Cisco Systems 3750E manual Configuring Interface Speed and Duplex Mode, 11-22

Chapter 11 Configuring Interface Characteristics

Configuring Ethernet Interfaces

Table 11-3 Default Layer 2 Ethernet Interface Configuration (continued)

Feature	Default Setting
Auto-MDIX	Enabled.
	Note The switch might not support a pre-standard powered
	device—such as Cisco IP phones and access points that do
	not fully support IEEE 802.3af—if that powered device is
	connected to the switch through a crossover cable. This is
	regardless of whether auto-MIDX is enabled on the switch
	port.
Power over Ethernet (PoE)	Enabled (auto).

Configuring Interface Speed and Duplex Mode

Ethernet interfaces on the switch operate at 10, 100, 1000, or 10,000 Mb/s and in either full- or half-duplex mode. In full-duplex mode, two stations can send and receive traffic at the same time. Normally, 10-Mb/s ports operate in half-duplex mode, which means that stations can either receive or send traffic.

Switch models include Gigabit Ethernet (10/100/1000-Mb/s) ports, 10-Gigabit Ethernet ports, and small form-factor pluggable (SFP) module slots supporting SFP modules.

These sections describe how to configure the interface speed and duplex mode:

•Speed and Duplex Configuration Guidelines, page 11-22

•Setting the Interface Speed and Duplex Parameters, page 11-23

Speed and Duplex Configuration Guidelines

When configuring an interface speed and duplex mode, note these guidelines:

•The 10-Gigabit Ethernet ports do not support the speed and duplex features. These ports operate only at 10,000 Mb/s and in full-duplex mode.

•Gigabit Ethernet (10/100/1000-Mb/s) ports support all speed options and all duplex options (auto, half, and full). However, Gigabit Ethernet ports operating at 1000 Mb/s do not support half-duplex mode.

•For SFP module ports, the speed and duplex CLI options change depending on the SFP module type:

–The 1000BASE-x(where -xis -BX, -CWDM, -LX, -SX, and -ZX) SFP module ports support the nonegotiate keyword in the speed interface configuration command. Duplex options are not supported.

–The 1000BASE-T SFP module ports support the same speed and duplex options as the 10/100/1000-Mb/s ports.

For information about which SFP modules are supported on your switch, see the product release notes.

•If both ends of the line support autonegotiation, we highly recommend the default setting of auto negotiation.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
11-22	OL-9775-02