Splitting IPsec Frames
A NIC can split IPsec frames at the beginning of the upper-layer-protocol header, the beginning of the TCP payload, or the beginning of the UDP payload. The NIC should treat the IPsec information the same as an IPv4 option or IPv6 extension header.
The NIC might not be able to split the frame if the resulting header buffer has a greater length than the maximum header size. For more information about the maximum header size, see Allocating the Header Buffer.