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The Topology of CERNET

The network implementation uses a multiple ring topology, which provides redundant paths between any two backbone nodes, as shown in the following figure.

CERNET Backbone

The Digital Data Network (DDN) provided by the Ministry of Post and Communication and/or some telecommunication corporations will be used as the basic communication carrier. The data transmission rate starts at 64 Kbps to 2.048 Mbps (E1). The public data network (X.25) will be used as the backup channel.

There are four links to the global Internet, each with a data transmission rate greater than or equal to 64 Kbps. The first external link is to the United States with the trunk speed 128 Kbps, the second with 2.048Mpbs. The others are located in Hong Kong (HARNET), Germany (DFN), the United Kingdom (JANET), Canada.

The backbone nodes are interconnected by routers. The backbone itself forms an autonomous system, OSPF is selected as the interior routing protocol. Eight regional networks also form their own autonomous systems, BGP-4 is selected as the exterior routing protocol between the CERNET backbone and regional networks. The CIDR technology is used in each regional network. At this moment, about thirty-four superblocks are reserved for the CERNET universities and institutes.


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