04-09-2010 10:04 AM - edited 03-06-2019 10:32 AM
Hi all,
I was studying for cisco exam and there is question if this address is valid IPv6 or not
2002:7654:a1ad:61:81af:ccc1
any answers
thanks
mahesh
Solved! Go to Solution.
04-09-2010 11:36 AM
Hello Mahesh,
an IPv6 address is made of 128 bits and it is represented using exadecimal digits.
Each hex digits represents 4 binary digits = 1 hex = 4 bits
So an IPv6 address is made of 128/4 = 32 hexadecimal digits
the usual hex dotted representation groups 4 hex and separate these groups using a ':'
So an IPv6 address is made of 8 4hex groups divided by :
the notation allows to represent one of more 4 hex consecutive groups made of all zeroes with a ::
This can appear only once in the number.
In your case the proposed hexadecimal sequence is:
2002:7654:a1ad:61:81af:ccc1
2002:7654:a1ad:0061:81af:ccc1
Here we see only 6 4-hex groups, no :: appears in the middle to represent all zero groups so it is too short.
an IPv6 prefix is represented with a final ::/prefix length
this is not a valid IPv6 address because it is too short, it could be an IPv6 prefix if written as:
2002:7654:a1ad:61:81af:ccc1::/96
see
http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-addrg_bsc_con.html#wp1027186
Hope to help
Giuseppe
04-09-2010 11:36 AM
Hello Mahesh,
an IPv6 address is made of 128 bits and it is represented using exadecimal digits.
Each hex digits represents 4 binary digits = 1 hex = 4 bits
So an IPv6 address is made of 128/4 = 32 hexadecimal digits
the usual hex dotted representation groups 4 hex and separate these groups using a ':'
So an IPv6 address is made of 8 4hex groups divided by :
the notation allows to represent one of more 4 hex consecutive groups made of all zeroes with a ::
This can appear only once in the number.
In your case the proposed hexadecimal sequence is:
2002:7654:a1ad:61:81af:ccc1
2002:7654:a1ad:0061:81af:ccc1
Here we see only 6 4-hex groups, no :: appears in the middle to represent all zero groups so it is too short.
an IPv6 prefix is represented with a final ::/prefix length
this is not a valid IPv6 address because it is too short, it could be an IPv6 prefix if written as:
2002:7654:a1ad:61:81af:ccc1::/96
see
http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-addrg_bsc_con.html#wp1027186
Hope to help
Giuseppe
04-09-2010 01:28 PM
Hi giuslar,
many thanks for correct reply
regards
mahesh
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