北京市电信管理局于1997年3月28日与上海贝尔电话设备制造有限公司签订合同引进由上海贝尔电话设备制造有限公司集成的美国Cisco公司的BPX和IGX设备纽成的多功能本地帧中继网。该网由41个地点的45个节点共2966个端口所组成,网络分核心层和接入层,核心层由4个汇接节点BPX组成网状网,用STM—1(155 Mbit/s)互连,接入层的节点间中继速率为34Mbit/s,业务量较少的节点用2Mbit/s互连,为保证网络安全,每个节点至少与2个节 Beijing Telecommunication Administration signed a contract with Shanghai Bell Telephone Equipment Manufacturing Co., Ltd. on March 28, 1997 to introduce the BPX and IGX equipment of Cisco Systems of the United States integrated by Shanghai Bell Telephone Equipment Manufacturing Co., Ltd. New Cheng’s multi-function local frame relay network. The network is composed of 2966 ports of 45 nodes in 41 locations. The network is divided into core layer and access layer. The core layer consists of four tandem nodes BPX mesh network, STM-1 (155 Mbit / s) Interconnection, access layer inter-node relay rate of 34Mbit / s, less traffic with 2Mbit / s interconnection nodes, to ensure network security, each node with at least 2 sections