When might tunnel negotiation errors occur in a Site-to-Site VPN configuration?

Tunnel negotiation errors in a Site-to-Site VPN configuration can often arise when there is a mismatch between the Local Network and the Destination Network. In this context, the Local Network is defined by the configuration on one end of the VPN, while the Destination Network is defined on the other end. If the settings do not correspond correctly, the VPN devices may fail to establish a secure tunnel because they cannot properly identify the traffic intended for the other network. This mismatch can lead to issues such as packets being dropped or sessions failing to initiate altogether, as the tunnel negotiation relies on both ends recognizing the correct IP ranges to facilitate communication.

Having aligned networks is crucial for a successful VPN setup, as they need to know how to route the traffic securely. Therefore, ensuring that the Local Network and Destination Network configurations match is essential for seamless communication and tunnel negotiation.