If the Home Agent flag is set in a binding cache entry, then the node maintaining that cache is acting as a Home Agent for the Mobile Node. If this is the case, and the packet was entered through a forwarding context, then the packet is encapsulated using IPv6 in IPv6 tunnelling, as illustrated in the following table.

IPv6 tunnelling is used by Home Agents to forward IPv6 packets routed to a Mobile Node’s home network while it is away from home, as illustrated in Figure 10-1. Tunnelling has the advantage of preserving the complete original IPv6 packet, which is important as any modification to an IPv6 header could cause problems with higher layer protocols, such as TCP. Intercepted packets are tunnelled directly to a Mobile Node’s current care-of address, where they are subsequently decapsulated by the Mobile Node.