Cisco Systems 3750E manual Gigabit Ethernet Interfaces, Power over Ethernet Ports, 11-6

Chapter 11 Configuring Interface Characteristics

Understanding Interface Types

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-channelglobal configuration command. Then you manually assign an interface to the EtherChannel by using the channel-groupinterface configuration command. For Layer 2 interfaces, use the channel-groupinterface 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.”

10-Gigabit Ethernet Interfaces

The Catalyst 3750-E and 3560-E switches have two 10-Gigabit Ethernet module slots. For uplink connections to other switches and routers, use the Cisco TwinGig Converter Modules.

A 10-Gigabit Ethernet interface operates only in full-duplex mode. The interface can be configured as a switched or routed port.

For more information about the Cisco TwinGig Converter Module, see the switch hardware installation guide and your transceiver module documentation.

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:

•Cisco pre-standard powered device (such as a Cisco IP Phone or a Cisco Aironet Access Point)

•IEEE 802.3af-compliant powered device

Each 10/100/1000 PoE port provides up to 15.4 W of power to the 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.

After the switch detects a powered device, the switch determines the device power requirements and then grants or denies power to the device. The switch can also sense the real-time power consumption of the device by monitoring and policing the power usage.

This section has this PoE information:

•Supported Protocols and Standards, page 11-6

•Powered-Device Detection and Initial Power Allocation, page 11-7

•Power Management Modes, page 11-8

•Power Monitoring and Power Policing, page 11-9

Supported Protocols and Standards

The switch uses these protocols and standards to support PoE:

•CDP with power consumption—The powered device notifies the switch of the amount of power it is consuming. The switch does not reply to the power-consumption messages. The switch can only supply power to or remove power from the PoE port.

•Cisco intelligent power management—The powered device and the switch negotiate through power-negotiation CDP messages for an agreed-upon power-consumption level. The negotiation allows a high-power Cisco powered device, which consumes more than 7 W, to operate at its highest

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

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