AWS Network Load Balancer (NLB) now supports Amazon Application Recovery Controller’s zonal shift and zonal autoshift features on load balancers that are enabled across zones. Zonal shift allows you to quickly shift traffic away from an impaired Availability Zone (AZ) and recover from events such as bad application deployment and gray failures. Zonal autoshift safely and automatically shifts your traffic away from an AZ when AWS identifies potential impact to it.
Enabling cross-zone on NLBs is a popular configuration for customers that require an even distribution of traffic across application targets in multiple AZs. With this launch, customers can shift traffic away from an AZ in the event of a failure just like they are able to for cross-zone disabled load balancers. When zonal shift or autoshift is triggered, the NLB will block all traffic to targets in the AZ that is impacted. You can configure this feature in two steps: First, enable configuration to allow zonal shift to act on your load balancer(s) using the NLB console or API. Second, trigger zonal shift or enable zonal autoshift for the chosen NLBs via Amazon Application Recovery Controller console or API.
Zonal shift and zonal autoshift support on NLB is available in all commercial AWS Regions, including the AWS GovCloud (US) Regions. To learn more, please refer to the NLB zonal shift documentation.
Source:: Amazon AWS