Etherchannel Port Groups; Power Over Ethernet Ports - Cisco Catalyst 2960-XR Configuration Manual

Configuring Interface Characteristics
• At least one Layer 2 (access or trunk) port exists, has a link in the up state on this VLAN, and is in the
spanning-tree forwarding state on the VLAN.
The protocol link state for VLAN interfaces come up when the first switchport belonging to the
Note
corresponding VLAN link comes up and is in STP forwarding state.
The default action, when a VLAN has multiple ports, is that the SVI goes down when all ports in the VLAN
go down. You can use the SVI autostate exclude feature to configure a port so that it is not included in the
SVI line-state up-or-down calculation. For example, if the only active port on the VLAN is a monitoring port,
you might configure autostate exclude on that port so that the VLAN goes down when all other ports go down.
When enabled on a port, autostate exclude applies to all VLANs that are enabled on that port.
The VLAN interface is brought up when one Layer 2 port in the VLAN has had time to converge (transition
from STP listening-learning state to forwarding state). This prevents features such as routing protocols from
using the VLAN interface as if it were fully operational and minimizes other problems, such as routing black
holes.

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, group multiple access ports into one logical access port, group multiple tunnel
ports into one logical tunnel port, or group multiple routed ports into one logical routed 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.

Power over Ethernet Ports

A PoE-capable switch port automatically supplies power to one of these connected devices if the switch senses
that there is no power on the circuit:
• a Cisco pre-standard powered device (such as a Cisco IP Phone or a Cisco Aironet Access Point)
• an IEEE 802.3af-compliant powered device
• an IEEE 802.3at-compliant powered device
A powered device can receive redundant power when it is connected to a PoE switch port and to an AC power
source. The device does not receive redundant power when it is only connected to the PoE port.
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Catalyst 2960-XR Switch Interface and Hardware Component Configuration Guide, Cisco IOS Release 15.0(2)EX1
Interface Types
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