The Need For IPv6 Network Addressing

need for IPv6 network addressing

 

IPv6 is designed to be the successor to IPv4. IPv6 has a larger 128-bit address space, providing 340 undecillion (i.e., 340 followed by 36 zeroes) possible addresses. However, IPv6 is more than just larger addresses. In this article, I want to discuss the need for IPv6 Network Addressing. 

 

When the IETF began its development of a successor to IPv4, it used this opportunity to fix the limitations of IPv4 and include enhancements. One example is Internet Control Message Protocol version 6 (ICMPv6), which includes address resolution and address autoconfiguration not found in ICMP for IPv4 (ICMPv4).

 

The depletion of IPv4 address space has been the motivating factor for moving to IPv6. As Africa, Asia and other areas of the world become more connected to the internet, there are not enough IPv4 addresses to accommodate this growth. As shown in the figure, four out of the five RIRs have run out of IPv4 addresses.

 

The graphic shows a global map of the five regional internet registries and there IPv4 exhaustion dates. ARINs IPv4 exhaustion date is July 2015, RIPE NCCs exhaustion data is September 2012, APNICs exhaustion date is June 2014, LACNICs exhaustion date is April 2011, and AfriNICs projected exhaustion date is 2020.

RIR IPv4 Exhaustion Dates

IPv4 has a theoretical maximum of 4.3 billion addresses. Private addresses in combination with Network Address Translation (NAT) have been instrumental in slowing the depletion of IPv4 address space. However, NAT is problematic for many applications, creates latency, and has limitations that severely impede peer-to-peer communications.

 

With the ever-increasing number of mobile devices, mobile providers have been leading the way with the transition to IPv6. The top two mobile providers in the United States report that over 90% of their traffic is over IPv6.

 

Most top ISPs and content providers such as YouTube, Facebook, and NetFlix, have also made the transition. Many companies like Microsoft, Facebook, and LinkedIn are transitioning to IPv6-only internally. In 2018, broadband ISP Comcast reported deployment of over 65% and British Sky Broadcasting over 86%.

 

Internet of Things

The internet of today is significantly different from the internet of past decades. The internet of today is more than email, web pages, and file transfers between computers. The evolving internet is becoming an Internet of Things (IoT). No longer will the only devices accessing the internet be computers, tablets, and smartphones. The sensor-equipped, internet-ready devices of tomorrow will include everything from automobiles and biomedical devices, to household appliances and natural ecosystems.

 

With an increasing Internet population, a limited IPv4 address space, issues with NAT and the IoT, the time has come to begin the transition to IPv6.

IPv6 Addressing Formats

The first step to learning about IPv6 in networks is to understand the way an IPv6 address is written and formatted. IPv6 addresses are much larger than IPv4 addresses, which is why we are unlikely to run out of them.

 

IPv6 addresses are 128 bits in length and written as a string of hexadecimal values. Every four bits is represented by a single hexadecimal digit; for a total of 32 hexadecimal values, as shown in the figure. IPv6 addresses are not case-sensitive and can be written in either lowercase or uppercase.

16-bit Segments or Hextets

Preferred Format

The previous figure also shows that the preferred format for writing an IPv6 address is x:x:x:x:x:x:x:x, with each “x” consisting of four hexadecimal values. The term octet refers to the eight bits of an IPv4 address. In IPv6, a hextet is the unofficial term used to refer to a segment of 16 bits, or four hexadecimal values. Each “x” is a single hextet which is 16 bits or four hexadecimal digits.

 

Preferred format means that you write IPv6 address using all 32 hexadecimal digits. It does not necessarily mean that it is the ideal method for representing the IPv6 address. In this module, you will see two rules that help to reduce the number of digits needed to represent an IPv6 address.

These are examples of IPv6 addresses in the preferred format.

2001 : 0db8 : 0000 : 1111 : 0000 : 0000 : 0000: 0200 
2001 : 0db8 : 0000 : 00a3 : abcd : 0000 : 0000: 1234 
2001 : 0db8 : 000a : 0001 : c012 : 9aff : fe9a: 19ac 
2001 : 0db8 : aaaa : 0001 : 0000 : 0000 : 0000: 0000 
fe80 : 0000 : 0000 : 0000 : 0123 : 4567 : 89ab: cdef 
fe80 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000: 0001 
fe80 : 0000 : 0000 : 0000 : c012 : 9aff : fe9a: 19ac 
fe80 : 0000 : 0000 : 0000 : 0123 : 4567 : 89ab: cdef 
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000: 0001 
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000: 0000 

Rule 1 – Omit Leading Zeros

The first rule to help reduce the notation of IPv6 addresses is to omit any leading 0s (zeros) in any hextet. Here are four examples of ways to omit leading zeros:

  • 01ab can be represented as 1ab
  • 09f0 can be represented as 9f0
  • 0a00 can be represented as a00
  • 00ab can be represented as ab

This rule only applies to leading 0s, NOT to trailing 0s, otherwise the address would be ambiguous. For example, the hextet “abc” could be either “0abc” or “abc0”, but these do not represent the same value.

