Dialogue with Tang Hong, Director of Data Communication Department, Guangdong Research Institute of China Telecom

The IP network traffic increases dramatically along with the fast development of services such as video conferencing, streaming, and peer-to-peer (P2P) services. As the network approaches swiftly to the ultra broadband era, more and more severe challenges are imposed to the network devices, and in particular, to the backbone network devices. A dialogue is conducted between a reporter of this publication and Tang Hong, Director of Data Communication Department, Guangdong Research Institute of China Telecom on a series of questions, such as how to precisely grasp the pulse of a market and respond with calm to changes in the market and how to clearly understand the prospects of network development among lots of misleading indications.

Huawei Technologies：Hello, Mr. Tang. The new 3G and IPTV services of China Telecom are currently in full swing, and are followed consequently by a surge of data traffic. What is the trend of network traffic of China Telecom?

Tang Hong：On July 16, 2009, the China Internet Network Information Center (CNNIC) released the 24th China Internet Development Statistics Report showing that the number of broadband users in China reached 320 million by the end of June 2009, still ranking the first in the world and that the Internet penetration rate took on a stable growth trend. Meanwhile, due to the impact of 3G services, mobile subscribers for Internet access has reached 155 million, accounting for 46% of total users and showing the momentum of rapid growth.

Four indicators, which are, the number of broadband users, the average online duration, the concurrent rate, and the average traffic, show rapid growth of broadband network. Communications with foreign leading operators tell that China Telecom ranks the first in the world not only in the network dimensioning but also the traffic. With the development and popularity of HDTV and P2P applications, the traffic of China Telecom increases by above 70% on a year-on-year basis, taking on an exponential growth trend.

Huawei Technologies：The surge of Internet traffic inevitably comes with a tremendous pressure on network bandwidths. What network planning strategies will be taken by China Telecom in response to the explosive demand for bandwidths?

Tang Hong：As we know, networks are driven by services. The substantial growth of service traffic imposes severe challenges to the network model and in particular to the egress of the backbone network and metropolitan area network (MAN).

At present, the flat and simplified network architecture turns into a general trend because the former hierarchical network has a series of weaknesses, such as the complexity of devices, interfaces and protocols, and high cost of network construction, maintenance and operations. The explosive growth trend of network bandwidths requires higher network scalability. What' s more, network intelligence is also a major feature recognized by the industry. Based on three considerations, China Telecom puts forward the mainstream idea of network construction with respect to flat infrastructure, higher capacity, and fewer offices. Thus, the network topology can be greatly simplified and the network quality can be improved, and as a result, the network services can be developed and scheduled in a fast and intelligent manner to help reduce the network construction cost and enhance the overall competitiveness.

Huawei Technologies：With this idea, what requirements does China Telecom raise for the backbone nodes in the network?

Tang Hong：High capacity is the most basic requirement for the backbone devices.

Currently, the required capacity of the backbone nodes in the ChinaNet of China Telecom surpasses 2.5 Tbps and this figure is still growing. As forecasted, the required capacity of some backbone nodes will reach 10 Tbps in one or two years. Luckily, leading vendors in the industry have launched 400G/slot router platform. This future-oriented design fully considers the long-term requirements of operators.

In addition, with the continuous expansion of capacity and increase of traffic, it' s more and more critical for the reliability and robustness of devices on backbone nodes. Generally, vendors can improve the reliability of the backbone nodes and networks through a large number of general or patent technologies, such as bidirectional forwarding detection (BFD) for fast link failure detection, fast rerouting for link switching, non-stop routing (NSR) and non-stop forwarding (NSF) technologies.

Moreover, the capabilities of hot swap and smooth upgrade are also essential without service interruption. That' s to say, the increase of services or capabilities can' t impact the traffic and services of existing users. Operators urgently need to expand the capacity and upgrade the network smoothly through the flexible scalability of backbone routers and safeguard investment without changing the network architecture.

China Telecom is a pioneer in China on transforming the challenges into opportunities for backbone network construction. A number of new technologies and products are rolled out on a large scale, such as the router cluster technology.

Huawei Technologies：It's true. Clustering is an effective solution for bandwidths at present and is the future development direction of backbone routers. Could you tell us something about the researches or verifications performed by China Telecom on the cluster technology and product?

Tang Hong：Viewed from the traffic forecast model of China Telecom, traditional routers can hardly satisfy the requirements of users. For example, dozens of 10G ports are required to converge the downstream traffic in a level-B city of China Telecom, while the traditional routers can only realize the capacity growth through adding more ports or slots. In this sense, clustering is a best choice.

China Telecom is the earliest operator engaged in the research and deployment of the cluster technology in China and the scale of router cluster deployment is the largest in China. We have made a lot of verifications regarding the features of devices, such as the test on mandatory features of large capacity, multi-chassis cascade and smooth upgrade, congestion test with full configuration of a single chassis, and test on non-stop forwarding without packet loss. The tests are focused on the cluster capacity, stability and scalability.

Last year, China telecom conducted comprehensive tests on Huawei 2+2/2+4 router clusters system, covering the capacity under the full configuration, and smooth upgrade from single chassis to 2+2 cluster and from 2+2 cluster to 2+4 cluster. As one of the few router cluster vendors, Huawei has made a rapid and conspicuous progress during recent years. The subsidiaries and branches of China Telecom in Shaanxi, Jiangsu and Gansu have chosen the Huawei cluster products, and the products run stably.

Huawei Technologies：Thank you for your recognition. You just mentioned that Shaanxi Branch of China Telecom utilized the Huawei cluster routers and doubled the port capacity at the backbone nodes of the MAN. Do you think it is a trend of MAN development? Will China Telecom promote this network construction model?

Tang Hong：The growth of network bandwidths is of great significance to the entire network. In the past, a monthly package with 1 Mbps can meet the demand of an MAN user for Internet access, but the fast development of IPTV and P2P services leads to a sharp increase of bandwidth demands. Moreover, the number of broadband users is growing continuously. For example, in Xi' an Branch of China Telecom, the maximum access bandwidth of a user reaches 8 Mbps, and the traffic carried in the MAN exceeds the threshold. Under such circumstances, the cluster system with large capacity must be migrated to the MAN.

Clusters are currently deployed in both the backbone network and MAN backbone nodes of China Telecom. China Telecom must resolve the problems in IP backbone networks and localize MAN or LAN traffic. For effective traffic grooming against long-distance traversal, and in particular, P2P traffic grooming, China Telecom applies the QoS strategy and direct grooming strategy to distribute traffic more evenly and scientifically and support the flattening of networks.

Anticipated from the network development speed of China Telecom, more than half of the backbone network nodes and about one third of the MAN backbone nodes will require the use of router clusters in 2 years. In this regard, clustering is a necessary condition for device selection of backbone nodes of China Telecom in the future.

Huawei Technologies：Could you please round up the main factors the operators may consider when they select the cluster products?

Tang Hong：To ensure better ROI (return on investment) is a key consideration of operators for the selection of a cluster product. But this completely depends on whether the cluster capacity can meet the bandwidth growth requirement, and whether the cluster can be expanded in capacity and upgraded smoothly. Besides, the energy saving and emission reduction is another key consideration of operators, which in fact has become an issue of social responsibility. The concept of sustainable development has been deeply rooted in the minds of operators and put into real practice.

Huawei Technologies：We wish to hear some of your thoughts on the evolution of networks in the future. Could you give us an outlook for the future development trends of the telecom industry?

Tang Hong：The network tomorrow must be a converged network. The telecom industry is in face of a new pattern of convergence which has become the main theme of its development. The single industry chain pattern will be gradually transformed to multiple ecological systems of the telecom, Internet, media & entertainment (TIME) type. The software industry, IT industry and telecom industry are beginning to have an overall convergence on a gradual basis.

The multi-play service is a golden key to the business success of telecom operators. The multi-play service operation may help operators to transform successfully from traditional operators to information service providers. Some new technologies like cloud computing, IP and Web 2.0 application will give people an experience of converged new services including voice, video, data and instant messaging.

Huawei Technologies：As an expert in the data communication industry for many years, could you please give some remarks on the development of Huawei Datacom?

Tang Hong：To promote the sustainable and sound development of industry chains and welcome the network convergence in the future, vendors should work together closely with operators from now on and spare no efforts in moving toward technology peaks. Being able to provide competitive solutions for wireless, IP, transmission and backbone network fields, Huawei has grown up into an end-to-end solution expert in communications. I believe that Huawei can make a positive response to the coming situation of network convergence and contribute to the sustainable development of networks with rich experience in the fields.

I expect that Huawei, as a native manufacturer, will be more successful and go further to become a distinguished one of the science and technology innovators in China.

Huawei Technologies：Thank you very much for your trust and support, and for your sharing of information and insight. The vision of Huawei is to enrich people's life through communications. Huawei will strive to establish a high-end brand and invigorate the national industries through self-innovation. We will keep moving forward to realize this dream.