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- What's New
- Function Overview
-
Service Overview
- What Is ELB?
- Product Advantages
- How ELB Works
- Application Scenarios
- Differences Between Dedicated and Shared Load Balancers
- Load Balancing on a Public or Private Network
- Network Traffic Paths
- Specifications of Dedicated Load Balancers
- Quotas and Constraints
- Billing (Dedicated Load Balancers)
- Permissions
- Product Concepts
- How ELB Works with Other Services
- Change History
- Getting Started
-
User Guide
-
Load Balancer
- Overview
- Preparations for Creating a Load Balancer
- Creating a Dedicated Load Balancer
- Creating a Shared Load Balancer
- Modifying the Bandwidth
- Changing the Specifications of a Dedicated Load Balancer
- Changing an IP Address
- Binding an IP Address to or Unbinding an IP Address from a Load Balancer
- Adding to or Removing from an IPv6 Shared Bandwidth
- Enabling or Disabling a Load Balancer
- Exporting the Load Balancer List
- Deleting a Load Balancer
- Listener
- Advanced Features of HTTP/HTTPS Listeners
- Backend Server Group
- Backend Server (Dedicated Load Balancers)
- Backend Server (Shared Load Balancers)
- Certificate
- Access Control
- TLS Security Policy
- Tag
- Access Logging
- Monitoring
- Auditing
- Permissions Management
- Quotas
- Appendix
- Change History
-
Load Balancer
- Best Practices
-
API Reference
- Before You Start
- API Overview
- Calling APIs
- APIs (V3)
- Examples
- Permissions and Supported Actions
- Appendix
- SDK Reference
-
FAQs
- Popular Questions
-
ELB Use
- Service Abnormality
-
ELB Functionality
- Can ELB Be Used Separately?
- Does ELB Support Persistent Connections?
- Does ELB Support FTP on Backend Servers?
- Can ELB Block DDoS Attacks and Secure Web Code?
- Is an EIP Assigned Exclusively to a Load Balancer?
- How Many Load Balancers and Listeners Can I Have?
- What Types of APIs Does ELB Provide? What Are Permissions of ELB?
- Can I Adjust the Number of Backend Servers When a Load Balancer is Running?
- Can Backend Servers Run Different OSs?
- Can I Configure Different Backend Ports for a Load Balancer?
- Are There Any Restrictions on the Frequency of Access from an IP Address?
- Can ELB Be Used Across Accounts or VPCs?
- Can Backend Servers Access the Ports of a Load Balancer?
- Can I Bind a Public IP Address Purchased from a Third-Party Cloud Provider to My Load Balancer?
- Can Both the Listener and Backend Server Group Use HTTPS?
- Can I Change the VPC and Subnet for My Load Balancer?
- Does ELB Support IPv6 Networks?
- Load Balancing Performance
-
Load Balancers
- What Is Quota?
- How Does ELB Distribute Traffic?
- How Can I Access a Load Balancer Across VPCs?
- How Can I Configure Load Balancing for Containerized Applications?
- Why Can't I Delete My Load Balancer?
- Do I Need to Configure Bandwidth for My Load Balancers?
- Can I Bind Multiple EIPs to a Load Balancer?
- Why Multiple IP Addresses Are Required When I Create or Enable a Load Balancer?
- Why Are Requests from the Same IP Address Routed to Different Backend Servers When the Load Balancing Algorithm Is Source IP Hash?
- Can Backend Servers Access the Internet Using the EIP of the Load Balancer?
- Will Traffic Routing Be Interrupted If the Load Balancing Algorithm Is Changed?
- What Is the Difference Between the Bandwidth Included in Each Specification of a Dedicated Load Balancer and the Bandwidth of an EIP?
- How Do I Combine ELB and WAF?
-
Listeners
- What Are the Relationships Between Load Balancing Algorithms and Sticky Session Types?
- Can I Bind Multiple Certificates to a Listener?
- Do HTTP and HTTP Listeners Support the X-Forwarded-Host Header?
- Will ELB Stop Distributing Traffic Immediately After a Listener Is Deleted?
- Does ELB Have Restrictions on the File Upload Speed and Size?
- Can Multiple Load Balancers Route Requests to One Backend Server?
- How Is WebSocket Used?
- What Are the Three Timeouts of a Listener and What Are the Default Durations?
- Why Can't I Select the Target Backend Server Group When Adding or Modifying a Listener?
- Why Cannot I Add a Listener to a Dedicated Load Balancer?
-
Backend Servers
- Why Is the Interval at Which Backend Servers Receive Health Check Packets Different from What I Have Configured?
- Can Backend Servers Access the Internet After They Are Associated with a Load Balancer?
