AWS Elastic IP architecture

Blair Trosper blair.trosper at
Thu May 28 17:14:12 UTC 2015

I can tell you that EC2 Classic and VPC EIPs come from separate
netblocks...if that gives you any hints whatsoever.

There's no crossover between the two platforms in IP space.

On Thu, May 28, 2015 at 12:08 PM, Christopher Morrow <
morrowc.lists at> wrote:

> On Thu, May 28, 2015 at 11:44 AM, Luan Nguyen (CBU)
> <luan.nguyen at> wrote:
> > What I am trying to get at is yeah, you still need the l2 extension
> > encapsulation, but on top you need something for disaster recovery,
> machines
> > mobility between data centers, sort of like Vshield Edge using NAT – you
> can
> probably what the vm mobilty looks like is a change in the L2 path,
> right? why make it anymore complicated than that? inside a single
> availability domain I would expect the L2 domain a vm sees doesn't
> change, even if the VM itself is moved from physical machine to
> physical machine.
> making it more complex at the vm level is probably a bunch of work
> that doesn't have to happen.
> > change the NAT pool and update the DNS record, but the internal would
> remain
> that sounds like a bunch of work though, which I don't think is really
> necessary. I'm just a plumber, though so I don't actually know what
> anyone does with this stuff.
> > the same no matter where you move it to. LISP seems like a simple
> > solution…so as specific host route injection, which for enterprise
> shouldn’t
> lisp wasn't really finalized (still sort of isn't) when aws/ec2
> started going like gang busters. They might have changed technology
> under the hood, but it doesn't seem like they would have had to (not
> in a drastic 'change encap type' sort of way at least).
> > be much of a problem, but DRaaS cloud provider, this could ballooning the
> > routing table pretty quickly.
> how so? does the external and internal view from the vm have to be the
> same? do the public /32's have to be individually routed ? inside what
> scope at the datacenter?
> > What does Google use? :)
> no idea, probably rabbits with different colored carrots?

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