IPv6 making space to grow for IP addresses

What if the Internet ran out of room?
In fact, it's already happening.

Vint Cerf, Chief Internet Evangelist at Google, and a founding father of the Internet, discusses the next version of the Internet, IPv6, and why we need it.

   

IPv6 Addressing

The most obvious difference between IPv6 and IPv4 is address size. An IPv6 address is 128 bits long, which is four times larger than an IPv4 address.


A 32-bit address space allows for


4,294,967,296


 possible addresses.... 2**32


A 128-bit address space allows for 2**128 or


340,282,366,920,938,463,463,374,607,431,768,211,456


(or 3.4**1038) possible addresses.  


128-bit address space provides 655,570,793,348,866,943,898,599 (6.5x1023) addresses for every square meter of the Earth’s surface.


The use of 128 bits allows for multiple levels of hierarchy and flexibility in designing hierarchical addressing and routing, which the IPv4-based Internet lacks.


RFC 3513 describes the IPv6 addressing architecture.


The following is an IPv6 address in binary form:
0011111111111110001010010000000011010000000001010000000000000000
0000001010101010000000001111111111111110001010001001110001011010




The 128-bit address is divided along 16-bit boundaries:




0011111111111110   0010100100000000   1101000000000101   0000000000000000  0000001010101010   0000000011111111   1111111000101000   1001110001011010

Each 16-bit block is converted to hexadecimal, and adjacent blocks are separated with colons. The result is:




3FFE:2900:D005:0000:02AA:00FF:FE28:9C5A


removing the leading zeros


3FFE:2900:D005:0:2AA:FF:FE28:9C5A

Table 3-4 lists decimal, hexadecimal, and binary equivalents of the numbers 0-15.

Decimal	Hexadecimal	Binary
0	0	0000
1	1	0001
2	2	0010
3	3	0011
4	4	0100
5	5	0101
6	6	0110
7	7	0111
8	8	1000
9	9	1001
10	A	1010
11	B	1011
12	C	1100
13	D	1101
14	E	1110
15	F	1111

           

Types of IPv6 Addresses

IPv6 has three types of addresses:

• Unicast
  A unicast address identifies a single interface within the scope of the type of unicast address. With the appropriate unicast routing topology, packets addressed to a unicast address are delivered to a single interface. A unicast address is used for communication from one source to a single destination.
• Multicast
  A multicast address identifies multiple interfaces. With the appropriate multicast routing topology, packets addressed to a multicast address are delivered to all interfaces that are identified by the address. A multicast address is used for communication from one source to many destinations, with delivery to multiple interfaces.
• Anycast
  An anycast address identifies multiple interfaces. With the appropriate routing topology, packets addressed to an anycast address are delivered to a single interface, the nearest interface that the address identifies. The “nearest” interface is defined as being closest in terms of routing distance.  An anycast address is used for communication from one source to one of multiple destinations, with delivery to a single interface.

IPv6 addresses always identify interfaces, not nodes. A node is identified by any unicast address assigned to one of its interfaces.

The fields within the global unicast address as defined in RFC 3587 create a three-level structure, as Figure 3-9 shows.

Figure 3-9  The three-level structure of a global unicast address as defined in RFC 3587

The public topology is the collection of larger and smaller ISPs that provide access to the IPv6 Internet and the organizations that connect to the IPv6 Internet. The site topology is the collection of subnets within an organization’s site. The interface identifier identifies a specific interface on a subnet within an organization’s site.
Local-use unicast addresses fall into two categories:

• Link-local addresses are used between on-link neighbors and for Neighbor Discovery processes, which define how nodes on an IPv6 subnet interact with hosts and routers.
• Site-local addresses are used between nodes communicating with other nodes in the same site of an organization’s intranet.

Why is the internet running out of room?

Just as phones use a system of phone numbers in order to place calls, every Internet-connected device gets a unique number known as an "IP address" that connects it to the global online network.

The problem is that the current Internet addressing system, IPv4, only has room for about 4 billion addresses -- not nearly enough for the world's people, let alone the devices that are online today and those that will be in the future: computers, phones, TVs, watches, fridges, cars, and so on. More than 4 billion devices already share addresses. As IPv4 runs out of free addresses, everyone will need to share.

How are we making space to grow?

Clearly the Internet needs more IP addresses. How many more, exactly? Well, how about 340 trillion trillion trillion (or, 340,000,000,000,000,000,000,000,000,000,000,000,000)? That's how many addresses the Internet's new "piping," IPv6, can handle. That's a number big enough to give everyone on Earth their own list of billions of IP addresses. Big enough, in other words, to offer the Internet virtually infinite room to grow, from now into the foreseeable future.

When is the transition happening?

At Google we believe IPv6 is essential to the continued health and growth of the Internet and that by allowing all devices to talk to each other directly, IPv6 enables new innovative services. Replacing the Internet's plumbing will take some time, but the transition has begun. World IPv6 Launch on June 6, 2012, marks the start of a coordinated rollout by major websites and Internet service and equipment providers.