文档介绍：光网络郭薇上海交通大学电子信息与电气工程学院区域光纤与新型光通信系统国家重点实验室 E-mail: ******@sjtu. Tel: 021-34205419 Office: SEIEE 5-515 第一部分电信网及光传送网什么是通信网? ? Consists of a collection of switching nodes and links ? End devices (computer, terminal, phone, etc) are stations ? Data routed by being switched from node to node ? Two different switching technologies ? Circuit switching ? Packet switching 电路交换?优点? munication path between two stations ? Circuit capacity not reduced by work traffic ? Typically allows full duplex transmission ? Multiple protection/restoration schemes ? Once connected, transfer is transparent ? Low loss, low latency, and minimal jitter ?缺点? Channel provides for transmission at constant rate. The capacity dedicated for duration of connection. ? must transmit and receive at same data rate. Limits versatility ? If no data, capacity wasted ? Set up (connection) takes time 包交换?优点? Data transmitted in small packets, Packets are received, buffered and passed on to the next node ? Single node to node link can be shared by many packets over time ? Each station connects to the local node at its own speed ?缺点? May have concurrent transmissions over physical channel ? May have delays and congestion 电路交换 vs. 包交换- Circuit Switch Package Switch Bandwidth Guaranteed ?× Protection / Restoration ?× QoS ?× Service Provisioning ×? Scalability ×? work based on circuit switching is well suited in work 电信运营网络基本架构 7 协议复杂性 ($$$) 详细的业务管理和 QoS 保障每业务和每用户的管理高层的协议处理与业务层关联的丰富的 OAM 关注业务层的连接处理业务网络传送网络 OSI 协议层, 成本带宽的效率 ($) 高效的带宽的管理和 QoS 透明的传送(业务层)低层的协议处理高可靠性和健全的 OAM 需要支持灵活的网络拓扑连接 Geographic Reach 合理的将网络需要处理的功能分布在业务网络和传送网络中将有助于降低网络的整体拥有成本不同的作用,功能(以及成本): 光纤用户/应用 1 2 3 4 5 6 7IP业务需求 6 x Growth in Traffic 2004 2008 Source: Alcatel Study 2005 6x 50% 10% 3% 7% 24% 6% 25% 4% 27% 11% 31% 2% 专线业务(Enterprise DIA, Retail, Wholesale) 语音业务 (固定+移动) 视频业务中小企业的宽带 接入普通住宅用户的宽带 接入数据业务(ATM/FR, L2-VPN, L3-VPN) ?大业务流量? Moore ’ s law doesn ’ t apply here ?高可靠性?低成本 Data Center DWDM DWDM 接入长途/骨干接入