Joseph B wrote:
I know Matt mentioned the 3G angle, and it looks like a mobile only operator is a large source of requests, however I was under the impression that phone handsets didn't use NTP for time sync, the various GSM/3G protocols have their own time sync built in.
My experience locally is that this almost never works. It appears it was not in the initial GSM standard and later added by different base station manufacturers in incompatible ways. When your provider had Nokia base stations and you had a Nokia phone, it might work. In mixed manufacturer cases not. But even then a lot of operators were not enabling it. I don't know if they simply don't care, or if they are reluctant to provide a service that is not essential to the operation of the network and that may malfunction, causing claims by customers who had damages because of incorrect time on their phone. Also, there is always the decision in such a system if it should be sending local time or UTC time (and have the phone user set a timezone). The latter is confusing to non-techical users, the former may cause further problems e.g. when a timezone border is inside or close to the operating area of the provider, and phones roam to base stations on either side of the border. Anyway, in my experience the GSM time sync is a no-op. Only smartphones have synchronized time, and they use NTP over the internet to do it. Of course requiring the setting of a timezone in the process. Normally there is no ntpd running on a smartphone, but they use regularly scheduled SNTP requests. The scheduling (e.g. "do it at the top of the hour") can cause large load peaks. And of course when the phones are configured to use the caching DNS forwarder of the provider, that also causes load peaks because many phones get served the same TTL interval of the pool.ntp.org request. It is also likely that many phones are behind the same carrier-grade NAT that uses a small subnet to translate all customer addresses. Of course a provider that cares about technical issues would set up a local NTP server and have their customer phones use that. But again, (envisioned) legal issues may hold back providers from doing that. When the pool returns incorrect time, any legal claims can be waived away with "but that is an internet service, we have no control over it". Rob _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
