IPv6 Addressing Help

Jack Bates jbates at brightok.net
Mon Aug 17 09:15:23 CDT 2009

Jon Lewis wrote:
> On Fri, 14 Aug 2009, David Freedman wrote:
>> Will keep it simple, this is what I (and I suspect many others) do
>> /128 - Loopback (what else?)
>> /126 - Router p2p
>> /112 - Router LAN shared segments (p2mp)
> Why even go that big on LAN segments?  i.e. If you have a LAN/VLAN where 
> you have say 20 devices (routers, switches, etc.) and know you'll never 
> have more than say 50-100 devices, why not go as far as using a /120?

As long as it makes the nibble, I don't think it really matters much. I 
wouldn't assign anything to a router p2p unless it's on the nibble, just 
for administrative ease. That being said, presentation in routers is 
much cleaner using /64's, with perhaps 1 /64 broken into loopbacks, 
which will still stay relatively short in display. It may be wasteful, 
but minimal in waste compared to the /48's we hand out to customers.

My first /48 was assigned for internal use, and as an ISP, I doubt I'll 
ever use it all even with an extreme amount of waste.

My favorite shortcut was 2607:f780::1 which is assigned to the 
reachability server, as easy as I could make it for customers to ping by 
number when troubleshooting with the helpdesk.


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