2-3request, in which the target IP address is the IP address of Host B. After obtaining the MAC address ofHost B, the gateway sends the packet to Host B.ARP TableAfter obtaining the MAC address for the destination host, the device puts the IP-to-MAC mapping intoits own ARP table. This mapping is used for forwarding packets with the same destination in future.An ARP table contains ARP entries, which fall into one of two categories: dynamic or static.Dynamic ARP entryA dynamic entry is automatically created and maintained by ARP. It can get aged, be updated by a newARP packet, or be overwritten by a static ARP entry. When the aging timer expires or the interfacegoes down, the corresponding dynamic ARP entry will be removed.Static ARP entryA static ARP entry is manually configured and maintained. It cannot get aged or be overwritten by adynamic ARP entry.Using static ARP entries enhances communication security. You can configure a static ARP entry torestrict an IP address to communicate with the specified MAC address only. After that, attack packetscannot modify the IP-to-MAC mapping specified in the static ARP entry. Thus, communicationsbetween the protected device and the specified device are ensured.Static ARP entries can be classified into permanent or non-permanent.z A permanent static ARP entry can be directly used to forward packets. When configuring apermanent static ARP entry, you must configure a VLAN and an outbound interface for the entrybesides the IP address and the MAC address.z A non-permanent static ARP entry has only an IP address and a MAC address configured. If anon-permanent static ARP entry matches an IP packet to be forwarded, the device sends an ARPrequest first. If the sender IP and MAC addresses in the received ARP reply are the same asthose in the non-permanent static ARP entry, the device adds the interface receiving the ARPreply to the non-permanent static ARP entry. Then the entry can be used for forwarding IPpackets.Usually ARP dynamically resolves IP addresses to MAC addresses, without manual intervention.Configuring ARPConfiguring a Static ARP EntryA static ARP entry is effective when the device works normally. However, when a VLAN or VLANinterface to which a static ARP entry corresponds is deleted, the entry, if permanent, will be deleted,and if non-permanent and resolved, will become unresolved.Follow these steps to configure a static ARP entry:
