- Release Notes and Announcements
- CLB Release Notes
- [April 15, 2024] Domain Name Upgrade for Domain Name-based Public Network CLB
- [July 25, 2023] Adding Rate Limits on Shared CLB Instances
- [July 3, 2023] CLB API Authentication Upgrade
- [June 9, 2023] Adjusting the Grace Period for Pay-as-you-go CLB Instances
- [March 6, 2023] Launching Domain Name-Based Public CLBs
- [Feb. 24, 2023] Changing Health Check Source IP to 100.64.0.0/10 IP Range
- Product Introduction
- Purchase Guide
- Getting Started
- Directions
- CLB Instance
- Directions for Upgrading to Domain Name-Based CLB
- Creating CLB Instances
- Creating an IPv6 CLB Instance
- Creating IPv6 NAT64 CLB Instances
- Configure CLB Forwarding Domain Name
- Configuring CLB Security Group
- Binding Private Network CLB to EIP
- Enabling or Disabling a CLB Instance
- Cloning CLB Instances
- Exporting CLB Instances
- Upgrade to a LCU-supported instances
- Adjusting Specification of LCU-supported CLBs
- Deleting CLB Instances
- Releasing Idle CLB Instances
- Configuring Deletion Protection
- Adjusting Instance Public Network Configurations
- CLB Listener
- CLB Listener Overview
- Configuring TCP Listener
- Configuring a UDP Listener
- Configuring TCP SSL Listener
- Configuring a QUIC Listener
- Configuring an HTTP Listener
- Configuring HTTPS Listener
- Load Balancing Methods
- Session Persistence
- Layer-7 Redirection Configuration
- Layer-7 Custom Configuration
- Layer-7 Domain Name Forwarding and URL Rules
- Using QUIC Protocol on CLB
- SNI Support for Binding Multiple Certificates to a CLB Instance
- Configuring gRPC Support for Layer-7 Protocols
- Real Server
- Health Check
- Certificate Management
- Log Management
- Monitoring and Alarm
- Cloud Access Management
- Classic CLB
- CLB Instance
- Practical Tutorial
- Enabling Gzip Compression & Testing
- HTTPS Forwarding Configurations
- Obtaining Real Client IPs
- Best Practices for Configuring Load Balancing Monitoring Alerts
- Implementing HA Across Multiple AZs
- Load Balancing Algorithm Selection and Weight Configuration Examples
- Configuring WAF protection for CLB listening domain names
- Ops Guide
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Instance APIs
- Listener APIs
- Backend Service APIs
- Target Group APIs
- Redirection APIs
- Other APIs
- DescribeClsLogSet
- CreateLoadBalancerSnatIps
- DeleteLoadBalancerSnatIps
- DescribeLoadBalancerListByCertId
- DescribeQuota
- ModifyLoadBalancersProject
- ReplaceCertForLoadBalancers
- SetLoadBalancerClsLog
- SetLoadBalancerSecurityGroups
- SetLoadBalancerStartStatus
- SetSecurityGroupForLoadbalancers
- CreateClsLogSet
- CreateTopic
- DescribeLoadBalancerTraffic
- DescribeResources
- DescribeTaskStatus
- InquiryPriceCreateLoadBalancer
- InquiryPriceModifyLoadBalancer
- InquiryPriceRenewLoadBalancer
- Classic CLB APIs
- Making API Requests
- Load Balancing APIs
- Data Types
- Error Codes
- CLB API 2017
- FAQs
- Service Level Agreement
- Contact Us
- Glossary
- Release Notes and Announcements
- CLB Release Notes
- [April 15, 2024] Domain Name Upgrade for Domain Name-based Public Network CLB
- [July 25, 2023] Adding Rate Limits on Shared CLB Instances
- [July 3, 2023] CLB API Authentication Upgrade
- [June 9, 2023] Adjusting the Grace Period for Pay-as-you-go CLB Instances
- [March 6, 2023] Launching Domain Name-Based Public CLBs
- [Feb. 24, 2023] Changing Health Check Source IP to 100.64.0.0/10 IP Range
- Product Introduction
- Purchase Guide
- Getting Started
- Directions
- CLB Instance
- Directions for Upgrading to Domain Name-Based CLB
- Creating CLB Instances
- Creating an IPv6 CLB Instance
- Creating IPv6 NAT64 CLB Instances
- Configure CLB Forwarding Domain Name
- Configuring CLB Security Group
- Binding Private Network CLB to EIP
- Enabling or Disabling a CLB Instance
- Cloning CLB Instances
- Exporting CLB Instances
- Upgrade to a LCU-supported instances
- Adjusting Specification of LCU-supported CLBs
- Deleting CLB Instances
- Releasing Idle CLB Instances
- Configuring Deletion Protection
- Adjusting Instance Public Network Configurations
- CLB Listener
- CLB Listener Overview
- Configuring TCP Listener
- Configuring a UDP Listener
- Configuring TCP SSL Listener
- Configuring a QUIC Listener
- Configuring an HTTP Listener
- Configuring HTTPS Listener
- Load Balancing Methods
- Session Persistence
- Layer-7 Redirection Configuration
- Layer-7 Custom Configuration
- Layer-7 Domain Name Forwarding and URL Rules
- Using QUIC Protocol on CLB
- SNI Support for Binding Multiple Certificates to a CLB Instance
- Configuring gRPC Support for Layer-7 Protocols
- Real Server
- Health Check
- Certificate Management
- Log Management
- Monitoring and Alarm
- Cloud Access Management
- Classic CLB
- CLB Instance
- Practical Tutorial
- Enabling Gzip Compression & Testing
- HTTPS Forwarding Configurations
- Obtaining Real Client IPs
- Best Practices for Configuring Load Balancing Monitoring Alerts
- Implementing HA Across Multiple AZs
- Load Balancing Algorithm Selection and Weight Configuration Examples
- Configuring WAF protection for CLB listening domain names
- Ops Guide
- Troubleshooting
- API Documentation
- History
- Introduction
- API Category
- Instance APIs
- Listener APIs
- Backend Service APIs
- Target Group APIs
- Redirection APIs
- Other APIs
- DescribeClsLogSet
- CreateLoadBalancerSnatIps
- DeleteLoadBalancerSnatIps
- DescribeLoadBalancerListByCertId
- DescribeQuota
- ModifyLoadBalancersProject
- ReplaceCertForLoadBalancers
- SetLoadBalancerClsLog
- SetLoadBalancerSecurityGroups
- SetLoadBalancerStartStatus
- SetSecurityGroupForLoadbalancers
- CreateClsLogSet
- CreateTopic
- DescribeLoadBalancerTraffic
- DescribeResources
- DescribeTaskStatus
- InquiryPriceCreateLoadBalancer
- InquiryPriceModifyLoadBalancer
- InquiryPriceRenewLoadBalancer
- Classic CLB APIs
- Making API Requests
- Load Balancing APIs
- Data Types
- Error Codes
- CLB API 2017
- FAQs
- Service Level Agreement
- Contact Us
- Glossary
What is Cloud Load Balancer?
Tencent Cloud Load Balancer (CLB) is a service that distributes traffic to multiple real servers so as to elevate service capabilities of applications and eliminate single points of failure for a higher availability.
CLB virtualizes multiple real servers in the same region into a high-performance and high-availability application service pool by setting a virtual IP address (VIP) and then distributes the network requests from clients to the pool in the manner specified by the applications.
CLB checks the health of real servers in the pool and automatically isolates unhealthy ones, thus resolving single points of failure issues and improving the overall service capabilities of the applications.
Tencent CLB, featuring self-service management, self-service fault repair, and defense against network attacks, is applicable for application scenarios such as enterprises, communities, e-commerce, and games.
Components
A working CLB group usually consists of the following components:
Cloud Load Balancer: A CLB instance used for traffic distribution.
Backend/Real Server: A set of server instances in the backend used for processing requests.
VPC/Classic Network: Overall network environment.
The access requests from outside the CLB are distributed by CLB instances to the real servers for processing based on policies and forwarding rules.
Glossary
Term | Full Name | Description |
CLB | Cloud Load Balancer | A network load balancing service provided by Tencent Cloud, which works with real servers to provide users with TCP/UDP- and HTTP-based load balancing services. |
CLB Listener | Cloud Load Balance Listener | CLB listeners allow you to configure listening ports, load balancing policies, and health check settings. Each listening item corresponds to an application service in the backend. |
RS | Real Server | CLB forwards requests to a group of real server instances for processing based on the rules specified by users. |
How it Works
Basic working principle
A CLB instance receives traffic from clients and routes requests to real servers in one or more availability zones for processing.
The CLB service works primarily by the load balancing listener. The listener monitors the requests on the CLB instance and distributes them to real servers based on policies. The CLB can forward the requests to real servers directly by configuring the Client - CLB and CLB - Real server forwarding protocols and protocol ports.
We recommend that you configure real server instances of CLB across multiple availability zones. This enables CLB to route traffic to healthy instances in other availability zones when one availability zone becomes unavailable, thereby avoiding service interruptions caused by availability zone failures.
Request routing
The client requests to access the service through the domain name. Before the request is sent to the load balancer, the DNS server resolves the CLB domain name and returns the requested CLB IPs to the client. When the CLB listener receives a request, it uses different load balancing algorithms to distribute the request to the real servers. Tencent Cloud currently supports multiple balancing algorithms including weighted round robin and
ip_hash weighted minimum connections.Real server monitoring
A CLB instance can also monitor the running status of real server instances to ensure that traffic is only routed to the normally running instances. The CLB instance will stop routing traffic to an abnormal instance and reroute traffic to it when it is running normally again.
Additional Services
CLB works with the following services to improve application availability and scalability:
Cloud Virtual Machine instance: A virtual server where the application runs on the cloud.
Auto Scaling: Controls the instance quantity elastically. If CLB is enabled in auto scaling, the scaled instance is automatically added to the CLB group, and the terminated instance is automatically removed from the CLB group.
Tencent Cloud Observability Platform: Helps you monitor CLB instances and the running status of all real server instances and performs required operations.
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