Configuring Arp Automatic Scanning And Fixed Arp; Configuration Guidelines - HP 6125XLG Configuration Manual

[SwitchB-vlan10] arp detection enable
# Configure the upstream interface as a trusted interface (an interface is an untrusted interface by
default).
[SwitchB-vlan10] interface ten-gigabitethernet 1/1/7
[SwitchB-Ten-GigabitEthernet1/1/7] arp detection trust
[SwitchB-Ten-GigabitEthernet1/1/7] quit
# Configure a static IP source guard binding entry on interface Ten-GigabitEthernet 1/1/6 for user
validity check.
[SwitchB] interface ten-gigabitethernet 1/1/6
[SwitchB-Ten-GigabitEthernet1/1/6] ip source binding ip-address 10.1.1.6 mac-address
0001-0203-0607 vlan 10
[SwitchB-Ten-GigabitEthernet1/1/6] quit
# 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
After the configurations are completed, ARP packets received on interfaces Ten-GigabitEthernet
1/1/5 and Ten-GigabitEthernet 1/1/6 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.

Configuring ARP automatic scanning and fixed ARP

ARP automatic scanning is usually used together with the fixed ARP feature in small-scale networks such
as a cybercafe.
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 convert existing dynamic ARP entries (including those generated through
ARP automatic scanning) to static ARP entries. The fixed ARP feature prevents ARP entries from being
modified by attackers. Static ARP entries can also be manually configured by the arp static command.

Configuration guidelines

Follow these guidelines when you configure ARP automatic scanning and fixed ARP:
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.
The arp fixup command is a one-time operation and converts existing dynamic ARP entries to static
•
ones.
The device has a limit on the total number of static ARP entries, including the manually configured
•
and the converted. As a result, some dynamic ARP entries may fail the conversion.
• To delete a specific static ARP entry converted from a dynamic one, use the undo arp ip-address
[ vpn-instance-name ] command. Use the reset arp all command to delete all ARP entries or the
reset arp static command to delete all static ARP entries.
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