Specifications

11-12
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-07
Chapter 11 Configuring the Switch Interfaces
Configuring Switch Interfaces
• When connecting an interface to a Gigabit Ethernet device that does not autonegotiate, disable
autonegotiation on the switch and set the duplex and flow control parameters to be compatible with
the remote device.
• 100BASE-FX ports operate only at 100 Mbps and in full-duplex mode.
• 1000BASE-SX ports operate only at 1000 Mbps and in full-duplex mode.
• 1000BASE-T GBICs operate only at 1000Mbps and in full-duplex mode.
• 10/100/1000 ports on the Catalyst 2950T-24 switch operate only in full-duplex mode.
• 10/100/1000 ports on the Catalyst 2955T-12 switch can operate at 10 or 100 Mbps in either half- or
full-duplex mode. The ports can operate at 1000 Mbps only in full-duplex mode.
• GigaStack-to-GigaStack cascade connections operate in half-duplex mode, and
GigaStack-to-GigaStack point-to-point connections operate in full-duplex mode.
• When Spanning Tree Protocol (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.
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 Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode and the physical interface
identification.
Step 3
speed {10 | 100 | 1000 | auto| nonegotiate} Enter the appropriate speed parameter for the interface, or enter auto
or nonegotiate.
Note The 1000 keyword is available only for 10/100/1000 Mbps
ports. 100BASE-FX ports operate only at 100 Mbps.
1000BASE-SX ports and GBIC module ports operate only at
1000 Mbps. The nonegotiate keyword is available only for
1000BASE-SX, -LX, and -ZX GBIC ports.
Step 4
duplex {auto | full | half} Enter the duplex parameter for the interface.
Note The 100BASE-FX, 1000BASE-SX, and the 10/100/1000
ports operate only in full-duplex mode.
Note The duplex keyword is not available on GBIC ports.
Note The duplex keyword is not available on the 10/100/1000 ports
on the Catalyst 2950T-24 switch.
Step 5
end Return to privileged EXEC mode.
Step 6
show interfaces interface-id Display the interface speed and duplex mode configuration.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.