IPsec Packet Flow
Figure 19-1 shows how an IP addressed packet, as part of an IP datagram, proceeds
when IPsec has been invoked on an outbound packet. The flow diagram illustrates
where authentication header (AH) and encapsulating security payload (ESP) entities can be applied
to the packet. How to apply these entities, as well as how to
choose the algorithms, are described in subsequent sections.
Figure 19-2 shows the IPsec inbound process.
Figure 19-1 IPsec Applied to Outbound Packet Process
Figure 19-2 IPsec Applied to Inbound Packet Process