D-Link DGS-3000 Series Reference Manual page 281

For every consecutive checking interval that reveals the high CPU utilization issue, the Switch will double the time to
enter the Exhausted mode to limit the specified traffic to the Switch. In the example above, the Switch doubled the
time in the Exhausted mode when consecutive high CPU utilization issues were detected at 5-second intervals. (First
stop = 5 seconds, second stop = 10 seconds, third stop = 20 seconds) Once the CPU utilization is below the Falling
Threshold, the wait period for the Exhausted mode will return to 5 seconds and the process will resume.
In Fuzzy mode, once the Safeguard Engine has entered the Exhausted mode, the Safeguard Engine will decrease the
packet flow to the Switch by half. After returning to Normal mode, the packet flow will be increased by 25%. The
switch will then return to its interval checking and dynamically adjust the packet flow to avoid overload of the Switch.
Users can enable the Safeguard Engine or configure advanced Safeguard Engine settings for the Switch.
To view this window, click Security > Safeguard Engine Settings as shown below:
The fields that can be configured are described below:
Parameter
Safeguard Engine State
Rising Threshold (20% -
100%)
Falling Threshold (20%
- 100%)
Trap / Log
Mode
Click the Apply button to accept the changes made.
DGS-3000 Series Gigabit Ethernet Switch Web UI Reference Guide
Figure 8-78 Safeguard Engine Settings window
Description
Use the radio button to globally enable or disable Safeguard Engine settings for the
Switch.
Used to configure the acceptable level of CPU utilization before the Safeguard Engine
mechanism is enabled. Once the CPU utilization reaches this percentage level, the
Switch will move into Exhausted mode, based on the parameters provided in this
window.
Used to configure the acceptable level of CPU utilization as a percentage, where the
Switch leaves the Safeguard Engine state and returns to normal mode.
Use the drop-down menu to enable or disable the sending of messages to the
device's SNMP agent and switch log once the Safeguard Engine has been activated
by a high CPU utilization rate.
Used to select the type of Safeguard Engine to be activated by the Switch when the
CPU utilization reaches a high rate. The user may select:
Fuzzy – If selected, the Switch will adjust the bandwidth dynamically depend on some
reasonable algorithm.
Strict – If selected, the Switch will stop receiving all 'IP broadcast' packets, packets
from un-trusted IP address and reduce the bandwidth of 'ARP not to me' packets (the
protocol address of target in ARP packet is the Switch itself) to the Switch. That
means no matter what reasons cause the high CPU utilization (may not be caused by
ARP storm), the Switch reluctantly processes the specified traffic mentioned in
previous in the Exhausted mode.
The default setting is Fuzzy mode.
272