Network latency is a key indicator of user experience. Latency varies across different network links, impacting data transmission efficiency and quality. China Telecom's next-generation bearer network (CN2) exhibits significant differences in latency from standard international internet links. This difference stems from their distinct technical architectures and operational philosophies.
Technically, network latency is primarily determined by transmission distance, number of routing hops, and network congestion. Standard international links generally adhere to the principle of optimal cost. Data packets traverse multiple autonomous systems and switching nodes during transmission, and the chosen path is often not the most direct. This is like traveling from point A to point B. Standard routes are like public transportation requiring multiple transfers, while CN2 routes are more like direct high-speed trains, with independent right-of-way and priority.
The core advantage of CN2 lies in its meticulously designed network topology. As China Telecom's premium backbone network, CN2 utilizes a three-layer architecture: core, aggregation, and edge. The core layer comprises core nodes in Beijing, Shanghai, and Guangzhou, interconnected by high-speed, direct fiber optic connections. This architecture ensures that data packets always flow within a controlled, high-quality network during transmission, avoiding the inter-carrier congestion common on conventional routes. Actual test data shows that on a link from Shanghai to Los Angeles, CN2 maintains a stable latency of around 168 milliseconds, while latency on conventional routes fluctuates between 210 and 280 milliseconds.
Routing strategy is another key factor contributing to latency differences. Conventional international routes typically use BGP for routing, with path decisions often based on inter-carrier peering agreements and cost considerations rather than optimal performance. Data packets may repeatedly hop between multiple autonomous systems, increasing unnecessary transmission distance and processing time. In contrast, CN2 utilizes rigorous traffic engineering and routing strategies to plan optimal paths for critical business data. This difference can be clearly observed using the traceroute tool:
Typical CN2 route path
1 202.97.xx.xx 0.5ms
2 59.43.xx.xx 2.1ms CN2 backbone network entry
3 59.43.xx.xx 35.2ms
4 59.43.xx.xx 168.3ms Direct to destination
Typical normal route path
1 202.97.xx.xx 0.6ms
2 202.97.xx.xx 12.3ms
3 203.100.xx.xx 45.6ms May pass through a congested node
4 199.255.xx.xx 89.7ms
5 198.32.xx.xx 156.2ms
6 198.32.xx.xx 218.4ms Multiple hops increase latency.
Quality of service (QoS) mechanisms further widen the performance gap between the two. CN2 implements a comprehensive DiffServ differentiated service model at the network layer. By tiering data packets, it ensures that services with high real-time requirements (such as VoIP and video conferencing) receive priority transmission. This traffic management capability, based on MPLS TE, enables CN2 to maintain stable latency even in congested conditions. Conventional lines typically lack this refined QoS control. When congestion occurs, all packets compete equally for bandwidth resources, resulting in a sharp increase in latency and jitter.
Differences in physical infrastructure also underlie latency performance. CN2's backbone network utilizes a high-speed fiber optic transmission system, with core nodes interconnected by 40G/100G circuits and equipped with high-performance core routers. These devices possess powerful processing capabilities and intelligent buffer management mechanisms, minimizing packet processing latency. Conventional international lines often rely on the splicing of multiple carrier networks, which may include older network equipment, creating potential latency bottlenecks.
The difference between the two routes is particularly pronounced in trans-Pacific transmission scenarios. CN2 connects via a direct submarine fiber-optic cable between China and the United States, combined with optimized BGP routing strategies, ensuring that data packets reach their destinations via the most direct path. Conventional routes may detour through Japan, Hong Kong, or other regions, inadvertently increasing transmission distance. Geophysical laws dictate inherent latency in optical signal transmission, increasing latency by approximately 5 milliseconds for every 1,000 kilometers of distance. This latency introduced by path differences is particularly critical in real-time interactive applications.
The impact of network congestion on latency also varies depending on the route type. CN2 ensures that network load is always optimized through strict inbound traffic control and capacity planning. Even during periods of high traffic volume, the MPLS-based fast reroute mechanism promptly avoids network failure points and maintains stable latency levels. Conventional international routes often experience congestion during peak traffic periods, especially at certain international egress nodes, where data packets are queued for transmission, significantly increasing latency.
This latency difference is clearly reflected in real-world experience. In video conferencing scenarios, the CN2 route can keep end-to-end latency below 150 milliseconds, ensuring a natural conversation experience. Ordinary lines often experience latency exceeding 250 milliseconds, resulting in noticeable voice asynchrony. For financial trading systems, the stable, low latency provided by CN2 is crucial. This millisecond advantage can directly translate into higher priority for trade execution.
Cost-benefit analysis is an essential factor when selecting a line. CN2's superior performance comes at the expense of higher construction and operating costs, which are directly reflected in service prices. Ordinary international lines, thanks to their economies of scale and shared model, offer more competitive pricing. Users need to make a trade-off based on their business characteristics: latency-sensitive mission-critical services may merit investing in CN2 lines, while more cost-effective ordinary lines may be a reasonable choice for more latency-tolerant, general-purpose applications.
