Hi, On 31-05-16 19:34, [email protected] wrote: >> I would suggent a double-check on first drop mechanism: resend probing >> packet to no responding servers after serveral minutes. >> a. If the server is running fine, only overloading, it may be able to
The monitoring is not (only) about checking if a server keeps good time, it is about checking if a server provides good time _to remote clients_ . >> reply to probing packet after some time. We have double-check to >> confirm this, then go back to 20 mins checking cycle. No score >> modification (addition/deduction) is performed in this scenario. >> Further no-responding checks will still be double-checked. > > Maybe the NTP probing could be combined with some pings - just to check the > amount of packet loss. > This would imply that the server needs to respond to ICMP echo requests but > would help the monitoring > system to detect if a server is overloaded (maybe by comparing RTT times), > totally offline or just a bit lossy. What does this detection matter? In the end, the server will not reliably respond to normal clients, so it should be removed from "the" pool. Remember, we only have one big pool with valid servers. From that pool, some servers are selected to be included in the answer to specific DNS queries. Note that you can request to exclude your server from the global or regional pools. Just reply to the automatic e-mail that the monitor sends you in case the score drops deep. > Besides that, I have no packet loss to China or Taiwan from Germany (tested > with the pool servers for CN and TW). > I assume this will be the same for most other european countries, so maybe a > monitoring system located in europe > might help resolving this issue AND could make monitoring more reliable since > you have two fully (carrier) independet > monitoring locations. And hosting in Europe is really cheap. With two monitors, they may not agree with each other. What do you do in that case? For which DNS queries do you in- or exclude the system? As far as I can see, a (much more complex) multi monitoring system might work, if we define a pool for each individual DNS entry on country, region and global level. In that situation, each pool can have its own local monitoring system for inclusion of the server in that specific pool. However, you need long term committed volunteers to run each monitoring system. Given that we have many countries with only a few servers, I guess this is not feasible. Once we have many servers (and better chance to find volunteers for monitoring) in a country, we don't have problems with overloading in the first place. So, in that case our current simple, single monitoring system will do. Just my € 0,02 Arnold _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
