Swedish Distributed Time Service

Welcome to the Swedish Distributed Time Service. This service delivers time over the Internet using NTP, and several other protocols upon request.

The service is operated by Netnod, monitored by RISE Research Institutes of Sweden and financed by The Swedish Post and Telecom Authority (PTS).

There are four time nodes in different locations in Sweden, with a fifth one expected during the first half of 2019. The time nodes are continuously monitored and steered to follow UTC(SP). Each time node has two atomic clocks generating separate time scales for high availability. Even if a time node would lose all contact with all its sources for timekeeping, it is expected to be able to keep its time within narrow limits for months.

NTP service

For redundancy, the NTP service has two independent NTP servers in each time node.

To use the NTP service, you can use the anycast address which will direct the client to the closest available server:

If you want to get time from more than one server, you can use some or all of the unicast addresses:

The NTP service is free to use for anyone anywhere.

The NTP servers use a custom-build FPGA-based hardware implementation for responding to the NTP requests, using IPv4 or IPv6, unsigned or signed, at a full line-rate speed of 10Gb/s per interface. They use 1PPS and 10MHz signals from the local time scales to achieve high accuracy and precision of the NTP timestamps.

Operational Status Log

NTP statistics

Other information

PTP

If you have mission-critical systems that need a level of accuracy beyond the capability of software NTP implementations, you can also consider using PTP.

Contact

For more information about the service, please contact Netnod or The Swedish Post and Telecom Authority (PTS).

Network information

The NTP service uses the following IP networks and AS number:
IPv4 - 8 subnets: 194.58.200.0/24 ... 194.58.207.0/24
IPv6 - 8 subnets: 2a01:3f7:0::/48 ... 2a01:3f7:7::/48
AS: 57021

NOTE: The system also serves addresses from earlier generations of the system. These should NOT be used for new installations.