Why the CPU usage will be high when we configure many vlanif interfaces?

When a VLANIF interface is configured on the S3700 / S5700EI switch, the switch sends an ACL to capture ARP packets from the VLAN to the control plane. When the configured VLANIF interface is too large (more than 8 for S3700s and more than 32 for S5700EIs), the switch sends an ACL to capture ARP packets from all VLANs to the control plane for software forwarding due to ACL resource restrictions. The ACL will also capture Layer 2 ARP packets from VLANs that are not VLANIF interfaces. If the number of ARP packets forwarded by Layer 2 packets is high, the ACL will be overloaded and the CPU occupancy rate will be too high.

For the S2752 / S3700 series switches, it is not recommended to configure more VLANIF interfaces due to specifications and hardware performance. In order to avoid excessive ARP and ARP-Miss packets, CPU usage is too high. It is recommended to configure the arp-fake expire-time 30 in each VLANIF interface view to optimize the ARP entries to reduce CPU usage and recommend the latest patches.

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