Advantages and Applications of EoPDH Converters

1 Introduction

Due to the maturity of Ethernet technology and its low-cost advantages, Ethernet access has become the first choice for many users. The earliest customers used Ethernet to E1 converters, occupying several 64kbit/s time slots, and then gradually expanded to the entire E1, with a rate of 2.048Mbit/s. With the introduction of services such as images, a single E1 can no longer meet the needs of customers. Therefore, the technology of bundling multiple E1s to carry Ethernet came into being. In recent years, this inverse multiplexing technology has attracted more and more attention from customers. Due to the relative lag of standards, many manufacturers have successively launched similar products. Although the transmission means of Ethernet on the wide area network have been increased, due to the different standards, it has also brought many inconveniences in use and maintenance.

2. Generation of EoPDH

At present, most of the popular ETH to E1 converters in the market still use the high-speed data link protocol (HDLC) as the encapsulation method, and the specific processing process such as how to allocate the encapsulated data frames to each E1 channel is defined by each manufacturer, which creates obstacles for the interconnection of equipment from different manufacturers. At the same time, since there is no unified definition and requirements on the encapsulation method, link adjustment mechanism, delay difference and other issues, it is difficult to ensure the quality of service transmission.

In order to better solve the above problems, EoPDH that complies with ITU standards came into being, and the details of EoPDH were standardized through the following standards: G.7041 defines the encapsulation format (GFP-F); G.7042 defines virtual concatenation (VCAT) and link capacity adjustment specification (LCAS); G.7043 and G.8040 define the mapping method from VCAT&LCAS to E1; Ethernet interface requirements must comply with IEEE 802.3 standards; E1 interface requirements must comply with G.703, G.704, and G.823 standards. Through the above standards, it is possible for converters from different manufacturers to communicate with each other. At the same time, through the specific definition of cascading mode, capacity adjustment, mapping mode, delay difference between E1s, etc., the transmission quality of the service is better guaranteed.

3. Features and application modes of RAYCOM's EoPDH chip

Based on the above standards, Beijing Raycom Technology Development Co., Ltd. (RAYCOM CO., LTD.) has developed a series of EoPDH ASIC chips such as RC6105 (1VCG 5E1), RC6116 (1VCG 16E1), RC6621F (6VCG 21E1) after years of hard work, making its own contribution to solving related technical problems.

3.1 Features of RAYCOM's EoPDH Chip

RAYCOM's EoPDH chip family provides a more competitive solution for converter interoperability and service quality assurance for a wide range of equipment manufacturers. The functional block diagram of the chip is shown in Figure 1. At the same time, RAYCOM's EoPDH chip also has the following features:

Figure 1 RC6116 chip functional block diagram

(1) Provides management based on OAM frames.
　　(2) Provides unique network management channels: three types of network management channels based on the SA bit in E1, making configuration and application more flexible.
　　(3) By optimizing the registers, the setting operation is simple, which facilitates the understanding of chip design and software development.
　　(4) The E1 link delay difference can reach 224ms.
　　(5) The default configuration can be interoperable, which facilitates board-level debugging by equipment manufacturers.
　　(6) Compared with the FPGA solution, the ASIC solution has the characteristics of fewer power supply types, lower power consumption, and higher reliability.

3.2 Application Mode

Equipment manufacturers using this solution have all passed the protocol converter entry test conducted by China Mobile in 2009. At the same time, RAYCOM's EoPDH solution has also helped many equipment manufacturers achieve excellent test scores in other domestic and foreign biddings. In the actual networking process, the application modes of this solution are mainly the following two:

(1) Point-to-point application (see Figure 2)

Figure 2 EoPDH point-to-point application

Ethernet signals are transmitted through 1-16 E1 channels, traversing the transmission network to achieve point-to-point Ethernet service interoperability.

(2) Star networking

As shown in Figure 3, the client EoPDH converter and the traditional HDLC converter (RC7222) are converged through the RC6621F (6VCG 21E1 GFP) and RC7240F (16MII 16E1 HDLC) independently developed by Runguang Taili. In particular, the central office convergence chipset solution built by adding RAYCOM's single-chip SDH solution RC7880 (STM-1×2, 24E1, STB×2, built-in clock and CDR, embedded DCN×2) to the application scheme of RC6621F and RC7240F enables equipment manufacturers to build a new convergence device with high convergence ratio, small size, low power consumption, saving central office router ports, and saving a large number of E1 cables at the central office. Once launched, it has been widely praised by the market.

Figure 3 EoPDH star networking application

4 Conclusion

Through 10 years of continuous efforts in the field of access network dedicated ASIC, RAYCOM has not only developed a complete product series such as Converter, PDH, SDH, EOP and EOS, but also can provide a full set of MSAP chipset solutions. We hope to assist the majority of equipment manufacturers to design solutions faster and better by providing complete reference designs and considerate technical support services. If you are interested in any technical solutions of RAYCOM, you are welcome to log in to www.raycom.com.cn. We will provide you with tailor-made system solutions through professional technical support.