North American Network Operators Group

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RE: IPV4 as a Commodity for Profit

  • From: michael.dillon
  • Date: Fri Feb 22 04:55:50 2008

> Operational comment: Look on the bright side, they may follow 
> Comcast's example and deploy ipv6 instead!

Or they may not, and their share price will suffer as a
result. People making the technical decision to stick
with IPv4 for their large network are also making a
decision to limit the growth of the network and to
limit the growth of the business. As the IPv4
exhaustion issue becomes more widely understood,
companies who have not prepared themselves to
deploy IPv6 will find themselves under increasing
scrutiny by shareholders.

Comcast moved to IPv6 because their network was 
running out of RFC 1918 space. Since DOCSIS 3 includes
IPv6 support, they made the decision to go to IPv6
rather than continue to spend money on shoehorning
themselves into the limited IPv4 address space.

Many people have not yet come to terms with how big
the IPv6 space is, even the /32 that an ISP gets or
the /48 that a site gets. We probably need to start
talking about the number of subnetting bits available.

For instance, an IPv4 ISP who assigns a /24 to subnets within
their architecture and who has a /16 allocated for their
architecture, has 8 bits available to subnet with.
If an IPv6 ISP decides to assign a /64 to subnets and
allocate a single /48 then they will also have 
8 subnet bits available. So you could consider
a /48 to be roughly equivalent to an IPv4 /16.

Now, if an IPv6 ISP decides to strictly follow the
rule of assigning a /48 per site internally, then
each PoP or data center will be allocated a /48
meaning that each PoP or data center now has
8 subnet bits available.

This amount of legroom allows you to do things like
standardize subnet layouts for all sites, regardless
of size, including the actual bits used from the
8 subnet bits. For instance, you can predict that
if a PoP has 2001:1918:123/48 you know that if there
is a switch connecting to a data center at that site,
it will have the IPv6 address 2001:1918:123:d033::1
because your standard design has ::d033/64 assigned
to the switch filling that role and Interface ID 1
assigned to its management interface.

This kind of standardization makes it much easier to
deploy PoPs regardless of whether it is in Dubai,
where the data center is a half rack of webservers,
or The Dalles where it is a 40,000 square foot warehouse.
It also simplifies management and troubleshooting
of the network.

--Michael Dillon