AWS Elastic IP architecture

Michael Helmeste elf at
Thu May 28 15:59:57 UTC 2015

> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at] On Behalf Of Christopher
> Morrow
> Subject: Re: AWS Elastic IP architecture
> [...]
> i sort of doesn't matter right? it is PROBABLY some form of encapsulation
> (like gre, ip-in-ip, lisp, mpls, vpls, etc) ...
> [...]

I don't know how the public blocks get to the datacenter (e.g. whether they are using MPLS) but after that I think it is pretty straightforward. All of the VMs have only one IPv4 address assigned out of 10/8. This doesn't change when you attach an Elastic IP to them.

All that is happening is that they have some NAT device somewhere (maybe even just a redundant pair of VMs?) that has a block of public IPs assigned to it and they are static NAT'ing the Elastic IP to the VM. They control the allocation of the Elastic IPs, so they just pick one that is routed out of that datacenter already. They probably don't need to do anything out of the ordinary to get it there.

(See: )

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