Point 2 point IPs between ASes

Wed Jun 28 12:20:57 UTC 2017

You should be using /126 or /127 for point to point links that touch
external networks unless you like extraneous NS messages and full neighbor
cache tables. :)

On Tue, Jun 27, 2017 at 4:36 PM, Job Snijders <job at instituut.net> wrote:

> On Tue, 27 Jun 2017 at 22:29, Krunal Shah <KShah at primustel.ca> wrote:
>
> > Hello,
> >
> > What subnet mask you are people using for point to point IPs between two
> > ASes? Specially with IPv6, We have a transit provider who wants us to use
> > /64 which does not make sense for this purpose. isn’t it recommended to
> use
> > /127 as per RFC 6164 like /30 and /31 are common for IPv4.
>
>
>
> Yes, "longer than /64" subnets are fine for point2point. If the equipment
> on both sides supports RFC 6164 I'd use a /127, otherwise a /126.
>
>
> I was thinking, if someone is using RFC7404 for point to point IP between
> > two ASes and establish BGP over link local addresses. This way you have
> > your own IP space on your router and transit provider does not have to
> > allocate IP space for point to point interface between two ASes. In
> > traceroutes you would see only loopback IP address with GUA assigned from
> > your allocated routable address space. Remotely DDoS to this link isn’t
> > possible this way. Thoughts?
>
>
> I wouldn't use link-local in context of Inter-Domain Routing. Too hard to
> troubleshoot, many networks expect globally unique IP addresses for their
> BGP neighbors, you want to be able to call a NOC and have the IPs function
> as semaphore for the circuit ID.
>
> What you could do is set aside a block which you blackhole or tarpit
> through ingress ACLs, and use linknets from that "globally unusable ip
> space". Some providers can offer you a router2router linknet from such
> unreachable IP space so you don't have to set it apart.
>
> Kind regards,
>
> Job
>
> >
>