Are the IPv6 address space and IPv4 address space completely disjoint? The 2019 Stack Overflow Developer Survey Results Are InIPv4 shortage is now becoming a reality - what is needed for IPv6 to work?MLD messages during IPv6 duplicate address detectionWhat is the advantage of multicasting in IPv6 (compared to broadcast)?Is it ok if multiple non-router devices send IPv6 RAs with same prefix in the same network?Why do we need IPv6?IPv6 6to4 mechanismHow does address resolution work with multicast, specifically IPv6?Are all the private IPv6 addresses nonoverlapping? If yes, is Route distinguisher required for IPv6?Cisco 3560G not passing IPv6 RA when VLAN without IPv6 addressHow are IPv6 addresses grouped?
How to support a colleague who finds meetings extremely tiring?
Origin of "cooter" meaning "vagina"
Why isn't airport relocation done gradually?
Right tool to dig six foot holes?
Are there incongruent pythagorean triangles with the same perimeter and same area?
Shouldn't "much" here be used instead of "more"?
What tool would a Roman-age civilization have for the breaking of silver and other metals into dust?
If a Druid sees an animal’s corpse, can they Wild Shape into that animal?
Why hard-Brexiteers don't insist on a hard border to prevent illegal immigration after Brexit?
What is the most effective way of iterating a std::vector and why?
Why do we hear so much about the Trump administration deciding to impose and then remove tariffs?
Who coined the term "madman theory"?
How to deal with fear of taking dependencies
slides for 30min~1hr skype tenure track application interview
Why didn't the Event Horizon Telescope team mention Sagittarius A*?
Return to UK after having been refused entry years ago
Reference request: Oldest number theory books with (unsolved) exercises?
Apparent duplicates between Haynes service instructions and MOT
Output the Arecibo Message
Have you ever entered Singapore using a different passport or name?
Did 3000BC Egyptians use meteoric iron weapons?
What are the motivations for publishing new editions of an existing textbook, beyond new discoveries in a field?
Why can Shazam fly?
Can a rogue use sneak attack with weapons that have the thrown property even if they are not thrown?
Are the IPv6 address space and IPv4 address space completely disjoint?
The 2019 Stack Overflow Developer Survey Results Are InIPv4 shortage is now becoming a reality - what is needed for IPv6 to work?MLD messages during IPv6 duplicate address detectionWhat is the advantage of multicasting in IPv6 (compared to broadcast)?Is it ok if multiple non-router devices send IPv6 RAs with same prefix in the same network?Why do we need IPv6?IPv6 6to4 mechanismHow does address resolution work with multicast, specifically IPv6?Are all the private IPv6 addresses nonoverlapping? If yes, is Route distinguisher required for IPv6?Cisco 3560G not passing IPv6 RA when VLAN without IPv6 addressHow are IPv6 addresses grouped?
Tanenbaum's Computer Networks says
Finally, IPv4 addresses can be written as a pair of colons and an old dotted
decimal number, for example:::192.31.20.46
- Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space? Is such embedding fixed? Can the IPv4 address space be embedded
into any continuous subrange of the IPv6 address space?Does https://en.wikipedia.org/wiki/IPv6_address#Transition_from_IPv4 list several alternative ways of translation? If it is correct, then the embedding is not fixed.
Does it mean that for any IPv4 address, there is some IPv6 address that refers to the same address as the IPv4 address?
For example, are
::192.31.20.46
and192.31.20.46
effectively the same address?if I send a message to
::192.31.20.46
, will192.31.20.46
receive my message?if I send a message to
192.31.20.46
, will::192.31.20.46
receive my message?
Will
::127.0.0.1
still be a loopback IP address, and if yes, is it effectively the same address as127.0.0.1
?Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
Thanks.
ip ipv4 ipv6 protocol-theory ip-address
add a comment |
Tanenbaum's Computer Networks says
Finally, IPv4 addresses can be written as a pair of colons and an old dotted
decimal number, for example:::192.31.20.46
- Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space? Is such embedding fixed? Can the IPv4 address space be embedded
into any continuous subrange of the IPv6 address space?Does https://en.wikipedia.org/wiki/IPv6_address#Transition_from_IPv4 list several alternative ways of translation? If it is correct, then the embedding is not fixed.
