Feature Comparison Details

Protocols

**Table 1** Protocols supported by each load balancer type
Protocol	Description	Dedicated Load Balancer	Shared Load Balancer
TCP/UDP (Layer 4)	After receiving TCP or UDP requests from the clients, the load balancer directly routes the requests to backend servers. Load balancing at Layer 4 features high routing efficiency.	√	√
HTTP/HTTPS (Layer 7)	After receiving an access request, the listener needs to identify the request and forward data based on the fields in the HTTP/HTTPS packet header. Load balancing at Layer 7 provides some advanced features such as encrypted transmission and cookie-based sticky sessions.	√	√
HTTPS support	HTTPS can be used as both the frontend and backend protocol.	√	x
QUIC	If you use UDP and QUIC as the frontend protocol, you can select QUIC as the backend protocol, and select the connection ID algorithm to route requests with the same connection ID to the same backend server. QUIC has the advantages of low latency, high reliability, and no head-of-line blocking (HOL blocking), and is very suitable for the mobile Internet. No new connections need to be established when you switch between a Wi-Fi network and a mobile network.	√	x
HTTP/2	Hypertext Transfer Protocol 2.0 (HTTP/2) is a new version of the HTTP protocol. It is compatible with HTTP/1.X and provides improved performance and security. Only HTTPS listeners support this feature.	√	√
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.	√	√

Network Configurations

**Table 2** Network configuration comparison
Feature	Description	Dedicated Load Balancer	Shared Load Balancer
Public IPv4 network	The load balancer routes requests from the clients to backend servers over the Internet.	√	√
Private IPv4 network	The load balancer routes requests from the clients to backend servers in a VPC.	√	√
IPv6 network	Load balancers can route requests from IPv6 clients.	√	x
Changing a private IPv4 address	You can change the private IPv4 address into another one in the current subnet or other subnets.	√	x
Binding or unbinding an EIP	You can bind an EIP to a load balancer or unbind the EIP from a load balancer based on service requirements.	√	√
Modifying the bandwidth	You can change the bandwidth of public network load balancers as required.	√	√

Key Features of Listeners

**Table 3** Comparison of key features
Feature	Description	Dedicated Load Balancer	Shared Load Balancer
Access Control	You can add IP addresses to a whitelist or blacklist to control access to a listener. A whitelist allows specified IP addresses to access the listener. A blacklist denies access from specified IP addresses.	√	√
Mutual Authentication	This feature allows the clients and the load balancer to authenticate each other. Only authenticated clients will be allowed to access the load balancer. Mutual authentication is supported only by HTTPS listeners.	√	√
SNI	Server Name Indication (SNI) is an extension to TLS and is used when a server uses multiple domain names and certificates. After SNI is enabled, certificates corresponding to the domain names are required. SNI can be enabled only for HTTPS listeners.	√	√
Transfer Client IP Address	This feature allows backend servers to obtain the real IP addresses of the clients. This feature is enabled for dedicated load balancers by default and cannot be disabled.	√	√
Advanced features of HTTP/HTTPS listeners
Default Security Policy	Allows you to select appropriate security policies to improve service security when you add HTTPS listeners. A security policy is a combination of TLS protocols and cipher suites.	√	√
Custom Security Policy	Allows you to select a TLS protocol and cipher suite to custom a security policy when you add HTTPS listeners.	√	x
Transfer Load Balancer EIP	Allows you to store the EIP bound to the load balancer in the X-Forwarded-ELB-IP header and pass it to backend servers.	√	√

Forwarding Capabilities

You can add forwarding policies to HTTP or HTTPS listeners to forward requests to different backend server groups. Advanced forwarding policies are available only for dedicated load balancers.

You can set forwarding rules and actions for a forwarding policy. For details, see Table 4 and Table 5.

**Table 4** Forwarding rules supported by each load balancer type
Forwarding Rule	Description	Dedicated Load Balancer	Shared Load Balancer
Domain name	Route requests based on the domain name. The domain name in the request must exactly match that in the forwarding policy.	√	√
URL	Route requests based on the URLs. There are three URL matching rules: exact match, prefix match, and regular expression match.	√	√
HTTP request method	Route requests based on the HTTP method. The options include GET, POST, PUT, DELETE, PATCH, HEAD, and OPTIONS.	√	x
HTTP header	Route requests based on the HTTP header. An HTTP header consists of a key and one or more values. You need to configure the key and values separately.	√	x
Query string	Route requests based on the query string.	√	x
CIDR block	Route requests based on source IP addresses from where the requests originate.	√	x

**Table 5** Actions supported by each load balancer type
Action	Description	Dedicated Load Balancer	Shared Load Balancer
Forward to a backend server group	Forward requests to the specified backend server group.	√	√
Redirect to another listener	Redirect requests to an HTTPS listener, which then routes the requests to its associated backend server group.	√	x
Redirect to another URL	Redirect requests to the configured URL. When clients access website A, the load balancer returns 302 or any other 3xx status code and automatically redirects the clients to website B. You can custom the redirection URL that will be returned to the clients.	√	x
Return a specific response body	Return a fixed response to the clients. You can custom the status code and response body that load balancers directly return to the clients without the need to route the requests to backend servers.	√	x

Key Features of Backend Server Groups

**Table 6** Key features supported by each load balancer type
Key Feature	Description	Dedicated Load Balancer	Shared Load Balancer
Health check	ELB periodically sends requests to backend servers to check their running statuses. This process is called health check. You can perform health checks to determine whether a backend server is available.	√	√
Sticky session	Requests from the same client will be routed to the same backend server during the session.	√	√
Slow start	The load balancer linearly increases the proportion of requests to the new backend servers added to the backend server group. Slow start gives applications time to warm up and respond to requests with optimal performance.	√	x
Active/Standby forwarding	The load balancer routes the traffic to the active server if it works normally and to the standby server if the active server becomes unhealthy. You must add two backend servers to the backend server group, one acting as the active server and the other as the standby server.	√	x

Load Balancing Algorithms

**Table 7** Load balancing algorithm comparison
Load Balancing Algorithm	Description	Dedicated Load Balancer	Shared Load Balancer
Weighted round robin	Route requests to backend servers using the round robin algorithm. Backend servers with higher weights receive proportionately more requests, whereas equal-weighted servers receive the same number of requests.	√	√
Weighted least connections	Route requests to backend servers with the smallest ratio (current connections divided by weight).	√	√
Source IP hash	Route requests from the same client to the same backend server within a period of time.	√	√
Connection ID	Calculate the source IP address of each request using the consistent hashing algorithm to obtain a unique hash key and route the requests to the particular server based on the generated key.	√	x

Backend Server Type

**Table 8** Supported backend server types
Backend Server Type	Description	Dedicated Load Balancer	Shared Load Balancer
IP as backend server	You can add servers in a peer VPC, in a VPC that is in another region and connected through a cloud connection, or in an on-premises data center at the other end of a Direct Connect or VPN connection, by using the server IP addresses.	√	x
Supplementary network interface	You can attach supplementary network interfaces to backend servers.	√	x
ECS	You can use load balancers to distribute incoming traffic across ECSs.	√	√
BMS	You can use load balancers to distribute incoming traffic across BMSs.	√	√
CCE Turbo cluster	You can use load balancers to distribute incoming traffic across CCE Turbo clusters. For details, see the Cloud Container Engine User Guide.	√	√