Ccna i0v6 questions

[daniel4579329]

hi im learning for ccna and i wonder

1.1 hex digit 4 bit my question is this, could there be prefix that doesent divide by 4

2. Is there NAT in ipv6

3. If i want to use unique local what are the option in ipv6

[ngkin2010 · Accepted solution]

1. Prefix or the subnet mask is counting bit by bit, not hex by hex. So it not necessary to be dividable by 4.

For example, fe80::0/126 is still a valid IPv6 subnet. 

Add one more note here, although it's technically valid, it's not the best practice to assign /126 as prefix theoretically.

2.  Yes, there is NAT in IPv6 in certain products. 

3. Not quite sure your question

[daniel4579329]

i will try to ask it in a better way

does SLAAC and DHCP can be used on global unicast / unique local or both ?

[daniel4579329]

so if is see /53 how the format of the ipv6 will be?

[ngkin2010 · Accepted solution]

does SLAAC and DHCP can be used on global unicast / unique local or both ?

You could them on both global unicast and unique local. 

so if is see /53 how the format of the ipv6 will be?

/53 mean it's masking first 53 bits. For example:

Given an IPv6 address FD08:1111:2222:8888::9999/53
  
  [HEX]   F    D    0    8 :    1    1    1    1 :     2    2    2    2
 [BIN] 1111 1101 0000 1000 : 0001 0001 0001 0001 :  0010 0010 0010 0010 
[MASK] 1111 1111 1111 1111 : 1111 1111 1111 1111 :  1111 1111 1111 1111  

   8    8    8    8   ::      9    9    9    9
1000 1000 1000 1000   ::   1001 1001 1001 1001
1111 1000 0000 0000   ::   0000 0000 0000 0000

The subnet ID for FD08:1111:2222:8888::9999/53 would be :
      <------------------------------ 53 bits -------------------------------><--------------75 bits------------->
[BIN] 1111 1101 0000 1000 : 0001 0001 0001 0001 : 0010 0010 0010 0010 : 1000 1000 0000 0000 :: 0000 0000 0000 0000 /53
[HEX] FD08:1111:2222:8800::/53

[daniel4579329]

if the prefix length was /54 so the 8888 part of the ip would have been 8C00 ?

thanks for the help :)

[Giuseppe Larosa]

Hello @daniel4579329 ,

about unique local

see

https://tools.ietf.org/html/rfc4193

you can assign unique local prefixes to router interfaces using stateless autoconfiguration via neighbor discovery process.

I think it is also possible to deploy them using a DHCPv6 server.

Hope to help

Giuseppe