In routine maintenance, you can run the display arp command in any view to check ARP entry information on the device.
By checking ARP entries on a gateway device, the network administrator can view information about the connected users, including IP addresses, MAC addresses, and interfaces. For example, the network administrator can check ARP entry information to query the MAC address based on the IP address of a user.
When the gateway does not learn the IP address of a connected user, the network administrator can ping the broadcast address on the network segment on the gateway. For example, if the gateway IP address is 10.10.10.1/24, the network administrator runs the ping 10.10.10.255 command on the gateway. Then the user on the same network segment sends an ARP Reply packet. After receiving the ARP Reply packet, the gateway can learn the user's IP address.
# Check ARP entries on the network segment 172.16.0.0/16.
<HUAWEI> display arp network 172.16.0.0 16 IP ADDRESS MAC ADDRESS EXPIRE(M) TYPE INTERFACE VPN-INSTANCE VLAN/CEVLAN ------------------------------------------------------------------------------ 172.16.10.3 0025-9efb-be55 S-- GE1/0/6 100/- 172.16.20.3 0200-0000-00e8 S-- GE1/0/19 172.16.10.1 0025-9ef4-abcd I - Vlanif100 172.16.10.2 0025-9efb-be55 20 D-0 GE1/0/6 100/- 172.16.20.1 0025-9ef4-abcd I - GE1/0/19 172.16.20.2 0200-0000-00e8 18 D-0 GE1/0/19 ------------------------------------------------------------------------------ Total:6 Dynamic:2 Static:2 Interface:2
- The IP address is 172.16.10.3, MAC address is 0025-9efb-be55, and type is S (indicating a static ARP entry). For this static ARP entry, the outbound interface is GE1/0/6 and VLAN ID is 100.
- The IP address is 172.16.20.3, MAC address is 0200-0000-00e8, and type is S (indicating a static ARP entry). For this static ARP entry, the outbound interface is GE1/0/19.
- The IP address is 172.16.10.1, MAC address is 0025-9ef4-abcd, and type is I (indicating an interface ARP entry). This ARP entry indicates that 172.16.10.1 is the IP address of the interface VLANIF 100.
- The IP address is 172.16.10.2, MAC address is 0025-9efb-be55, and type is D (indicating a dynamic ARP entry). This dynamic ARP entry is learned from the interface GE1/0/6, the VLAN ID is 100, and the remaining lifetime is 20 minutes.
- The IP address is 172.16.20.1, MAC address is 0025-9ef4-abcd, and type is I (indicating an interface ARP entry). This ARP entry indicates that 172.16.20.1 is the IP address of the interface GE1/0/19.
- The IP address is 172.16.20.2, MAC address is 0200-0000-00e8, and type is D (indicating a dynamic ARP entry). This dynamic ARP entry is learned from the interface GE1/0/19, and the remaining lifetime is 18 minutes.
NOTE:
- When a temporary ARP entry is not aged out:
- Before receiving an ARP Reply packet, the device discards the IP packets matching the temporary ARP entry, and no ARP Miss message is triggered.
- After receiving the ARP Reply packet, the device generates a correct ARP entry to replace the temporary entry.
- After the temporary ARP entry ages out, the device deletes this entry.
More Information: S Series Switches Common Operation Guide
