Dfrandin:
No no no no no, Cogent DOES peer with other networks, just more selectively, and in some cases requires others pay them to access their chunk of the internet (paid peering, transit, etc). HE openly peers with anyone that wants to (open peering policy versus selective), or sells transit (no paid peering product). Your provider pays Cogent to access the internet as their transit provider.
Sixxs doesn't actually operate a network, they deploy POPs into other network operators' locations and utilize their connectivity.
evantkh:
I already explained why IPv6 packets can't be routed between HE and Cogent: neither HE or Cogent PAY another network to deliver IPv6 traffic to other networks (transit). And you see those partial Cogent routes because some Cogent customers got an LOA (letter of authorization) issued from Cogent, to re-announce that IPv6 space to other BGP networks; like HE, NTT, etc. You need a better basic understanding of both how BGP works, as well as the overall internet design. The IPv4 example shows exactly how both transit and peering work. Your provider buys transit from their upstream ASN, who then in turn peers off that traffic to the destination either for free or paid (you'll never know).