Configuring Adaptive CPCAR Adjustment for Protocol Packets
Context
The default CPCAR values for protocol packets may not meet the dynamic requirements on the rate of protocol packets to be sent to the CPU. To resolve this problem, you can enable the adaptive CPCAR adjustment function for protocol packets.
After adaptive CPCAR adjustment is enabled for a specified type of protocol packets, the device periodically detects whether the protocol packets are lost. If packet loss occurs in the last detection period, the device adjusts the CPCAR value of the protocol packets according to the CPU usage. If the CPU usage is low, the device increases the CPCAR value. If the CPU usage is high, the device decreases the CPCAR value. The new CPCAR values must be within the allowed range. If packet loss occurs due to congestion in the queue of protocol packets, the device restores the default CPCAR value of the protocol packets. You can run the display cpu-defend dynamic-adjust history-record command to view the historical adaptive CPCAR adjustment records.
The following table lists the supported protocol packet types and the maximum CPCAR values allowed after adjustment.
| Protocol Packet Type | Description | Maximum CPCAR Value After Adjustment |
|---|---|---|
| arp-reply | ARP reply packets | Twice the default value |
| arp-request | ARP request packets | Twice the default value |
| arp-request-uc | Unicast ARP request packets | Twice the default value |
| dhcp-client | Packets sent by DHCP clients | 1.5 times the default value |
| dhcp-server | Packets sent by DHCP servers | 1.5 times the default value |
| igmp | IGMP packets | Twice the default value |
| nd | IPv6 neighbor discovery packets | Twice the default value |
Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, 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.
- Run cpu-defend dynamic-adjust [ packet-type { arp-reply | arp-request | arp-request-uc | dhcp-client | dhcp-server | igmp | nd } ] enable
Adaptive CPCAR adjustment for protocol packets is enabled.
By default, adaptive CPCAR adjustment for protocol packets is enabled.
If the packet-type parameter is not specified, adaptive CPCAR adjustment for protocol packets is enabled globally and takes effect for all supported types of protocol packets.