H3C Technologies H3C SecPath F1000-E - Manual (Page 497)

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Dynamic ARP entry
A dynamic entry is automatically created and maintained by ARP. It can get aged, be updated by a
new ARP packet, or be overwritten by a static ARP entry. When the aging timer expires or the interface
goes down, the corresponding dynamic ARP entry will be removed.
Static ARP entry
A static ARP entry is manually configured and maintained. It cannot get aged or be overwritten by a
dynamic ARP entry.
Using static ARP entries enhances communication security. After a static ARP entry is specified, only a
specific MAC address is associated with the specified IP address. Attack packets cannot modify the
IP-to-MAC mapping. Thus, communications between devices are protected.
Static ARP entries can be classified into permanent or non-permanent.
• A permanent static ARP entry can be directly used to forward packets. When configuring a
permanent static ARP entry, you must configure a VLAN and an outbound interface for the entry
besides the IP address and the MAC address.
• A non-permanent static ARP entry has only an IP address and a MAC address configured. If the
outbound interface is a Layer 3 Ethernet interface, the non-permanent ARP entry can be directly
used for forwarding data; if the outbound interface is a VLAN interface, it cannot be directly used
for forwarding data. If a non-permanent static ARP entry matches an IP packet to be forwarded,
the device sends an ARP request first. If the sender IP and MAC addresses in the received ARP
reply are the same as those in the non-permanent static ARP entry, the device adds the interface
receiving the ARP reply to the non-permanent static ARP entry. Then the entry can be used for
forwarding IP packets.
NOTE:
Usually ARP dynamically resolves IP addresses to MAC addresses, without manual intervention.
Configuring ARP Entries
Displaying ARP Entries
Select Firewall > ARP Management > ARP Table from the navigation tree to enter the page
shown in
Figure 3 . All ARP entries are displayed on the page.
Figure 3 ARP Table configuration page