Configuring The Mdi Mode For An Ethernet Port - 3Com 4500G Family Configuration Manual

To do...
Enter system view
Enable global loopback
detection
Configure the interval for port
loopback detection
Enter Ethernet port view
Enable loopback detection on a
port
Enable loopback detection
control on a trunk port or a
hybrid port
Enable loopback detection in all
the VLANs to which trunk or
hybrid ports belong
Loopback detection on a given port is enabled only after the loopback-detection enable
command has been configured in both system view and the port view of the port.
Loopback detection on all ports will be disabled after the configuration of the undo
loopback-detection enable command under system view.

Configuring the MDI Mode for an Ethernet Port

10-Gigabit Ethernet ports and optical ports of SFP ports do not support this function.
Two types of Ethernet cables can be used to connect Ethernet devices: crossover cable and
straight-through cable. To accommodate these two types of cables, an Ethernet port on a device can
operate in one of the following three Medium Dependent Interface (MDI) modes:
Across mode
Normal mode
Auto mode
An Ethernet port is composed of eight pins. By default, each pin has its particular role. For example, pin
1 and pin 2 are used for transmitting signals; pin 3 and pin 6 are used for receiving signals. You can
change the pin roles through setting the MDI mode. For an Ethernet port in normal mode, the pin roles
are not changed. For an Ethernet port in across mode, pin 1 and pin 2 are used for receiving signals; pin
Use the command...
system-view
loopback-detection enable
loopback-detection
interval-time time
interface interface-type
interface-number
loopback-detection enable
loopback-detection control
enable
loopback-detection per-vlan
enable
1-8
Remarks
—
Required
Disabled by default
Optional
30 seconds by default
—
Required
Disabled by default
Optional
Disabled by default
Optional
Enabled only in the default
VLAN(s) with trunk port or
hybrid ports