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  • I have an internet-facing ALB in VPC1 and an internal NLB in VPC2
  • The NLB is pointed at an ECS service and health-checks are healthy
  • The ECS Task Security Group allows traffic from VPC1 CIDR as well
  • The ALB has an IP target group with the NLB's local IPs registered
  • There is an active VPC Peering Connection between the VPCs
  • There is a Route Table entry on both of VPC1's subnets to route VPC2's CIDR to the peering connection
  • VPC2's default security group also has traffic from VPC1 allowed
  • All NACLs are set to allow all traffic

I can hit the ALB fine but I cannot hit the NLB. The ALB target group targets (the two NLB IPs) show as unhealthy.

Is this possible? As far as I can tell the AWS docs say it is. If it is, where is my misconfiguration likely to be?

codeself
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1 Answers1

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The issue in my case was that while I did set up the route table on VPC1's subnets to send traffic to VPC2, I did not do the reverse of that in VPC2, so the services couldn't respond back.

codeself
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