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12-4
Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 12 Configuring Interface Characteristics
Understanding Interface Types
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.
Note You cannot delete interface VLAN 1.
SVIs provide IP host connectivity only to the system.Beginning with Cisco IOS release 12.2(55)SE, you
can enable routing and configure static routes on SVIs.
Note Static routing is supported on SVIs only when the switch is running the LAN base image.
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 encapsulated trunk
port 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. For more information, see the “Manually
Assigning IP Information” section on page 3-15.
Note When you create an SVI, it does not become active until it you associate it with a physical port.
EtherChannel Port Groups
EtherChannel port groups treat multiple switch ports as one switch port. An EtherChannel port group
acts as a single logical port for high-bandwidth connections between switches or between switches and
servers. An EtherChannel balances the traffic load across the links in the channel. If a link within the
EtherChannel fails, traffic previously carried over the failed link changes to the remaining links.You can
group multiple trunk ports into one logical trunk port or multiple access ports into one logical access
port. Most protocols operate over either single ports or aggregated switch ports and do not recognize the
physical ports within the port group. The DTP, the Cisco Discovery Protocol (CDP), and the Port
Aggregation Protocol (PAgP) operate only on physical ports.
When you configure an EtherChannel, you create a port-channel logical interface and assign an interface
to the EtherChannel. Use the channel-group interface configuration command to dynamically create the
port-channel logical interface. This command binds the physical and logical ports together.
For more information, see Chapter 37, “Configuring EtherChannels and Link-State Tracking.”
Dual-Purpose Uplink Ports
Note Catalyst 2960-S switches do not have dual-purpose uplink ports.