Using existing E1 circuit to realize Ethernet access

Ethernet is the most widely used local area network transmission mode, it uses baseband transmission, through twisted pair and transmission equipment, realize 10m/100m network transmission, application is very extensive, the technology is quite mature. Ethernet is widely accepted as the preferred scheme of broadband access for its low cost, simple network management and easy upgrade. In the face of the current-dotted SDH ring and the large number of E1 circuits provided by SDH and PDH, a more realistic question is how to use these existing resources to transmit Ethernet data.
At present, the most widely used solution to solve such problems is the Ethernet network Bridge, that is, using the E1 circuit to provide Ethernet access. However, with the rapid development of Ethernet, the amount of Ethernet data needed to be transmitted is getting bigger and larger. In particular, the transmission of images, due to the user's image clarity requirements are higher, so that the transmission bandwidth has a new demand, the traditional Ethernet network bridge is difficult to meet the needs of users, will gradually be replaced by the new technology program.
Here we introduce a flexible, the simple, practical application plan, it is by the embellish light Thai power company design based on own encapsulation agreement special-purpose integrated circuit--rc7210, this chip can not only make up the traditional Ethernet network Bridge's insufficiency, but also has the system design simple, the application convenient, the low cost and so on compared with other plans characteristic.
RC7210 can support Ethernet MAC frame data to be transparently transmitted in 1-4 E1 lines through point-to-point, each E1 can select any path separately, and provide up to 8ms transmission Shiyancha to support large-scale metropolitan area network transmission. and in order to facilitate the system design, RC7210 E1 interface built-in clock recovery circuit and HDB3 codec circuit. The Ethernet port of the chip is a 10m/100m full/Half-duplex mii port conforming to the IEEE802.3 standard. The chip has MAC address filtering and self-learning function, which can reduce the transmission load of E1 line and enhance the E1 bandwidth utilization for small users through sharing hub access. RC7210 externally configured a 64Mbit large capacity SDRAM, the sending queue Ethernet data cache, which greatly alleviated the Ethernet side data burst and E1 circuit end fixed 2M bandwidth contradictions.
The RC7210 to implement is to use existing resources to provide broadband access to Ethernet, or to provide a E1 WAN interface for the LAN, which can provide more bandwidth than the original Ethernet network Bridge, the E1 can provide standby protection. And in the specific system implementation process has a variety of different application methods. The specific application plan is elaborated as follows:
(1) Realize the basic function of the broadband Ethernet bridge equipment, directly using the existing E1 circuit to provide simple, low-cost Ethernet access. The specific implementation plan is shown in figure I:

(2) embedded in the SDH equipment directly for the ADM/TM to provide 10m/100m Ethernet port, this scheme because each E1 can be independently distributed in the SDH frame anywhere and easy SDH network management, E1 can directly out HDB3 or NRZ to increase the flexibility of the choice of mapper, Its specific programme is shown in figure II below:

(3) embedded in the Ethernet switch, for Ethernet switching to provide wide-area network, or multiple RC7210 and Ethernet switching chip for the application of RC7210 as a local device, and the use of a single RC7210 chip devices can be placed at the remote end as user access, the application of the program as shown in Figure three:

To sum up RC7210 can directly use the existing SDH, PDH provided by the E1 circuit to transmit Ethernet data, or for SDH to provide flexible and practical Ethernet interface. Although its application protocol is private, however, since the current applications are point-to-point applications, both local and remote use of the same manufacturer's equipment, practice does not need to pay too much attention to compatibility issues, so the agreement is not public and has no practical significance. And due to the introduction of the chip timely and mature technology, it has been the vast number of equipment vendors support and application.
For the vast number of operators, they built high-density SDH ring and surplus a large number of E1 channels, is very suitable for the original network to provide new LAN access business. For example, China Mobile and Unicom, most of their base stations are connected by the SDH ring, and each base station is generally only 1-2 E1 channel, if the SDH equipment near these base stations to open access to the LAN business, not only small investment and benefits are obvious, Therefore, the equipment factory commercial this chip made of Ethernet to E1 interface conversion Equipment has rapidly entered the respective network.