Redundant time-of-day (TOD) oscillators are aligned, within a master
oscillator path, to local logic oscillator and used to create independent
step-sync signals. A step checker validates and provides selection
signals to identify which of the TOD oscillators operates according to a
criterion. Independent step-sync signals are transmitted to several
sibling chips. Local step and sync signals are delayed to arrive at TOD
register nearly synchronous with TOD registers in sibling chips. A slave
oscillator path may be used to select time signals generated in a sibling
chip, whereby the master oscillator path is deselected. A primary control
register set may be used to configure which among several chips is a
master chip using the master oscillator path. All remaining chips are
slave chips. All segments of the topology are redundant. One of multiple
possible alternate topologies is defined in a secondary control register
set. Commands and TOD values are passed on the fabric at predefined time
increment boundaries to establish, restore, or maintain synchronization
across all chips.