Cloud Load Balancer

A secure, stable and elastically scalable traffic distribution service.


Tencent Cloud Cloud Load Balancer (CLB) is a secure and fast traffic distribution service. Inbound traffic can be automatically distributed to multiple Cloud Virtual Machine (CVM) instances in the cloud via CLB, improving service capabilities systematically and eliminating single points of failure. CLB supports hundreds of millions of connections and tens of millions of concurrent requests, making it easy to handle high-traffic access and meet demanding business needs.


High Performance

One single CLB cluster (not one instance) supports up to 120 million concurrent connections and can handle up to 40 Gbps of traffic bandwidth or process 6 million data packets per second. This enables you to easily sustain ecommerce websites, social networking platforms and gaming businesses with over 10 million daily page views.

High Availability

One CLB cluster consists of 4 physical servers, offering an availability of up to 99.95%. In the extreme case where only one CLB instance is available, it can still support over 30 million concurrent connections. The cluster system will remove faulty instances in time and keep the healthy ones to ensure that the backend server continues to operate properly.

Elastic Scalability

The CLB cluster scales the service capabilities of the application system elastically according to the business load, and automatically creates and releases CVM instances through the dynamic scaling group of Auto Scaling. These features, in conjunction with a dynamic monitoring system and a billing system that is accurate to the second, eliminate your need to manually intervene or estimate resource requirements, helping you reasonably allocate computing resources and prevent resource waste.

Security and Stability

With the aid of BGP Anti-DDoS system, CLB is capable of defending against most network attacks (such as DDoS, CC and web intrusion attacks) and cleansing attacking traffic in a matter of seconds, which greatly avoids the occurrence of blocked IPs and full occupancy of bandwidth. CLB's built-in synproxy anti-attack mechanism prevents backend CVMs from being attacked and overloaded before BGP system takes effect, ensuring the data security and stability.

Low Costs

CLB eliminates your need to invest in additional load balancing hardware and time devoted to tedious OPS work, saving you up to 99% of hardware and labor costs. CLB is billed on a pay-as-you-go basis. You only pay for what you use, and you can create and terminate CLB instances at any time according to the business needs.


CLB automatically distributes the access traffic of an application among multiple CVM instances to improve access fluency and fault tolerance of the application.
Multi-protocol Forwarding

CLB supports requests from layer 4 protocols (including TCP and UDP) and layer 7 protocols (including HTTP and HTTPS). Its centralized certificate management system supports HTTPS protocol, making data transfer faster, more secure and more reliable.


Professional Scenario

Business Type

- The business has obvious peaks and valleys, and business stability and low costs is desired

Scenario Description

- The business goes through significant peaks and troughs, and require flexible control of backend resources.

The business has requirements that are highly time-sensitive. For example, during ecommerce promotion campaigns, web page views may increase by over 10 times in a few hours, and a large number of backend CVMs need to be added when visitor quantity surges. When the traffic drops, the unnecessary CVMs needs to be terminated. CLB can be used to distribute traffic to the business systems, which helps flexibly enhance the service capabilities of the application systems and elastically adjust the backend resources in real time.

- The business has high peak traffic, and needs to build a low-cost architecture.

When a business has high peak traffic, using traditional hardware to build a cluster will be very costly and require tedious OPS work. CLB can work together with the Cloud Monitor to effectively deal with high peak traffic and reduce deployment costs, relieving you from hardware OPS duties and allowing you to focus on developing product features.

Separation Scenario

Business Type

- The business has complex modules and requires separation of dynamic and static services

Scenario Description

- The business requires separation of dynamic and static services and flexible forwarding

When the number of requests is high, targeted distribution of requests to the website can be achieved by differentiating the static and dynamic requests, effectively reducing the backend load pressure. The dynamic requests can be processed by separately deployed CLB and associated backend CVM clusters, while the static content can be connected to CDN and optimized by COS to significantly improve the loading speed.

Hybrid Cloud Scenario

Business Type

- The website or business requires data interconnection

Scenario Description

- The business requires content-based routing and forwarding for IP convergence

A large website generally has hundreds of business modules. CLB can analyze HTTP headers by setting different forwarding rules or groups to separate the business modules and achieve content-based routing and forwarding. In addition, custom forwarding paths can be used instead of second-level domain names to reduce the number of DNS polls, converge IP and improve the service accessing speed.

- Direct Connect- hybrid cloud solution achieves stable data transfer and flexible migration

With Tencent Cloud's hybrid cloud solution, the core internal systems and data of the business can be stored in the user-built IDC, and the services can be deployed in the cloud to cope with the surge in user traffic. The stability and speed of in/off-cloud data transfer is ensured by Direct Connect to guarantee data consistency. In addition, the business can be gradually migrated to the cloud through flexible weight configuration, and combined with the data transfer through Direct Connect, an elastic, fast, reliable and low-cost business deployment is easily achieved.


CLB fees consist of instance fees and bandwidth fees generated on real servers. For bill-by-CVM accounts, CLB instance fees are pay-as-you-go and settled daily (24 hours); bandwidth can be purchased with CVMs. Bill-by-IP accounts support two billing modes: monthly subscription and pay-as-you-go. For more information, see Billing Overview.