,中国电信下一代承载网络 China telecom Next Carrier Network(CN2）,China Telecom Corporation http:/www.chinatelecom.com.cn,韦乐平 Wei Leping,Challenges Total voice traffic and revenue decreases by the end of 2005. The mobile phone and IP phone calls have cannibalized part of the voice traffic businesses Traditional communication network is unable to support China Telecoms strategy to become a Integrated Information Service Provider. This is due to its lack of capability in offering value-added service. High OPEX (Operating Expenses) is required for traditional hetergeneous/multiple networks Existing ChinaNet is not a profit generating business Opportunities Acceleration of the Information and Communications Technology (ICT) adoption in government and enterprises would drives the demand for telecom services Adoption of the SIP-based soft-switch technology The impending releases of 3G license Rapid development of the broadband service,Background,Migration of voice service from PSTN to soft-switch-based VoIP technology Preparation for 3G-based mobile services Accelerate the development and application of the broadband services base on xDSL access technology Drive managed service and system integration service Built an Integated IP/MPLS-based multi-service platform CN2,solutions,Philosophy of Building CN2,CN2 strengthnetwork topologyScalable routing architecture Highest level of redundancyHighest level of securityDifferent class serviceAll services have edge functionalityEnd to end control and managment,Homogeneous Global Architecture Single Global ASN(AS4809) IP Layer Redundancy Drives Accountability ISIS level2-only with sub-second convergence Diffserv-based QOS enabled network MPLS and multicast enabled network MPLS FRR with sub-50ms reroute Robust Architecture Allows for Unsurpassed Stability Offer Layer-2/3 over IP or MPLS Leading SLAs via Zero Loss & Speed of Light Delays 6PE-based IPV6 ready Offer Layer-2/3 over IP or MPLS Leading SLAs via Zero Loss & Speed of Light Delays End to end service provision and fault management,CN2 Strength,Simple Network Topology,CN2 comprises of two functional planes and four structural layers to offer a seamless connectivity for customers. CN2网络包括2个网络功能层面和4个网络结构层次，实现承载和业务提供相对独立 The two functional planes are high speed data forwarding plane and service provisioning plane 2个功能层面分别是高速转发层和业务提供层 The four structural layers are core layer, aggregation layer, edge layer and services connecting layer 4个结构层次指核心层、汇聚层、边缘层和业务接入层 The high speed data forwarding plane and service offering plane is supported by 4 and 1 vendors respectively. This is to ensure minimum service disruption and better edge services control. 高速转发层包括4个厂家设备，业务提供层1个厂家。减少业务互通障碍，保证业务提供，边缘业务管理。,Core,Aggregation,Edge,Service,高速转发层,业务接入层,SR/PE,SR/PE,SR/PE,Simple Network Topology(cont),IP/MPLS Network All-Optical，Dense Wave Division Multiplexing (DWDM) SONET/SDH framing Per flow load-sharing and fail- over load-sharing with ISIS MPLS is enabled with traffic to the PE Loopback is tagged. Hence, only VPN traffic is encapsulated in MPLS, all others is transported native IP,MPLS,SONET FRAMING,DWDM,IP,IP,Scalable route architecture,To ensure networks scalability and security, only infrastructure address blocks are redistributed into the IS-IS (IGP) routing table. Non-infrastructure addresses are redistributed in BGP. Keeping the IS-IS routing table to a minimum would greatly enhance the network stability. 只有中继链路地址和管理地址通过ISIS,其他路由通过BGP,控制IGP路由表的条目,保证网络设备和链路数量的扩展性. Single Global ASN (AS4809), CN2 have two type Route reflector VPN RR for RFC2547-based VPN service,(VRR) Global RR for internet service(GRR) VPN RR is independent of global RR, both use one level Route Reflector(RR) (VRR和GRR是独立设置的,各自专用的) BGP Communities are deployed for routes control and netflow-based traffic monitor Global iBGP: Scaling the Global Internet Routing Table involve the increase in the number of GRR group. 通过增加并列的GRR组来分担部分public 路由处理,这样具有很大的扩展性. VPN iBGP: Likewise, scaling the VPN routing Table involve the increase of VRR group. Example, VPN1-500 is handled by VRR-G1 while VPN501-1000 can be handled by VRR-G2 通过增加并列的VRR组来分担部分VPN路由表的处理,比如VPN1-500的路由表有G1转发,VPN501-1000通过G2转发. 通过以上两种设计解决网络路由表的扩展性.,Scalable route architecture (Cont),Full mesh Peers,Full mesh Peers,Internet,GRR1,GRR2,GRR3,GRR4,Client,Client,Client,Client,Group 1 for part1 routes,Group 2 for Part2 routes,Internet,EBGP,EBGP,iBGP architecture for global routes,Scalable route architecture (Cont),Full mesh Peers,Full mesh Peers,VRR1,VRR2,VRR3,VRR4,Client,Client,Client,Client,Group 1 for VPN 1-500 routes,PE,PE,PE,PE,Group 2 for VPN 501-1000 routes,iBGP architecture for VPN routes,Highest Level of redundancy,All network links are deployed in pairs over diverse facilities Only POS interface are used on backbone interconnection to facilitate faster failures detection All network links are active (NOT working and protect) Each PoPs router pair is connected by multiple routers. Link failure protection is the function of IS-IS (layer 3 control) and would not be carried out on transport layer (layer 2 control) (不依赖SDH或者DWDm的传输层保护) IS-IS routing protocol Per flow load sharing between dual pairs Fail-over load sharing Sub-second fast convergence for gold service Three priority LSP flooding and FIB update MPLS FRR 1:1 mode FRR is deployed in core layer for 50 links Sub-50ms reroute time Built to maintain utilization not to exceed 50% during normal running As a congestion-free network, CN2 ensures premium priority for delivery of all packets in the core,