Configuring Auto-Mdix On An Interface - Cisco WS-C3750-48PS-S Software Configuration Manual

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, workstations, or routers and
crossover cables to connect to other switches or repeaters. 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, refer to 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 in order for the feature to operate correctly. Auto-MDIX is supported on all
10/100 and 10/100/1000 Mbps interfaces and on 10/100/1000 BASE-T/TX SFP interfaces. It is not
supported on 1000 BASE-SX or -LX SFP interfaces.
Table 11-2
Table 11-2 Link Conditions and Auto-MDIX Settings
Local Side Auto-MDIX
On
On
Off
Off
Beginning in privileged EXEC mode, follow these steps to configure Auto-MDIX on an interface:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3 speed auto
Step 4 duplex auto
Step 5 mdix auto
Step 6
end
Step 7 show controllers ethernet-controller
interface-id phy
Step 8 copy running-config startup-config
To disable Auto-MDIX, use the no mdix auto interface configuration command.
This example shows how to enable Auto-MDIX on a port:
Switch# configure terminal
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# speed auto
Switch(config-if)# duplex auto
Switch(config-if)# mdix auto
Switch(config-if)# end
Catalyst 3750 Switch Software Configuration Guide
11-18
shows the link states that results from Auto-MDIX settings and correct and incorrect cabling.
Remote Side Auto-MDIX With Correct Cabling
On
Off
On
Off
Purpose
Enter global configuration mode
Enter interface configuration mode for the physical interface to be
configured.
Configure the interface to autonegotiate speed with the connected device.
Configure the interface to autonegotiate duplex mode with the connected
device.
Enable Auto-MDIX on the interface.
Return to privileged EXEC mode.
Verify the operational state of the Auto-MDIX feature on the interface.
(Optional) Save your entries in the configuration file.
Chapter 11 Configuring Interface Characteristics
With Incorrect Cabling
Link up Link up
Link up Link up
Link up Link up
Link up Link down
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