In-depth analysis of core technology of Optical Fiber Access Network

The optical fiber access network is worth learning a lot. Here we mainly introduce the current situation and development trend of the access network in China's communication industry, including the TMN status of the access network and the remote network management technology of the optical fiber access network, for your reference only.

I. Current Situation and Development Trend of access networks in China's communications industry
With the rapid development of social informatization, the communication business requires a larger capacity and a higher speed. In addition to transmitting voice information, it also needs to be able to transmit data, videos, images and other multimedia information. Traditional communication access networks that use a pair of twisted pair wires to connect to the local telephone terminal cannot meet the requirements. Therefore, many more advanced access network technologies have emerged, such
ISDN, xDSL includes HDSL, ADSL ......) .

In the wired access network, fiber-optic access networks have the fastest development and the best prospects. This has greatly replaced the traditional twisted pair access networks. Compared with other access network technologies, optical fiber access network has the following advantages:
1) the transmission rate on the line is greatly improved. The optical fiber wavelength division multiplexing (WDM) technology can increase the transmission capacity of an optical fiber to the Tbit/s level, the WDM Technology of the 4-optical path enables a single optical fiber to transmit 4x10 Gbit/s = 40 Gbit/s of information simultaneously; the DWDM of the 100 optical path enables an optical fiber to transmit 100 x 10Gbit/S = 1 Tbit/S of information simultaneously, which is unmatched by other wired access networks.
2) high-power gain and gain frequency bandwidth can be obtained. In the modern WDM/DWDM Optical Fiber System, the EPFA-based bait-doped fiber amplifier can extend the bandwidth from 20-30nm to 80-100nm, providing sufficient power gain for the 1550nmn window.
3) benefits to traditional telephone communication networks (PSTN), Internet), and cable television broadcast networks (CATV. The recent trend in communication business operation shows that cable TV networks are also preparing to provide communication services to make full use of their functions. for TV sets of home users, you only need to install Set-top box ), fiber-optic and coaxial cables are used in hybrid HFCs). The operator connects the fiber-optic cables to the locations where users are concentrated, and then each user is connected to each coaxial splitter. In this way, any user is connected to the Internet, the data transmission rate can be up to 56 kbit/s-10Mbit/s through the Set-top box and the hfcline. It can even provide telephone services.

To truly achieve triple play, wired Bandwidth communication networks can only be achieved through passive optical fiber networks. Currently, it cannot be implemented immediately, mainly because of the cost of optical/electrical and optical conversion end machines. Once the power supply obstacles of the end machines are overcome, when the household power supply can be used to provide optical terminal power and the cost of the end machine is reduced, it is expected that optical fiber will be delivered to the household to achieve all-optical network communication. Thanks to the above advantages of optical fiber network, communication owners in various countries are struggling to develop the optical fiber access network technology in order to expand their operation scope. At present, China's local telecom departments are transforming the existing wired communication network, and the optical fiber access network is rapidly expanding.

Ii. Status Quo of TMN in Access Networks
As we all know, due to the constant expansion of its functions and the rapid development of advanced technologies, the communication network has become a very complex network. Various manufacturers constantly launch their own network devices and propose new technologies, including access networks and their corresponding network management technologies, to form a wide range of access networks. There is no unified network management system for hardware devices in multiple access networks. At present, communication networks in various regions in China are gradually being transformed, and fiber optic networks are used to replace backward wired access networks. The established optical fiber access network is still in scattered state. Of course, there is no uniform TMN Network. The Organization for Standardization of ITU-T Telecom hopes to draw on the ideas and technologies of system management in OSI to manage telecommunication business, and formulate the structure network system to realize the management function of telecommunication network. This large system project is being gradually researched and improved.

Iii. Remote network management technology for optical fiber access networks
In the distribution of access networks in our telecom branch, the proportion of optical fiber access networks is less than 30%, but it is accelerating the transformation of old networks, there are currently access network devices under A, B, C, and D4 branch offices. Because the construction time is different, the manufacturer of the purchased equipment is also different. Each manufacturer has its own set of network management interfaces and solutions, and the OAMP is placed in the data center of the access device connected to the Home Office, real-time Monitoring of the running status, environmental parameters, and Power status of devices in the remote ONU data center.

However, various data centers gradually transition to fewer people and unattended. If you still need a dedicated person to go to the site for routine testing, not only do you spend a lot of unnecessary manpower, but you cannot know the operation status of each remote device in time. When obstacles arise, you cannot handle them in time, delay the normal operation time of the access network. In view of this situation, we have tested a remote network management method suitable for optical fiber access networks.
Technology. After many tests, the results are very good.

All manufacturers can provide local network management OAMP, which monitors the running environment and running status of each optical fiber endpoint device by the OAMP of the Swiss Bureau. The device and OAMP are connected by serial port or V.11 or other interfaces, different manufacturers may be different. However, this remote monitoring solution does not require special network devices and special protocols. You only need to install the Modem on the monitored OAMP and the Centralized Monitoring Workstation, install the remote monitoring server and the customer on the Windows platform respectively. The server software at each site is in the waiting status. On the workstation of the centralized monitoring room, dial in the OAMP that connects to various bureaus to display the OAMP monitoring content locally: ONU and OLT device running status. Using this monitoring method not only facilitates access to the monitoring status of each OAMP, but also enables quick operations and processing on the OAMP when encountering obstacles. You can even save the number of monitors on the screen to a local hard disk as a technical reference.

Iv. Conclusion
From the implementation of the optical fiber access network technology to the completion, the solution is simple and feasible, and is not limited by technical conditions and engineering environments. All grass-roots Bureaus with optical fiber networks can achieve this. Low cost and no special technical equipment are required. You only need to install remote control software. Promotion. According to the system running status, in addition to completing the predefined functions, the operation is simple, convenient, and reliable, and the file creation can be automatically recorded. It saves a lot of manpower, shortens inspection time, and achieves good economic and social benefits. The disadvantage of this solution is that the phone number is occupied. Although the cost for separately constructing the network is saved, it is not an independent TMN Network after all. In accordance with the relevant standards of the ITU-T organization, it is still necessary to draw on the ideas and technologies of system management in OSI to gradually unify the implementation and interface standards.

1. Block hacker attacks start with access switch
2. Remedy the "sequelae" of VPN access"
3. Network Management Note: IP addresses of new devices are constantly accessing
4. Easy VPN application: remote access to mobile office
5. Instance: Implements dual-line VPN access through Windows soft route