North American Network Operators Group
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Re: IPv6 Address Planning

  • From: Iljitsch van Beijnum
  • Date: Tue Aug 09 16:30:41 2005 
On 9-aug-2005, at 19:24, Cody Lerum wrote:
Here is our current plan, but we are looking for suggestions from people
who have been down this road before. The plan is to break out a /48 for
our organization. Then break out the first /64 for loopbacks, and the
next /64 for point-to-point connections. The PTP /64 then breaks out
further into 1 /80 for core links, and 1 /80 for each of our
distribution sites. Within these /80's are individual /112's for PTP
links. What this will allow us to do is aggregate each sites PTP
connections into /80's within our IGP.
Hm, I would keep the first /48 apart for your own services. Addresses in that first /64 are nice and short.

Then a /48 for the routers. You only need /128s for the loopbacks of course, but you may not even need IPv6 loopbacks if you only have iBGP sessions between the IPv4 loopbacks and also exchange IPv6 BGP routes over those. (This does create a dependency on IPv4 for IPv6, but it saves you a lot of BGP sessions.)

If you use /64s for router links, you can use eui-64 addressing within those, which has the advantage that you don't have to keep track of which router has the ...1 and which router has the ...2 address. If you use a lot of vlans in your own network (as opposed to customer links) you may also want to endcode the vlan id in bits 48 - 63. Makes everything really simple to debug!

I generally like to use a /48 per customer and a separate /64 out of a dedicated /48 for the link to the customer to avoid breaking up their /48 or having to do other hard to remember tricks.