On 2023-06-19 14:50, Dave Hart wrote:
On Friday, June 9, 2023 at 7:10:13 AM UTC, Roger wrote:
On Thu, 08 Jun 2023 15:05:42 +0100, Roger <inv...@invalid.invalid>
wrote:
Does ntp-4.2.8p16 have the voting code in it which
ntp-dev-3792-msm and ntp-dev-3792-msm-v2 has? Dave Hart recently
posted links to tarballs with a request for feedback?
Please ignore; I've just spotted that p17 has been released.
I'm sorry I didn't notice this earlier. Neither one has the 3792
pool preemption changes. There's still a bit of work needed to
prevent continuous turnover in some relatively pathological cases,
and likely a bit more work to eventually cycle out even surviving
servers very slowly to allow servers that withdraw from a pool to
eventually stop receiving queries from updated clients.
Dave Hart
For the latter, maybe talk to the pool guys to find or create a DNS way
to check if a previously chosen pool server is still listed?
Such a mechanism could be polled every 8 * maxpoll seconds, so with a
1024s maxpoll that will be about every 2h16m (note: maxpoll, not current
poll). As always DNS, keysetup and other non-sync activities should be
kept out of the timing loops. One scheme could be to check
base32(crc32(IP)).pooldomain, like abc9xyz.1.de.pool.ntp.org will return
the IP if still in the pool for clients asking for 1.de.pool.ntp.org,
client code is needs to check all returned IPs for equality with their
current choice, as hash clashes are explicitly permitted. The crc32
would be calculated over the binary IP (4 or 16 bytes). Base32 is the
RFC4648/RFC3548 Base32 with padding omitted.
Another option would be a KOD message from the retracted server, but
that might not work across NTP protocol implementations and could also
conflict with a desire to keep serving some roaming users or a smaller
part of the pool client population (such as removing
badvendor.pool.ntp.org,, or limiting to payingvendor.pool.ntp.org),
in contrast the above proposal is easily implemented by a parallel
thread or process using a fairly trivial call sequence much easier
than the usual NTP algorithms.
Enjoy
Jakob
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Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
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