Configuring Generic Flow Control On An Ethernet Interface; Configuring Link Change Suppression On An Ethernet Interface - H3C S5500-EI Series Configuration Manual

CAUTION:
After you change the link mode of an Ethernet interface, all the settings of the Ethernet interface are
•
restored to their defaults under the new link mode.
If you set the link mode of the active port of a Combo interface to Layer 3, you cannot activate the other
•
port with the undo shutdown command. To change the active port of the Combo interface, make sure
that the optical and electrical ports of the Combo interface operate in Layer 2 mode.

Configuring generic flow control on an Ethernet interface

An interface implements generic flow control by sending and receiving common pause frames. The
following generic flow control modes are available:
TxRx mode enables an interface to both send and receive common pause frames.
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• Rx mode enables an interface to receive but not send common pause frames.
In 1, when both Port A and Port B forward packets at 1000 Mbps, Port C is congested. To avoid
Figure
packet loss, enable flow control on Port A and Port B.
Figure 1 Flow control application scenario
Configure Port B to operate in TxRx mode, Port A in Rx mode.
When congestion occurs on Port C, Switch B buffers frames. When the amount of buffered frames
•
exceeds a certain value, Switch B sends a common pause frame out of Port B to ask Port A to
suspend sending packets. This pause frame also tells Port A for how long it is expected to pause.
Upon receiving the common pause frame from Port B, Port A suspends sending packets to Port B for
•
a period.
• If congestion persists, Port B keeps sending common pause frames to Port A until the congestion
condition is removed.
Follow these steps to configure flow control on an interface:
To do...
Enter system view
Enter Ethernet interface view
Enable TxRx mode flow control
Enable Rx mode flow control

Configuring link change suppression on an Ethernet interface

An Ethernet interface has two physical link states: up and down. Each time the physical link of an
interface goes up or comes down, the physical layer reports the change to the upper layers, and the
upper layers handle the change, resulting in increased overhead.
Use the command...
system-view
interface interface-type
interface-number
flow-control
flow-control receive enable
4
Remarks
—
—
Required
Use either command.
By default, flow control is disabled
on an Ethernet interface.