Discuss the advantages and disadvantages of constructing IPv6 addresses directly from IPv4 addresses by adding the 32 bits of the IPv4 address to the network prefix 2002/16, along with an IPv6 site-level address and the interface ID, so the resulting IPv6 address takes form 2002:IPv4address:SLA:Interface ID/16.  Here, the interface ID remains set at the 48 bits normal for IPv4 MAC layer addresses, and the site-level address remains set at its normal 16-bit level for IPv6.  What does this do from the perspective of ease of implementation?  What does it do to IPv6 routing behavior?