Setting An Ethernet Interface Mdi Mode - HP A5830 Configuration Manual

Step...
8. Set the protective
action to take on
the interface when
a loop is detected
To use loopback detection on an Ethernet interface, you must enable the function both globally and on
the interface.
To disable loopback detection on all interfaces, run the undo loopback-detection enable command in
system view.
To enable a hybrid or trunk port to take the administratively-specified protective action, you must use the
loopback-detection control enable command on the port.
When you change the link type of an Ethernet interface by using the port link-type command, the switch
removes the protective action configured on the interface. For more information about the port link-type
command, see Layer 2—LAN Switching Command Reference.

Setting an Ethernet interface MDI mode

NOTE:
Fiber ports do not support the MDI mode setting.
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 MDI
modes:
 Across mode
Normal mode

Auto mode

A copper Ethernet interface uses an RJ-45 connector, which comprises eight pins, each of which plays 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, make sure that the 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.
Command...
loopback-detection action { no-
learning | semi-block | shutdown }
11
Remarks
Optional
By default, a looped interface does not
receive or send packets
With the shutdown parameter specified,
the switch shuts down the looped ports
and set their physical state to Loop down
When a looped port recovers, you must
use the undo shutdown command to
restore its forwarding capability