H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 20)

11
Setting the MDI mode of an Ethernet interface
NOTE:
Fiber interfaces do not support the MDI mode setting.
You can use both crossover and straight-through Ethernet cables to connect copper Ethernet interfaces.
To accommodate these two types of cables, a copper Ethernet interface can operate in one of the
following Medium Dependent Interface (MDI) modes:
• Across mode
• Normal mode
• Auto mode
A copper Ethernet interface uses an RJ-45 connector, which comprises eight pins, each playing a
dedicated role. For example, pins 1 and 2 transmit signals, and pins 3 and 6 receive signals. The pin
role varies by the following MDI modes:
• In normal mode, pins 1 and 2 are transmit pins, and pins 3 and 6 are receive pins.
• In across mode, pins 1 and 2 are receive pins, and pins 3 and 6 are transmit pins.
• In auto mode, the interface negotiates pin roles with its peer.
To enable the interface to communicate with its peer, ensure that its transmit pins are connected to the
remote receive pins. If the interface can detect the connection cable type, set the interface in auto MDI
mode. If not, set its MDI mode using the following guidelines:
• When a straight-through cable is used, set the interface to work in the MDI mode different than its
peer.
• When a crossover cable is used, set the interface to work in the same MDI mode as its peer, or set
either end to work in auto mode.
Follow these steps to set the MDI mode of an Ethernet interface:
To do… Use the command… Remarks
Enter system view system-view —
Enter Ethernet interface view
interface interface-type
interface-number
—
Set the MDI mode of the Ethernet
interface
mdi { across | auto | normal }
Optional
By default, a copper Ethernet
interface operates in auto mode to
negotiate pin roles with its peer.
Enabling bridging on an Ethernet interface
When an incoming packet arrives, the device looks up the destination MAC address of the packet in the
MAC address table. If an entry is found, but the outgoing interface is the same as the receiving interface,
the device discards the packet.
To enable the device to forward such packets rather than drop them, enable the bridging function on the
Ethernet interface.
Follow these steps to enable bridging on an Ethernet interface: