• Elastic Load Balancing

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  5. Differences Between Classic and Enhanced Load Balancers

Differences Between Classic and Enhanced Load Balancers

ELB provides two types of load balancers: classic load balancer and enhanced load balancer. You can select an appropriate type based on application scenarios and service requirements.

  • Classic load balancers are applicable to web services with low access traffic and simple application models.
  • Enhanced load balancers are good choices for web services with high access traffic. They forward the requests based on domain names or URLs, making request routing more flexible.

    Enhanced load balancers provide comprehensive Layer 7 load balancing capabilities and more powerful forwarding performance. Classic and enhanced load balancers feature differently. Table 1 lists the comparisons.

Table 1 Feature comparisons


Classic Load Balancer

Enhanced Load Balancer

Public and private network load balancing

Layer 4 (TCP or UDP) and Layer 7 load balancing (HTTP or HTTPS)

√ (UDP not supported for private network load balancers)

Load balancing algorithm (round robin, least connections, and source IP hash)

Sticky session

WebSocket protocol

Forwarding based on domain name and URL

Elastic Cloud Servers (ECSs) as backend servers

Access control (whitelist)

Standard OpenStack APIs

Bare Metal Servers (BMSs) as backend servers

SNI for certificates

SSL protocol and SSL encryption algorithms

SSL protocol

OBS storage for access logs

Weight assigned for ECSs

Certificate content modification

Mutual authentication