Modify DDN Network

In the existing data network technology, the multi-service network platform with ATM as the core technology is very suitable for the transformation task of DDN network.

DDNDigital Data Network) is a Network that provides Data leased line services for users. DDN is a time-division multiplexing (TDM) transmission technology that provides users with an exclusive end-to-end transparent transmission channel. You can attach various high-level services on this channel without the involvement of service providers. Because DDN channels are completely isolated from each other and have good security, users with high security requirements are very willing to choose, such as financial institutions and enterprise groups.

DDN dilemmas

With the development of data services and the expansion of network scale, the DDN Network exposes some insurmountable problems. For example, DDN is a time-division multiplexing (TDM) transmission technology, it cannot meet the burstable requirements of data services. The DDN device can only provide users with low-speed access N * 64 K), low-relay rate N * E1), and has many network structures, difficult operation management and maintenance; low management overhead, weak network management functions, long troubleshooting time, high operation and maintenance costs; always exclusive bandwidth time slot, Low Circuit utilization; the DDN link does not have the auto-recovery function and does not support point-to-point connections. The frame relay board of the DDN node host has low processing capability, and the DDN network has poor Frame Relay Service capability; when you need to access a large bandwidth> 512 kbps), the cost of performance is very low. It can be said that the DDN network does not meet the development needs of broadband multi-service in the future.

DDN Network Plan for Yunnan Province Transformation

With the development of ATM and Frame Relay PVC services, due to higher availability, more flexible technology, and cheaper prices than DDN, more and more users will switch from ddn to the pvc service of Frame Relay. Therefore, in the future, a considerable number of Frame Relay users will come from the current DDN user base.
DDN Integration Technology
In the existing data network technology, the multi-service network platform with ATM as the core technology is very suitable for the transformation task of DDN network.
In the network services supported by ATM devices, TDM transmission can be supported through circuit simulation technology. It encapsulates data input from DDN as AAL1 to form CBR data streams transmitted over the ATM network, ensuring the time sensitivity of such services. Because the CBR service type has the highest priority in multiple service networks, the services carried by the CBR service can be prioritized in the case of network congestion, which can effectively ensure the quality of user services. In a multi-service network, an ATM node device can act as the backbone bearer System for the DDN core network. The high-Port-density circuit is used to simulate the access of port E1 to the DDN node host, at the core of the network, the current DDN network can be integrated through a high-speed 155M or higher-speed relay circuit. At the same time, the ATM node equipment should also be able to implement the system's switching connection function, and the aggregated user circuit can realize business switching and convergence locally, thus improving the flexibility of the network solution.
DDN network integration using multi-service networks of ATM has the following advantages:
1. The entire DDN network structure can be simplified, the scheduling circuit is convenient, and easy to manage and maintain;
2. The combination of the ATM Switching Network and the domestic DDN multiplexing can reduce the DDN network investment;
3. the ATM network can provide flexible traffic management and channel protection for DDN Services;
4. A central network is composed of an ATM switch. DDN is used as an access method for network services, which can avoid repeated investment of DDN backbone equipment;
5. Multi-service networks of ATM can be used as the bearer platforms for various businesses to achieve multi-network convergence.

Multi-Service Switch Solution

Based on a comprehensive consideration of the development of network services and the smooth transition of existing networks, Yunnan Telecom decided to use multi-service networks to integrate existing DDN networks, this solution solves the problem of insufficient DDN backbone relay circuit and provides network guarantee for the evolution of the leased line network to broadband, intelligent and diversified directions.

DDN Network in Yunnan Province adopts the Passport series multi-service switch of beidian network company, and integrates and transforms DDN Network Services in Kunming, the provincial capital.

1. Network Architecture before Transformation

The DDN Network in Kunming uses six AlcatelNewbridge) 36170 as the core and contains about 80 MUX: 20 new Alcatel bridges) 3600, 20 AM70, and 40 CP4000. For details, see the left section ).

Next, let's look at the DDN Network's current circuit status, the dynamic Path between nb and Static Path and MUX of other vendors). There are 4000 CES circuits in MUX) 1000 Fr-Fr circuit, 200 Fr-Atm circuit, 30 dedicated E1, and 2 dedicated ATM ports.

2. Network Integration Process

In this network transformation, DDN networks are integrated through multi-service network access nodes, and the original 2 m ddn relay circuit for interconnection is adjusted to the multi-service network through network cutover, the DDN Circuit Based on circuit simulation is provided by the backbone devices of the Multi-Service Network to replace the original DDN Network Relay.

The network-wide circuit adjustment lasted three months, with more than 4900 DDN circuits in the network. At present, all the circuits have been cut into a multi-service network composed of Passport. The network runs stably, the circuit runs normally, and the network cutover is successful.

Multi-level protection of User Services

The Passport series of Multi-Service ATM Switches of the Nortel Network have excellent performance in China's ATM network construction. Currently, they have the largest share in China's ATM switch market. The MSA32, the processing board for multi-service access functions launched by beidian network, is an interface module with strong functions and the highest port density.

Currently, in addition to accessing the DDN service, the DDN node device can also access the Frame Relay Service. The flexible access capability can be achieved through the channel-based MSA multi-service card board. With the MSA card board on Passport7480, you can connect the DDN access node and the ATM switch through only one 2 m line.

The Multi-Service channelized card board is also very important in the whole network transformation process. If there is no multi-service channelized card board, you can only use a single business card board to access the DDN Access Node, as a result, each DDN Access Node can only access a single type of business. It cannot provide both the Frame Relay and DDN Services on the same DDN Access Node, causing great inconvenience to business development. For DDN networks, the reliability of network services is an extremely important indicator. The network solution of beidian can protect users' services at multiple layers.

With the large-scale application of multi-service networks in domestic telecom networks, traditional DDN networks will gradually be integrated into multi-service networks. Integration of various data networks, including DDN networks, has become a trend. The DDN network transformation of Yunnan Telecom laid a solid foundation for network integration of multiple business networks in the future.