H3C Technologies H3C S10500 Series Switches - Manual (Page 16)

5
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.
Follow these steps to enable flow control on an Ethernet interface:
To do… Use the command… Remarks
Enter system view system-view —
Enter Ethernet interface view
interface interface-type
interface-number
—
Enable TxRx flow control flow-control
Required
By default, Rx flow control is disabled on an
Ethernet interface.
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.
To prevent physical link flapping from affecting system performance, configure link change suppression
to delay the reporting of physical link state changes. When the delay expires, the interface reports any
detected change.
Link change suppression does not suppress administrative up or down events. When you shut down or
bring up an interface by using the shutdown or undo shutdown command, the interface reports the event
to the upper layers immediately.
Link-down event suppression enables an interface to suppress link-down events and start a delay timer
each time the physical link goes down. During this delay, the interface does not report the link-down
event, and the display interface brief or display interface command displays the interface state as UP. If
the physical link is still down when the timer expires, the interface reports the link-down event to the upper
layers.
Link-up event suppression enables an interface to suppress link-up events and start a delay timer each
time the physical link goes up. During this delay, the interface does not report the link-up event, and the
display interface brief or display interface command displays the interface state as DOWN. If the
physical link is still up when the timer expires, the interface reports the link-up event to the upper layers.
Configuring link-down event suppression
Follow these steps to enable an Ethernet interface to suppress link-down events:
To do… Use the command… Remarks
Enter system view system-view —
Enter Ethernet interface view
interface interface-type
interface-number
—