[arin-discuss] Trying to Understand IPV6

[michael.dillon at bt.com]

> > Anyone in this position should simply assign a /48 to every customer
> site
> > no matter how big or small. A one bedroom apartment gets a /48. A
> manufacturing
> > plant with 5 buildings including a 4-story office block, gets a /48.
> > No exceptions.
> 
> 	This is slightly different than I have been led to think...  It
> seems wise, when you know the customer has no intention of having
> multiple networks, to provide a /64.  

That is not wise, it is foolish. If you don't understand IPv6 then assign
everyone a /48 and you cannot go wrong. But do take some time to study
IPv6 and learn how it is vastly different from IPv4, especially when
it comes to addressing architectures. Also, a little humility helps,
i.e. how do you *KNOW* that a customer has no intention of having
multiple networks within the next 10 years? Fact is that only in extremely
special circumstances can you know this, for instance if you provide 
a wireless service for some sort of handset which you also supply, then
perhaps a /64 assignment makes sense. Very, very few ISPs are in this
position.

> The IPv6 equiv to that would be a /64 connecting
> range and another /64 range to use for their LAN.  This has been my
> plan

That is an IPv4 plan, not an IPv6 plan. IPv6 is not just IPv4
with longer addresses, it has a very different idea of how 
addressing is done, and it intentionally wastes space to make
sure that networks can be expanded at several levels without 
needing to change the addressing architecture. If you don't provide
the slack, then you are breaking IPv6 and recreating the problems
of IPv4.

> 	Anyone wanting/needing multiple networks (or who even thinks they
> might, and knows what a /48 is) can and should have a /48, no problem.
> 
> 	I am just a small provider with mostly small business accounts
> and colo, so maybe my situation isn't typical...

It is very typical. /48 to every customer, no exceptions. If a customer
wants less, assign them a /48 anyway and only tell them the first part
of the prefix. When they get wiser, tell them the /48 that you 
"reserved" for them. 

The non-typical case is an ISP with very large numbers of residential
customers (something like Comcast for instance) where it makes sense
to assign /56 to private residences and /48 to everyone else.

> /48 per customer with more than one network (so they can have /64 per
> network)
> 
> 	Is this flawed or no longer the prevailing way of thinking?

The flaw is in thinking that a customer has only one network. Most folks
these days have two, one wired and one wireless. They may not be using
both, but it is there in the gateway router and they could turn on the
second network any day now. Maybe Google TV will be what it takes to get
them to add a wired network, maybe something else.

Don't gamble on this. ARIN expects you to assign a /48 to everyone, and
if you use less then you are only punishing yourself by increasing the
complexity of your network and your management processes.

--Michael Dillon