FAQ-Why Is the Actual Rate Limit Different from the ICMP Packet Rate Limit Configured on the Interface Board

Publication Date:  2015-05-06 Views:  173 Downloads:  0
Issue Description
Why Is the Actual Rate Limit Different from the ICMP Packet Rate Limit Configured on the Interface Board?
Solution

ARa 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.

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