Configuring Arp Automatic Scanning And Fixed Arp; Configuration Guidelines - HP 10500 Series Configuration Manual

# Enable ARP packet validity check by checking the MAC addresses and IP addresses of ARP
packets.
[SwitchB] arp detection validate dst-mac ip src-mac
# Configure port isolation.
[SwitchB] interface gigabitethernet 1/0/1
[SwitchB-GigabitEthernet1/0/1] port-isolate enable
[SwitchB-GigabitEthernet1/0/1] quit
[SwitchB] interface gigabitethernet 1/0/2
[SwitchB-GigabitEthernet1/0/2] port-isolate enable
[SwitchB-GigabitEthernet1/0/2] quit
After the preceding configurations are complete, ARP packets received on interfaces
GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 have their MAC and IP addresses checked
first, and then are checked against the static IP source guard binding entries and finally DHCP
snooping entries. However, ARP broadcast requests sent from Host A can pass the check on
Switch B. Port isolation fails.
# Enable ARP restricted forwarding.
[SwitchB] vlan 10
[SwitchB-vlan10] arp restricted-forwarding enable
[SwitchB-vlan10] quit
After the configuration, Switch B forwards ARP broadcast requests from Host A to Switch A
through the trusted port GigabitEthernet 1/0/3. Therefore, Host B cannot receive such packets.
Port isolation works normally.

Configuring ARP automatic scanning and fixed ARP

ARP automatic scanning is usually used together with the fixed ARP feature.
With ARP automatic scanning enabled on an interface, the device automatically scans neighbors on the
interface, sends ARP requests to the neighbors, obtains their MAC addresses, and creates dynamic ARP
entries.
Fixed ARP allows the device to change the existing dynamic ARP entries (including those generated
through ARP automatic scanning) into static ARP entries. The fixed ARP feature effectively prevents ARP
entries from being modified by attackers.
Use both ARP automatic scanning and fixed ARP in small-scale networks such as a cybercafe.

Configuration guidelines

When you configure ARP automatic scanning and fixed ARP, follow these guidelines:
The interface view can be Layer 3 Ethernet interface view, Layer 3 Ethernet subinterface view, VLAN
•
interface view, Layer 3 aggregate interface view, or Layer 3 aggregate subinterface view.
• IP addresses existing in ARP entries are not scanned.
ARP automatic scanning may take some time. To stop an ongoing scan, press Ctrl + C. Dynamic
•
ARP entries are created based on ARP replies received before the scan is terminated.
Static ARP entries changed from dynamic ARP entries have the same attributes as the manually
•
configured static ARP entries.
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