Configuring Rate Limiting on ARP Packets based on Source MAC Addresses
Context
A large number of ARP packets with a fixed source MAC address and variable IP addresses will cause the CPU of a device to be overloaded and exhaust ARP entries.
To prevent this problem, configure the gateway to rate-limit ARP packets based on source MAC addresses. The gateway then collects statistics on ARP packets sent from certain source MAC addresses to the CPU. If the number of ARP packets received in one second from the specified source MAC address exceeds the threshold, the device discards the excess ARP packets.
Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735S-S, S5735-S-I, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support this function.
Procedure
- Run system-view
The system view is displayed.
- Configure rate limiting on ARP packets based on source MAC addresses.
Run arp speed-limit source-mac maximum maximum
The maximum rate of ARP packets from any source MAC address is set.
Run arp speed-limit source-mac mac-address maximum maximum
The maximum rate of ARP packets from the specified source MAC address is set.
When both the preceding commands are executed, the maximum rate set using the arp speed-limit source-mac mac-address maximum maximum command takes effect on ARP packets from the specified source MAC address, and the maximum rate set using the arp speed-limit source-mac maximum maximum command takes effect on ARP packets from other source MAC addresses.
By default, the maximum rate of ARP packets from each source MAC address is set to 0; that is, ARP packets are not rate-limited based on source MAC addresses.
After the optimized ARP reply function (disabled by default) is enabled using the undo arp optimized-reply disable command, rate limiting on ARP packets based on the source MAC address does not take effect.