31.2 Planning for Time Synchronization

Use the information in this section to understand the basics of time synchronization planning. For more detailed planning information, refer to the following resources:

31.2.1 NetWork Size Determines the Level of Planning Required

The level of time synchronization planning required for your network is largely dictated by how many servers you have and where they are located, as explained in the following sections.

Time Synchronization for Trees with Fewer Than Thirty Servers

If your tree will have fewer than thirty servers, the default installation settings for time synchronization should be sufficient for all of the servers except the first server installed in the tree.

You should configure the first server in the tree to obtain time from one or more time sources that are external to the tree. (See Step 1 in Section 31.2.3, Planning a Time Synchronization Hierarchy before Installing OES.)

All other servers (both Linux and NetWare) automatically point to the first server in the tree for their time synchronization needs.

Time Synchronization for Trees with More Than Thirty Servers

If your tree will have more than thirty servers, you need to plan and configure your servers with time synchronization roles that match your network architecture and time synchronization strategy. Example roles might include the following:

  • Servers that receive time from external time sources and send packets to other servers further down in the hierarchy

  • Servers that communicate with other servers in peer-to-peer relationships to ensure they are in sync

Basic planning steps are summarized in Section 31.2.3, Planning a Time Synchronization Hierarchy before Installing OES.

Refer to the following sources for additional help in planning time server roles:

Time Synchronization across Geographical Boundaries

If the servers in the tree will reside at multiple geographic sites, you need to plan how to synchronize time for the entire network while minimizing network traffic. For more information, see Wide Area Configuration in the Novell Network Time Protocol Administration Guide for OES .

31.2.2 Choosing between Timesync and NTP (NetWare Only)

When you install an OES NetWare server, you can choose between Timesync and NTP for time synchronization.

If you select the Timesync option, you can fully configure each server as you install it to match your time synchronization plan.

If you choose the XNTPD option, you can designate up to three NTP time sources, but fine tuning your NTP hierarchy will require some manual configuration after the installation is complete. For help, consult the Novell Network Time Protocol Administration Guide for OES .

About Timesync

Timesync is the Novell legacy time synchronization protocol first delivered with NetWare 4. Over the years it has evolved and is now capable of both consuming and delivering NTP packets and Timesync packets.

Timesync is installed and configured by default to ensure the smooth integration of earlier versions of NetWare. However, many system administrators are migrating away from Timesync and implementing NTP.

About NTP

NTP is the emerging choice for many network administrators because

  • They feel it is easier to manage a single time synchronization protocol.

    For example, the same basic configuration file ( ntp.conf) can be used on both Linux and NetWare.

  • NTP is a cross-platform industry standard available on multiple platforms.

  • The XNTPD NLM that runs on OES NetWare provides Timesync packets for NetWare servers that can’t consume NTP (NetWare 5.0 and 4.2), enabling them to coexist on an NTP time network.

Where to Specify in the NetWare Install

The dialog box that lets you choose between Timesync and NTP is available as an advanced option in the Time Zone panel during the NetWare installation. Choosing between Timesync and NTP is documented in Setting the Server Time Zone and Time Synchronization Method in the OES NetWare Installation Guide .

31.2.3 Planning a Time Synchronization Hierarchy before Installing OES

The obvious goal for time synchronization is that all the network servers (and workstations, if desired) have the same time. This is best accomplished by planning a time synchronization hierarchy before installing the first OES server, then configuring each server at install time so that you form a hierarchy similar to the one outlined in Figure 31-7.

Figure 31-7 A Basic Time Synchronization Hierarchy

Time synchronization is accomplished by configuring servers in a time synchronization hierarchy.

As you plan your hierarchy, do the following:

  1. Identify at least two authoritative, external NTP time sources for the top positions in your hierarchy.

    1. If your network already has an NTP server hierarchy in place, identify the IP address of an appropriate time server. This might be internal to your network, but it should be external to the eDirectory tree and it should ultimately obtain time from a public NTP server.

    2. If your network doesn’t currently employ time synchronization, refer to the list of public NTP servers published on the ntp.org Web site and identify a time server you can use.

  2. Plan which servers will receive time from the external sources and plan to install these servers first.

  3. Map out the position for each Linux server in your tree, including its time sources and the servers it will provide time for.

  4. Map out the position for each NetWare server in your tree.

    1. Include the server’s time sources and the servers it will provide time for.

    2. Decide whether to use Timesync or NTP for your servers. (See Section 31.2.2, Choosing between Timesync and NTP (NetWare Only).)

    3. If your network currently has only NetWare 4.2 or 5.0 servers, be sure to plan for their time synchronization needs by including at least one newer NetWare server in the tree and configuring the older servers to use the newer server as their time source. (See NetWare 5.0 and 4.2 Servers.)

  5. Be sure that each server in the hierarchy is configured to receive time from at least two sources.

  6. (Conditional) If your network spans geographic locations, plan the connections for time-related traffic on the network and especially across WANs.

    For more information, see Wide Area Configuration in the Novell Network Time Protocol Administration Guide for OES .

For more planning information, see the following documentation: