Finding the IPv6 Prefix from an Address/Length Value

Daughterofrnbsoul

Hi can anyone help me with these given prefixes ? I am suppose to find the prefix length / value and I am having a lot of trouble in Wendell Odoms ICN1 book. It seems like he doesn't explain this concept very well as most prefixes I've seen so far are /32 /48 /64 most common.


34BA:B:B:0:5555:0:6060:707/80

3124::DEAD:CAFE:FF:FE00:1/80

2BCD::FACE:BEFF:FEBE:CAFE/48

3FED:F:E0:D00:FACE:BAFF:FE00:0/48

210F:A:B:C:CCCC:B0B0:9999:9009/40

34BA:B:B:0:5555:0:6060:707/36

3124::DEAD:CAFE:FF:FE00:1/60

2BCD::FACE:1:BEFF:FEBE:CAFE/56

3FED:F:E0:D000:FACE:BAFF:FE00:0/52

3BED:800:0:40:FACE:BAFF:FE00:0/44

Daughterofrnbsoul

Daughterofrnbsoul wrote: »

Hi can anyone help me with these given prefixes ? I am suppose to find the prefix length / value and I am having a lot of trouble in Wendell Odoms ICN1 book. It seems like he doesn't explain this concept very well as most prefixes I've seen so far are /32 /48 /64 most common.


34BA:B:B:0:5555:0:6060:707/80

3124::DEAD:CAFE:FF:FE00:1/80

2BCD::FACE:BEFF:FEBE:CAFE/48

3FED:F:E0:D00:FACE:BAFF:FE00:0/48

210F:A:B:C:CCCC:B0B0:9999:9009/40

34BA:B:B:0:5555:0:6060:707/36

3124::DEAD:CAFE:FF:FE00:1/60

2BCD::FACE:1:BEFF:FEBE:CAFE/56

3FED:F:E0:D000:FACE:BAFF:FE00:0/52

3BED:800:0:40:FACE:BAFF:FE00:0/44

made an error the smiley Faces are a D lol

subnet.ninja

try to add "34ba:b:b:0:5555::/80" to the post

rob42

You made me laugh so much with your post! Class...

All of the examples here have a prefix (I prefer to call it the 'subnet ID') that is divisible by 4

80/4 = 20

48/4 = 12

40/4 = 10

... and so on.

This makes things a little simpler, as the results (20, 12, 10) represents the number of HEX digits for the subnet ID, the rest can be zeroed.

So, 34BA:B:B:0:5555:0:6060:707/80 is actually...

34BA:000B:000B:0000:5555:0000:6060:0707

You can see that the 20th digit is 5, so the 0000:6060:0707 can be zeroed and represented with ::

If we then contract it back using the 'Key Topic' on page 698, we get...

34BA:B:B:0:5555::/80

Is that of any help?

satishtech

Example :

2001:1:2:3::1/64

/64 is the prefix or mask

each quartet is 4 hex digits and each hex digit is represented by 4 bits
/64 is 64 bits
Therefore above example prefix is 2001:1:2:3::/64 (1 is 0001 , 2 is 0002, 3 is 0003)
4 blocks of 4 hex digits each 16*4 =64

another example

1111::2/80
prefix is 1111:0000:0000:0000:0000::/80
16*5 = 80 bits

kindly correct me if I am wrong.