D-Link DES-3528 User Manual page 143

xStack DES-3528 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual
If the Switch detects
too many packets, it
will rate limit all ingress
ARP and IP broadcast
packets for 5 seconds.
For every consecutive checking interval that reveals a packet flooding issue, the Switch will double the time it will
accept a few ingress ARP and IP broadcast packets. In the example above, the Switch doubled the time for dropping
ARP and IP broadcast packets when consecutive flooding issues were detected at 5-second intervals. (First stop = 5
seconds, second stop = 10 seconds, third stop = 20 seconds) Once the flooding is no longer detected, the wait period
for limiting ARP and IP broadcast packets will return to 5 seconds and the process will resume.
Once in Exhausted mode, the packet flow will decrease by half of the level that caused the Switch to enter Exhausted
mode. After the packet flow has stabilized, the rate will initially increase by 25% and then return to a normal packet
flow.
To configure the Safeguard Engine for the Switch, click Security > Safeguard Engine, which will open the following
window.
If the second checking
interval reveals there are
still too many ingress
packets, the Switch will
rate limit all ARP and IP
broadcast packets for 10
seconds (5*2=10)
Figure 9- 1. Mapping QoS on the Switch
Figure 9- 2. Safeguard Engine window
If the third checking
interval reveals there are
still too many ingress
packets, the Switch will
rate limit all ARP and IP
broadcast packets for 20
seconds (10*2=20).
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If the fourth interval reveals
the packet flooding has
subsided, the Switch will
return to accepting ARP
and IP broadcast packets.