Smart Radio LTE Failover: Device Configuration

Smart Radio LTE Failover: Device Configuration

Device Configuration

In our example, we assume that we have PC 1 connected to Smart Radio 1 at ETH0, and Smart Radio 1 is connected to LTE Modem 1 from ETH1. Likewise, PC 2 is connected to Smart Radio 2 at ETH0 and Smart Radio 2 is connected to LTE Modem 2 from ETH1. The steps below need to be repeated for all LTE Modems and Smart Radios.

 

LTE Modem

LTE Modem configuration varies from device to device and so we will not go into any detail. Most importantly, it will be necessary to forward ports for WireGuard and L2TP through the modem. We set WireGuard’s default network port to 5000, and L2TP uses port 1701.

Our LTE Modem 1 has been assigned the IP address 10.124.16.3 and LTE Modem 2 has been assigned the IP address 10.124.16.2. Each LTE Modem will also create a local network (LAN) and perform NAT from the LAN to the WAN(LTE). In our case, we used the subnet 192.168.8.0/24. To avoid confusion, we assigned LTE Modem 1 with LAN IP address 192.168.8.1 and LTE Modem 2 with LAN IP address 192.168.8.2. DHCP was also disabled for simplicity.

 

Smart Radio Configuration

Setup

The Smart Radio LTE Failover license has a wizard for automatic setup.  In order to run the wizard, first SSH into the radio.

user@host-pc:~$ ssh root@<IP ADDRESS>

After logging in, run the Smart Radio LTE Failover wizard.

root@smartradio:~# dl-lte-wizard

The wizard will prompt the user with several questions including

1.      Encryption key generation and sharing

2.      The IP address settings of the local connection to the LTE modem.

3.      The IP address of the VPN interface. You will need to choose an IP address for the local VPN interface, and also input the IP address of the remote VPN interface.

The wizard will then reconfigure the Mesh Rider networking stack and the settings.

Verification

At this point, the setup is complete. To confirm that the failover link is active, check Mesh Rider’s list of originatory nodes. This will only work once both nodes are setup.

root@smartradio-301a4ebb10:~# batctl o
[B.A.T.M.A.N. adv 2021.0-openwrt-1, MainIF/MAC: l2tp0/1a:04:32:ac:26:53 (bat0/4a:9b:e6:37:f9:87 BATMAN_V)]
   Originator        last-seen ( throughput)  Nexthop           [outgoingIF]
 * ea:ab:88:d0:05:c2    0.030s (       41.0)  00:30:1a:4e:bb:09 [     wlan0]
   ea:ab:88:d0:05:c2    0.030s (        4.0)  ea:ab:88:d0:05:c2 [     l2tp0]

Instead of just one path to the destination, there are now two paths. The preferred path has a star (*) next to it, and in this case it is the Mesh Rider link which has an estimated throughput of 41 Mbps. The LTE link is the failover path, but if the throughput of the Mesh Rider link were to go below 3 Mbps, the LTE link would become the preferred path.   

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