On Thu, Jul 29, 2021 at 4:58 PM Joe Maimon <jmaimon@jmaimon.com> wrote:


Vimal wrote:
> (Unsure if this is the right forum to ask this question, but here goes:)
>
> From what I understand, IP Anycast can be used to steer traffic into a
> server that's close to the client.
>
> I am curious if anyone here has/encountered a setup where they use
> anycast IP on their gateways... to have a predictable egress IP for
> their traffic, regardless of where they are located?
>
> For example, a search engine crawler could in principle have the same
> IP advertised all over the world, but it looks like they don't...  I
> wonder why?
>
> --
> Vimal
>
Its definitely possible, but would need a layer of software (kernel
mode) on all the anycast holders synchronizing state to ensure
asymmetric replies/connections get forwarded/shifted to the correct host.


is it actually that hard? isn't it more like:
  "use an outbound path local to that inbound path cone which NAT's (or proxy's or...) to a small set of staticlly assigned addresses"

Provided you don't re-use the outbound addresses on different deployments  this should 'just work'[tm]

'anycast but outbound' is really: "get me local nat pools for my service by locality"
I think this is, bascially, what every enterprise network in the world does, effectively.


If the goals are worth that kind of effort is another question. And
performance is likely to be "tricky".