OSF DCE Administration Guide--Core Components

OSF DCE Administration Guide—Core Components

23.3.2.1 The Local Server Set

Local servers reside on the same LAN and maintain their clocks by synchronizing with

each other. Due to the high throughput on this type of network, the skews between the

local servers on a LAN are normally maintained at under 200 milliseconds. If at least

one of the servers in the local set synchronizes with an accurate time-provider,

inaccuracies at each server may be less.

When a server is ﬁrst initialized, it exports its binding to its entry in the namespace and

adds its name entry to the LAN proﬁle. Every server is automatically entered in the LAN

proﬁle for the related portion of the network. Local servers also import bindings from the

LAN proﬁle to build lists of servers with which they can synchronize.

Local servers perform time interval computations, adjust their clocks, and provide time

values to each other for synchronization purposes. Each server attempts to synchronize

with every other server in the local set at periodic intervals. At longer intervals, clerks

request time values from the local servers. Clerks, however, need only to request

intervals from the number of servers determined by the minservers attribute, which is

usually a subset of all the local servers.

23.3.2.2 The Global Server Set

Local servers are available only to the servers and clerks that are in a single LAN, but

global servers are available throughout a cell. Any server can be conﬁgured as either a

local or a global server (See the DCE control program dts conﬁgure command). The

number of global servers is usually small, but global servers have several important

functions that enable DTS to synchronize every node in the network. Global servers are

necessary in the following situations:

• When a network has multiple LANs or an extended LAN

• When systems that are not on LANs have access to LANs through point-to-point

links

• When clerks or local servers cannot access the required number of local servers

determined by the minservers attribute

You can reconﬁgure a local server as a global server by using the dcecp dts conﬁgure

command with the -global option. Conﬁguring a server as a global server causes the

server to export its binding to its entry in the namespace and its name to the cell proﬁle.

Local servers and clerks request time values from global servers when they cannot obtain

the number of local server responses that are mandated by the minservers attribute.

Certain local servers also regularly request the time from global servers. See the

following subsection.

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