Electing a new TSP master
To ensure that the time synchronization service provided is
continuous and reliable
in the face of unusual events, an election algorithm is
available to elect a new master. Unusual events include:
This algorithm allows slaves to detect that a master has
stopped functioning and to elect a new master from among the
Because the failure of a master time daemon results
in only a gradual divergence of clock times among the slaves,
the election of a new master need not occur immediately.
the host running the current master time daemon crashes.
the master time daemon terminates because of a runtime error.
the network on which the master time daemon is running is partitioned
Running timed on gateways that connect distinct
Local Area Networks (LANs) requires particular care,
because the time daemon may act as a ``submaster''.
A submaster is a time daemon that functions as a slave on one of
the networks the gateway is connected to
and as a master on one or more of the remaining networks.
Submasters are necessary to overcome the restriction of
current transmission protocols' preventing broadcasts from
being transmitted over multiple physical networks.
A submaster classifies the networks that the gateway is connected
to into the following three types:
The submaster tries periodically to become master on ignored
networks, but gives up immediately once it detects that a master already exists
on that network.
A slave network, which is a network on which the submaster acts as a slave.
Only one of the networks can be a slave network.
Master networks, which are networks on which the submaster acts as a master.
Ignored networks, which are networks
that are neither slave networks nor master networks.
How the time daemon works
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003