3Com SuperStack 4 Configuration Manual page 41

By default, the VLAN of a hybrid port and a trunk port is VLAN 1 and that of the
access port is the VLAN to which it belongs.
Note that to guarantee the proper packet transmission, the default VLAN ID of the
local hybrid port or trunk port should be identical with that of the hybrid port or
trunk port on the peer Switch.
Setting Loopback Detection for an Ethernet Port
Use the following command to enable port loopback detection and set the
detection interval for the external loopback condition of each port. If there is a
loopback port found, the Switch will put it under control.
Other correlative configurations function only when port loopback detection is
enabled in System View.
Perform the following configuration in the view listed in
Table 42 Setting Loopback Detection for the Ethernet Port
Operation
Enable loopback detection on the port (System
View/Ethernet Port View)
Disable loopback detection on the port (System
View/Ethernet Port View)
Enable the loopback controlled function of the
trunk and hybrid ports (Ethernet Port View)
Disable the loopback controlled function of the
trunk and hybrid ports (Ethernet Port View)
Set the external loopback detection interval of
the port (System View)
Restore the default external loopback detection
interval of the port (System View)
Configure that the system performs loopback
detection to all VLANs on Trunk and Hybrid
ports (Ethernet Port View)
Configure that the system only performs
loopback detection to the default VLANs on the
port (Ethernet Port View)
By default, port loopback detection and the loopback detection control function
on trunk and hybrid ports are disabled. The detection interval is 30 seconds, and
the system detects the default VLAN on the trunk and hybrid ports.
Copying Port Configuration to Other Ports
To keep the configuration of other ports consistent with a specified port, you can
copy the configuration of that specified port to other ports. The configuration may
include: STP setting, QoS setting, VLAN setting, port setting, and LACP setting.
The STP setting includes STP enabling/disabling, link attribute (point-to-point or
not), STP priority, path cost, max transmission speed, loop protection, root
protection, edge port or not. The QoS setting includes traffic limiting, priority
marking, default 802.1p priority, bandwidth assurance, congestion avoidance,
traffic redirection, traffic statistics. The VLAN setting includes permitted VLAN
types, and default VLAN ID. The port setting includes port link type, port speed,
and duplex mode. LACP setting includes LACP enabling/disabling.
Ethernet Port Configuration
Table 42.
Command
loopback-detection enable
undo loopback-detection enable
loopback-detection control
enable
undo loopback-detection control
enable
loopback-detection
time
interval-time
undo loopback-detection
interval-time
loopback-detection per-vlan
enable
undo loopback-detection
per-vlan enable
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