In-depth introduction to Ethernet Access Networks

After a long period of development, many users are familiar with Ethernet access networks. Here I will share my personal understanding and discuss with you. High-speed Ethernet Access Network Based on five lines is undoubtedly a good choice. It is particularly suitable for intensive living environments and is very suitable for China's national conditions. Because the residents of China do not live in similar situations as in western developed countries, individual users are scattered and most Chinese residents are concentrated. This is especially suitable for the development of optical fiber to residential areas, connect to the user through a fast Ethernet. In Lan, the IP protocol runs on Ethernet, that is, IP packets are directly encapsulated in Ethernet frames. The Ethernet protocol is currently one of the best protocols used with IP addresses.

The Ethernet access method has become a new trend in broadband access, and it will quickly enter the home. At present, most of the commercial buildings and new residential buildings have integrated wiring, and 5 types of UTP are deployed to deploy Ethernet sockets to the table. The Ethernet access network can provide each user with a 10 Mbit/s or 100 Mbit/s access rate. It has several or dozens of times the bandwidth of other methods. It can fully meet users' needs for bandwidth access. Although ADSL is faster than 56 K, there is still a big gap with Ethernet. It is just a transitional technology in the process of broadband. Both ADSL and Cable Modem are expensive. The cost and cost of each household will exceed 1000 RMB on average. The cost of Ethernet is about several hundred yuan per household. Therefore, the Ethernet access network method is applicable to China's national conditions and the future development trend of the network. Ethernet access will be the most promising means of broadband access in commercial buildings and new high-end residential buildings.

Optical fiber access technology

Optical Fiber Communication has the advantages of large communication capacity, high quality, stable performance, anti-electromagnetic interference, and strong confidentiality. In trunk communication, optical fiber plays an important role. In the access network, optical fiber access will also become the focus of development. The optical fiber access network refers to the optical fiber access network with the transmission media in the access network. The Optical fiber access Network technology can be divided into two categories: AON and Active Optical Networks and PON and Passive OpticaOptical networks ). Active optical networks can be divided into SDH-based AON and PDH-based AON. This article only discusses SDH synchronous optical network systems.

1) SDH system for access networks

The CE (local device) of the Active Optical Network and the RE (remote device) are connected through the active optical transmission device. The transmission technology is a lot of SDH and PDH technologies used in the backbone network, but SDH technology is the main technology. Remote devices are used to collect, adapt, reuse, and transmit services. Local devices provide interface adaptation, multiplexing, and transmission functions. In addition, local devices also provide network management interfaces to the network management system. In actual access network construction, the topology of the Active Optical Network is usually star or ring. The main advantage of applying SDH to access networks is that SDH can provide ideal network performance and business reliability; the inherent flexibility of SDH makes it especially suitable for developing cellular communication systems using SDH systems. Of course, considering the high cost sensitivity of the access network and the bad performance of the operating environment, SDH devices suitable for Ethernet Access networks must be highly compact, low-power and low-cost new systems, and their market prospects are promising.

The Latest Development Trend of SDH for Ethernet Access networks is to support IP access. At present, at least Ethernet interface ing is required. In addition to carrying voice traffic, some SDH net loads can be used to transmit IP services, so that SDH can also support IP Access. There are many supported methods. In addition to the existing PPP method, it is also highly efficient to support IP transmission using the hierarchical scheme of VC12. In short, as a mature and reliable transmission technology that provides the main business revenue, it will continue to improve and support the smooth transition from a circuit switching network to a branch network in the foreseeable future.

2) Passive Optical Network PON

Passive Optical Network (PON) is a pure media network that avoids electromagnetic interference and lightning impact on external devices, reduces the failure rate of lines and external devices, and improves system reliability, at the same time, it saves maintenance costs and is a technology that the telecommunications maintenance department has long expected. PON has good business transparency and can be applied to any standard and speed signal in principle. In particular, an ATM-based Passive Optical Network (APON) can be used to share optical fiber and optical line terminals by means of centralized and Statistical Multiplexing of ATM, the cost is expected to be 20%-40% lower than the traditional PDH/SDH Access System Based on circuit switching.

APON business development is implemented in stages, and the initial stage is the VP leased line business. Compared with common leased line services, APON provides low-cost and small-size VP leased line service equipment, featuring power saving, reliable and stable system, and advantageous in performance-to-price ratio. The second step is to implement a group and secondary group circuit simulation service to provide Intranet connections and enterprise telephone and data services. Step 3: Implement Ethernet interfaces to provide Internet and VLAN services. In the future, it will gradually expand to other services and become a veritable Ethernet access network system.