Configuration Procedure; Configuring Flow Control On An Ethernet Interface - HP 3100 Series Configuration Manual

•
The speed and speed auto commands supersede each other, and whichever is configured last
takes effect.

Configuration procedure

To set speed options for auto negotiation on an Ethernet interface:
Step
Enter system view.
1.
Enter Ethernet interface view.
2.
Set speed options for auto
3.
negotiation.

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.
Flow control is implemented by receiving and sending Pause frames on ports. Flow control can
operate in one of the following modes on an interface:
•
TxRx mode (configured by using the flow-control command)—The interface can both send
and receive flow control frames.
•
Rx mode (configured by using the flow-control receive enable command)—The interface can
receive, but not send flow control frames.
As shown in
is congested. To avoid packet loss, enable flow control on Port A and Port B.
Figure 2 Flow control on ports
Configure flow control in TxRx mode on Port B and flow control in Rx mode on Port A:
•
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.
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 implement flow control on the local Ethernet port, you must enable flow control on both the local
Ethernet port and the remote port. If flow control is enabled on the local Ethernet port but disabled on
the remote port, forwarding of packets received on the other Ethernet ports of the local switch is
affected.
Figure 2, when both Port A and Port B forward packets at the rate of 1000 Mbps, Port C
Command
system-view
interface interface-type
interface-number
speed auto { 10 | 100 | 1000 } *
4
Remarks
N/A
N/A
Optional.