Does it mean that for any IPv4 address, there is some IPv6 address that refers to the same address as the IPv4 address?
For example, are
::192.31.20.46
and192.31.20.46
effectively the same address?if I send a message to
::192.31.20.46
, will192.31.20.46
receive my message?if I send a message to
192.31.20.46
, will::192.31.20.46
receive my message?
Will
::127.0.0.1
still be a loopback IP address, and if yes, is it effectively the same address as127.0.0.1
?Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
Thanks.
ip ipv4 ipv6 protocol-theory ip-address
3
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45
add a comment |
Tanenbaum's Computer Networks says
Finally, IPv4 addresses can be written as a pair of colons and an old dotted
decimal number, for example:::192.31.20.46
- Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space? Is such embedding fixed? Can the IPv4 address space be embedded
into any continuous subrange of the IPv6 address space?Does https://en.wikipedia.org/wiki/IPv6_address#Transition_from_IPv4 list several alternative ways of translation? If it is correct, then the embedding is not fixed.
Does it mean that for any IPv4 address, there is some IPv6 address that refers to the same address as the IPv4 address?
For example, are
::192.31.20.46
and192.31.20.46
effectively the same address?if I send a message to
::192.31.20.46
, will192.31.20.46
receive my message?if I send a message to
192.31.20.46
, will::192.31.20.46
receive my message?
Will
::127.0.0.1
still be a loopback IP address, and if yes, is it effectively the same address as127.0.0.1
?Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
Thanks.
ip ipv4 ipv6 protocol-theory ip-address
Tanenbaum's Computer Networks says
Finally, IPv4 addresses can be written as a pair of colons and an old dotted
decimal number, for example:::192.31.20.46
- Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space? Is such embedding fixed? Can the IPv4 address space be embedded
into any continuous subrange of the IPv6 address space?Does https://en.wikipedia.org/wiki/IPv6_address#Transition_from_IPv4 list several alternative ways of translation? If it is correct, then the embedding is not fixed.
Does it mean that for any IPv4 address, there is some IPv6 address that refers to the same address as the IPv4 address?
For example, are
::192.31.20.46
and192.31.20.46
effectively the same address?if I send a message to
::192.31.20.46
, will192.31.20.46
receive my message?if I send a message to
192.31.20.46
, will::192.31.20.46
receive my message?
Will
::127.0.0.1
still be a loopback IP address, and if yes, is it effectively the same address as127.0.0.1
?Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
Thanks.
ip ipv4 ipv6 protocol-theory ip-address
ip ipv4 ipv6 protocol-theory ip-address
edited Mar 23 at 17:19
Ron Maupin♦
68.3k1369126
68.3k1369126
asked Mar 23 at 14:38
TimTim
665518
665518
3
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45
add a comment |
3
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45
3
3
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45
add a comment |
3 Answers
3
active
oldest
votes
Are the IPv6 address space and IPv4 address space completely disjoint?
Yes, they are two separate, incompatible protocols with completely different addressing.
That book is out-of-date. The addressing to which it refers was deprecated a long time ago. it is referring to the old IPv4-Compatible addressing for IPv6 that was deprecated. See RFC 5156, Special-Use IPv6 Addresses:
2.3. IPv4-Compatible Addresses
::/96 are the IPv4-compatible addresses [RFC4291].
These addresses are deprecated and should not appear on the public
Internet.
There is IPv4-Mapped addressing for IPv6, but it is not really used as addressing for packets:
2.2. IPv4-Mapped Addresses
::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses
within this block should not appear on the public Internet.
Also see the referenced RFC 4291, IP Version 6 Addressing Architecture:
2.5.5. IPv6 Addresses with Embedded IPv4 Addresses
Two types of IPv6 addresses are defined that carry an IPv4 address in
the low-order 32 bits of the address. These are the "IPv4-Compatible
IPv6 address" and the "IPv4-mapped IPv6 address".
