3Com Switch 7750 Configuration Guide

178 CHAPTER 22: PORT BASIC CONFIGURATION
Configuring Loopback
Detection for a Port
Loopback detection is used to monitor if loopback occurs on a switch port.
After you enable loopback detection on Ethernet ports, the switch can monitor if
external loopback occurs on each port periodically. If loopback occurs on a port,
the system will process the port in the user-defined mode.
Enabling the System to
Test Connected Cable
You can enable the system to test the cable connected to a specific port. The test
result will be returned in five minutes. The system can test these attributes of the
cable: Receive and transmit directions (RX and TX), short circuit/open circuit or not,
the length of the faulty cable.
Configuring the Interval
to Perform Statistical
Analysis on Port Traffic
By performing the following configuration, you can set the interval to perform
statistical analysis on the traffic of a port.
When you use the display interface interface-type interface-number command
to display the information of a port, the system performs statistical analysis on the
traffic flow passing through the port during the specified interval and displays the
average rates in the interval. For example, if you set this interval to 100 seconds,
the displayed information is as follows:
Table 113 Set loopback detection for a port
Operation Command Description
Enter system view system-view -
Set time interval for port
loopback detection
loopback-detection
interval-time time
Optional
The default interval is 30
seconds.
Enter Ethernet port view interface interface-type
interface-number
-
Enable loopback detection on
the specified port
loopback-detection enable Required
By default, loopback
detection is disabled by
default.
Set the processing mode for
the port where loopback is
detected
loopback-detection
control { block | nolearning
| shutdown }
Optional
By default, the port where
loopback is detected is
blocked.
Configure the system to
detect loopback in all the
VLANs where the current
Trunk port or Hybrid port
resides
loopback-detection
per-vlan enable
Optional
By default, the system detects
loopback only in the default
VLAN of the current Trunk
port or hybrid port.
Table 114 Enable the system to test connected cables
Operation Command Description
Enter system view system-view -
Enter Ethernet port view interface interface-type
interface-number
-
Enable the system to test
connected cables
virtual-cable-test Required