- What's New
- Function Overview
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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
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User Guide
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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
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FAQs
- Popular Questions
-
ELB Use
- Service Abnormality
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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
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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?
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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?
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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
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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
Product Advantages
Advantages of Dedicated Load Balancers
- Robust performance
Each load balancer has exclusive use of isolated resources, meeting your requirements for handling a massive number of requests. A single load balancer deployed in one AZ can handle up to 20 million concurrent connections.
If you deploy a load balancer in multiple AZs, its performance such as the number of new connections and the number of concurrent connections will multiply. For example, if you deploy a dedicated load balancer in two AZs, it can handle up to 40 million concurrent connections.
NOTE:
- If requests are from the Internet, the load balancer in each AZ you select routes the requests based on source IP addresses. If you deploy a load balancer in two AZs, the requests the load balancers can handle will be doubled.
- For requests from a private network:
- If clients are in an AZ you select when you create the load balancer, requests are distributed by the load balancer in this AZ. If the load balancer is unhealthy, requests are distributed by the load balancer in another AZ you select.
If the load balancer is healthy but the connections that the load balancer needs to handle exceed the amount defined in the specifications, service may be interrupted. To address this issue, you need upgrade specifications. You can monitor traffic usage on private network by AZ.
- If clients are in an AZ that is not selected when you create the load balancer, requests are distributed by the load balancer in each AZ you select based on source IP addresses.
- If clients are in an AZ you select when you create the load balancer, requests are distributed by the load balancer in this AZ. If the load balancer is unhealthy, requests are distributed by the load balancer in another AZ you select.
- If requests are from a Direct Connect connection, the load balancer in the same AZ as the Direct Connect connection routes the requests. If the load balancer is unavailable, requests are distributed by the load balancer in another AZ.
- If clients are in a VPC that is different from where the the load balancer works, the load balancer in the AZ where the original VPC subnet resides routes the requests. If the load balancer is unavailable, requests are distributed by the load balancer in another AZ.
- Ultra-high security
ELB supports TLS 1.3 and can route HTTPS requests to backend servers. You can select security policies or customize security policies that fit your security requirements.
- Multiple protocols
ELB supports Quick UDP Internet Connection (QUIC), TCP, UDP, HTTP, and HTTPS, so that they can route requests to different types of applications.
- High flexibility
ELB can route requests based on their content, such as the request method, header, URL, path, and source IP address. They can also redirect requests to another listener or URL, or return a fixed response to the clients.
- No limits
ELB can route requests to both servers on the cloud and on premises, allowing you to leverage cloud resources to handle burst traffic.
- Ease-of-use
ELB provides a diverse set of algorithms that allow you to configure different traffic routing policies to meet your requirements while keeping deployments simple.
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