NAT Server Fails to Be Configured on an AR Router Due to an IP Address Conflict

Publication Date:  2015-08-19 Views:  1136 Downloads:  0
Issue Description
When the nat server command is run on an AR router, the system displays the following error message:

[Huawei-GigabitEthernet0/0/0] nat server protocol tcp global 10.1.1.1 9008 inside 192.168.130.11 8080                                
  Error: The address conflicts with interface or ARP IP. 

The main configuration of the AR router is as follows:

#
interface GigabitEthernet0/0/0
ip address 10.1.1.3 255.255.255.0     
nat server protocol tcp global current-interface 2121 inside 10.0.1.10 2121
nat server protocol tcp global current-interface www inside 192.168.130.10 8008
nat outbound 2000
#
interface GigabitEthernet0/0/1
ip address 10.0.0.1 255.255.255.0
#
interface GigabitEthernet0/0/2
ip address 10.0.1.1 255.255.255.0
nat outbound 2000
Handling Process
1. The configuration of GE0/0/0 shows that the IP address 10.1.1.1 is not used. The IP address may be used by another interface. Change the IP address and run the nat server command again.

[Huawei-GigabitEthernet0/0/0] nat server protocol tcp global 10.1.1.4 9008 inside 192.168.130.11 8080                                
[Huawei-GigabitEthernet0/0/0] 

The changed public IP address successfully maps the private IP address.

2. Run the display arp command to check ARP entries on the router. The IP address 10.1.1.1 is in the ARP table, indicating that the IP address has been used.

<Huawei> display arp                                                                                                                    
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE                                                      
                                          VLAN/CEVLAN PVC                                                                           
------------------------------------------------------------------------------                                                      
10.1.1.3        0819-a6cd-a895            I -         GE0/0/0                                                                       
10.1.1.1        5489-98f4-5a8e  19        D-0         GE0/0/0                                                                       
10.0.0.1        0819-a6cd-a896            I -         GE0/0/1                                                                       
10.0.1.1        0819-a6cd-a897            I -         GE0/0/2                                                                       
200.1.1.1       5489-9874-b897            I -         Eth1/0/1                                                                      
192.168.1.1     0819-a6cd-a894            I -         Vlanif10                                                                      
172.1.1.2       0819-a6cd-a894            I -         Eth-Trunk10                                                                   
------------------------------------------------------------------------------                                                      
Total:7         Dynamic:1       Static:0     Interface:6            
Suggestions
If an IP address conflict occurs when NAT server is correctly configured, check whether the IP address is correct. For example, the IP address has been used on another device in this example.

END