The apparatus includes each timing server of the multiple pluralities of {HEAD ~ timing servers} configured to transmit, receive, and monitor {TAIL ~ synchronization signals} 
configured to receive
The apparatus includes each timing server of the multiple pluralities of { HEAD ~ timing servers } configured to transmit , receive , and monitor { TAIL ~ synchronization signals }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL