If the ‘Home Agent’ flag is cleared in a binding cache entry, or the packet was not received from a forwarding context, then an IPv6 routing header is used to redirect the IPv6 packet through the relevant care-of address, as shown in Figure 10-2.

As can be seen from Table 10-3, the use of the IPv6 routing header reduces the effective bandwidth required for the encapsulation of the packet in comparison to IPv6 in IPv6 tunnelling by 16 bytes. This reduction in packet size is possible due to spatial redundancy - i.e. if IPv6 tunnelling were used then the IPv6 source address of both the inner and outer IPv6 headers would be identical, resulting in a waste of bandwidth.