1, Metro Transmission Network Status In accordance with the business flow, the flow divides, China Telecom's metro transport network now can be divided into relay layer and access layer, access layer can be divided into the trunk layer and user layer. Among them, the relay layer 2.5Gbit / s and 10Gbit / s SDH ring network of main equipment, the main provider of 2Mbit / s and 155Mbit / s interface; access layer of the trunk floor to 622Mbit / s and 155Mbit / s of the SDH ring Web-based, leading provider of equipment, 2Mbit / s interfaces. Network layers mainly between 2Mbit / s connection particles, scheduling.
Metro transport network, mainly through the following two ways to load data service: First, the circuit data service bearer in the cable line directly to the main network star way; 2 is the rate of less demanding, can be Circuit data services into 2Mbit / s circuits to connect.
Existing metro transport network are the following problems:
* Network interface type is single, poor service provision, resource scheduling, management of complex, high cost for large customer network. Currently, the main provider of metro transport network 2Mbit / s interfaces, 155Mbit / s interface, there are very few, to IP-based data services with strict QoS can not be directly in the transmission line transmission, the user access device only when the circuit is converted to data services standard 2Mbit / s, 155Mbit / s before to transfer. Can be seen, the existing metro transport network can not be flexible to meet the user multi-service (especially data service) access, and traffic scheduling many links, the workload can not quickly meet the business needs.
* Resource utilization is not high. Currently metro transport network resource utilization is generally less than 50%.
* Fiber resources take up too much. Currently, data services occupy 60% of the fiber access network resources. With the further development of data services, cable access network resources will become increasingly strained due to channel resources become very serious.
* Poor network security. Use of existing IP MAN star bare fiber network, security, and poor management.
2, MSTP application of ideas and strategies
Quite a long time in the future, the traditional TDM services (such as fixed voice, base stations, video conferencing, etc.) will continue to grow steadily, while the statistical multiplexing operations (such as data services, enterprise VPN, portal, server hosting, Internet access, IP phone, etc.) showed a trend of rapid growth, will gradually become the main source of income. Front investment in effective protection of the premise, how to apply MSTP transformation Metro Transmission Network in order to better carry TDM and data services, this requires further examination. By combining experience, proposed metro MSTP transmission network in the application of existing ideas and specific application strategies.
2.1 Application Ideas * New transmission network equipment should be used MSTP network, used to carry TDM and data unification.
* Phases, step by step to the transmission conditions MSTP network upgrade. First, consider upgrading the software version upgrade, increase the veneer, etc.. For high demand, fiber and resource-deficient areas of existing equipment, new equipment could be considered MSTP network.
* Metro transmission networks in order to carry through the relay layer of the main transmission business, the layer with the powerful data node equipment, and most devices have a generation of MSTP function, so its business on open MSTP The most effective way to carry through point to point transmission services (such as 100Mbit / s line, 155Mbit / s line).
* Should be based on the actual situation, in the metro transport network access layer step by step open MSTP business, and ultimately integrated converged access, unified carry TDM and data services. Currently, a large number of access nodes to a generation of MSTP transport nodes, only supports a generation of MSTP function, this can be opened through the transfer of some operations to provide customers with unique differentiated solutions. Should eventually be reunified carrying data services and traditional TDM services.
* MSTP mainly defined as aggregation, access, uniform load, does not consider replacing the second, three-tier data devices.
2.2 Application Strategy (1) New Access Network Strategies
Should be able to meet the data and TDM and other business needs. At present, the data service includes the access point DSLAM uplink circuit (ATM or IP), large customers IP Internet circuit, IP line circuit. Should focus on building a new access network to consider the following aspects: equipment rate should be 622Mbit / s or more, with two MSTP function on behalf of the above, the composition of ATM sharing ring