Cisco Catalyst 2960 Series, Configuration Manual

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VLAN by a VLAN Membership Policy Server (VMPS). The VMPS can be a Catalyst 6500 series switch;
the switch cannot be a VMPS server.
You can also configure an access port with an attached Cisco IP Phone to use one VLAN for voice traffic and
another VLAN for data traffic from a device attached to the phone.
Trunk Ports
A trunk port carries the traffic of multiple VLANs and by default is a member of all VLANs in the VLAN
database.
The switch supports only IEEE 802.1Q trunk ports. An IEEE 802.1Q trunk port supports simultaneous tagged
and untagged traffic. An IEEE 802.1Q trunk port is assigned a default port VLAN ID (PVID), and all untagged
traffic travels on the port default PVID. All untagged traffic and tagged traffic with a NULL VLAN ID are
assumed to belong to the port default PVID. A packet with a VLAN ID equal to the outgoing port default
PVID is sent untagged. All other traffic is sent with a VLAN tag.
Although by default, a trunk port is a member of every VLAN known to the VTP, you can limit VLAN
membership by configuring an allowed list of VLANs for each trunk port. The list of allowed VLANs does
not affect any other port but the associated trunk port. By default, all possible VLANs (VLAN ID 1 to 4094)
are in the allowed list. A trunk port can become a member of a VLAN only if VTP knows of the VLAN and
if the VLAN is in the enabled state. If VTP learns of a new, enabled VLAN and the VLAN is in the allowed
list for a trunk port, the trunk port automatically becomes a member of that VLAN and traffic is forwarded
to and from the trunk port for that VLAN. If VTP learns of a new, enabled VLAN that is not in the allowed
list for a trunk port, the port does not become a member of the VLAN, and no traffic for the VLAN is forwarded
to or from the port.
Switch Virtual Interfaces
A switch virtual interface (SVI) represents a VLAN of switch ports as one interface to the routing or bridging
function in the system. You can associate only one SVI with a VLAN. You configure an SVI for a VLAN
only to route between VLANs or to provide IP host connectivity to the switch. By default, an SVI is created
for the default VLAN (VLAN 1) to permit remote switch administration. Additional SVIs must be explicitly
configured.
You cannot delete interface VLAN 1. Note
SVIs provide IP host connectivity only to the system. SVIs are created the first time that you enter the vlan
interface configuration command for a VLAN interface. The VLAN corresponds to the VLAN tag associated
with data frames on an ISL or IEEE 802.1Q encapsulated trunk or the VLAN ID configured for an access
port. Configure a VLAN interface for each VLAN for which you want to route traffic, and assign it an IP
address.
Although the switch stack or switch supports a total of 1005 VLANs and SVIs, the interrelationship between
the number of SVIs and routed ports and the number of other features being configured might impact CPU
performance because of hardware limitations.
When you create an SVI, it does not become active until it is associated with a physical port.
SVI Autostate Exclude
The line state of an SVI with multiple ports on a VLAN is in the up state when it meets these conditions:
• The VLAN exists and is active in the VLAN database on the switch
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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Information About Configuring Interface Characteristics