qos lr outbound
Function
The qos lr outbound command configures traffic shaping in the outbound direction on an interface.
The undo qos lr outbound command cancels traffic shaping in the outbound direction on an interface.
By default, traffic shaping is not configured in the outbound direction on an interface.
Format
qos lr outbound cir cir-value [ cbs cbs-value ]
undo qos lr outbound
The S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, and S5731S-S do not support cbs cbs-value.
Parameters
Parameter |
Description |
Value |
|---|---|---|
cir cir-value |
Specifies the committed information rate (CIR). |
The value is an integer, in kbit/s. The value range differs depending on the interface type:
|
cbs cbs-value |
Specifies the committed burst size (CBS). |
The value is an integer that ranges from 4000 to 4294967295, in bytes. If this parameter is not specified, the default CBS is 125 times the CIR. NOTE:
On the S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735-S-I, and S5735S-S, the maximum CBS is 65535 bytes. |
Views
Ethernet interface view, MultiGE interface view, GE interface view, XGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, port group view
Usage Guidelines
Usage Scenario
When a large amount of data flows are sent from the upstream device to its downstream device, to prevent congestion or packet loss, run the qos lr outbound command to configure traffic shaping on the outbound interface of the device to limit the traffic and burst traffic transmitted over a connection so that packets are sent at an even rate.
Similar to traffic policing, traffic shaping limits the traffic rate. When traffic policing is used, the system directly discards the packets whose rate is larger than the traffic policing rate. Traffic shaping, however, buffers the packets whose rate is larger than the traffic shaping rate. When there are sufficient tokens in the token bucket, the device forwards buffered packets at an even rate. Traffic shaping increases the delay, whereas traffic policing does not.
Precautions
When interface-based 802.1X authentication is configured and the RADIUS server delivers the rate limit, the interface does not support the rate limit.
If you need to set the same traffic shaping rate on multiple interfaces, you can perform the configuration on a port group to reduce the workload.
If both traffic shaping and queue shaping (configured by using the qos queue shaping command) are configured on an interface, the CIR of traffic shaping cannot be lower than the sum of CIR values of all the queues on the interface; otherwise, the traffic shaping result may be incorrect. For example, the queue with a lower priority may occupy the bandwidth of the queue with a higher priority.
Traffic shaping increases the delay because it uses the buffer mechanism.
If you run the qos lr outbound command multiple times on the same interface, only the latest configuration takes effect.
After traffic shaping is configured on an interface, the number of packets that can be forwarded on the interface every second is relevant to the packet length calculation method. By default, the device calculates the 20-byte inter-frame gap and preamble. That is, the device calculates the actual packet length plus 20-byte inter-frame gap and preamble.
On the S5730S-EI, S5730-SI, S6720-LI, S6720-SI, S6720S-LI, and S6720S-SI, the cbs cbs-value parameter specified in the qos lr outbound command does not take effect and has a fixed value of 132000, in bytes.
On the S2720-EI, S5720I-SI, S5720-LI, S5720S-LI, S5720S-SI, and S5720-SI, the maximum value of cbs cbs-value specified in the qos lr outbound command is 16380000, in bytes, even if the specified value is greater than 16380000.