Synchronizing a Linux Machine Using NTP
TSync boards can also be used to provide very accurate time stamps via the PC's bus system to either NTPv4 (freeware) or Spectracom TimeKeeper software running on the TSync host computer. In order to be able to synchronize Linux using NTP, the 3rd party NTP module (if not already included in the Linux kernel on your machine) must be downloaded, as described below in detail. This module includes the Reference Clock Driver that gets applied as a patch to the Linux driver.
- The NTP patch for syncing NTP via an installed TSync timing board is only available in the Linux drivers for Spectracom bus-level timing boards. It is not provided in the Solaris driver. Solaris can only be synced via NTP time stamps from a networked NTP time server or via ASCII time stamps from the Serial output port of a Spectracom time reference.
Note: NTPv4.2.8 and above now include the TSync reference clock driver, i.e. it is no longer necessary to patch NTP using the NTP patch in the Spectracom Linux driver.
Windows, Linux and Solaris drivers for TSync boards are available from Spectracom. The Linux driver files contain README files. The README file contains the instructions to configure the timing card as a reference time source for NTP.
In summary of the instructions in the README file, with NTP software already installed on the PC, the driver contains a patch that is installed into the NTP software. Once the NTP patch has been installed into the NTP software, the NTP software is then recompiled and is then run from the newly compiled location. With the patch applied, NTP can then obtain time from the Spectracom timing board.
The Linux machine with NTP software compiled and with a TSync board installed can be made into an NTP Server that can provide time to synchronize the rest of the network. Refer to the NTP website of http://www.ntp.org/ to obtain both the NTP software and more information on how to build and configure NTP to be a network time server. In this scenario, the computer is synced to the timing board and the network clients are synced to the PC.
Please note that the instructions for the NTP patch were written for a specific version NTP version of NTP (please refer to the README file for the most current, specified version of NTP to use). If another version of NTP is installed on the computer, other changes not listed in the README file may be required to make the timing card work with that particular version of NTP.
Specific Notes about the Linux driver NTP README file:
- When using an IRIG input to synchronize the timing card, the current year needs to be either automatically calculated by the timing card based on the IRIG input, or it must be manually entered by you.
- After installing the patch and then recompiling NTP, run NTP from the newly compiled location.
- Use the “-g” switch to start NTP.
- Make sure the PC is within ±4hours of the time reported by the TSync board. NTP will not correct a time offset of a PC that is greater than 4 hours.
- Based on customer feedback, the
NTP.conffile may need to be edited. The “keys” made need to be rem’d out in order for NTP to use the timing board as its reference.
Note regarding synchronization of the TSync board: When using a TSync board to sync NTP, the TSync board itself must be synced to IRIG or GPS. However, it can also be manually synced using the hst1/epp0 input references. The TSync board can declare sync with the self/epp0 input references, but NTP will not sync to the board with these input references being used to sync the timing board. The minimum requirement for NTP synchronization is hst1/epp0.