Load Balancing Implementation Strategies For Multiple Circuit Deployments In Hong Kong’s CN2 Circuit

With the growth of cross-border operations and the demand for low-latency, high-stability access, Hong Kong CN2 route has become the preferred choice for many companies in their multi-route deployments, thanks to its excellent quality as part of China Unicom’s backbone routing network. This article will start by examining the differences between CN2 routes, and by combining load balancing and DDoS protection practices, it will provide practical deployment solutions and purchasing recommendations.

First, explain the common classifications of CN2: CN2 GIA (Global Internet Access) and CN2 GT (Global Transit). GIA is usually directly connected to international exports, offering better peering, lower latency, but at a higher cost ； GT is suitable for high-volume or cost-sensitive scenarios, where the route may pass through more intermediate nodes, resulting in relatively higher jitter and packet loss probabilities.

In multi-line deployments, it is important to understand the nature of these two types of CN2 lines: Using CN2 GIA as the primary connection to ensure a good experience for critical transactions as well as voice and video services, while using CN2 GT or other international links as backups or for high-volume traffic, allows for a balance between cost and performance.

The key design aspects of multi-line load balancing include the coordination between the routing layer and the transport layer: At the routing layer, BGP can utilize multiple upstream carriers, AS path policies, and MED priority control ； At the transport/application layer, Anycast, LVS, HAProxy, Nginx, or the layer-4/layer-7 load balancing services provided by cloud providers can be used. Combining these approaches enables more flexible traffic distribution and failover.

Common load balancing strategies include: DNS-based Geo-DNS/Weighted DNS for global traffic distribution ； BGP-based traffic engineering (such as AS path preference) is used for link-level switching ； ECMP is suitable for concurrent distribution of equal-cost routes ； Software load balancing is responsible for session persistence, health checks, and application-layer traffic routing.

A sound health inspection and monitoring system is essential. Proactive monitoring of connectivity, latency, packet loss rate, and jitter should be implemented for each CN2 line as well as the backup lines. Automated scripts can be used to adjust BGP priorities or switch load balancing weights via APIs, ensuring smooth migration of services in case of changes in link quality.

To reduce the load on the origin server and improve its resistance to attacks, it is recommended to use CDN acceleration and caching strategies. CDNs can distribute static content to the edge, reducing the number of requests to the origin server ； For dynamic services, separation of static and dynamic components, source-proximity acceleration, and intelligent routing can be used to improve the cross-border access experience.

To counter DDoS attacks, it is necessary to deploy high-level protection and scrubbing capabilities at the network edge. A common approach is to first direct traffic to cleaning nodes or use a CDN with cleaning capabilities, combined with BGP traffic grooming, traffic mirroring, and rate-limiting policies. For critical services, you can choose either on-demand Elastic High Protection or long-term High Protection products.

Practical Example: The primary link uses Hong Kong’s CN2 GIA to connect to the core data center, ensuring low latency. CN2 GT and other international carriers are used as backups, with higher MED values set through BGP ； Inside the server room, Keepalived+HAProxy is used for L4/L7 load balancing, while Anycast DNS and CDN are utilized to enable nearby access worldwide and fault isolation.

In terms of procurement and cost management, it is recommended to use a mixed procurement strategy: For core business operations, purchase high-quality CN2 GIA dedicated lines or priority bandwidth; for non-critical traffic, use CN2 GT or cheaper VPS/cloud servers. At the same time, when purchasing domain name resolution, certificates, and CDN services, pay attention to SLAs and scrubbing capabilities. If necessary, buy on-demand high-security packages to handle sudden traffic spikes.

In terms of operations and maintenance, it is very important to establish SLA monitoring, audit routing changes, and conduct emergency drills. Regularly conduct link switching drills to test the DNS response time, session migration compatibility, and the effectiveness of cleaning strategies. Also, maintain communication with bandwidth providers to quickly allocate resources and adjust routes in case of abnormalities.

If you are considering purchasing Hong Kong CN2 lines, VPS, data center bandwidth, or DDoS protection services, it is recommended to prioritize providers with stable backbone interconnections, a wide range of connection options, and professional operation and maintenance support. For easy rapid deployment and subsequent operation and maintenance, I recommend using Desun Telecom’s line and host products; they are Hong Kong CN2 It offers a comprehensive range of products and technical support for access, CDN acceleration, and advanced DDoS protection, making it a reliable choice for enterprises seeking multi-path load balancing and attack resistance solutions. Contact Desun Telecom immediately for purchase and consultation to complete testing and go live quickly.