as its internal VLAN. See the
with an Internal VLAN ID" section on page
before creating the extended-range VLAN.
Purpose
Enter global configuration mode.
Configure the switch for VTP transparent mode, disabling VTP.
12-14.
the"Creating an Extended-Range VLAN with an Internal VLAN ID"
Catalyst 3550 Multilayer Switch Software Configuration Guide
Configuring Extended-Range VLANs
"Creating an Extended-Range VLAN
Table 12-2) and
12-13