Re: IPv4 smaller than /24 leasing?

[William Herrin <bill () herrin us>]

On Thu, Jan 4, 2018 at 2:16 PM, Job Snijders <job () instituut net> wrote:

> On Thu, 4 Jan 2018 at 20:13, Filip Hruska <fhr () fhrnet eu> wrote:
> > I thought that the smallest prefix size one could get routed globally is
> > /24? So how does this work?
> Probably with GRE, IPIP or OpenVPN tunnels.

Hi Flip, Job:

With the cooperation of your local ISP, it's possible to get clever about
this.

If your ISP sets its filter to allow it, you can send packets from the /27
directly without having to transit the GRE tunnel. So, half the path has no
latency hit at all.

The tunnel ingress which takes the /24 off the Internet and sends the /27
to you does not have to be a single node in a single location. GRE and IPIP
both support stateless multipoint tunnels where they can receive packets
from multiple sources. The /24 can be anycasted from multiple nodes around
the world allowing near-optimal routing from most origins.

Regards,
Bill Herrin

-- 
William Herrin ................ herrin () dirtside com  bill () herrin us
Dirtside Systems ......... Web: <http://www.dirtside.com/>