I am having issues with tunnels flapping across sites on our network, our network is airgapped and we use the customer's already in place network as our backbone to communicate across sites. I have combed left and right through everything I can think of and cannot locate any issues with how our network is setup. I have had the engineers who setup our network look over everything and verify it's good.
Is there a way I can prove that the issue is on their devices / network infrastructure causing these issues?
Note: I do not have access to their network and cannot check any devices, I have to rely on their technicians to tell me if something is messed up, and we are locked in the endless battle of "It's not me, it's you!"
The hello / hold time for these tunnels on our side is 1/3.
We know very little about what is going on here. We are told that there are tunnels. But what kind of tunnels? Is it standard GRE? Is it GRE with IPSec? Is it an IPSec tunnel? Is it a VTI tunnel? Any detail you can provide may help us to better understand the issue.
We are told that there is flapping. Is it tunnel interfaces flapping? Is it EIGRP neighbor relationship flapping? Any detail you can provide may help us to better understand the issue.