 
Type Format
Preferred
2001 : 0db8 : 0000 : 1111 : 0000 : 0000 : 0000 : 0200
No leading 0s
2001 :  db8 :    0 : 1111 :    0 :    0 :    0 :  200
Preferred
2001 : 0db8 : 0000 : 00a3 : ab00 : 0ab0 : 00ab : 1234
No leading 0s
2001 :  db8 :    0 :   a3 : ab00 :  ab0 :   ab : 1234
Preferred
2001 : 0db8 : 000a : 0001 : c012 : 90ff : fe90 : 0001
No leading 0s
2001 :  db8 :    a :    1 : c012 : 90ff : fe90 :    1
Preferred
2001 : 0db8 : aaaa : 0001 : 0000 : 0000 : 0000 : 0000
No leading 0s
2001 :  db8 : aaaa :    1 :    0 :    0 :    0 :    0
Preferred
fe80 : 0000 : 0000 : 0000 : 0123 : 4567 : 89ab : cdef
No leading 0s
fe80 :    0 :    0 :    0 :  123 : 4567 : 89ab : cdef
Preferred
fe80 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0001
No leading 0s
fe80 :    0 :    0 :    0 :    0 :    0 :    0 :    1
Preferred
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0001
No leading 0s
   0 :    0 :    0 :    0 :    0 :    0 :    0 :    1
Preferred
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000
No leading 0s
   0 :    0 :    0 :    0 :    0 :    0 :    0 :    0

Rule 2- Double Colon

The second rule to help reduce the notation of IPv6 addresses is that a double colon (::) can replace any single, contiguous string of one or more 16-bit hextets consisting of all zeros. For example, 2001:db8:cafe:1:0:0:0:1 (leading 0s omitted) could be represented as 2001:db8:cafe:1::1. The double colon (::) is used in place of the three all-0 hextets (0:0:0).

The double colon (::) can only be used once within an address, otherwise there would be more than one possible resulting address. When used with the omitting leading 0s technique, the notation of IPv6 address can often be greatly reduced. This is commonly known as the compressed format.

Here is an example of the incorrect use of the double colon: 2001:db8::abcd::1234.

The double colon is used twice in the example above. Here are the possible expansions of this incorrect compressed format address:

  • 2001:db8::abcd:0000:0000:1234
  • 2001:db8::abcd:0000:0000:0000:1234
  • 2001:db8:0000:abcd::1234
  • 2001:db8:0000:0000:abcd::1234

If an address has more than one contiguous string of all-0 hextets, best practice is to use the double colon (::) on the longest string. If the strings are equal, the first string should use the double colon (::).

 
Type Format
Preferred
2001 : 0db8 : 0000 : 1111 : 0000 : 0000 : 0000 : 0200
Compressed/spaces
2001 :  db8 :    0 : 1111 :                    :  200
Compressed
2001:db8:0:1111::200
Preferred
2001 : 0db8 : 0000 : 0000 : ab00 : 0000 : 0000 : 0000
Compressed/spaces
2001 :  db8 :    0 :    0 : ab00 ::
Compressed
2001:db8:0:0:ab00::
Preferred
2001 : 0db8 : aaaa : 0001 : 0000 : 0000 : 0000 : 0000
Compressed/spaces
2001 :  db8 : aaaa :    1 ::
Compressed
2001:db8:aaaa:1::
Preferred
fe80 : 0000 : 0000 : 0000 : 0123 : 4567 : 89ab : cdef
Compressed/spaces
fe80 :                    :  123 : 4567 : 89ab : cdef
Compressed
fe80::123:4567:89ab:cdef
Preferred
fe80 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0001
Compressed/spaces
fe80 :                                         :    1
Compressed
fe80::0
Preferred
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0001
Compressed/spaces
::                                                  1
Compressed
::1
Preferred
0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000
Compressed/spaces
::
Compressed
::
6.6.5

IPv6 Prefix Length

The prefix, or network portion, of an IPv4 address can be identified by a dotted-decimal subnet mask or prefix length (slash notation). For example, an IPv4 address of 192.168.1.10 with dotted-decimal subnet mask 255.255.255.0 is equivalent to 192.168.1.10/24.

In IPv4 the /24 is called the prefix. In IPv6 it is called the prefix length. IPv6 does not use the dotted-decimal subnet mask notation. Like IPv4, the prefix length is represented in slash notation and is used to indicate the network portion of an IPv6 address.

The prefix length can range from 0 to 128. The recommended IPv6 prefix length for LANs and most other types of networks is /64, as shown in the figure.

The graphic shows an IPv6 address divided into a 64-bit prefix and a 64-bit interface ID. The 64-bit prefix is 2001:0db8:000a:0000. The 64-bit interface ID is 0000:0000:0000:0000.

IPv6 Prefix Length

It is strongly recommended to use a 64-bit Interface ID for most networks. This is because stateless address autoconfiguration (SLAAC) uses 64 bits for the Interface ID. It also makes subnetting easier to create and manage.

Action Point

I know you might agree with some of the points that I have raised in this article. You might not agree with some of the issues raised. Let me know your views about the topic discussed. We will appreciate it if you can drop your comment. Thanks in anticipation.

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About Adeniyi Salau 889 Articles
I am an IT enthusiast and a man of many parts. I am a Certified Digital Marketer, Project Manager and a Real Estate Consultant. I love writing because that's what keeps me going. I am running this blog to share what I know with others. I am also a Superlife Stem Cell Distributor. Our Stem Cell Products can cure many ailments.

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