Security; Safeguard Engine - D-Link DGS-3200 Series User Manual

Security

Safeguard Engine

Trusted Host
IP-MAC-Port Binding
Port Security
Guest VLAN
802.1X
SSL Settings
SSH
Access Authentication Control
MAC Based Access Control
Web Authentication (Web-based Access Control)
JWAC
Safeguard Engine
Periodically, malicious hosts on the network will attack the Switch by utilizing packet flooding (ARP Storm) or other methods.
These attacks may increase the switch load beyond its capability. To alleviate this problem, the Safeguard Engine function was
added to the Switch's software.
The Safeguard Engine can help the overall operability of the Switch by minimizing the workload of the Switch while the attack is
ongoing, thus making it capable to forward essential packets over its network in a limited bandwidth. The Safeguard Engine has
two operating modes that can be configured by the user, Strict and Fuzzy. In Strict mode, when the Switch either (a) receives too
many packets to process or (b) exerts too much memory, it will enter the Exhausted mode. When in this mode, the Switch will
drop all ARP and IP broadcast packets and packets from untrusted IP addresses for a calculated time interval. Every five seconds,
the Safeguard Engine will check to see if there are too many packets flooding the Switch. If the threshold has been crossed, the
Switch will initially stop all ingress ARP and IP broadcast packets and packets from untrusted IP addresses for five seconds. After
another five-second checking interval arrives, the Switch will again check the ingress flow of packets. If the flooding has stopped,
the Switch will again begin accepting all packets. Yet, if the checking shows that there continues to be too many packets flooding
the Switch, it will stop accepting all ARP and IP broadcast packets and packets from untrusted IP addresses for double the time of
the previous stop period. This doubling of time for stopping these packets will continue until the maximum time has been reached,
which is 320 seconds and every stop from this point until a return to normal ingress flow would be 320 seconds. For a better
understanding, please examine the following example of the Safeguard Engine.
DGS-3200 Series Layer 2 Gigabit Ethernet Managed Switch
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Section 9