Ronan Flood wrote:
> At my workplace we're slipping in IPv6 on our NTP servers, and I've
> been watching the traffic and checking out the clients which pop up,
> to see if they hit any problems when unintentionally using IPv6
> instead of IPv4.
>
> Native-IPv6 and 6to4-tunnel clients seem OK, but I've found one client
> using a Teredo tunnel (RFC 4380), and it looks like that is something
> to be avoided:
>
> remote refid st t when poll reach delay offset jitter
> ---------------------------------------------------------------------
> +2001:630:1:101: .GPS. 1 u 621 1024 177 350.111 115.061 2.000
> -2001:630:1:102: .MSF. 1 u 617 1024 177 355.528 114.905 0.734
> -2001:630:1:103: .PPS. 1 u 631 1024 177 575.602 222.278 0.056
> +195.66.241.3 .PPS. 1 u 524 1024 377 22.724 -15.799 0.788
> *195.66.241.10 .IRIG. 1 u 753 1024 377 27.490 -15.864 0.775
> 127.127.1.0 .LOCL. 13 l 28 64 377 0.000 0.000 0.002
>
> Being a UK client, using a Teredo server on the west coast of the US
> probably doesn't help, but it could also be inherent latency in Teredo.
>

You might ask why they have configured their NTP server to go to the
west coast of the US in the first place, irrespective of Teredo since
network wise it a much longer distance than say some other location in
London.

All tunnels will have additional delays being Teredo, VPN or something else.

> "server -4" would be wise here :-/
>

Only if the really need to go distances like this.

Danny

On Mon, 18 Feb 2008 02:59:58 GMT, mayer@ntp.isc.org (Danny Mayer) wrote:

> > Being a UK client, using a Teredo server on the west coast of the US
> > probably doesn't help, but it could also be inherent latency in Teredo.
>
> You might ask why they have configured their NTP server to go to the
> west coast of the US in the first place, irrespective of Teredo since
> network wise it a much longer distance than say some other location in
> London.

The NTP servers are in the UK. As for the Teredo server, that's
teredo.ipv6.microsoft.com, which I'd guess is the most well known
owing to its use in Windows Vista et al.

--
Ronan Flood

Ronan Flood wrote:
> On Mon, 18 Feb 2008 02:59:58 GMT, mayer@ntp.isc.org (Danny Mayer) wrote:
>
>>> Being a UK client, using a Teredo server on the west coast of the US
>>> probably doesn't help, but it could also be inherent latency in Teredo.
>> You might ask why they have configured their NTP server to go to the
>> west coast of the US in the first place, irrespective of Teredo since
>> network wise it a much longer distance than say some other location in
>> London.
>
> The NTP servers are in the UK. As for the Teredo server, that's
> teredo.ipv6.microsoft.com, which I'd guess is the most well known
> owing to its use in Windows Vista et al.
>

I just knew you were going to tell me that! Can you set a local/domain
policy not to use that Teredo server? There is a registry setting to
turn this off in Vista:
netsh interface ipv6 isatap set state state=disabled


Search for isatap in the KB.

Danny

On Sat, 23 Feb 2008 03:36:23 GMT, mayer@ntp.isc.org (Danny Mayer) wrote:

> > teredo.ipv6.microsoft.com, which I'd guess is the most well known
> > owing to its use in Windows Vista et al.
>
> I just knew you were going to tell me that! Can you set a local/domain
> policy not to use that Teredo server? There is a registry setting to
> turn this off in Vista:
> netsh interface ipv6 isatap set state state=disabled

Useful to know (for everyone but not applicable to this particular
case as the client is not under local policy, and was in any case IIRC
running Linux. Presumably the admin chose the MS server as it is likely
to stay around and keep working.

--
Ronan Flood