| 摘要 |
A distributive communications network comprises groups of nodes (11-22, 31-36, 4 1-43, 51) at different levels (1, 2, 3, 4). Each set of nodes at one level is connected to an associated node in the level a bove for transmission and reception of traffic. Traffic is assigned to one of a number of bands of wavelengths according to whether it i s local or wider area traffic. At the first level of node (11-22) local area traffic in the corresponding band of wavelengths is l ooped back and retransmitted to all of the terminals (a-x) that are connected to that node. At each level of node, traffic is either passed on to a higher level, or looped back according to the band of wavelengths to which it is assigned. Thus, the waveleng th band determines the node level at which the traffic is looped back, and the breadth of terminals ultimately exposed to this traffic. It is possible to re-use bands of wavelengths for communicating between terminals.
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