The packet format of GRE with IPsec transport mode follows RFC 4303, IP Encapsulating Security Payload (ESP), Section 3.1.1. The following example shows an IPv4 GRE packet with IPsec transport mode enabled:
Figure: IPv4 GRE packet with IPsec transport mode enabled
The following example shows an IPv6 GRE packet with IPsec transport mode enabled:
Figure: IPv6 GRE packet with IPsec transport mode enabled
