IPv6

Welcome to our IPv6 Addressing short Blog!!! Get ready to uncover the efficiency and innovation behind IPv6. We'll explore its unique features like auto-configuration and EUI-64 host number generation, revealing how it transforms the way we connect in the digital landscape. Let's dive in!

It is a 128 bit addressing scheme that can support very large number of addresses. It is expressed in hexadecimal notation as eight blocks of 16 bit hexadecimal numbers, separated by colon (:) . Each 16 bit hexadecimal block has 4 hexadecimal digits each representing 4 bits. Each 16 bit hex block is called quartet.

??????????????????????????????? 4 Bits

2101:00AB:ACFF:BBCC:ABCD:00EB:00CD:AC12

????????????????????????????????16 Bits Each

Each 16 bit hexadecimal block has 4 hexadecimal digits each representing 4 bits. Each 16 bit hex block is called quartet.

Example:--

2101:0000:0000:0000:abcd:00eb:00cd:ac12

Although it may seem very large and complicated to remember but very efficiently it can be reduced by using the following 2 steps

1) Leading 0s can be dropped

2) Consecutive blocks of 0 can be replaced by :: but only once

So following step 1 the address becomes

2101:0:0:0:abcd:eb:cd:ac12

And following step 2 the address becomes

2101::abcd:eb:cd:ac12

The subnet mask for an IPv6 address is always expressed in slash notation and the default subnet mask is /64. IPv6 is always classless and it has a lot of advantages over IPv4.

Advantages of IPv6 over IPv4 :

1)Very large address space – IPv6 can support theoretically 3.4*1038 number of addresses

2) Global reach ability – Usually IPv6 does not need NAT, so very easily a direct point to point connectivity can be established between 2 devices across the internet

3) Scoped address – IPv6 has distinct Global Scoped (Global Uni-cast) and Local Scoped (Link Local) addresses. The routers understand that Global Scoped addresses are routable and Local Scoped addresses are no routable

4) New header format – The IPv6 header is much streamlined than IPv4 header which makes it easier and faster for the routers to process it

5) IPv6 supports multiple addresses on a single interface.

6) Automatic generation of address (Auto-configured address).

7) Inbuilt support for IPSec and Mobile IP.

8) Better support for prioritized delivery – IPv6 header contains an additional FLOW label to facilitate more priority specification.

9) Has no concept of Broadcast address – only Uni-cast and Multicast

10) Introduced the concept of Any-cast address – It is a common secondary uni-cast address for a group of device but at a time only the nearest device will respond to that address

?11) Has replaced ARP with ICMP v6 to identify neighbors on the same LAN.

Types of IPv6 address::

Global Uni cast – These are routable addresses and they have the format 2000::/3

Link Local Uni cast – These are non routable addresses like IPv4 APIPA. They have the format FE80::/10

Anycast – This is a common unicast address that can be given to several IPv6 devices, but at a time only the nearest device responds to it.

All routers Multicast –>> FF02::2

All nodes Multicast –>> FF02::1

Methods of obtaining IPv6 address ::

IPv6 host can get it’s address in 4 ways

? Static Manual –> The entire IP address is provided manually by the admin

? Static Auto-config –> The network admin provides only the network number. The host number is auto generated by the system itself

? DHCP for IPv6 –> The entire IP address is provided by a DHCP server

? IPv6Autoconfig –> The network number is provided by the default router of the network and the host number is auto-generated by the system itself

>>>> It is to be noted that any kind of automatic IPv6 address is always /64 address<<<

How the IPv6 host gets it’s network number from the default router :: Steps are...

1)The IPv6 host sends Router Solicitation (RS) message to the all routers multicast address FF02::2

2) If there is a router in the network it replies back with Router Advertisement (RA) message to the all hosts multicast address FF02::1.

3) When the IPv6 host receives this RA message it gets its network number from it.

How the IPv6 host auto generates it’s host number :: >>>>

The host number is calculated as a 64 bit number called EUI-64 (Extended Unique Identifier). EUI-64 is calculated on the basis of MAC address. The MAC address is 48 bits. It is converted into 64 bit EUI-64 by the following steps

1) A 16 bit hex number FFFE is inserted in the middle of the 2nd quartet of the 48 bit MAC

????? 48 bit MAC??? XXXX.XXXX.XXXX

FFFE??????

?????? 64 bit number? XXXX.XXFF.FEXX.XXXX

2) The 7th bit (from the left) of the 64 bit number is flipped

????????????????????????????? XXXX.XXFF.FEXX.XXXX

?xxxxxx x xxxxxxxxx

flipped

3)?? The result is 64 bit EUI-64.

In the realm of networking, IPv6's ingenious addressing methods like auto-configuration and EUI-64 host number generation pave the way for seamless connections. Embracing these techniques is key to unleashing the full power of IPv6 and ensuring a smoother digital future.

Kamruzzaman Khan- Dated 28 August