The Design And Realization Of IP Broadband Access Network

This article expounds on the concept and the recent development of the broadband access network. In the beginning, I compare different accessing measures, such as ADSL,LMDS,HFC,VSAT and FTTLan, and then draw a conclusion that FTTLan is a accessing measure that suit china very well and has high quality with low cost. Later, the systematic structure of FTTLan and the mode to realizing it is mainly discussed. FTTLan originates from Ethernet, and if it's applied to the broadband access network for operation, it should has the function such as 802.1D/802.1P/802.1Q/802.3X/802.3AD just as Ethernet has. There are also several problems as follows have to be solved: 1. Security: The first problem is the security of the consumers'data. The public operation access network shared to customers attaches more importance to the security of its data. There is hidden trouble in the security of the users'data, the foundation stone of which lies in that FTTLan mainly consist of ZAN and BAN switches that originates from the shared Ethernet techniques. In order to solve that problem, isolation techniques are needed, which can isolate different users'data and avoid attacking,juggling and wiretapping one another. Standard Ethernet supports 802.1Q to isolate consumers'data through VLAN, but theoretically, 802.1Q can only support 4096 VLAN and the configuration of this functionality is very complex, which cannot satisfy the requirements of the access network that is large-scale constructed. This system applies techniques such as port isolation,QINQ and PVLAN, etc and realizes the isolation of users'data, and the configuration is also predigested and can support 4096* 4096 VLAN, as a result, the network will be more expandable. The second problem is the security of the management data of the service provider. Recently, most network management software of the providers are realized through SNMP, but SNMPV1 and V2 both use clear text to deliver the network management data, which brings great hidden trouble to the security of the data. This system support out-of-band management, and only VLAN1 users can manage the security of the normal and technical equipment such as SNMPV3; network management like TELNET and WEB can apply SSH to encrypt the network management data and realize the security management. Thirdly, because FTTLan switches are usually used in bad surroundings, the adaptation to the temperature and the quality of dustproof is very important. 2. Multicast service It is inevitable that the broadband access network supportsmedia business, so is that the network will support multicast. The protocol of multicast can be divided into 3 parts: The multicast routing protocol among domains such as MBGP,MSDP; The multicast routing protocol inter-domain such as PIM,DVMRP,MOSPF; The multicast routing protocol between router and host like IGMP. FTTLan has little relation to the multicast routing protocol, so this article only go into details of how IGMP is realized. 3. Quality of service As the high-speed network and the media techniques develop in a high speed, new applications such as remote education ,video meeting ,remote medical, etc emerge in endlessly, and the generalizing of those applications largely depends on the service index, such as delay,scrambling,sync, which are called QOS. Control congestion and QOS is the important quality in the media service network. The accessed method,the accessed speed,the application method and the data property is various, so the network burst of data is inevitable. Therefore, it is very important that network can control the congestion and dispose different data stream in different ways. Several aspects should be considered to guarantee the QOS: Traffic category and traffic shapping; Access speed control;Queue mechanism; Congestion control in advance; Resource reserved; This system can realize end-to-end QOS and congestion control from aspects as follows: Line-rate route per port Eliminate the bottleneck of the route, realize the overall control of the network. Non-block and multiple exchanges matrix Isolate the blocked node from the network to avoid the influence to other data. Great buffer capacity Avoid discarding packets when the data bursts due to the capability of the output port. The segment can up to 64K. Flux classify and priority 802.1p, which based on the second layer protocol; The third DIFFSERV category/TOS bits mapped can guarantee the line-rate differentiation service. Stream exchanges of the fourth layer Provide the tactics route of the application layer. RMON and Learn the flow situation of existing network to4,Authentication and account: The authentication and authorization is an important problem in network security. Only when the identity of the customers has been effectively and safely been checked and certificated, can their action on network be controlled and the security and healthy operation of the whole network system be guaranteed. At present, there are three certification techniques in the business, they are PPPoE,WEB,802.1X, all of which have already been applied in telecom operation network and have played a significant role in supporting its healthy running and security keeping. This system chooses 802.1X as the better authentication method. Broadband IP network must be a telecom network access platform that can be operated and managed, other than a simple and open...