# Why is the actual rate limit different from the ICMP packet rate limit configured on the interface board

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AR series routers convert the number of packets to a number of bytes when limiting the rate of Layer 3 unicast packets on the interface board. Each Internet Control Message Protocol (ICMP) packet is converted to 84 bytes. For example, if the ICMP packet rate limit is configured as 10 packets per second, the actual rate limit is 840 (84 x 10) bytes per second. If the actual length of ICMP packets is not 84 bytes, the actual rate limit is different from the configured value.

-If the actual length of ICMP packets is greater than 84 bytes, the actual rate limit is less than the configured rate limit. For example, if the ICMP packet rate limit is configured to be 10 packets per second, and the actual packet length is 320 bytes, the actual rate limit is 840/320 (rounded down) packets per second, that is, 2 packets per second.
-If the actual length of ICMP packets is less than 84 bytes, the actual rate limit is greater than the configured rate limit. For example, if the ICMP packet rate limit is configured to be 10 packets per second, and the actual packet length is 64 bytes, the actual rate limit is 840/64 (rounded down) packets per second, that is, 13 packets per second.

###### Other related questions:
Why is the rate limit for ICMP packets configured on an interface card inconsistent with the actual rate limit
An AR router implements rate limit to Layer 3 unicast packets by converting the number of packets into the number of bytes. ICMP packets are converted based on 84 bytes per packet. For example, if the rate limit configured for ICMP packets is 10, then the actual rate limit is calculated as 84 x 10 = 840 byte/s. If the actual packet length is not equal to 84 bytes, the actual rate limit will deviate from the configured value.

How to delete the rate limiting configuration from an interface
1. Log in to the web system, and choose QoS > Interface Rate Limit to access the parameter configuration page for interface-based rate limiting. On the Interface Rate Limit List toolbar, select the check box of the interface from which the rate limiting configuration is to be deleted, and click Delete. Click OK in the displayed dialog box. The rate limiting configuration is deleted from on the interface. 2. Using commands: You can also run the undo command to delete configurations from the interface to which a traffic policy is applied or the interface with rate limiting configured.

Configure rate limiting based on IP addresses
You can run the qos car command in the interface view to configure rate limiting based on IP addresses.

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