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Cisco Catalyst Blade Switch 3020 for HP Software Configuration Guide
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Chapter 9 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. Only one SVI can be associated with a VLAN, but you need to configure
an SVI for a VLAN only when you wish to route between VLANs, to fallback-bridge nonroutable
protocols 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; in Layer 3 mode, you can configure routing across
SVIs.
Although the switch supports a total or 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. See the
“Configuring Layer 3 Interfaces” section on
page 9-19
for information about what happens when hardware resource limitations are reached.
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. For more
information, see the
“Manually Assigning IP Information” section on page 3-14
.
Note
When you create an SVI, it does not become active until it is associated with a physical port.
SVIs support routing protocols and bridging configurations. For more information about configuring IP
routing, see
Chapter 34, “Configuring IP Unicast Routing.”
EtherChannel Port Groups
EtherChannel port groups treat multiple switch ports as one switch port. These port groups act 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. Exceptions are the DTP, the Cisco Discovery Protocol (CDP), and
the Port Aggregation Protocol (PAgP), which operate only on physical ports.
When you configure an EtherChannel, you create a port-channel logical interface and assign an interface
to the EtherChannel. For Layer 3 interfaces, you manually create the logical interface by using the
interface port-channel
global configuration command. Then you manually assign an interface to the
EtherChannel by using the
channel-group
interface configuration command. For Layer 2 interfaces, 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 33, “Configuring EtherChannels and Layer 2 Trunk Failover.”
