cpu-defend dynamic-car enable

Function

The cpu-defend dynamic-car enable command enables a switch to dynamically adjust the default CIR value for protocol packets.

The undo cpu-defend dynamic-car enable command disables a switch from dynamically adjusting the default CIR value for protocol packets.

By default, dynamic adjustment of the default CIR value is enabled globally, but the switch is disabled from dynamically adjusting the default CIR value for VRRP and ARP protocol packets.

Only the S5720-EI, S5720-HI, S5720I-SI, S5720S-SI, S5720-SI, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735S-S, S5735-S-I, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720-LI, S6720S-EI, S6720S-LI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S support this command.

Format

cpu-defend dynamic-car [ arp | vrrp ] enable

undo cpu-defend dynamic-car [ arp | vrrp ] enable

Parameters

Parameter	Description	Value
arp	Enables the switch to dynamically adjust the default CIR value for ARP protocol packets.	-
vrrp	Enables the switch to dynamically adjust the default CIR value for VRRP protocol packets.	-

Views

System view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

A fixed default CIR value may not adapt to dynamic requirements on rate limiting for protocol packets. The cpu-defend dynamic-car enable command enables a switch to dynamically adjust the default CIR value for protocol packets.

If the default CIR value for a protocol has never been changed, the switch dynamically adjusts the default CIR value for the protocol packets based on service scale (for example, number of dynamic ARP entries) and CPU usage to meet various service requirements. For details, see Table 1.

**Table 1** Default CPCAR adjustment for ARP packets
X = Number of ARP Entries	Adjusted CPCAR
X ≤ 512	Unchanged
512 < X ≤ 1024	128 kbit/s (remain unchanged if the default CIR is greater than 128 kbit/s)
1024 < X ≤ 3072	256 kbit/s
3072 < X ≤ 4096	512 kbit/s
X > 4096	512 kbit/s

**Table 2** Default CPCAR adjustment for VRRP packets
X = Number of VRRP Groups	Adjusted CPCAR
X ≤ 200	192 kbit/s
200 < X ≤ 300	256 kbit/s
300 < X ≤ 400	320 kbit/s
400 < X ≤ 500	384 kbit/s
500 < X ≤ 600	448 kbit/s
600 < X ≤ 1000	512 kbit/s

When the number of entries increases, the CPCAR value is dynamically increased. When the CPU usage is between 70% to 98%, the dynamic CPCAR adjustment stops. If the CPU usage is greater than 98%, the default CPCAR value is used.

Precautions

The switch dynamically adjusts the default CIR value for VRRP or ARP protocol packets only when the function is enabled globally and on VRRP or ARP protocol packets.

The default CIR value dynamically adjusted only takes effect when the CIR value of the protocol packet is not manually changed.

After the default CPCAR setting is modified for ARP, only the CIR value for ARP reply, Unicast ARP request, and ARP request packets is adjusted.

Example

# Enable the switch to dynamically adjust the default CIR value for ARP protocol packets.

<HUAWEI> system-view
[HUAWEI] cpu-defend dynamic-car enable
[HUAWEI] cpu-defend dynamic-car arp enable