08-ACL and QoS Configuration Guide

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04-Data buffer configuration
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04-Data buffer configuration 49.78 KB

Configuring data buffers

About data buffers

Data buffer types

Data buffers temporarily store packets.

The following data buffers are available:

·     Ingress buffer—Stores incoming packets when the CPU is busy.

·     Egress buffer—Stores outgoing packets when network congestion occurs.

Enabling the Burst feature

About the Burst feature

The Burst feature enables the device to automatically allocate cell and packet resources. It is well suited to the following scenarios:

·     Traffic enters a device from a high-speed interface and goes out of a low-speed interface.

·     Traffic enters a device from multiple same-rate interfaces at the same time and goes out of an interface with the same rate.

This feature takes effect only on known unicast packets.


1.     Enter system view.


2.     Enable the Burst feature.

burst-mode enable

By default, the Burst feature is disabled.

Configuring data buffer monitoring

About data buffer monitoring

The data buffer on a switch is shared by all interfaces for buffering packets during periods of congestion.

This feature allows you to identify the interfaces that use an excessive amount of data buffer space. Then, you can diagnose those interfaces for anomalies.

You can set a per-interface buffer usage threshold. The buffer usage threshold for a queue is the same as the per-interface threshold value. The switch automatically records buffer usage for each interface. When a queue on an interface uses more buffer space than the set threshold, the system counts one threshold violation for the queue.


1.     Enter system view.


2.     Set a per-interface buffer usage threshold.

In standalone mode:

buffer usage threshold slot slot-number ratio ratio

In IRF mode:

buffer usage threshold chassis chassis-number slot slot-number ratio ratio

The default setting is 100%.

Display and maintenance commands for data buffers

Execute display commands in any view.




Display buffer size settings.

In standalone mode:

display buffer [ slot slot-number ]

In IRF mode:

display buffer [ chassis chassis-number slot slot-number ]

Display data buffer usage.

In standalone mode:

display buffer usage [ slot slot-number ]

In IRF mode:

display buffer usage [ chassis chassis-number slot slot-number ]

Display buffer usage statistics for interfaces.

display buffer usage interface [ interface-type [ interface-number ] ] [ verbose ]




The verbose keyword in the display buffer usage interface command is available only for H-series cards on the S12500X-AF switch.



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