12-3
Catalyst 3560 Switch Software Configuration Guide
78-16156-01
Chapter 12 Configuring VLANs
Understanding VLANs
Supported VLANs
The switch supports 1005 VLANs in VTP client, server, and transparent modes. VLANs are identified
with a number from 1 to 4094. VLAN IDs 1002 through 1005 are reserved for Token Ring and FDDI
VLANs. VTP only learns normal-range VLANs, with VLAN IDs 1 to 1005; VLAN IDs greater than
1005 are extended-range VLANs and are not stored in the VLAN database. The switch must be in VTP
transparent mode when you create VLAN IDs from 1006 to 4094.
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.
The switch supports per-VLAN spanning-tree plus (PVST+) or rapid PVST+ with a maximum of 128
spanning-tree instances. One spanning-tree instance is allowed per VLAN. See the
“Normal-Range
VLAN Configuration Guidelines” section on page 12-6
for more information about the number of
spanning-tree instances and the number of VLANs. The switch supports both Inter-Switch Link (ISL)
and IEEE 802.1Q trunking methods for sending VLAN traffic over Ethernet ports.
VLAN Port Membership Modes
You configure a port to belong to a VLAN by assigning a membership mode that determines the kind of
traffic the port carries and the number of VLANs to which it can belong.
Table 12-1
lists the membership
modes and membership and VTP characteristics.
Table 12-1 Port Membership Modes
Membership Mode
VLAN Membership Characteristics
VTP Characteristics
Static-access
A static-access port can belong to one VLAN and is
manually assigned to that VLAN. For more information,
see the
“Assigning Static-Access Ports to a VLAN”
section on page 12-11
.
VTP is not required. If you do not want
VTP to globally propagate information, set
the VTP mode to transparent to disable
VTP. To participate in VTP, there must be
at least one trunk port on the switch
connected to a trunk port of a second
switch.
Trunk (ISL or
IEEE 802.1Q)
A trunk port is a member of all VLANs by default,
including extended-range VLANs, but membership can be
limited by configuring the allowed-VLAN list. You can
also modify the pruning-eligible list to block flooded
traffic to VLANs on trunk ports that are included in the
list. For information about configuring trunk ports, see the
“Configuring an Ethernet Interface as a Trunk Port”
section on page 12-19
.
VTP is recommended but not required.
VTP maintains VLAN configuration
consistency by managing the addition,
deletion, and renaming of VLANs on a
network-wide basis. VTP exchanges
VLAN configuration messages with other
switches over trunk links.