Existing TCP streams pinned to old instance after moving Elastic IP to new instance

Question

I am seeing something strange with Elastic IPs.

When moving Elastic IPs between instances, existing TCP streams are not being directed to the new instance. New connections correctly hit the new instance but existing streams seem pinned to the old instance.

Is this expected behavior?

Answer

Yes. In the [docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/elastic-ip-addresses-eip.html):

```
You can disassociate an Elastic IP address from a resource, and then associate it with a different resource. 
To avoid unexpected behavior, ensure that all active connections to the resource named in the 
existing association are closed before you make the change. After you have associated your 
Elastic IP address to a different resource, you can reopen your connections to the newly 
associated resource.
```

Existing TCP streams pinned to old instance after moving Elastic IP to new instance

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