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Chapter12 Configuring VLANs
Understanding VLANs
VLAN Port Membership Modes
You configure a port to belong to a VLAN by assigning a membership mode that specifies the kind of
traffic the port carries and the number of VLANs to which it can belong. Table12-1 lists the membership
modes and membership and VTP characteristics.
Table12-1 Port Membership Modes and Characteristics
For more detailed definitions of access and trunk modes and their functions, se e Table12-4 on
page 12-15.
When a port belongs to a VLAN, the switch learns and manages the addresses associated with the port
on a per-VLAN basis. For more information, see the “Managing th e MAC Address Table” section on
page 6-19.
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 12-10.
VTP is not required. If you do not want
VTP to globally propagate information, set
the VTP mode to transparent. 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 (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 12-16.
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.
Dynamic access A dynamic-access port can belong to one VLAN (VLAN
ID 1 to 4094) and is dynamically assigned by a VMPS. The
VMPS can be a Catalyst 5000 or Catalyst 6500 series
switch, for example, but never a Catalyst2960 switch. The
Catalyst2 960 switch is a VMPS client.
You can have dynamic-access ports and trunk ports on the
same switch, but you must connect the dynamic-access
port to an end station or hub and not to another switch.
For configuration information, see the “Configuring
Dynamic-Access Ports on VMPS Clients” section on
page 12-26.
VTP is required.
Configure the VMPS and the client with
the same VTP domain name.
To participate in VTP, at least one trunk
port on the switch must be connected to a
trunk port of a second switch.
Voice VLAN A voice VLAN port is an access port attached to a Cisco
IP Phone, configured to use one VLAN for voice traffic
and another VLAN for data traffic from a device attached
to the phone.
For more information about voice VLAN ports, see
Chapter 14, “Configuring Voice VLAN.”
VTP is not required; it has no affect on a
voice VLAN.