Hello,
It's better not to "simplify" scenarios during troubleshooting like this because details like these may change the whole story completely.
Initially, assuming that all you did was to flap the
Tunnel interface
and did not perform further config changes, I suspected the NHRP registration interval to have collided in an unfortunate way with the ISP outage. Since it is 200 seconds by default, if the registration fails, it will take up to 200 seconds for the router to register to the hub again. That could have explained it if the registration fell into the 4-minute outage of the ISP (and if
Gi1/0
didn't go down which I only learned when you shared the logs). Very importantly, if the
Tunnel2
came up just by flapping it but keeping
Gi1/0
as the source interface, it would have confirmed that the internet connectivity through
Gi1/0
worked after the ISP came back.
However, you have changed the source interface and only then flapped the Tunnel interface. This means that we can not assume anything about the apparently restored connectivity through the ISP on
Gi1/0
For what it is worth, just because
Gi1/0
came back up does not mean that the internet was actually reachable through it.
So based on the fact that the
Tunnel2
became operable after you changed the source interface opens a whole set of questions on how the connectivity was restored, if at all, through
Gi1/0
It is not possible to say with certainty whether the problem was NHRP or the connectivity through
Gi1/0
I suspect for now that when
Gi1/0
came up, it still did not provide connectivity through that ISP to internet. Why would that be the case - that's something I can't say without seeing the full
show logging and full show running-config
because there are too many unknowns, and we cannot afford assuming.
All depends now on whether it is possible to share the following full outputs (no line may be removed, only sensitive data replaced with safe placeholders):
- show logging
- show running-config
- show ip interface brief
- show ip protocols
- show ip route
- show ip route vrf *
- show ip arp
The reason I am asking for this information is that I need to understand what is the momentary runtime state of this router, whether it appears to have at least a local connectivity to the ISP, and how is the routing set up on it. Changing the source interface on
Tun2
would have changed the source IP but not the outgoing interface itself - the outgoing interface is still determined by the routing table based on the destination IP address of the packet, not by the
tunnel source
command.
If those outputs cannot be shared, I'm afraid this is as far as we can get.
Best regards,
Peter
