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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 9 Configuri ng th e Switch Interfaces Configuring Switch Interfaces

Setting the Interface Speed and Duplex Parameters

Note Th e Ether net link set tings on the CPE Ethe rnet por ts have specia l considera tions a nd different default
settings from the 10/100 ports. For this information, see the “Ports on the 2950 L RE ” sect ion on
page 10-1.
Beginn in g in pr ivileged EXEC mode, follow these steps to set the speed and duplex mode for a physical
interface:
Use the no spee d and no duplex inter face confi gur ation co mman ds to re turn th e interf ace to th e d efault
speed and duple x settin gs (autone gotiate ). To return all interf ace settings to the def aults, use the default
interface interface-id interface configurati on comma nd.
This exampl e shows how to set the inter face speed to 10 Mbps and the du plex mode to half on
FastEthern et int erfac e 0/3 a nd to verif y th e co nfigur ati on :
Switch# configure terminal
Switch(config)# interface fastethernet0/3
Switch(config-if)# speed 10
Switch(config-if)# duplex half
Switch(config)# end
Switch# show running-config
Building configuration...
Current configuration : 1954 bytes
!
version 12.1
no service pad
service timestamps debug uptime
Command Purpose
Step 1 configure terminal Enter gl obal configurat ion mode.
Step 2 int er fa ce interface-id Ente r interface co nfiguration mo de and the physical interface
identification.
Step 3 speed {10 | 100 | 1 000 | auto | none goti ate} Enter the app rop ria te sp eed p ar ameter for the int erf ac e, or en ter auto
or nonegotiate.
Note The 1000 keyword is availab le only for 10/ 100/100 0-Mbp s
ports. 1 00BASE-FX por ts op er ate o nly at 1 00 M bps.
1000BASE-SX port s and GBI C mod ule ports ope rat e onl y at
1000 Mbps. The nonegotiate keyword is available only fo r
1000 BASE-SX, -LX, and -Z X GBI C-m odu le ports .
Step 4 duplex {auto | full | half} Ente r the dupl ex parameter for the inte rface.
Note The 100BASE-FX, 10 00BASE-SX, and t he 1 0/100 /1000
ports operate only in full-duplex mode for non-LRE switches.
The 1 0/100 / 1000 p ort s can ru n at ei the r ful l- or hal f- du pl ex
for 10 /100 M bps but only ope rate in ful l-du plex fo r 1 000
Mbp s for LR E swit che s.
Step 5 end Retur n to privileged EXEC mode .
Step 6 show in terfac es interface-id Display the interface speed and duplex mode configuratio n.
Step 7 copy running-config startup-config (Opti onal) Save your entries in the co nfiguration file.