HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 2 - LAN Switching Co - Page 13

Configuring flow control on an Ethernet interface

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Figure 1 Speed auto negotiation application scenario GE1/0/3 As shown in Figure 1, all ports on Switch A are operating in speed auto negotiation mode, with the highest speed of 1000 Mbps. If the transmission rate of each server in the server cluster is 1000 Mbps, their total transmission rate will exceed the capability of port GigabitEthernet 1/0/4, the port providing access to the Internet for the servers. To avoid congestion on GigabitEthernet 1/0/4, set 100 Mbps as the only option available for speed negotiation on port GigabitEthernet 1/0/1, GigabitEthernet 1/0/2, and GigabitEthernet 1/0/3. As a result, the transmission rate on each port connected to a server is limited to 100 Mbps. To set speed options for auto negotiation on an Ethernet interface: Step Command 1. Enter system view. system-view 2. Enter Ethernet interface view. interface interface-type interface-number 3. Set speed options for auto negotiation. speed auto { 10 | 100 | 1000 } * Remarks N/A N/A Optional. NOTE: The speed and speed auto commands supersede each other, and whichever is configured last takes effect. 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. 4

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4
Figure 1
Speed auto negotiation application scenario
As shown in
Figure 1
, all ports on Switch A are operating in speed auto negotiation mode, with the
highest speed of 1000 Mbps. If the transmission rate of each server in the server cluster is 1000 Mbps,
their total transmission rate will exceed the capability of port GigabitEthernet 1/0/4, the port providing
access to the Internet for the servers.
To avoid congestion on GigabitEthernet 1/0/4, set 100 Mbps as the only option available for speed
negotiation on port GigabitEthernet 1/0/1, GigabitEthernet 1/0/2, and GigabitEthernet 1/0/3. As a
result, the transmission rate on each port connected to a server is limited to 100 Mbps.
To set speed options for auto negotiation 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.
Set speed options for auto negotiation.
speed
auto
{
10
|
100
|
1000
} *
Optional.
NOTE:
The
speed
and
speed auto
commands supersede each other, and whichever is configured last takes effect.
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.
GE1/0/3