On 6 Jun 2011, at 13:48, Adrian Kägi wrote: Not necessarily. IMHO it's the same encapsulation (type 41, which has to be allowed by the firewall) but the addressing is another story. 6rd is an extension to 6to4 with the notable difference of not having a publicly available anycast relay out there (controlled by any random entity). The relay is operated by the ISP instead. Have a look at my IOS config for this (the relevant bits, firewall config and crypto maps removed): ipv6 general-prefix 6RD-SWISSCOM 6rd Tunnel6 interface Tunnel6 description Swisscom 6rd Tunnel no ip address no ip redirects ipv6 enable ipv6 mtu 1480 tunnel source Vlan2 tunnel mode ipv6ip 6rd tunnel 6rd prefix 2A02:1200::/28 tunnel 6rd br 164.128.155.23 ! interface Vlan1 ip address 192.168.23.1 255.255.255.0 ip nat inside ip virtual-reassembly in ipv6 address 6RD-SWISSCOM ::1:0:0:0:1/64 ipv6 enable ! ipv6 route ::/0 Tunnel6 2A02:120A:4809:B170:: The BR's address is subject to change, I think. Vlan2 is the interface facing Swisscom. I've got large part of the config from here: http://labs.swisscom.ch/en/news/ipv6-sneak-preview Cheers! - Mathias Mathias Seiler MiroNet GmbH, Strassburgerallee 86, CH-4055 Basel T +41 61 201 30 90, F +41 61 201 30 99 mathias.seiler(a)mironet.ch www.mironet.ch