H3C Technologies H3C S10500 Series Switches - Manual (Page 26)

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You can use both crossover and straight-through Ethernet cables to connect copper Ethernet interfaces.
To accommodate these 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 MDI modes as follows:
• 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 by 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.
Testing the cable connection of an Ethernet interface
NOTE:
•
Fiber ports do not support this feature.
• If the link of an Ethernet port is up, testing its cable connection will cause the link to come down and then
go up.
You can test the cable connection of an Ethernet interface for a short or open circuit. The switch displays
cable test results within five seconds. If any fault is detected, the test results include the length of the faulty
cable segment.