I am looking for some advice on how to properly setup a site to site VPN when there's overlapping subnets.
i.e. if you have 172.16.x.x on both sides of the tunnel.
I have set this up before and here's my config but I'm not sure if this is the best way to do it.
access-list outboundpolicy_NAT extended permit ip 172.31.21.0 255.255.255.128 19
static (outside,inside) 192.168.0.0 172.16.0.0 netmask 255.255.248.0
static (inside,outside) 192.168.0.0 access-list outboundpolicy_NAT
On the VPN tunnel, I configured this ACL:
access-list tac-VPN-domain extended permit ip 192.168.0.0 255.255.248.0 172.16.0.0 255.255.248.0