--A Live-Recording of Construction of the World's Largest IP Bearer Network by China Mobile
China Mobile Celebrating Spring Festival with the Whole Nation
Spring Festival is the most important and joyous holiday in China. It is recorded that the Spring Festival has a history of over 4,000 years. During the Spring Festival, people go home and get together with family members, visit relatives and friends, pay holiday calls for each other, and wish each other a happy and lucky lunar new year. With the rapid spread of handsets, phones have now become a major means of communication for paying holiday calls between goods friends and close relatives.
By the Spring Festival Eve of 2006, the China Mobile IP private bearer network (IP private network for short) has witnessed more than 40 million subscribers passing on their greetings for the Spring Festival within an hour through the network. The busy-hour traffic has reached 471,000 erl, which is 2.3 times of the busy-hour traffic during weekends. The Busy Hour Call Attempt (BHCA) has exceeded 20 million. Both of them have hit a record-high.
In the Spring Festival of 2007, a new record was made. Substantial increase in the total number of subscribers and total call duration was seen in the IP private network. The peak-hour traffic during the eve of Spring Festival has approached 900,000 erl, an increase of 90% compared with the 2006 Spring Festival. The BHCA has increased to more than 40 million, twice of the figure in the 2006 Spring Festival.
China Mobile is the largest mobile carrier in China, boasting the largest subscriber population and network scale in the world. Each year during the Spring Festival, the traffic in several days can be compared to the annual traffic in each of other countries in the world. In 2004, to satisfy the rapid growth of service and embrace the 3G age, China Mobile built the world's first mobile IP bearer network. Two years later, upgrade and expansion of the IP bearer network was completed smoothly. Now, this IP network runs stably, carrying more than 70% of the toll call traffic for more than 0.3 billion mobile subscribers.
Tough and Rugged Road towards Transformation
As early as 2003, China Mobile was already operating the world's largest GSM mobile telecomm network. At that time, the subscriber base had reached 0.15 billion and the number of 2G subscribers was still increasing at a speed of 50 million subscribers per year. The GSM tandem network faced a huge pressure in expansion. On the other hand, the voice service now could not meet the subscribers' growing demands and achieve the maximum profit for China Mobile. With the emergence and rise of multi-media services like Internet, VOIP, and video service, the priority of development for telecom carriers has gradually shifted from the voice service towards the multi-media service. Although the TDM-based GSM network was very mature by that time, it could hardly support these new services.
"Under such circumstance, China Mobile has only two choices. One is not to acquire new subscribers, which is obviously impossible. The other is to associate the network expansion with technical innovations. The telecom network consists of two parts, core network and wireless system. During the reconstruction of core network, China Mobile upgrades the original circuit-switched system into the IP-based softswitch system. In this way, the 2G network and the future 3G network can share the same core network and it is not necessary to build a new core network for the 3G network." Said by Wang Jianzhou, CEO of China Mobile, in the 2006 China Enterprise Summit when he recalled the network transformation process of China mobile.
There was an obvious gap, however, between the status quo of IP technologies at that time and requirements of telecom services. Bearing multiple services over the IP network was still in the exploration stage. More improvements were expected in terms of reliability, quality of service (QoS), and security of the IP network. Meanwhile, the operation and management (OAM) model of the IP network also differed a lot from the traditional circuit-switched network. In addition, no proven mature experience was available for reference in bearing multiple services over the IP network. It was highly risky to build a large-scale IP bear network.
After exchanging opinions with Huawei for several times, China Mobile began to turn to the IP bearer network solution proposed by Huawei. This solution was tailored according to characteristics of the telecom network and the mobile voice service. It involved:
- The ever-developing high-reliability technology. All key components of the IP bearer network equipment adopted the redundancy backup design. The protocol fast convergence, fast re-route (FRR), and bidirectional fault detection (BFD) technologies were deployed across the network. Switchover within 50ms upon failure was realized to ensure the uninterrupted operation of telecom services.
