Using /126 for IPv6 router links

Christopher Morrow morrowc.lists at
Tue Jan 26 03:55:07 UTC 2010

On Mon, Jan 25, 2010 at 9:26 PM, Tim Durack <tdurack at> wrote:

>> An ISP allocation is /32, which is only 2^16 /48s. Again, not that big.
>> That's just the starting minimum.  Many ISPs have already gotten much larger
>> IPv6 allocations.
> Understood. Again, the problem for me is medium/large end-user sites
> that have to justify an assignment to a RIR that doesn't have clear
> guidelines on multiple /48s.

some of what you're saying (tim) here is that you could: (one of these)

1) go to all your remote-office ISP's and get a /48 from each
2) go to *RIR's and get /<something> to cover the number of remote
sites you have in their region(s)
3) keep on keepin' on until something better comes along?

I think for each you have this at least as pitfalls:
  o no simple way to aggregate internally the 48's or subsets of the 48's
  o no simple way to define 'internal' vs 'external' at the address
level for your remote/main sites
  o renumbering concerns when/if you decide to change ISP's at remote offices
  o multihoming concerns with PA space in v6-land

  o justification in light of 'unclear' policies for an address block
of the right size. NOTE:I don't think the policies is unclear, but
that could be my misreading of the policies.
  o will your remote-office's ISP's accept the /48's per site? (vz/vzb
is a standout example here)
  o will your remote-office's have full reachability to the parts of
the network they need access to? (remote ISP's filtering at/above the
/48 boundary)

For the Enterprise still used to v4-land ipv6 isn't a win yet... for
an ISP it's relatively[0] simple.


0: address interfaces, turn up protocols, add 'security' assign
customers /48's...(yes fight bugs/problems/'why is there a colon in my
ip address?"

(what if you do have 200 offices in the US which aren't connected on a
private network today?)

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