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Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
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Chapter9 Configuring Interface Characteristics
Configuring Ethernet Interfaces
Configuring Auto-MDIX on an Interface
When automatic medium-dependent interface crossover (auto-MDIX) is enabled on an interface, the
interface automatically detects the required cable connection type (straight through or crossover) and
configures the connection appropriately. When connecting switches without the auto-MDIX feature, you
must use straight-through cables to connect to devices such as servers, work stations, o r routers a nd
crossover cables to connect to other switches or rep ea ter s . With auto-MDIX enabled, you can use either
type of cable to connect to other devices, and the interface automatically corrects for any incorrect
cabling. For more information about cabling requirements, see the hardware installation guide.
Auto-MDIX is enabled by default. When you enable auto-MDIX, you must also set the speed and duplex
on the interface to auto so that the feature operates correctly. Auto-MDIX is supported on all 10/100 and
10/100/1000 Mbps interfaces and on Cisco 10/100/1000 BASE-T/TX SFP module interfaces. It is not
supported on 1000 BASE-SX or -LX SFP module interfaces.
Table 9 -3 shows the link states that result from auto-MDIX settings and correct and incorrect cabling.
Beginning in pr ivileged EXEC mode , follow these ste ps to configure auto-MDIX on an interface:
To disable auto-MDIX, use the no mdix auto interface configuration command.
Table9-3 Link Conditions and Auto-MDIX Settings
Local Side Auto-MDIX Remote Side Auto-MDIX With Correct Cabling With Incorrect Cabling
On On Link up Link up
On Off Link up Link up
Off On Link up Link up
Off Off Link up Link down
Command Purpose
Step1 configure terminal Enter global configuration mode
Step2 interface interface-id Specify the physical interface to be configured, and enter interface
configuration mode.
Step3 no shutdown Enable the port, if necessary. By default, UNIs are disab l ed , an d NN Is ar e
enabled.
Step4 speed auto Configure the interface to autonegotiate speed with the connected device.
Step5 duplex auto Configure the interface to autonegotiate duplex mode with the connected
device.
Step6 mdix auto Enable auto-MDIX on the interface.
Step7 end Return to privileged EXEC mode.
Step8 show controllers ethernet-controller
interface-id phy Verify the operational state of the auto-MDIX feature on the interface.
Step9 copy running-config startup-config (Optional) Save your entries in the configuration file.