To configure Layer 2
parameters, if the interface is in Layer 3 mode, you must enter the
switchport interface configuration command without any parameters to put
the interface into Layer 2 mode. This shuts down the interface and then
re-enables it, which might generate messages on the device to which the
interface is connected. When you put an interface that is in Layer 3 mode into
Layer 2 mode, the previous configuration information related to the affected
interface might be lost, and the interface is returned to its default
medium-dependent interface crossover (auto-MDIX) is enabled by default.
supported on all 10/100/1000-Mb/s and on 10/100/1000BASE-TX small form-factor
pluggable (SFP)-module interfaces. It is not supported on 1000BASE-SX or -LX
SFP module interfaces.
might not support a pre-standard powered device—such as Cisco IP phones and
access points that do not fully support IEEE 802.3af—if that powered device is
connected to the
through a crossover cable. This is regardless of whether auto-MIDX is enabled
on the switch port.
Information about Configuring Auto-MDIX
Auto-MDIX on an
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.
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
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, see the
hardware installation guide.
This table shows
the link states that result from auto-MDIX settings and correct and incorrect
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