Can't place RM520 in IP Passthrough (IPPT) mode

Technical Subjects Software Internet Protocol
1

Hi,

I’ve converted the RM520N-GL to the NAT mode to NAT between its WWAN and its LAN interface. The RM520N-GL came with the IP Passthrough (IPPT) mode, so I was able to get a public IP from my 5G carrier onto a host connected to the RM520-GL. Once I converted IPPT to NAT, the RM520N started serving a private DHPC lease to the host connected via Ethernet to the RM520N.

The command I used was;
at+qmap="mpdn_rule",0,1,0,0,1

The third parameter (0) is the VLAN tag. VLAN 0 means no tagged VLAN on the LAN interface.
The fourth parameter (0) disables the IPPT mode and puts the RM520N into the NAT mode.
The fifth parameter (1) enables the MPDN rule

Once I issued this command and renewed the DHCP lease on the connected host, the connected host received an IP address from the DHCP pool configured in RM520N:

at+qmap=“lanip”
+QMAP: "LANIP",192.168.225.20,192.168.225.100,192.168.225.1

I was able to use the Internet with the RM520N doing NAT. This was an experiment - not that I am planning to run the RM520N in the NAT mode - at least not yet until I figure out more AT commands that I can fine-tune the firewall rules to be applieed to the RM520N’s WWAN interface.

However, my problem is that I can’t revert the RM520N back into the IPPT mode. The command (according to the beta version of the AT manual) is:

at+qmap="mpdn_rule",0,1,0,1,1

The fourth parameter (set to 1) is supposed to enable IPPT (IP Passthorugh) on the Ethernet interface, but the RM520N rejects this command with an error.

at+qmap="mpdn_rule"
+QMAP: "MPDN_rule",0,1,0,0,1
+QMAP: "MPDN_rule",1,0,0,0,0
+QMAP: "MPDN_rule",2,0,0,0,0
+QMAP: "MPDN_rule",3,0,0,0,0

OK
at+qmap="mpdn_rule",0,1,0,1,1
ERROR

at+qmap="mpdn_rule",0,1,0,1                                                     
ERROR 
                                                                          
at+qmap="mpdn_rule",0                                                           
OK

at+qmap="mpdn_rule"                                                             
+QMAP: "MPDN_rule",0,0,0,0,0                                                    
+QMAP: "MPDN_rule",1,0,0,0,0                                                    
+QMAP: "MPDN_rule",2,0,0,0,0                                                    
+QMAP: "MPDN_rule",3,0,0,0,0         

OK                                                                         
at+qmap="wwan"                                                                  
+QMAP: "WWAN",0,1,"IPV4","0.0.0.0"                                              
+QMAP: "WWAN",0,1,"IPV6","0:0:0:0:0:0:0:0"                                      
                                                                                
OK                                                                              
                                                                     
at+qmap="lanip"                                                                 
+QMAP: "LANIP",192.168.225.20,192.168.225.100,192.168.225.1                     
                                                                                
OK

at+qmap="wwan"                                                                  
+QMAP: "WWAN",0,1,"IPV4","0.0.0.0"                                              
+QMAP: "WWAN",0,1,"IPV6","0:0:0:0:0:0:0:0"                                      
                                                                                
OK                                                                              
 
at+qmap="mpdn_rule",0,1,0,1,1
ERROR
                                                                                                                         
at+qmap="mpdn_rule",0,1,0,0,1                                                   
OK                                                                              
at+qmap="mpdn_rule"                                                             
+QMAP: "MPDN_rule",0,1,0,0,1                                                    
+QMAP: "MPDN_rule",1,0,0,0,0                                                    
+QMAP: "MPDN_rule",2,0,0,0,0                                                    
+QMAP: "MPDN_rule",3,0,0,0,0                                                    
                                                                                
OK                                                                              
at+qmap="wwan"                                                                  
+QMAP: "WWAN",1,1,"IPV4","162.191.XXX.YYY"                                       
+QMAP: "WWAN",0,1,"IPV6","0:0:0:0:0:0:0:0"

Any ideas on how to revert the RM520N back to IPPT (IP Passthrough) mode to bridge its WWAN to its LAN interfaces?

Thank you.

2

Dear @sirozha
I have sent the description of AT+QMAP to you via Message, please check.
It seems there are some misunderstanding for this command, please double confirm.

3

Hi, thanks for the response. I used that very manual to find the QMAP command that I described in my post to put the RM520N to NAT mode. I can’t return it back to IPPT mode.

Where is the misunderstanding? Can you help me with returning the RM520N back to IPPT mode on that would pass the IP address from the WWAN interface to the Ethernet interface of the RM520N?

4

The solution is to use the following command:

at+qmap=“mpdn_rule”,0,1,0,1,1,“FF:FF:FF:FF:FF:FF”

If “FF:FF:FF:FF:FF:FF” is used, then the first connected host’s Ethernet interface MAC address will be used to bridge the WWAN interface to, so only the first connected host’s Ethernet interface will be able to get the IP addressed leased to the 5G modem by the cellular carrier. No other network interfaces can receive the DHCP lease bridged from the WWAN interface to the Ethernet interface by the 5G modem until the modem is restarted.

or

at+qmap=“mpdn_rule”,0,1,0,1,1,“A1:B2:C3:D4:E5:F6”

where A1:B2:C3:D4:E5:F6 is the MAC address of the connected Ethernet interface. In this case, only the host with the specified Ethernet interface MAC address will be able to get the IP addressed leased to the 5G modem by the cellular carrier. This setting survives the 5G modem restart, so only the host with the specified MAC address can get a DHCP lease from the 5G modem with the IP information that the 5G modem gets from the carrier.

5

In regard to QMAPs IP Passthrough Mode: Is this mode actually a passthrough mode (where connection ends at the modem and there is still a double NAT in reality) or is it a true bridge mode?

6

It’s a real bridge mode.

1 Like
7

are you able to revert back with IP passthrough?

I have same issues now. and having double NAT :frowning:

8

Hello, please can you send me information on the at+qmap command, and any related commands for managing IP addresses, DHCP and similar?

Many thanks!