Failover, link monitor, and SD-WAN
This is my first time working with multiple ISPs on a Firebox. I have a client with Spectrum Cable as their primary ISP, AT&T Fiber for secondary, and AT&T LTE wireless backup for tertiary connection. I have their T35 running 12.5.7 U3 doing Multi-WAN failover in the order above, along with Link Monitor and SD-WAN.
Link Monitor is monitoring all the connections just so I can see how loss, latency, and jitter compare (so far, it's AT&T Fiber, AT&T LTE, then Spectrum for quality). I just asked my AT&T provider if it is OK to keep monitoring the LTE or if that will somehow incur extra charges for uptime or data usage. That made me wonder if I am doing this correctly.
Assuming that monitoring the LTE would incur extra charges, I can turn off Link Monitor on the LTE and still have it as an SD-WAN action, BUT I don't know what the outcome of that would be or if it is needed.
For failover to happen, do I need either Link Monitor or SD-WAN active? Without LM or SD-WAN on the LTE connection, if Spectrum and AT&T Fiber go down, I just want it to fail over to the LTE, then fail back to Spectrum and AT&T when they come up again.
Thank you for your help!