Sync two RPI using NMP?

[cyborg1992]

Hi every one...
I have the next problem: I need that two RPis have the exactly time in their internals clocks, NOT USING A RTC HARDWARE, looking in the internet I found that I can use the NMP server for this, but I can't up the NMPServer in one of my RPi for give to the other the time because all the tutos that I see required an Internet conection and the two RPIs dont will have an Internet conection. Any one has a ttutorial for set a NMP server without an Internet conection? Or any idea?
Thxs

[fsr]

NTP server is trivial to install and run.
https://wiki.debian.org/NTP
Any linux distro will do it. Most CPE routers do it

you PIs are using NTP to get their time off internet servers, you just point them to the local one once you have one -> /etc/ntp.conf

[drgeoff]

Depending on your definition of "exact" you may find it impossible to sync the time in two or more RPis exactly. How close do they need to be?

[cyborg1992]

@fsr the ntp server i could start up, but theorethically the precision of the RealTimeServer over ethernet is 200microsecs and I need a precision of 1microsec

@dregoff so I need a precision of less than a 1 microseconds...but I well-read that's impossible

thxs

PD>sorry for my english