HP ProCurve 9304M Installation And Configuration Manual page 138

Installation and Basic Configuration Guide
8. Select the Save link at the bottom of the dialog. Select Yes when prompted to save the configuration change
to the startup-config file on the device's flash memory.
Specifying Threshold Values for Flow Control
The 802.3x flow control specification provides a method for slowing traffic from a sender when a port is receiving
more traffic than it can handle. Specifically, the receiving device can send out 802.3x PAUSE frames that request
that the sender stop sending traffic for a period of time.
In software release 07.6.00 and higher, the HP device generates 802.3x PAUSE frames when the number of
buffers available to a module's Buffer Manager (BM) drops below a threshold value. A module's BM can start
running out of buffers when a port receives more traffic than it can handle. In addition, the device drops the lowest
priority traffic when the number of available buffers drops below a second threshold. When the number of
available buffers returns to a higher level, the device sends out another PAUSE frame that tells the sender to
resume sending traffic normally. You can specify values for both thresholds, as well as the module where the
thresholds are to take effect.
NOTE: To use this feature, 802.3x flow control must be enabled globally on the device. By default, 802.3x flow
control is enabled on HP devices, but can be disabled with the no flow-control command.
To specify threshold values for flow control, enter the following command:
HP9300(config)# qd-flow sink 75 sunk 50 slot 1
Syntax: qd-flow sink <sinking-threshold> sunk <sunk-threshold> slot <slot>
The threshold values are percentages of the total number of buffers available to a module's Buffer Manager.
When the <sinking-threshold> is reached, the HP device sends out 802.3x PAUSE frames telling the sender to
stop sending traffic for a period of time.
When the <sunk-threshold> is reached, the HP device drops traffic at the specified priority level.
The <slot> parameter specifies the location of the module where the thresholds are to take effect.
Changing the 802.3x Gigabit Negotiation Mode
The globally configured Gigabit negotiation mode for 802.3x flow control is the default mode for all Gigabit ports.
You can override the globally configured default and set individual ports to the following:
• Negotiate-full-auto – The port first tries to perform a handshake with the other port to exchange capability
information. If the other port does not respond to the handshake attempt, the port uses the manually
configured configuration information (or the defaults if an administrator has not set the information). This is
the default.
• Auto-Gigabit – The port tries to perform a handshake with the other port to exchange capability information.
• Negotiation-off – The port does not try to perform a handshake. Instead, the port uses configuration
information manually configured by an administrator.
USING THE CLI
To change the mode for individual ports, enter commands such as the following:
HP9300(config)# int ethernet 4/1 to 4/4
HP9300(config-mif-4/1-4/4)# gig-default auto-gig
This command overrides the global setting and sets the negotiation mode to auto-Gigabit for ports 4/1 – 4/4.
Syntax: gig-default neg-full-auto | auto-gig | neg-off
USING THE WEB MANAGEMENT INTERFACE
To override the global 802.3x negotiation mode for an Gigabit individual port:
1. Log on to the device using a valid user name and password for read-write access. The System configuration
panel is displayed.
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