- The gradually-improving QoS technology. The IP bearer network could provide QoS policies by different service type. It could provide the real-time services such as VoIP with service quality similar to the PSTN network, and had the capability of connection admission control (CAC).
- The powerful network security capability. The IP bearer network could be divided into different security regions according to the security networking principle to realize safe isolation of services.
- The IP bearer network featured an open architecture, flexible networking capability, and service scalability. It could implement the centralized network monitoring and role-based management.
From the end of 2003 to March 2004, China Mobile took a long time proving the feasibility of IP bearer network and exploring a best solution. Facing the real-life demands of rapidly increasing 2G subscribers and the surge of 3G and broadband networks, China Mobile decided to cooperate with Huawei, selected the IP private bearer network solution, and developed the phase-based development strategy.
Birth of the World's Largest IP Bearer Network
April 2004 marked the start-up of the T1 softswitch tandem network and IP private bearer network project, which was of the largest scale in the history of China Mobile. After more than six months from signup of contract to project cutover, the whole project, which involved transmission, data communication, and switching, was completed by the end of November 2004. The cutover was smooth and the network ran stably.
On December 22, 2004, China Mobile conducted a comprehensive test over the reliability indices of the network. When the link or node was faulty, the mean time between failure (MTBF) was 22.7ms, far lower than the design value 50ms. During the operation period, several transmission intermittent events did not affect the service, which demonstrated the huge superiority of the IP private network over the traditional IP network.
In June 2005, after the successful commercial use of phase one IP private network, China Mobile further determined the development strategy of the next-generation IP telecom network. In the phase-II network, routers with larger capacity and links with higher bandwidth and new IP technologies would be employed to enhance the service bearer capacity of the IP private network.
In October 2005, China Mobile launched the Phase II project of its IP private network. After careful consideration, China Mobile finally decided to introduce the top core router Quidway® NetEngine 5000E in eight cities, and the core router Quidway® NetEngine 80E to access nodes, and upgrade the 2.5G platform of backbone network into the 10G platform. Migration of bulk traffic was also carried out. The whole network covered more than a hundred of devices and thousands of ports. It was extended to 31 provinces, cities, or autonomous regions, and over 40 cities. About 200 Huawei field technical engineers worked side by side across the country and completed upgrade and service cutover of all devices in less tan two months. The network also withstood severe tests of the record-high peak traffic.
Experiencing Values of IP Private Network and Creating Boundless Communication World
After the network construction in Phase I and II, China Mobile IP private network could fully meet the requirement of wireless voice service in terms of reliability, QoS, and security. The multi-service MPLS VPN security isolation technology was deployed across the network. This effectively prevented virus and malicious attacks. During two years of operation, core devices of the IP private network have never been attacked by virus.
As an open network, the IP private network not only carried the long-distance traffic of wireless voice service, but also signaling, SS7 monitoring, data service monitoring, and softswitch network management. It also provided effective support for bandwidth-hungry services like the 3G, NGN, VIP customers, and video services. Compared with the traditional TDM network, the IP private network allowed easy expansion, increased bandwidth utilization rate, simplified the network structure, and effectively reduced the network construction cost and maintenance cost.
In November 2006, Phase III project of the China Mobile IP private network kicked off. In this phase, the IP private network would be extended from 31 provinces or autonomous cities (except Taiwan province) to more than 300 cities across the country. Again, China Mobile chose Huawei as its partner. Hundreds of core routers, Quidway® NetEngine5000E/80E/40E series, will be deployed in the Phase III project, to create another legend.
An expert of China Mobile Research Institute believes that the Phase III project plays a significant role for China Mobile. With the completion of network expansion and equipment upgrade, China Mobile has realized dual-network differential operation in a real sense, that is, the old CMNET carries the public Internet service, while the new IP private network carries QoS-sensible key services like 3G services and VIP customer service. This paves the road towards full-service operation for China Mobile.