2.5.5.1. IPv4-Compatible IPv6 Address
The "IPv4-Compatible IPv6 address" was defined to assist in the IPv6
transition. The format of the "IPv4-Compatible IPv6 address" is as
follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
Note: The IPv4 address used in the "IPv4-Compatible IPv6 address" must
be a globally-unique IPv4 unicast address.
The "IPv4-Compatible IPv6 address" is now deprecated because the
current IPv6 transition mechanisms no longer use these addresses. New
or updated implementations are not required to support this address
type.
2.5.5.2. IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of IPv4
nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6 address"
is as follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
See [RFC4038] for background on the usage of the "IPv4-mapped
IPv6 address".
Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space?
Only under certain circumstances, but this is not normally recommended.
Is such embedding fixed? Can the IPv4 address space be embedded into
any continuous subrange of the IPv6 address space?
Only a couple of IPv6 address ranges are designed for this, and they are not used for sending packets. This is not used in Global IPv6 addressing.
Does it mean that for any IPv4 address, there is some IPv6 address
that refers to the same address as the IPv4 address?
Not really. Conceptually, yes, for IPv4-Mapped addressing for IPv6, but that is not actually used for sending packets.
For example, are
::192.31.20.46
and192.31.20.46
effectively the
same address?
- if I send a message to ::192.31.20.46, will 192.31.20.46 receive my message?
- if I send a message to 192.31.20.46, will ::192.31.20.46 receive my message?
Will ::127.0.0.1 still be a loopback IP address, and if yes, is it
effectively the same address as 127.0.0.1?
No, ::192.31.20.46
is an invalid IPv6 address because the IPv4-Compatible addressing for IPv6 has been deprecated.
IPv4 and IPv6 are two separate, incompatible protocols that can coexist, but cannot directly communicate.
IPv6 has a loopback address of ::1
.
Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
IPv4 and IPv6 have completely separate addressing. IPv4 uses 32-bit addressing that is incompatible with the IPv6 128-bit addressing. The protocol headers are also very different in other ways. IPv6 was created after lessons learned in IPv4. Remember that IPv4 was an academic/government experiment that was never intended to be used the way it is today, and IPv6 is an attempt to correct the deficiencies in IPv4, but it is incompatible with IPv4 because of that.
add a comment |
Number 4 is correct. V4 and v6 protocols are completely different with different formats and addressing schemes. The two addresses have the same relationship as telephone numbers and lottery numbers— that is, none.
There have been many proposed methods of mapping v4 to v6 to allow for protocol translation, but most are deprecated today.
add a comment |
I'm somewhat surprised that no existing answer mentioned 6to4.
It allows to send an IPv6 packet to an IPv4 host, encapsulated within IPv4 packet of protocol type 41.
6to4 addresses are of the type 2002:AABB:CCDD:suffix corresponding to IPv4 address A.B.C.D where A,B,C,D are decimal and AA,BB,CC,DD are hexadecimal. So, each IPv4 address actually has a whole /48 block of IPv6 addresses.
6to4 is not just some notation mechanism allowing IPv4 addresses to be notated using IPv6 addresses, it's a real and working IPv6 transition mechanism.
The performance and latency of 6to4 connectivity will be poor, however, so native IPv6 is preferred where such connectivity is available.
So, my answer to IPv4 and IPv6 spaces being disjoint: not really, each IPv4 address has a /48 block of IPv6 addresses.
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
add a comment |
Your Answer
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "496"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fnetworkengineering.stackexchange.com%2fquestions%2f57903%2fare-the-ipv6-address-space-and-ipv4-address-space-completely-disjoint%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
Are the IPv6 address space and IPv4 address space completely disjoint?
Yes, they are two separate, incompatible protocols with completely different addressing.
That book is out-of-date. The addressing to which it refers was deprecated a long time ago. it is referring to the old IPv4-Compatible addressing for IPv6 that was deprecated. See RFC 5156, Special-Use IPv6 Addresses:
2.3. IPv4-Compatible Addresses
::/96 are the IPv4-compatible addresses [RFC4291].
These addresses are deprecated and should not appear on the public
Internet.
There is IPv4-Mapped addressing for IPv6, but it is not really used as addressing for packets:
2.2. IPv4-Mapped Addresses
::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses
within this block should not appear on the public Internet.