- Can ELB Distribute Traffic Across Servers That Are Not Provided by Huawei Cloud?
- Can ELB Route Traffic Across Regions?
- Does Each Backend Server Need an EIP to Receive Requests from a Public Network Load Balancer?
- How Do I Check the Network Conditions of a Backend Server?
- How Can I Check the Network Configuration of a Backend Server?
- How Do I Check the Status of a Backend Server?
- How Long Is the Timeout Duration of Connections Between a Load Balancer and Backend Servers?
- When Is a Backend Server Considered Healthy?
- How Do I Check Whether a Backend Server Can Be Accessed Through an EIP?
- Why Is the Number of Active Connections Monitored by Cloud Eye Different from the Number of Connections Established with the Backend Servers?
- Why Can I Access Backend Servers After a Whitelist Is Configured?
- When Will Modified Weights Take Effect?
- How Much Time Is Required for a Load Balancer to Disconnect from Backend Servers After The Servers Are Removed?
- Why Must the Subnet Where the Load Balancer Resides Have at Least 16 Available IP Addresses for Enabling IP as a Backend?
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Health Checks
- How Do I Troubleshoot an Unhealthy Backend Server?
- Why Is the Interval at Which Backend Servers Receive Health Check Packets Different from the Configured Interval?
- How Does ELB Perform UDP Health Checks? What Are the Precautions for UDP Health Checks?
- Why Does ELB Frequently Send Requests to Backend Servers During Health Checks?
- When Does a Health Check Start?
- Do Maximum Retries Include Health Checks That Consider Backend Servers Unhealthy?
- What Do I Do If a Lot of Access Logs Are Generated During Health Checks?
- What Status Codes Will Be Returned If Backend Servers Are Identified as Healthy?
- Obtaining Source IP Addresses
-
HTTP/HTTPS Listeners
- Which Protocol Should I Select for the Backend Server Group When Adding an HTTPS Listener?
- Why Is There a Security Warning After a Certificate Is Configured?
- Why Is a Forwarding Policy in the Faulty State?
- Why Can't I Add a Forwarding Policy to a Listener?
- Why Cannot I Select an Existing Backend Server Group When Adding a Forwarding Policy?
- Sticky Sessions
- Certificates
- Monitoring
- Billing
- Videos
Show all
Basic Concepts
Term |
Definition |
---|---|
Load balancer |
A load balancer distributes incoming traffic across backend servers. |
Listener |
A listener listens on requests from clients and routes the requests to backend servers based on the settings that you configure when you add the listener. |
Backend server |
A backend server is a cloud server added to a backend server group associated with a load balancer. When you add a listener to a load balancer, you can create or select a backend server group to receive requests from the load balancer by using the port and protocol you specify for the backend server group and the load balancing algorithm you select. |
Backend server group |
A backend server group is a collection of cloud servers that have same features. When you add a listener, you select a load balancing algorithm and create or select a backend server group. Incoming traffic is routed to the corresponding backend server group based on the listener's configuration. |
Health check |
ELB periodically sends requests to backend servers to check whether they can process requests. If a backend server is detected as unhealthy, the load balancer stops routing requests to it. After the backend server recovers, the load balancer will resume routing requests to it. |
Redirect |
HTTPS is an extension of HTTP. HTTPS encrypts data between a web server and a browser. |
Sticky session |
Sticky sessions ensure that requests from a client always get routed to the same backend server before a session elapses. |
WebSocket |
WebSocket is a new HTML5 protocol that provides full-duplex communication between the browser and the server. WebSocket saves server resources and bandwidth, and enables real-time communication. Both WebSocket and HTTP depend on TCP to transmit data. A handshake connection is required between the browser and server, so that they can communicate with each other only after the connection is established. However, as a bidirectional communication protocol, WebSocket is different from HTTP. After the handshake succeeds, both the server and browser (or client agent) can actively send data to or receive data from each other. |
SNI |
SNI, an extension to Transport Layer Security (TLS), enables a server to present multiple certificates on the same IP address and port number. SNI allows the client to indicate the domain name of the website while sending an SSL handshake request. Once receiving the request, the load balancer queries the right certificate based on the hostname or domain name and returns the certificate to the client. If no certificate is found, the load balancer will return the default certificate. |
Persistent connection |
A persistent connection allows multiple data packets to be sent continuously over a TCP connection. If no data packet is sent during the connection, the client and server send link detection packets to each other to maintain the connection. |
Short connection |
A short connection is a connection established when data is exchanged between the client and server and immediately closed after the data is sent. |
Concurrent connection |
Concurrent connections are total number of TCP connections initiated by clients and routed to backend servers by a load balancer per second. |
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