IPv6 Address Planning

Tue Aug 9 20:29:26 UTC 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.