Also see the referenced RFC 4291, IP Version 6 Addressing Architecture:
2.5.5. IPv6 Addresses with Embedded IPv4 Addresses
Two types of IPv6 addresses are defined that carry an IPv4 address in
the low-order 32 bits of the address. These are the "IPv4-Compatible
IPv6 address" and the "IPv4-mapped IPv6 address".
2.5.5.1. IPv4-Compatible IPv6 Address
The "IPv4-Compatible IPv6 address" was defined to assist in the IPv6
transition. The format of the "IPv4-Compatible IPv6 address" is as
follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
Note: The IPv4 address used in the "IPv4-Compatible IPv6 address" must
be a globally-unique IPv4 unicast address.
The "IPv4-Compatible IPv6 address" is now deprecated because the
current IPv6 transition mechanisms no longer use these addresses. New
or updated implementations are not required to support this address
type.
2.5.5.2. IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of IPv4
nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6 address"
is as follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
See [RFC4038] for background on the usage of the "IPv4-mapped
IPv6 address".
Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space?
Only under certain circumstances, but this is not normally recommended.
Is such embedding fixed? Can the IPv4 address space be embedded into
any continuous subrange of the IPv6 address space?
Only a couple of IPv6 address ranges are designed for this, and they are not used for sending packets. This is not used in Global IPv6 addressing.
Does it mean that for any IPv4 address, there is some IPv6 address
that refers to the same address as the IPv4 address?
Not really. Conceptually, yes, for IPv4-Mapped addressing for IPv6, but that is not actually used for sending packets.
For example, are
::192.31.20.46
and192.31.20.46
effectively the
same address?
- if I send a message to ::192.31.20.46, will 192.31.20.46 receive my message?
- if I send a message to 192.31.20.46, will ::192.31.20.46 receive my message?
Will ::127.0.0.1 still be a loopback IP address, and if yes, is it
effectively the same address as 127.0.0.1?
No, ::192.31.20.46
is an invalid IPv6 address because the IPv4-Compatible addressing for IPv6 has been deprecated.
IPv4 and IPv6 are two separate, incompatible protocols that can coexist, but cannot directly communicate.
IPv6 has a loopback address of ::1
.
Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
IPv4 and IPv6 have completely separate addressing. IPv4 uses 32-bit addressing that is incompatible with the IPv6 128-bit addressing. The protocol headers are also very different in other ways. IPv6 was created after lessons learned in IPv4. Remember that IPv4 was an academic/government experiment that was never intended to be used the way it is today, and IPv6 is an attempt to correct the deficiencies in IPv4, but it is incompatible with IPv4 because of that.
add a comment |
Are the IPv6 address space and IPv4 address space completely disjoint?
Yes, they are two separate, incompatible protocols with completely different addressing.
That book is out-of-date. The addressing to which it refers was deprecated a long time ago. it is referring to the old IPv4-Compatible addressing for IPv6 that was deprecated. See RFC 5156, Special-Use IPv6 Addresses:
2.3. IPv4-Compatible Addresses
::/96 are the IPv4-compatible addresses [RFC4291].
These addresses are deprecated and should not appear on the public
Internet.
There is IPv4-Mapped addressing for IPv6, but it is not really used as addressing for packets:
2.2. IPv4-Mapped Addresses
::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses
within this block should not appear on the public Internet.
Also see the referenced RFC 4291, IP Version 6 Addressing Architecture:
2.5.5. IPv6 Addresses with Embedded IPv4 Addresses
Two types of IPv6 addresses are defined that carry an IPv4 address in
the low-order 32 bits of the address. These are the "IPv4-Compatible
IPv6 address" and the "IPv4-mapped IPv6 address".
2.5.5.1. IPv4-Compatible IPv6 Address
The "IPv4-Compatible IPv6 address" was defined to assist in the IPv6
transition. The format of the "IPv4-Compatible IPv6 address" is as
follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
Note: The IPv4 address used in the "IPv4-Compatible IPv6 address" must
be a globally-unique IPv4 unicast address.
The "IPv4-Compatible IPv6 address" is now deprecated because the
current IPv6 transition mechanisms no longer use these addresses. New
or updated implementations are not required to support this address
type.
