Default Vlan Configuration; Extended-Range Vlan Configuration Guidelines - Cisco Catalyst 3750 Software Configuration Manual

Chapter 10 Configuring VLANs

Default VLAN Configuration

See
MTU size and remote SPAN configuration state on extended-range VLANs; all other characteristics
must remain at the default state.

Extended-Range VLAN Configuration Guidelines

Follow these guidelines when creating extended-range VLANs:
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Table 10-2 on page 10-8 for the default configuration for Ethernet VLANs. You can change only the
To add an extended-range VLAN, you must use the vlan vlan-id global configuration command and
access config-vlan mode. You cannot add extended-range VLANs in VLAN database configuration
mode (accessed by entering the vlan database privileged EXEC command).
VLAN IDs in the extended range are not saved in the VLAN database and are not recognized by
VTP.
You cannot include extended-range VLANs in the pruning eligible range.
The switch must be in VTP transparent mode when you create extended-range VLANs. If VTP mode
is server or client, an error message is generated, and the extended-range VLAN is rejected.
You can set the VTP mode to transparent in global configuration mode or in VLAN database
configuration mode. See the
should save this configuration to the startup configuration so that the switch boots up in VTP
transparent mode. Otherwise, you lose the extended-range VLAN configuration if the switch resets.
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 15, "Configuring MSTP."
Each routed port on the 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
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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
Although the switch supports a total of 1005 (normal-range and extended-range) VLANs, the
number of routed ports, SVIs, and other configured features affects the use of the switch hardware.
If you try to create an extended-range VLAN and there are not enough hardware resources available,
an error message is generated, and the extended-range VLAN is rejected.
"Disabling VTP (VTP Transparent Mode)" section on page
10-15.
Catalyst 3750 Metro Switch Software Configuration Guide
Configuring Extended-Range VLANs
"Creating an Extended-Range VLAN
11-12. You
10-13