Today i discovered that my ISP cut off my internet, but still allowed ICMP traffic.
This confused my ping based failover script as it wasn't failing over despite there not being any real internet service.
Is there any alternative way for testing internet service other than ping?
Like try to download a webpage and check the result.
I haven't used ICMP for any kind of failover for years due to that reason and the somewhat common filtering of packets that many ISP's are doing. I use tunnels between 2 colo data center locations and the routers I wish to monitor. if both tunnels fails then we have an outage. The colo side send me alerts if they go down and the router side can take action from scripting to change gateway.