After you create an Edge Load Balancer (ELB) instance, you must add a listener to the instance, configure a health check, and distribute traffic to multiple backend Edge Node Service (ENS) instances based on listener policies.

ELB provides TCP and UDP listeners for Layer 4 load balancing and HTTP and HTTPS listeners for Layer 7 load balancing. The following table describes the features and use scenarios of the preceding listeners.

Listener typeScenario
Configure a TCP listenerSuitable for scenarios in which reliability and data accuracy are prioritized over transmission speed. These scenarios include file transmission, email sending and receiving, and remote logons.
Configure a UDP listenerSuitable for scenarios in which real-time transmission is more important than reliability, such as video chat and real-time financial market pushes.
Configure an HTTP or HTTPS listener
  • Suitable for applications that require identification of data content, such as web applications and mobile games.
  • Suitable for applications that require encrypted data transmission.
Health checkELB performs health checks to check the availability of backend ENS instances. The health check feature improves overall service availability and reduces the impact of backend server failures.