3Step Command Remarks6. Restore the defaultsettings for theinterface.default Optional.NOTE:Make sure that the fiber port speed matches the speed requirement of the inserted transceiver module. Forexample, after you insert a 1000-Mbps transceiver module into a fiber port, configure the port speed withthe speed 1000 or speed auto command.Shutting down an Ethernet interfaceCAUTION:Use this feature with caution. After you manually shut down an Ethernet interface, the Ethernet interfacecannot forward packets even if it is physically connected.You might need to shut down and then bring up an Ethernet interface to activate some configurationchanges, for example, the speed or duplex mode changes.To shut down an Ethernet interface or a group of Ethernet interfaces:Step Command Remarks1. Enter system view. system-view N/A2. Enter Ethernetinterface view orport group view.• Enter Ethernet interface view:interface interface-typeinterface-number• Enter port group view:port-group manual port-group-nameUse any command.To shut down an Ethernet interface,enter Ethernet interface.To shut down all Ethernet interfaces ina port group, enter port group view.3. Shut down theEthernet interfaceor interfaces.shutdown By default, Ethernet interfaces are up.Configuring flow control on an Ethernet interfaceTo avoid packet drops on a link, you can enable flow control at both ends of the link. When trafficcongestion occurs at the receiving end, the receiving end sends a flow control (Pause) frame to ask thesending end to suspend sending packets.Flow control is implemented by receiving and sending Pause frames on ports. Flow control can operatein one of the following modes on an interface:• TxRx mode (configured by using the flow-control command)—The interface can both send andreceive flow control frames.• Rx mode (configured by using the flow-control receive enable command)—The interface canreceive, but not send flow control frames.As shown in Figure 1, when both Port A and Port B forward packets at the rate of 1000 Mbps, Port C iscongested. To avoid packet loss, enable flow control on Port A and Port B.
