边际网关路由协议是因特网骨干线路的关键组成部分之一。

Border Gateway Protocol (BGP) is a key component of Internet backbone, and plays a very important role.

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接着，详细说明时分多路系统在长途主干线路上的应用，以及最近引伸至市内骨干网和接入网的应用。

Then, it describes in detail the application of WDM systems on long distance lines and possible applications in local networks, including those interoffice lines and some access lines.

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