Which setting must be enabled in a spoke IPsec phase 1 configuration to participate in ADVPN?

In a spoke IPsec phase 1 configuration intended to participate in an advanced dynamic VPN (ADVPN) setup, it is essential to enable the auto-discovery-sender setting. This configuration allows the spoke devices to automatically discover the other spoke peers in the network. Essentially, when this feature is enabled, the spokes register their presence and capabilities to a central hub or to each other, facilitating the formation of direct dynamic tunnels between spokes without requiring extensive manual configuration of each endpoint or static IP addressing.

This capability is crucial for enhancing scalability and efficiency in VPN deployments, enabling spoke devices to establish direct connections to one another as needed, rather than routing all traffic through the hub. The automatic discovery and connection mechanism is a foundational aspect of ADVPN, which significantly optimizes bandwidth and reduces latency by allowing direct communications.

Other settings like peer-to-peer connection may refer to specific types of connections, IPsec passthrough pertains to allowing encrypted traffic through non-IPsec-aware firewalls, and dynamic routing involves routing protocols that help in the exchange of routing information. While all these elements contribute to overall network function, it is the auto-discovery-sender specifically that enables the dynamic and scalable nature of the ADVPN architecture in spoke configurations.