| Abstract | The first phase of the construction of the public backbone DDN (Digital Data Network) in China was completed in July 1994. This-phase DDN consists of 21 node exchanges, each of them is located in a province or a city, and digital circuits among those nodes. There are three international gateways located in Beijing, Shanghai and Guangzhou respectively, which connect the domestic DDN with international DDNs. There are eight hub exchanges located in Beijing, Shanghai, Shenyang, Guangzhou, Wuhan, Chengdu, Nanjing and Xi'an. |
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