On Wed, Feb 1, 2012 at 9:20 AM, Bob Camp <li...@rtty.us> wrote: > Hi > > The "gotcha" with a public grandmaster is routing to it. Without 1588 > routers / hubs / switches / what ever, the result is compromised. You fall > back into the same routing delay mess as NTP. Since public pretty much means > internet accessible, you would need to upgrade a lot of stuff. Since that > includes the traditional "last mile" gear, it's not a simple proposition at > all. At least in my case, I get more delay from the ends of most connections > than I get from all the routing in-between.
I think except for testing you need the grand master to live on your own Ethernet. And I mean "Ethernet" in the most precise way. Two Ethernets with a router between them is not an Ethernet it is two Ethernets with a router. sub-uSec synchronization is very hard over over any network if packets get stored and forwarded and that is what routers do. NTP is better if the network path is complex and you don't have end-to-end control over all the equipment. I think it's best to start from requirements rather then starting from solutions. But if your requiremt is to get time to within a few uSec and all the machines are in the same lab PTP can work. Next you have to figure out some way to TEST is the machines are all in fact in sync at the uSec level and if yu are using PTP the test should not also use PTP. Testing, I think is the hardest part. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.