Normal-Range and Extended-Range VLANs
Some VLAN numbers are considered to be normal, whereas some others are considered to be extended.
Normal-range VLANs are VLANs 1–1005, and can be advertised via VTP versions 1 and 2. These
VLANs can be configured in VLAN database mode, with the details being stored in the vlan.dat file in
Flash.
Extended-range VLANs range from 1006–4094, inclusive. However, these additional VLANs
cannot be configured in VLAN database mode, nor stored in the vlan.dat file, nor advertised via
VTP. In fact, to configure them, the switch must be in VTP transparent mode. (Also, you should
take care to avoid using VLANs 1006–1024 for compatibility with CatOS-based switches.)
Both ISL and 802.1Q support extended-range VLANs today. Originally, ISL began life only
supporting normal-range VLANs, using only 10 of the 15 bits reserved in the ISL header to
identify the VLAN ID. The later-defined 802.1Q used a 12-bit VLAN ID field, thereby allowing
support of the extended range. Following that, Cisco changed ISL to use 12 of its reserved 15 bits
in the VLAN ID field, thereby supporting the extended range.
Table 2-5 summarizes VLAN numbers and provides some additional notes.
Valid VLAN Numbers, Normal and Extended
VLAN
Number
Normal or
Extended?
Can Be Advertised
and Pruned by VTP
Versions 1 and 2? Comments
0 Reserved — Not available for use
1 Normal No On Cisco switches, the default VLAN
for all access ports; cannot be deleted
or changed
2–1001 Normal Yes
VLAN
Number
Normal or
Extended?
Can Be Advertised
and Pruned by VTP
Versions 1 and 2? Comments
1002–1005 Normal No Defined specifically for use with FDDI
and TR translational bridging
1006–4094 Extended No