Cisco Systems WSC2960XR48FPSI Extended-Range VLAN Configuration Guidelines

Extended-Range VLAN Configuration Guidelines

VTP3 onlysupports extended-range VLANs. Extended-range VLANs are VLANs with IDs from 1006 to

4094.

Followthese guidelineswhen creating extended-range VLANs:

•VLANIDs in the extended range are not saved in the VLAN database and are not recognized by VTP

unlessthe switch is runningVTP version3.

•Youcannot include extended-range VLANs in the pruning eligible range.

•InVTP version 1 and 2, a 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

isrejected. VTP version 3 supports extended VLANs in server and transparent modes.

•ForVTP version1 or 2, you can set the VTP mode to transparent in global configurationmode. You

shouldsave 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. If you create

extended-rangeVLANs in VTP version 3, you cannot convert to VTP version 1 or 2.

•STPis enabled by default on extended-range VLANs, but you can disable it by using the no spanning-tree

vlanvlan-id global configurationcommand. When the maximum numberof spanning-tree instances

areon the switch, spanning tree is disabled on any newly created VLANs. If the number of VLANs on

theswitch exceeds the maximum number of spanning-tree instances, we recommend that you configure

theIEEE 802.1s Multiple STP (MSTP) on your switch to map multiple VLANs to a single spanning-tree

instance.

•Eachrouted port on the switch creates an internal VLAN for its use. These internal VLANs use

extended-rangeVLAN numbers, and the internal VLAN ID cannot be used for an extended-range VLAN.

Ifyou try to createan 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.

◦Becauseinternal VLAN IDs are in the lower part of the extended range, we recommend that you

createextended-range VLANs beginning from the highest number (4094) and moving to the lowest

(1006)to reducethe possibilityof using aninternal VLAN ID.

◦Beforeconfiguring extended-range VLANs, enter the show vlan internal usage privileged EXEC

commandto seewhich VLANs havebeen allocatedas internal VLANs.

◦Ifnecessary, you can shut down the routed port assigned to the internal VLAN, which frees up the

internalVLAN, and then create the extended-range VLAN and re-enable the port, which then uses

anotherVLAN asits internal VLAN.

•Althoughthe switch or switch stack supports a total of 1005 (normal-range and extended-range) VLANs,

thenumber of routed ports, SVIs,and otherconfigured features affects the use of the switch hardware.

Ifyou try to createan extended-range VLAN and there are not enough hardware resources available,

anerror message is generated, and the extended-range VLAN is rejected.

•Ina switchstack, the whole stack uses thesame running configuration and saved configuration,and

extended-rangeVLAN information is sharedacross thestack.