(PRWEB) December 16, 2004
The time servers can be configured with 4 different form factors (including 1U and 3U rack mount versions), several stratum 0 - reference time sources such as GPS, IRIG, DCF77 and can be equipped with several optional outputs. Even stratum 2+ models are available, which do not use an integrated time source, they aquire the correct time over the network from other NTP time servers. LANTIME time servers can be configured by using the easy and comfortable secure web interface or its console counterpart, accessible over a SSH2 or Telnet connection.
To provide centralized management and monitoring, they come with a very broad SNMP support, including SNMP traps, over 400 accessible variables and over 60 configuration parameters. The flexible notfication system allows the administrator to select which event triggers which notification type (SNMP Trap, eMail, Syslog entry, Windows Popup Message) and even provides a possibility to execute a user-provided shell script in case of an alert.
More and more networks have to provide synchronized time to their clients. Not only process automation and telecommunication applications are time-sensible, even "ordinary" company networks often require a reliable common time base for all desktop PCs, servers and infrastructure components like routers or switches. In order to avoid that databases are corrupted by unsynchronized replication processes and in order to be able to reconstruct hacker attacks or the chronology of technical problems (computer forensics), it is mandatory that all involved systems and components are using the same time when putting transactions in a processing order or creating log entries. Without a single, common time base it would be rather complicated (if not impossible) to find out the correct chronology of passed events.
An example: In the course of an investigation of a hacker attack, it is very important whether the attacker first broke into system A and then got into system B - or vice versa. When it comes to heavily used databases, it can be a catastrophe if transaction A is not processed before transaction B. A good example for this is a stock exchange order processing system.
The Network Time Protocol (NTP), that can be used to synchronize time between servers and clients, but also between servers and servers, is used for a long time now. NTP builds a hierarchy, where a so-called stratum level is assigned to all time servers. The stratum level indicates how "near" a time server is located to a highly accurate source of time.
The built-in real time clock of todays computer systems is not suitable to be this source of time, it is just to inaccurate and normally only used to keep time while the system is turned off (battery buffered). The system clock of a running computer is a software clock. It is not unusual that these software clocks are drifting a second per day (or even more). Such an error can cumulate to more than 30 seconds per month in always-on systems like network servers. This is not acceptable for the majority of professional applications.
The reference time sources of a NTP network are mostly radio clocks, so-called stratum 0 references. Stratum 0 represents the level with the highest accuracy, a NTP server directly connected to such a clock is a stratum 1 time server. These radio clocks are receiving their time from mostly governmental authorities, which keep their time by operating an atomic clock. They broadcast the time information for example by using long wave transmitters like the german Physikalisch-Technische Bundesanstalt (PTB) or the US-american National Institute of Standards and Technology. Often the signal of the 24 GPS-satellites is used, each of them equipped with an atomic clock. The advantage of the Global Positioning System (GPS),mainly used for navigational purposes, are better accuracy and worldwide availability of the signal. The longwave signals of PTB, NIST and others only covers a limited area (for example, the longwave radio sender DCF77 used by the german PTB covers an area of approx. 2000 km around its broadcasting station which is located near Frankfurt/Main).
The reference implementation of NTP is freely available and can be downloaded on the NTP website. In its newest Version 4 it supports all major operating systems and radio clocks. NTP Version 3 is defined in RFC1305, no RFC has been published for NTP V4 until today.
In order not to change the running configuration of an existing server, a number of companies developed specialized appliances which can be used as a time server in company networks. These standalone and ready-to-run systems are offering stability and easy configurability without needing too much attention from the administrator. Most of these systems are coming with a builtin radio clock, others can use an external clock with a serial connection.
The LANTIME time server models offered by Meinberg Radio Clocks from Bad Pyrmont, Germany, can be ordered with integrated DCF77- and/or GPS-radio clocks, as well as IRIG time code readers and other time sources. A LANTIME includes a single board computer with an i386 compatible CPU, booting Linux from a compact flash disk and running a version of the reference NTP software coming from ntp.org, which has been slightly optimized for a better interaction with the built in reference time source.
The administration of these systems can be handled by using a standard web browser (via HTTP or even encrypted via HTTPS), a terminal program (by using TELNET or SSH) and with a SNMP-compatible network management software. A sophisticated event notification system informs the responsible person by sending a mail, a SNMP trap, a syslog entry or by showing a message on a big wallmount display. Even a user-defined script can be executed in case of an event.
Besides the extensive configuration options and numerous hardware options the Meinberg LANTIME family of time servers comes with a very good IPv6 support, which has been developed in cooperation with the JOIN project of the University of Muenster. The LANTIME time servers are the first time servers especially designed to provide accurate time in IPv6 based networks or dual stack networks (running both IPv4 and IPv6).
An Online demo of the web interface, as well as detailed descriptions and datasheets of the LANTIME models and othe Meinberg time and frequency products can be found on their website.
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