| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical network such as medium scale IP system network and the like in order to ensure the capability of extension in low cost while holding high reliability. SOLUTION: As an example of physical constitution, a main node 2-1 and eight sub-nodes 2-11-2-18 at the most are connected to one OADM ring 2-21 or 2-22. In logical connection, a star constitution originated in the main node 2-1 is formed and all traffics are connected via the main node 2-1. The sub-nodes 2-11-2-18 are connected to the main node 2-1 in the wavelength unit optical channels (=optical paths) λ1-λ8 (refer to the solid lines). And then as indicated by the broken lines, the optical channels can be extended according to necessity. For example, although the main node 2-1 and the sub-node 2-5 are connected in λ5 at the start, λ13 can be extended according to necessity. Cost reduction is possible because of being able to use dielectric interference film filters and fiber Bragg reflectors which can extract only specific wavelength optical channels and are low in price, by means of restricting the branch insertion optical channels to about two channels in the sub-node of the logical star. The reliability coping with troubles in fiber transmission paths can be ensured in low cost by using optical switches providing for troubles. |
