ipv6 address short form

Answered Question
Oct 7th, 2007

hi every body

here is ipv6 address

2134:0000:1234:4567:2468:1236:2444:2106

can the above address be shortened as

2134::1234:4567:2468:1236:2444:2106

In one cisco book (ccnp bsci guide by catherine pacquet) it says consecutive zeroes field can be replaced by ::

but i read in different book by cisco

one or more than consecutive fields of zeros can be reduced by ::

now which one to believe

thanks a lot and have wonderful day!

I have this problem too.
0 votes
Correct Answer by GillieLucent about 9 years 2 months ago

Hi,

In your statement, 'one or more' represents 'one or more 16-bit group'

i.e.

0000 can be represented as :: , and

0000:0000 can also be represented as ::

See below for a brief explanation :

For eg. conside the below two addresses,

1080:0000:0000:0000:0008:0800:200C:417A

0000:0000:0000:0000:0000:0000:0A00:0001

In the above addresses, we do not need to write the leading zeros in each group of digits; for example, we can write

0 instead of 0000, 1 instead of 0001, 20 instead of 0020, and 300 insteadof 0300. If we apply this shortcut, the two preceding addresses become

1080:0:0:0:8:800:200C:417A

0:0:0:0:0:0:A00:1

A further simplification is represented by the symbol ::, which replaces a series of zeros. This method replaces zeros only when they fill a complete 16-bit group, and the double colon can be used only once in any given address.By applying this shortcut, the two preceding addresses become

1080::8:800:200C:417A

::A00:1

We make the assumption that the IPv6 address has a fixed length so that we can compute how many zeros have been omitted. This shortcut can be applied either to the center of the address (as in the case of the first address), or to the leading (as in the case of the second address) or trailing zeros.

In fact, the extended form of these addresses results in the following:

FF01:0:0:0:0:0:0:43 A multicast address

0:0:0:0:0:0:0:1 The loopback address

0:0:0:0:0:0:0:0 The unspecified address

They can be represented in compressed form as follows:

FF01::43 A multicast address

::1 The loopback address

:: The unspecified address

Thanks,

Vijaybabu

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Mohamed Sobair Mon, 10/08/2007 - 02:17

Hi,

Consecutive fields Of Zeroes can be expressed with two colons, and you can Only do this once in a single IPv6 address; Example:

1234:1234:0000:0000:00000:00000:3434:3434

could be written as:

Zero Comp: 1234:1234::3434:3434

The Leading Zero Compression; in any field can be dropped but each block you do this must have at least on number remaining and that is if the block is all Zeros, this is a leading Zero Compression.

Example:

1234:0000:1234:0000:1234:0000:1234:0234

colud be written as:

Leading Zero Comp: 1234:0:1234:0:1234:0:1234:234

HTH

Mohamed Sobair

Correct Answer
GillieLucent Mon, 10/08/2007 - 04:17

Hi,

In your statement, 'one or more' represents 'one or more 16-bit group'

i.e.

0000 can be represented as :: , and

0000:0000 can also be represented as ::

See below for a brief explanation :

For eg. conside the below two addresses,

1080:0000:0000:0000:0008:0800:200C:417A

0000:0000:0000:0000:0000:0000:0A00:0001

In the above addresses, we do not need to write the leading zeros in each group of digits; for example, we can write

0 instead of 0000, 1 instead of 0001, 20 instead of 0020, and 300 insteadof 0300. If we apply this shortcut, the two preceding addresses become

1080:0:0:0:8:800:200C:417A

0:0:0:0:0:0:A00:1

A further simplification is represented by the symbol ::, which replaces a series of zeros. This method replaces zeros only when they fill a complete 16-bit group, and the double colon can be used only once in any given address.By applying this shortcut, the two preceding addresses become

1080::8:800:200C:417A

::A00:1

We make the assumption that the IPv6 address has a fixed length so that we can compute how many zeros have been omitted. This shortcut can be applied either to the center of the address (as in the case of the first address), or to the leading (as in the case of the second address) or trailing zeros.

In fact, the extended form of these addresses results in the following:

FF01:0:0:0:0:0:0:43 A multicast address

0:0:0:0:0:0:0:1 The loopback address

0:0:0:0:0:0:0:0 The unspecified address

They can be represented in compressed form as follows:

FF01::43 A multicast address

::1 The loopback address

:: The unspecified address

Thanks,

Vijaybabu

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