D-Link DGS-3426 User Manual download pdf (Page 59)

xStack DGS-3400 Series Fast Ethernet Switch

Ping Test

Ping is a small program that sends ICMP Echo packets to the IP address you specify. The destination node then responds to

or "echoes" the packets sent from the Switch. This is very useful to verify connectivity between the Switch and other nodes

on the network.

Figure 6- 18. Ping Test window

The user may use Infinite times radio button, in the Repeat Pinging for field, which will tell the ping program to keep

sending ICMP Echo packets to the specified IP address until the program is stopped. The user may opt to choose a specific

number of times to ping the Target IP Address by clicking its radio button and entering a number between 1 and 255. Click

Start to initiate the Ping program.

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 CPU utilization beyond its capability. To alleviate this problem, the Safeguard

Engine function was added to the Switch’s software.

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. When the Switch

either (a) receives too many packets to process or (b) exerts too much memory, it will enter an Exhausted mode. When in

this mode, the Switch will perform the following tasks to mimimize the CPU usage:

1. It will limit bandwidth of receiving ARP packets. The user may implement this in two ways, by using the Mode

pull down menu in the screen below:

a. When Strict is chosen, the Switch will stop receiving ARP packets not destined for the Switch. This will

eliminate all unnecessary ARP packets while allowing the essential ARP packets to pass through to the

Switch’s CPU.

b. When Fuzzy is chosen, the Switch will mimimze the ARP packet bandwidth received by the switch by

adjusting the bandwidth for all ARP packets, whether destined for the Switch or not. The Switch uses an

internal algorithm to filter ARP packets through, with a higher percentage set aside for ARP packets

destined for the Switch.

2. It will limit the bandwidth of IP packets received by the Switch. The user may implement this in two ways, by

using the Mode pull down menu in the screen below:

a. When Strict is chosen, the Switch will stop receiving all unnecessary broadcast IP packets, even if the

high CPU utilization is not caused by the high receival rate of broadcast IP packets.

b. When Fuzzy is chosen, the Switch will mimimze the IP packet bandwidth received by the Switch by

adjusting the bandwidth for all IP packets, by setting a acceptable bandwidth for both unicast and

broadcast IP packets. The Switch uses an internal algorithm to filter IP packets through while adjusting

the bandwidth dynamically.

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D-Link DGS-3426 User Manual Page 59