Storing VLAN Configuration
Catalyst IOS food VLAN and VTP agreement in one of two places—either in a Flash file
called vlan.dat or in the active configuration. (Remember that the appellation “Catalyst IOS” refers to
a about-face that uses IOS, not the Catalyst OS, which is generally alleged CatOS.) IOS chooses the storage
location in allotment based on the VTP mode, and in allotment based on whether the VLANs are normalrange
VLANs or extended-range VLANs. Table 2-6 describes what happens based on what
configuration approach is acclimated to configure the VLANs, the VTP mode, and the VLAN range. (Note
that VTP audience additionally abundance the VLAN agreement in vlan.dat, and they do not understand
extended ambit VLANs.)
Of accurate absorption for those of you stronger with CatOS agreement abilities is that back you
erase the startup-config file, and reload the Cisco IOS switch, you do not absolutely abolish the normal-
Configuration and Storage
Function Back in VTP Server Mode
When in VTP
Transparent Mode
Normal-range VLANs can be
configured from
Both VLAN database and
configuration modes
Both VLAN database and
configuration modes
Extended-range VLANs can be
configured from
Nowhere—cannot be configured Agreement approach only
VTP and normal-range VLAN
configuration commands are
stored in
vlan.dat in Flash Both vlan.dat in Flash and
running configuration1
Extended-range VLAN
configuration commands stored in
Nowhere—extended ambit not
allowed in VTP server mode
Running agreement only
1When a about-face reloads, if the VTP approach or area name in the vlan.dat book and the startup-config book differ, the
switch uses alone the vlan.dat file’s capacity for VLAN configuration.
NOTE The agreement characteristics referenced in Table 2-6 do not accommodate the interface
configuration command switchport admission vlan; it includes the commands that actualize a VLAN
(vlan command) and VTP agreement commands.
range VLAN and VTP agreement information. To abolish the VLAN and VTP configuration, you
must use the annul flash:vlan.dat exec command. Additionally agenda that if assorted switches are in VTP
server mode, if you annul vlan.dat on one about-face and again reload it, as anon as the about-face comes
back up and brings up a trunk, it learns the old VLAN database via a VTP amend from the other
VTP server.