Chapter 10 IPsec VPN : Phase 2 parameters : Advanced Phase 2 settings : Using the add-route option
  
Using the add-route option
Consider using the add-route option to add a route to a peer destination selector. Phase 2 includes the option of allowing the add-route to automatically match the settings in Phase 1. For more information, refer to “Dynamic IPsec route control”.
Syntax
Phase 2
config vpn ipsec {phase2 | phase2-interface}
edit <name>
set add-route {phase1 | enable | disable}
end
end