Chapter 13 Configuring Vlan - Cisco Catalyst 2975 Software Configuration Manual

Understanding VLANs
Figure 13-1
Figure 13-1
Cisco router
VLANs are often associated with IP subnetworks. For example, all the end stations in a particular IP
subnet belong to the same VLAN. Interface VLAN membership on the switch is assigned manually on
an interface-by-interface basis. When you assign switch interfaces to VLANs by using this method, it is
known as interface-based, or static, VLAN membership.
Traffic between VLANs must be routed or fallback bridged.
Supported VLANs
The switch supports VLANs in VTP client, server, and transparent modes. VLANs are identified by a
number from 1 to 4094. VLAN IDs 1002 through 1005 are reserved for Token Ring and FDDI VLANs.
VTP version 1 and version 2 support only normal-range VLANs (VLAN IDs 1 to 1005). In these
versions, the switch must be in VTP transparent mode when you create VLAN IDs from 1006 to 4094.
Cisco IOS Release 12.2(52)SE and later support VTP version 3. VTP version 3 supports the entire
VLAN range (VLANs 1 to 4094). Extended range VLANs (VLANs 1006 to 4094) are supported only in
VTP version 3. You cannot convert from VTP version 3 to VTP version 2 if extended VLANs are
configured in the domain.
Although the switch stack supports a total of 255 (normal range and extended range) VLANs, the
number of 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
VLAN Configuration Guidelines" section on page 13-5
spanning-tree instances and the number of VLANs. The switch supports only IEEE 802.1Q trunking
methods for sending VLAN traffic over Ethernet ports.
Catalyst 2975 Switch Software Configuration Guide
13-2
shows an example of VLANs segmented into logically defined networks.
VLANs as Logically Defined Networks
Gigabit
Ethernet
Engineering Marketing
VLAN VLAN
for more information about the number of
Chapter 13 Configuring VLANs
Accounting
VLAN
Floor 3
Floor 2
Floor 1
"Normal-Range
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