Question

Hi,

I have two 5G sim cards with unlimited data plans.

My requirements are;

• Switch based on "no network" or "network denied"
  • I have enabled "Enable automatic switching" on both sim cards under sim switch
• I noticed on sim switch on "data connection failed" using ICMP constant switching between the two providers whilst one network was stable as opposed to the other
• I noticed on sim switch on "weak signal" constant switching between the two providers
  • I may have set the thresholds incorrectly not sure what is optimum or a medium values should be!?
• Should I also use Network>Failover>with the default rule for 0/0 also!?
  • Do the two conflict Sim Switch & Failover or I should use one only!?
• Also can the RUTX50 do some kind of latency/packet loss failover on data or is this feature to be introduced in the future?
  • Maybe the signal should catch this at lower layers of the Network OSI model?
  • My fear here is that the failback option in Sim Switch would failback to a worse performance network/sim card?
• If I don't use Network>Failover does that mean I can use Network>Load Balancing
  • As there is a single modem maybe the answer is no?
• Under Network>General>Low Signal Reconnect what does this do?

I have attached a picture of the signal from one of the providers which is currently active.

Comments

...............

---

I added the tar file now.

---

Please ignore the previous since I am lost in the amount of confusing failure scenarios I am getting and I'm losing track, I am trying to configure the best failover policy currently.

I wanted to ask on the following:

Performs a SIM switch when mobile data connection fails. Possible failure determination methods are:

• LCP echo
• ICMP echo

If no echo is received, the data connection is considered to be down.

How many ICMP pings does this test send? I have the default timeout for the ping as 3 secs is that 3secs x5 pings or x1 ping?

---

Hello,

  

ICMP echo sends 3 ping packets with the default timeout of 3 seconds.

This can be verified by monitoring the outgoing packets by connecting to the CLI, and running this command:

tcpdump -i qmimux0 icmp -Q out

Every few seconds you should see 3 requests being made to the specified host.

  

Best regards,
DaumantasG

Answer 1

Hello,

    

Since RUTX50 only has a single modem, neither Failover nor Load Balancing can be used between both the SIMs.

In this case, you will need to use SIM Switch. As for the weak signal threshold, there are no "correct" values, and it's basically a guessing game. Since you are connected to LTE B28, this band is used for covering wide areas, so I'd say a weak signal for this band could be -80. But for bands B1 and B3, this value could be much lower.

I noticed on sim switch on "data connection failed" using ICMP constant switching between the two providers whilst one network was stable as opposed to the other

Could you try pinging the specified address on the carrier that keeps failing by navigating to System → Administration → Troubleshoot and scrolling down to the page. This will let us know where the issue could be. Also, make sure the timeout is set high enough.

Should I also use Network>Failover>with the default rule for 0/0 also!? Do the two conflict Sim Switch & Failover or I should use one only!?

SIM Switch should be used. Failover or Load Balancing can also be utilized if you also have wired WAN.

 Also can the RUTX50 do some kind of latency/packet loss failover on data or is this feature to be introduced in the future?

On data connection fail parameter basically checks the same thing. If ping packets are lost, the SIM Switch is initiated.

Under Network>General>Low Signal Reconnect what does this do?

This option reboots the modem in case a very bad signal is detected, in hopes that the modem will connect to a different cell or mitigate other issues.

Let me know if you have any additional questions!

  

Best regards,
DaumantasG 

Comments

so another strange thing happened today logs correspond like this.

LAN2 port unplugged (which connects to wifi router providing the LAN users wifi)

The Teltonika detects this and causes the box to freeze almost and stop the VPN traffic into it thus I could not manage it, logs per below;

566	2023-06-11 21:56:03	Network Operator	Connected to operator (internal modem)
565	2023-06-11 21:56:03	Network Type	Joined network (internal modem)
564	2023-06-11 21:56:03	Mobile Data	Mobile data connected (internal modem)
553	2023-06-11 21:34:35	Switch Events	Port link state of port LAN2 changed to DOWN

Event @ 21:34 caused the zerotier interface to also not respond but seems also locked the modem up, it didn't attempt to switch sims with the sim switch policy in place etc etc - just smacks of buggy teltonika code!!

---

Hello,

  

Without having a troubleshoot file from the device after the issue occurs, there is not much I can comment on here, as only the logs might lead in the right direction.

If the device freezes constantly, in the same troubleshoot menu set the option "Save logs in" to Flash memory, then replicate the issue, if the device freezes it can be restarted, and after booting back up generate the troubleshoot file.

  

Best regards,
DaumantasG

---

not sure how to attach the troubleshoot tar !?

can you comment on why the email notification doesn't send on sim switch i gave the details above...

---

Hello,

I cannot comment on either of the issues without looking over the troubleshoot file. It can be attached by editing your original question and will only be visible to Teltonika moderators.

Best regards,
DaumantasG

---

Nothing seems to be visible from the troubleshoot file. Could you clarify which port you used on the RUTX50 and which on the third-party router (WAN / LAN)?

Your signal also seems very good, please regenerate the file with a poor signal, where the SIM switch rule should trigger (but doesn't).