IPv6 Loopback/Point-to-Point address allocation

Owen DeLong owen at delong.com
Mon Sep 11 18:53:05 UTC 2017


> On Sep 9, 2017, at 12:06 PM, Kody Vicknair <kvicknair at reservetele.com> wrote:
> 
> All,
> 
> I’ve been doing some reading in preparation of IPv6 deployment and figuring out how we will break up our /32. I think I’m on the right track in thinking that each customer will be allocated a /48 to do whatever they wish with it.

Yes, please. If it turns out a /32 isn’t enough space to do this, then a /32 is too small for your network and you should trade it for a larger block.

> I’ve read recent BCOP drafts that have been approved by the IETF:
> https://www.ripe.net/publications/docs/ripe-554
> It looks like the smallest subnet that should ever be assigned is a /64 on a particular link.
> 
> 
> Some questions that come to mind with IPv6:
> 
> In regards to Point to point links my thinking is this:
> Assign a unique /64 to each point to point link with these addresses being Globally routable. This seems to be what our IX providers do when assigning us an IPv6 address. Am I correct in this train of thought? Why/Why not?

Yes and no. An IX is usually _NOT_ a point to point, but a layer 2 fabric much like a LAN except that it connects a bunch of different ASNs.

Still assigning a /64 to point to points makes a lot of sense, even if you use them as /127s on the link.

> In regards to core loopback addressing my initial thoughts are as follows:
> Assign a single /64 encompassing all /128’s planned for loopback addressing schemes. Should I be using Unique Local addressing for loopbacks instead of going with a Globally routeable addressing scheme? Should each interface IP configuration have a /64 or a /128?

I prefer GUA. These might show up in traceroutes.

Each LO interface should have a /128. There’s no point (in most situations) in giving anything more).

> Also when talking about CPE mgmt addresses what do you think is a practical way of going about assigning “Private” addressing schemes for cpe management purposes.

That’s way too open ended to provide useful advice. It really depends on your particular situation, topology, political limitations, and more.

> I’m sure some of these questions will be answered when I dive deeper into how OSPFv6 works as well as BGP in regards to IPv6.

99.9% they work just like in IPv4.

> Are any of you currently running IPv6 and wished you had done something differently during the planning phase that may have prevented headaches down the road?

Sounds like you’re generally on the right track. You may want to look in the archives for the NANOG on the Road in Las Vegas. I gave an Address Planning talk there and the slides should be online. If you’re anywhere near Cambridge, MA Thursday, I’ll be doing it again there.

Owen

> 
> 
> 
> 
> Kody Vicknair
> Network Engineer
> 
> 
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