Hello Anssi On 03.06.11 13:32, Anssi Johansson wrote:
What do you think of adding NTP servers whose IPv6 connection is over 6to4 or some other tunneling method? I believe those should not be used in the pool as the connection to them may be unreliable and asymmetric. In any case, I also added my 6to4 home server at 2002:52b5:8c2b::e to the beta site, it might be interesting to see how it compares to the native IPv6 servers.
If two different systems/networks are using 6to4, then they will have a direct 6to4 tunnel between the two IPv4 addresses of each gateway.
I do not know if the DNS of the pool can do such magic, but if the lookup is coming from an 2002: IPv6 IP address, then it could eventually be a good idea to give back a server with also an 2002: IP address.
The second (WWXX) and third (YYZZ) part of the IPv6 6to4 IP address (2002:WWXX:YYZZ:) is the hexadecimal notation of the public IPv4 address (www.xxx.yyy.zzz) of the local 6to4 gateway. I guess this would help if any database with IPv4 location is used to find a near NTP server.
I do not know if the effort is worth, as 6to4 on the client side only makes sense with static IPv4 address, else the whole internal IPv6 networks needs to be adjusted every time the IPv4 address changes.
Probably it is just fine to give any near IPv6 address back to a 6to4 client. With 6to4 all traffic to the "real" IPv6 Internet is going to a gateway at the special anycast IPv4 address 192.88.99.1, which most often is quite local to the IPv4 address of the client 6to4 gateway.
A nice graphic and more details about 6to4 are in the Wikipedia article [1].
[1] http://en.wikipedia.org/wiki/6to4 bye Fabian _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
