According to CAIDA,
In comparison with the IPv4 AS graph, the IPv6 AS graph is much sparser with drastically fewer nodes and less richness of peering observed. The geographical patterns of the graphs also differ. While the majority of ISPs with the highest outdegrees in IPv4 space are all located in the U.S., the company with the richest observed IPv6 peering is NTT/Verio headquartered in Japan, with 141 peers. The largest cluster of high degree IPv6 AS nodes is in Europe (clustered around Tiscali which is headquartered in Germany) in the graph.
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