摘要 |
<p>In a digital communications network comprising a branched passive optical network (11, 13) connecting a head-end (15) with a plurality of optical network units (15), the time taken to synchronise, by ranging, all optical network units (15) and the head-end (10), when the network needs to be initialised from scratch, is minimised. This is achieved by making all bandwidth in the upstream direction of the network (14) available for the purpose of course ranging. Once the whole network is ranged, then bandwidth is made available, in the normal way, to combined data communications and operations and management functions.</p> |