The router has VPN pass-through but not multi-tunneling capabilities. I've tried to explain that his VPN pass-through is not capable of establishing multiple VPN tunnels for 20 users to connect to simultaneously.
Can you explain this for me?
Not all products handle IPsec the same way and that is the case with pass-through. Devices that support pass-through break the NAT traversal and usually are limited to only one host behind the firewall.
Multi-tunneling allows the system to discriminate and forward traffic based on destination. Devices that support multi-tunneling can connect VPN users and sort each of them into their own establishment tunnel.
This was first published in October 2008