Loopback - 3Com 5500-EI PWR Reference Manual

The port state change delay takes effect when the port goes down but not when the port goes up.
The delay configured in this way does not take effect for ports in DLDP down state. For information
about the DLDP down state, refer to DLDP.
Examples
# Set the port state change delay of Ethernet 1/0/5 to 8 seconds.
<Sysname> system-view
Enter system view, return to user view with Ctrl+Z.
[Sysname] interface Ethernet1/0/5
[Sysname-Ethernet1/0/5] link-delay 8

loopback

Syntax
loopback { external | internal }
View
Ethernet port view
Parameters
external: Performs external loop test. In the external loop test, self-loop headers must be used on the
port of the switch. The external loop test can locate the hardware failures on the port.
For 100M port, the self-loop headers are made from four cores of the 8-core cables, for 1000M port, the
self-loop headers are made from eight cores of the 8-core cables, and the packets forwarded by the port
will be received by itself.
internal: Performs internal loop test. In the internal loop test, self loop is established in the switching
chip to locate the chip failure which is related to the port.
Description
Use the loopback command to perform a loopback test on the current Ethernet port to check whether
the Ethernet port works normally. The loopback test terminates automatically after running for a specific
period.
By default, no loopback test is performed on the Ethernet port.
Examples
# Perform an internal loop test on Ethernet 1/0/1.
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