Site to Site VPN binding

Question

I have a pair of UTM 9 formed a S2SVPN, i saw the predecessor formed a vpn with declaring local network and remote network, 
 and Site-to-Site VPN tunnel status shows local network X remote network = total established connections....... 
 this seems be so burdensome.... 
 if i have 10 network in local, and 10 network in remote, there must be 100 connection between that 
 Can i just make a tunnel and let all the traffic through ?? with a static route???

apijnappels · Answer

This is the way that site2site IPSEC VPNs work with multiple security associations (SAs) between each and every subnet. 
 If you want to limit those, you need to summarize the subnets you use inside the tunnel (if that's possible and doesn't create routing issues).