How to Configure Site-to-Site IPSec VPN on Routers

This is a lab using six routers to build a network. R3 in the middle represents the ISP, and R2 represents the company headquarters, connecting the ISP and the internal LAN.

R1 acts as a PC host inside the company. The purpose of this lab is to complete the configuration and verification process for a Site-to-Site IPsec VPN. Below is the topology diagram: