Configuration Guidelines; Setting The Interface Speed And Duplex Parameters - Cisco WS-C3560-48PS-S Software Configuration Manual

Chapter 10 Configuring Interface Characteristics

Configuration Guidelines

When configuring an interface speed and duplex mode, note these guidelines:
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Caution Changing the interface speed and duplex mode configuration might shut down and re-enable the
interface during the reconfiguration.

Setting the Interface Speed and Duplex Parameters

Beginning in privileged EXEC mode, follow these steps to set the speed and duplex mode for a physical
interface:
Command
Step 1
configure terminal
Step 2 interface interface-id
78-16156-01
If both ends of the line support autonegotiation, we highly recommend the default setting of auto
negotiation.
If one interface supports autonegotiation and the other end does not, configure duplex and speed on
both interfaces; do not use the auto setting on the supported side.
For 10/100/1000 Mbps ports, if both the speed and duplex mode are set to specific values,
autonegotiation is disabled.
For 10/100 Mbps ports, if both speed and duplex are set to specific values, the link operates at the
negotiated speed and duplex value.
You cannot configure duplex mode on SFP module ports; they operate in full-duplex mode.
However, when a 1000BASE-T SFP module is inserted in an SFP module port, you can configure
the duplex mode to full or auto and half-duplex mode is supported with the auto configuration.
You cannot configure speed on SFP module ports, except to nonegotiate. However, when a
1000BASE-T SFP module is in the SFP module port, the speed can be configured to 10, 100, 1000,
or auto, but not nonegotiate.
When STP is enabled and a port is reconfigured, the switch can take up to 30 seconds to check for
loops. The port LED is amber while STP reconfigures.
Purpose
Enter global configuration mode.
Enter interface configuration mode and the physical interface
identification.
Catalyst 3560 Switch Software Configuration Guide
Configuring Ethernet Interfaces
10-13