Short: No, the space is delegated to your endsite and not to somebody else. Long: Primary reason is that you should not be 'reselling' this free space already donated by the ISP's in question. Ofcourse if you have a geographic neighbour and you delegate a couple of /64's into his house that won't bother us. As long as it's the same L2 path that is. But if you start you own tunnelbroker kind of system we will ofcourse be offended and you will be removed the very moment. Thus you should not start your own tunnelbroker from delegated IPv6 prefixes. Secondly an endsite should receive a /48 per minimum. A link receives a /64. So if you follow the rules you can't even do it. If these users want a tunnel, why don't you show them SixXS in the first place. Note that SixXS is ISP and country neutral and you can always try to persuade your ISP to start doing IPv6 which is one of the things you should be doing already. SixXS is the pie with the whipcream to make your appetite grow for native IPv6, so go mail your upstream ISP and let them provide you with IPv6. Ofcourse you can also notify them of the fact that we can setup a POP at your ISP allowing you to have better connectivity and a jumpstart into IPv6. oh and before you ask, the IPng POP is 'older' than these rules so it can be excluded because of that ;)