Dell N3200-ON Networking N-Series Switches CLI Reference Guide version 6.8.0 - Page 433

Command History Command introduced in version 6.8 release on N22xx series switches. rate-limit cpu Use the rate-limit cpu command to reduce the amount of unknown unicast/multicast packets forwarded to the CPU. Use the no form of the command to set the rate limit to the default value. Syntax rate-limit cpu direction input pps pps_value no rate-limit cpu direction input pps • pps_value-The packets per second. The range is 5-1024 packets per second. Default Configuration The default ingress rate limit is 512 packets per second. Command Modes Global Configuration mode User Guidelines Unknown unicast and multicast packets are copied to the CPU on the lowest priority QoS queue. Unknown packets are those that do not have hardware forwarding entries. Known unicast/multicast packets are hardware forwarded and are not queued to the CPU. Control plane packets (e.g. spanning tree BPDUs) are copied or forwarded to the CPU on higher priority queues. The rate limiting for unknown packets occurs on the internal CPU port and does not affect hardware based traffic routing/forwarding in any way. Typically, the switch examines the received packets in software to check if there is a forwarding entry, create a forwarding entry (e.g., add a L2 MAC address or ARP response), and then either discard the packet or software forward the packet (only occurs during the brief transitional period when the system is actively adding a hardware forwarding entry but the hardware is not yet updated). Processing delays for higher priority packets may occur when the internal CPU queue is continually kept busy handling low priority packets. Layer 2 Switching Commands 433