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 <j...@instituut.net> wrote: > On Tue, 27 Jun 2017 at 22:29, Krunal Shah <ks...@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 > > > >
