HP-UX Mobile IPv4 A.03.01 Administrator's Guide

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Chapter 1
7
Direct Delivery Style
Figure 1-4 shows the data path and a high-level representation of the IP packet
structure and addresses for Direct Delivery Style. With the Direct Delivery Style, the
Mobile Node node sends the packet without encapsulation, with its home address as the
source and the Correspondent Node’s address as the destination (a). The Foreign Agent
intercepts the packet and encapsulates it in a new packet with the Care-of Address (one
of its own addresses) as the source address and the Home Agent’s address as the
destination (b). When the Home Agent receives this packet, it de-capsulates the packet
and sends the original packet to the Correspondent Node (c).
Figure 1-4 Return Data Path for Reverse Tunnelling with Direct Delivery Style
Encapsulating Delivery Style
With the Encapsulating Delivery Style, the Mobile Node encapsulates the original
packet in a packet addressed to the Foreign Agent, as shown in Figure 1-5,(a). The
Foreign Agent decapsulates the packet, then re-encapsulates it in a new packet with the
Care-of Address as the source address and the Home Agent’s address as the destination
(b). When the Home Agent receives this packet, it de-capsulates the packet and sends
the original packet to the Correspondent Node (c).
The Encapsulating Delivery Style is useful in topologies where a Mobile Node needs to
send broadcast or subnet broadcast messages back to its home network.
Figure 1-5 Return Data Path for Reverse Tunneling with Encapsulating Delivery
Style