31.1 Overview of Time Synchronization

All servers in an eDirectory™ tree must have their times synchronized to ensure that updates and changes to eDirectory objects occur in the proper order.

eDirectory gets its time from the server operating system (NetWare® or Linux) of the OES server where it is installed. It is, therefore, critical that every server in the tree has the same time.

31.1.1 Understanding Time Synchronization Modules

Because your OES eDirectory tree might contain servers running OES Linux, OES NetWare, or previous versions of NetWare, you must understand the differences in the time synchronization modules that each operating system uses and how these modules can interact with each other.

OES Linux vs. OES NetWare

As illustrated in Figure 31-1, OES NetWare (and NetWare 6.5) can use either the Network Time Protocol (NTP) or Timesync modules for time synchronization. Both modules can communicate with OES Linux using NTP.

OES Linux must use the NTP daemon (xntpd).

Figure 31-1 Time Synchronization for Linux and NetWare

OES Linux uses an NTP time module. OES NetWare can use either an NTP or a TIMESYNC module.

OES Servers Communicate Using the Network Time Protocol (NTP)

Because OES Linux and NetWare servers must communicate with each other for time synchronization, and because Linux uses only NTP for time synchronization, it follows that both Linux and NetWare must communicate time synchronization information using NTP time packets.

However, this doesn’t limit your options on NetWare.

Figure 31-2 illustrates that OES Linux and NetWare servers can freely interchange time synchronization information because OES NetWare includes

  • A TIMESYNC NLM™ that both consumes and provides NTP time packets in addition to Timesync packets.

  • An XNTPD NLM that can provide Timesync packets in addition to offering standard NTP functionality.

NOTE:Although NetWare includes two time synchronization modules, only one can be loaded at a time.

Figure 31-2 NTP Packet Compatibilities with All OES Time Synchronization Modules

All OES time synchronization modules can interact.

Compatibility with Earlier Versions of NetWare

Earlier versions of NetWare (version 4.2 through version 6.0) do not include an NTP time module. Their time synchronization options are, therefore, more limited.

NetWare 5.1 and 6.0 Servers

Figure 31-3 illustrates that, although NetWare 5.1 and 6.0 do not include an NTP time module, they can consume and deliver NTP time packets.

Figure 31-3 NTP Compatibility of NetWare 5.1 and 6.0

The TIMESYNC NLM in NetWare 5.1 and 6.0 can consume and provide NTP time packets.
NetWare 5.0 and 4.2 Servers

Figure 31-4 illustrates that NetWare 4.2 and 5.0 servers can only consume and provide Timesync packets.

Figure 31-4 Synchronizing Time on NetWare 5.0 and 4.2 Servers

NetWare 5.0 can be a Timesync consumer and provider. NetWare 4.2 should only consume time, not provide it.

Therefore, if you have NetWare 4.2 or 5.0 servers in your eDirectory tree, and you want to install an OES Linux server, you must have at least one NetWare 5.1 or later server to provide a “bridge” between NTP and Timesync time packets. Figure 31-5 illustrates that these earlier server versions can synchronize through an OES NetWare server.

IMPORTANT:As shown in Figure 31-4, We recommend that NetWare 4.2 servers not be used as a time source.

31.1.2 OES Servers as Time Providers

Figure 31-5 shows how OES servers can function as time providers to other OES servers and to NetWare servers, including NetWare 4.2 and later.

Figure 31-5 OES Servers as Time Providers

31.1.3 OES Servers as Time Consumers

Figure 31-6 shows the time sources that OES servers can use for synchronizing server time.

IMPORTANT:Notice that NetWare 4.2 is not shown as a valid time source.

Figure 31-6 OES Servers as Time Consumers