[EKS] [request]: multicast support

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**Tell us about your request**
Multicast support on EKS, specifically in the VPC-CNI.

**Which service(s) is this request for?**
EKS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We would like to publish and subscribe for multicast traffic in our EKS cluster without having to use host networking.

**Are you currently working around this issue?**
Using host networking, which sucks :/

**Additional context**
We tried multus and macvlan but that didn't work as AWS VPC doesn't like macvlan.

**Attachments**
Nothing.

Start by understanding EKS networking and the VPC-CNI, then review the reported multus and macvlan workarounds and their limitations. The requested outcome is multicast publish/subscribe within an EKS cluster without host networking; the issue names no source files, tests, or implementation entry point.

Written by the indexing model from the issue text.