Hello Lind, In section 5.7, Figure 7 shows that all of network elements except "Exchange" are converted into "Dual", but the Exchange is still remained as "IPv4 + IPv6". Does it have any specific meaning? Some IXs seemed to be dual stack already. regards, -- SHIRASAKI Yasuhiro @ NTT Communications t: +81-3-6800-3262, f: +81-3-5365-2990