PPTP and GRE Tunneling Through NAT

You can configure NAT traversal support for GRE flows using simple translations (Basic NAT). Because PPTP uses an enhanced GRE encapsulation for the PPP payload, configuring for GRE flows also supports NAT traversal for PPTP tunnels.

Note: Network Address Port Translation (NAPT) for GRE packets is not supported for GRE flows.

When configured, the following types of translations are supported for GRE and PPTP tunnels: