H3C Technologies H3C SecPath F1000-E - Manual (Page 40)

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CAUTION:
Use this command with caution. After you manually shut down an Ethernet interface, the Ethernet interface
cannot forward packets even if it is physically connected.
Configuring flow control on an Ethernet interface
To avoid packet drops on a link, you can enable flow control at both ends of the link. When traffic
congestion occurs at the receiving end, the receiving end sends a flow control (Pause) frame to ask the
sending end to suspend sending packets
With the flow-control command configured, an interface can both send and receive flow control frames:
When congested, the interface sends a flow control frame to its peer. Upon receiving a flow control
frame from the peer, the interface suspends sending packets.
To handle unidirectional traffic congestion on a link, configure the flow-control receive enable command
at one end, and the flow-control command at the other. To enable both ends of the link to handle traffic
congestion, configure the flow-control command at both ends.
To enable flow control on an Ethernet interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Ethernet interface view.
interface interface-type
interface-number
N/A
3. Enable TxRx flow control. flow-control
By default, Rx flow control is
disabled on an Ethernet interface.
Configuring loopback testing on an Ethernet interface
If an Ethernet interface does not work normally, you can enable loopback testing on it to identify the
problem. Loopback testing has the following types:
• Internal loopback testing—Tests all on-chip functions related to Ethernet interfaces.
• External loopback testing—Tests hardware of Ethernet interfaces. To perform external loopback
testing on an Ethernet interface, connect a loopback plug to the Ethernet interface. The device sends
test packets out the interface, which are expected to loop over the plug and back to the interface.
If the interface fails to receive any test packet, the hardware of the interface is faulty.
An Ethernet interface in a loopback test does not forward data traffic.
To avoid loopback test failures, follow these guidelines when you perform a loopback test:
• Do not change the copper/fiber mode or the bridge/route mode of an interface.
• Do not perform a loopback test for interfaces in an interface collaboration group.
• Do not configure a loopback mode for an interface already configured with the other loopback
mode.
To enable loopback testing on an Ethernet interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Ethernet interface view. interface interface-type interface-number N/A