IPv6 Wow

Thu Oct 23 22:39:42 UTC 2008

Nathan Ward wrote:
...
> 2) If Teredo relays are deployed close to the service (ie. content,
> etc.) then performance is almost equivalent to IPv4. 6to4 relies on
> relays being close to both the client and the server, which requires
> end users' ISPs to build at least *some* IPv6 infrastructure, maintain
> transit, etc. When you consider that this infrastructure and transit
> is quite likely to be over long tunnels to weird parts of the world,
> this is a bad thing. Putting relays close to the content helps for the
> reverse path (ie. content -> client), however the forward path (client
> -> content) is likely to perform poorly.

Not quite correct. 6to4 does not require transiting a relay if the target is
another 6to4 site. What this means is that a clueful content provider will
put up a 6to4 router alongside whatever native service they provide, then
populate the dns with both the native and 6to4 address. A properly
implemented client will do the longest prefix match against that set, so a
6to4 client will go directly to the content provider's 6to4 router, while a
native client will take the direct path. The only time an anycast relay
needs to be used is when the server is native-only and the client is
6to4-only. 

Tony