3Com Switch 4800G 24-Port Configuration Manual page 150

150 C 16: P C
HAPTER ORT
n
Configuring a Port
Group
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ORRELATION ONFIGURATION
Internal loopback test, which is performed within switching chips to test the
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functions related to the Ethernet ports.
External loopback test, which is used to test the hardware functions of an
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Ethernet port. To perform external loopback testing on an Ethernet port, you
need to install a loopback plug on the Ethernet port. In this case, packets sent
from the port are received by the same port.
Follow these steps to enable Ethernet port loopback test:
To do...
Enter system view
Enter Ethernet port view
Enable loopback test
As for the internal loopback test and external loopback test, if a port is down,
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only the former is available on it; if the port is shut down, both are unavailable.
The speed, duplex, mdi, and shutdown commands are not applicable during
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a loopback test.
With the loopback test enabled, the Ethernet port operates in the full duplex
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mode. With the loopback test enabled, the original configurations will be
restored.
To make the configuration task easier for users, certain devices allow users to
configure on a single port as well as on multiple ports in a port group. In port
group view, the user only needs to input the configuration command once on one
port and that configuration will apply to all ports in the port group. This effectively
reduces redundant configurations.
A Port group belongs to one of the following two categories:
Manual port group: manually created by users. Multiple Ethernet ports can be
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added to the same port group;
Dynamic port group: dynamically created by the system. Currently, it refers in
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particular to a port aggregation group. A port aggregation port group is
automatically created together with the creation of a link aggregation group
and cannot be created by users through CLI. Adding or deleting of ports in a
port aggregation port group can only be achieved through operations on the
link aggregation group.
A port group enables you to configure ports in batch. You cannot display or save
the configuration of a port group. However, you can use the display
current-configuration or display this command to view the current
configuration of each member port of a port group.
Follow these steps to configure a port group:
Use the command...
system-view
interface interface-type
interface-number
loopback { external |
internal }
Remarks
-
-
Optional
Disabled by default.