Decimal   150              1             3           3
Binary   1001 0110    0000 0001     0000 0011    0000 0011

in hex, they are 16 digit groupings for hex representations,

1001=9  0110=6 so forth,

The results is

9601:0303

http://blog.ru.co.za/2009/03/19/converting-ipv4-to-ipv6/
Converting from IPv4 to IPv6

is so easy, yet everyone seem to convert a IPv4 address to binary, then to IPv6. Why? Why waste time and do things the long way? Not cool.

When would you need to do this? One specific use is IPv6 6-to-4 tunnels, which always concatenates 2002::/16 with the IPv4 address embedded.
 With Automatic 6-to-4-tunnels, your address format is as follow:
 2002:<32 bit IPv4 site address in Hex>:<16 bit network number in Hex>::/64

The question is how to do the conversion.

Firstly before starting I will assume everyone knows the following:

 Binary is a Base-2 numbering system, as it has only 0,1
 Decimal is a Base-10 numbering system, as it has 0,1,2,3,4,5,6,7,8,9
 Hexadecimal is a Base-16 numbering system, as it has 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F


I also assume you know the hex values in decimal:






A
=
10


B
=
11


C
=
12


D
=
13


E
=
14


F
=
15




Two more things I would like to mention before explaining the conversion.
 An IPv4 address : example 192.168.99.1

 Each Octet (8 bits) “between the dot-thingys” denote 1 byte


An IPv6 address : example 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Two Tuples (1 Tuple = 4 bits = 1 Hex character) denotes 1 byte


Then converting is easy. Lets take the following IPv4 address : 192.168.99.1 and convert it to Hex.

Step1 >

Divide the first octet (192) by 16 (since Hex is a Base-16)
 IE : 192/16 = 12 times exactly with 0 left over
 - 12 in Hex is represented as C
 - 0 (zero) in Hex is, you guessed it, 0
 Thus 192 in HEX is C0

Step2 >

Repeat step 1 with the second octet (168),
 IE : 168/16 = 10 times with 8 left over because 10*6 = 160,
 - 10 in HEX is A
 - 8 in HEX is 8
 Thus 168 in HEX is A8

Step3 >

Repetition rules!!! Third octet (99)
 IE : 99/16 = 6 times with 3 left over
 - 6 in HEX is 6
 - 3 in HEX is 3
 Thus 99 in HEX is 63

Step4 >

Last octet
 IE : 1/16 = 0 times with 1 left over
 - 0 in HEX is, yeah it is 0
 - 1 in HEX is 1
 Thus 1 in HEX is 01

So the IPv4 address of 192.168.99.1, represented in the IPv6 address portion would be C0A8:6301.
 So when using IPv6 6-to-4 Tunnels, on the one endpoint of the tunnel, with the IPv4 address of 192.168.99.1, the complete IPv6 address would be 2002:C0A8:6301::1/64
 See, not all that difficult, if you know your 16 multiplication table, you can do this in your head, no problems.

- – - -

.
Converting back from IPv6 to IPv4

Now to convert the same portion of the IPv6address 2002:C0A8:6301::1/64 back to IPv4, the reverse method would apply.

Let me point one more thing about Base-16 out to understand why I’m doing what I am below:

160 = 1

161 = 16

Taking the  portion C0A8:6301, first divide the address  into 2 Tuple-groupings (2 Hex Characters) = C0 A8 63 01

Step1 >

Take C0 and multiply the first character ‘C’ by 16 and the second character ‘0′ by 1.
 Add the two decimal values together to get the IPv4 decimal value
 IE: ((C=12)*16) + (0*1) = 192

Step2 >

Repeat the same process with A8,
 IE: ((A=10)*16) + (8*1) = 168

Step3 >

Repeat the same process with 63,
 IE: (6*16) + (3*1) = 99

Step4 >

Repeat the same process with 01,
 IE: (0*16) + (1*1) = 1

The following prerequisites apply to Cisco Express Forwarding and distributed Cisco Express Forwarding for IPv6: – To forward IPv6 traffic using Cisco Express Forwarding or distributed Cisco Express Forwarding, you must configure forwarding of IPv6 unicast datagrams globally on the router by using the ipv6 unicast-routing command, and you must configure an IPv6 address on an interface by using the ipv6 address command.

– You must enable Cisco Express Forwarding for IPv4 globally on the router by using the ip cef command before enabling Cisco Express Forwarding for IPv6 globally on the router by using the ipv6 cef command.

– To use Unicast Reverse Path Forwarding (RPF), enable Cisco Express Forwarding switching or distributed Cisco Express Forwarding switching in the router. There is no need to configure the input interface for Cisco Express Forwarding switching. As long as Cisco Express Forwarding is running on the router, individual interfaces can be configured with other switching modes.

Note For Unicast RPF to work, Cisco Express Forwarding must be configured globally in the router. Unicast RPF will not work without Cisco Express Forwarding.

http://www.potaroo.net/ispcol/2008-08/ipv6addr.html