IPsec Protocol: https://www.juniper.net/documentation/en_US/junos/topics/reference/general/ipsec-protocols-solutions.html
IPsec VPN Technologies and Solutions ( Video training)
https://juniper.csod.com/LMS/Video/LaunchVideo.aspx?loid=d7804270-0221-4b75-a8b8-7a65e26933e6
SRX & J Series Site-to-Site VPN Configuration Generator: https://www.juniper.net/support/tools/vpnconfig/#localSite
AutoVPN Feature Guide ( multi-remote site): https://www.juniper.net/documentation/en_US/junos12.1x46/information-products/pathway-pages/security/security-vpn-autovpn.html#configuration
Dynamic VPN (Remote access VPN or IPsec VPN client) : https://www.juniper.net/documentation/en_US/junos12.1x46/information-products/pathway-pages/security/security-vpn-dynamic.html#overview
Phase 1: AGGRESSIVE Mode Vs Main Mode:
Aggressive mode
takes part in fewer packet exchanged = is faster than Main mode.
does not give identity protection of the two IKE peers, unless digital certificates are used. This means VPN peers exchange their identities without encryption (clear text)