AWS Elastic IP architecture

Owen DeLong owen at
Sun May 31 17:57:41 UTC 2015


IPv6 has huge utility.

AWS’ implementation of IPv6 is brain-dead and mostly useless for most applications.

I think if you will review my track record over the last 5+ years, you will plainly see that I am fully aware of the utility and need for IPv6. <>

My network (AS1734) is fully dual-stacked, unlike AWS.

If AWS is so convinced of the utility of IPv6, why do they continue to refuse to do a real implementation that provides IPv6 capabilities to users of their current architecture.

Currently, on AWS, the only IPv6 is via ELB for classic EC2 hosts. You cannot put a native IPv6 address on an AWS virtual server at all (EC2 or VPC). Unless your application is satisfied by running an IPv4-only web server which has an IPv6 VIP proxy in front of it with some extra headers added by the proxy to help you parse out the actual source address of the connection, then your application cannot use IPv6 on AWS.

As such, I stand by my statement that there is effectively no meaningful support for IPv6 in AWS, period.

AWS may disagree and think that ELB for classic EC2 is somehow meaningful, but their lack of other support for any of their modern architectures and the fact that they are in the process of phasing out classic EC2 makes me think that’s a pretty hard case to make.


> On May 31, 2015, at 9:01 AM, Blair Trosper <blair.trosper at> wrote:
> Disagree, and so does AWS.  IPv6 has a huge utility:  being a universal, inter-region management network (a network that unites traffic between regions on public and private netblocks).   Plus, at least the CDN and ELBs should be dual-stack, since more and more ISPs are turning on IPv6.
> On Sun, May 31, 2015 at 8:40 AM, Owen DeLong <owen at <mailto:owen at>> wrote:
> I wasn’t being specific about VPC vs. Classic.
> The support for IPv6 in Classic is extremely limited and basically useless for 99+% of applications.
> I would argue that there is, therefore, effectively no meaningful support for IPv6 in AWS, period.
> What you describe below seems to me that it would only make the situation I described worse, not better in the VPC world.
> Owen
> > On May 31, 2015, at 4:23 AM, Andras Toth <diosbejgli at <mailto:diosbejgli at>> wrote:
> >
> > Congratulations for missing the point Matt, when I sent my email
> > (which by the way went for moderation) there wasn't a discussion about
> > Classic vs VPC yet. The discussion was "no ipv6 in AWS" which is not
> > true as I mentioned in my previous email. I did not state it works
> > everywhere, but it does work.
> >
> > In fact as Owen mentioned the following, I assumed he is talking about
> > Classic because this statement is only true there. In VPC you can
> > define your own IP subnets and it can overlap with other customers, so
> > basically everyone can have their own <> for example.
> > "They are known to be running multiple copies of RFC-1918 in disparate
> > localities already. In terms of scale, modulo the nightmare that must
> > make of their management network and the fragility of what happens
> > when company A in datacenter A wants to talk to company A in
> > datacenter B and they both have the same 10-NET addresses"
> >
> > Andras
> >
> >
> > On Sun, May 31, 2015 at 7:18 PM, Matt Palmer <mpalmer at <mailto:mpalmer at>> wrote:
> >> On Sun, May 31, 2015 at 01:38:05AM +1000, Andras Toth wrote:
> >>> Perhaps if that energy which was spent on raging, instead was spent on
> >>> a Google search, then all those words would've been unnecessary.
> >>>
> >>> Official documentation:
> >>> <>
> >>
> >> Congratulations, you've managed to find exactly the same info as Owen
> >> already covered:
> >>
> >> "Load balancers in a VPC support IPv4 addresses only."
> >>
> >> and
> >>
> >> "Load balancers in EC2-Classic support both IPv4 and IPv6 addresses."
> >>
> >> - Matt
> >>

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