The multimedia network has two layers and is composed of main net and access net . the main net maintains the network conlection of atm net stm - 16 relay circuit . access net maintains the double - star shaped structure and has 622m / 155m relay circuit 所设计并实现的宽带多媒体网采用两层结构,由骨干网络和接入网络组成,其中骨干网保持现有atm网stm - 16中继电路的全网状网连接,接入网的各市、州节点保持以双622m 155m中继电路分别与骨干节点连接的双星型结构。