Configuration Guidelines; Connecting To Devices That Do Not Autonegotiate; Setting Speed And Duplex Parameters - Cisco Catalyst 2950 Software Configuration Manual

Configuring the Port Speed and Duplex Mode

Configuration Guidelines

Follow these guidelines when configuring the duplex and speed settings:
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•
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Connecting to Devices That Do Not Autonegotiate

To connect to a remote 100BASE-T device that does not autonegotiate, set the duplex setting to Full or
Half, and set the speed setting to Auto. Autonegotiation for the speed setting selects the correct speed
even if the attached device does not autonegotiate, but the duplex setting must be explicitly set.
To connect to a remote Gigabit Ethernet device that does not autonegotiate, disable autonegotiation on
the local device, and set the duplex and flow control parameters to be compatible with the other device.

Setting Speed and Duplex Parameters

Beginning in privileged EXEC mode, follow these steps to set the speed and duplex parameters on a port:
Command
Step 1
configure terminal
Step 2
interface interface
Step 3
speed {10 | 100 | 1000 | auto}
Step 4
duplex {full | half | auto}
Step 5
end
Catalyst 2950 Desktop Switch Software Configuration Guide
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Gigabit Ethernet ports should always be set to 1000 Mbps and full duplex.
Gigabit Ethernet ports that do not match the settings of an attached device lose connectivity and do
not generate statistics.
GigaStack-to-GigaStack stack connections operate in half-duplex mode, and
GigaStack-to-GigaStack point-to-point connections operate in full-duplex mode.
If STP is enabled, the switch can take up to 30 seconds to check for loops when a port is
reconfigured. The port LED is amber while STP reconfigures.
Purpose
Enter global configuration mode.
Enter interface configuration mode, and enter the port to be
configured.
Enter the speed parameter for the port.
• The 10/100/1000 ports operate only in full-duplex mode.
The GBIC-module ports operate only at 1000 Mbps.
•
100BASE-FX ports operate only at 100 Mbps in full-duplex
•
mode.
Note The Catalyst 2950C-24 does not support the speed and
duplex interface configuration commands in
Release 12.1(6)EA2 or later.
Enter the duplex parameter for the port.
• The 10/100/1000 ports operate only in full-duplex mode.
100BASE-FX ports operate only at 100 Mbps in full-duplex
•
mode.
Note The Catalyst 2950C-24 does not support the speed and
duplex interface configuration commands in
Release 12.1(6)EA2 or later.
Return to privileged EXEC mode.
Chapter 9 Configuring Interface Characteristics
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