2.5.5.2. IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of IPv4
nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6 address"
is as follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
See [RFC4038] for background on the usage of the "IPv4-mapped
IPv6 address".
Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space?
Only under certain circumstances, but this is not normally recommended.
Is such embedding fixed? Can the IPv4 address space be embedded into
any continuous subrange of the IPv6 address space?
Only a couple of IPv6 address ranges are designed for this, and they are not used for sending packets. This is not used in Global IPv6 addressing.
Does it mean that for any IPv4 address, there is some IPv6 address
that refers to the same address as the IPv4 address?
Not really. Conceptually, yes, for IPv4-Mapped addressing for IPv6, but that is not actually used for sending packets.
For example, are
::192.31.20.46
and192.31.20.46
effectively the
same address?
- if I send a message to ::192.31.20.46, will 192.31.20.46 receive my message?
- if I send a message to 192.31.20.46, will ::192.31.20.46 receive my message?
Will ::127.0.0.1 still be a loopback IP address, and if yes, is it
effectively the same address as 127.0.0.1?
No, ::192.31.20.46
is an invalid IPv6 address because the IPv4-Compatible addressing for IPv6 has been deprecated.
IPv4 and IPv6 are two separate, incompatible protocols that can coexist, but cannot directly communicate.
IPv6 has a loopback address of ::1
.
Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
IPv4 and IPv6 have completely separate addressing. IPv4 uses 32-bit addressing that is incompatible with the IPv6 128-bit addressing. The protocol headers are also very different in other ways. IPv6 was created after lessons learned in IPv4. Remember that IPv4 was an academic/government experiment that was never intended to be used the way it is today, and IPv6 is an attempt to correct the deficiencies in IPv4, but it is incompatible with IPv4 because of that.
add a comment |
Are the IPv6 address space and IPv4 address space completely disjoint?
Yes, they are two separate, incompatible protocols with completely different addressing.
That book is out-of-date. The addressing to which it refers was deprecated a long time ago. it is referring to the old IPv4-Compatible addressing for IPv6 that was deprecated. See RFC 5156, Special-Use IPv6 Addresses:
2.3. IPv4-Compatible Addresses
::/96 are the IPv4-compatible addresses [RFC4291].
These addresses are deprecated and should not appear on the public
Internet.
There is IPv4-Mapped addressing for IPv6, but it is not really used as addressing for packets:
2.2. IPv4-Mapped Addresses
::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses
within this block should not appear on the public Internet.
Also see the referenced RFC 4291, IP Version 6 Addressing Architecture:
2.5.5. IPv6 Addresses with Embedded IPv4 Addresses
Two types of IPv6 addresses are defined that carry an IPv4 address in
the low-order 32 bits of the address. These are the "IPv4-Compatible
IPv6 address" and the "IPv4-mapped IPv6 address".
2.5.5.1. IPv4-Compatible IPv6 Address
The "IPv4-Compatible IPv6 address" was defined to assist in the IPv6
transition. The format of the "IPv4-Compatible IPv6 address" is as
follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
Note: The IPv4 address used in the "IPv4-Compatible IPv6 address" must
be a globally-unique IPv4 unicast address.
The "IPv4-Compatible IPv6 address" is now deprecated because the
current IPv6 transition mechanisms no longer use these addresses. New
or updated implementations are not required to support this address
type.
2.5.5.2. IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of IPv4
nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6 address"
is as follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
See [RFC4038] for background on the usage of the "IPv4-mapped
IPv6 address".
Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space?
Only under certain circumstances, but this is not normally recommended.
Is such embedding fixed? Can the IPv4 address space be embedded into
any continuous subrange of the IPv6 address space?
Only a couple of IPv6 address ranges are designed for this, and they are not used for sending packets. This is not used in Global IPv6 addressing.
Does it mean that for any IPv4 address, there is some IPv6 address
that refers to the same address as the IPv4 address?
Not really. Conceptually, yes, for IPv4-Mapped addressing for IPv6, but that is not actually used for sending packets.
For example, are
::192.31.20.46
and192.31.20.46
effectively the
same address?
- if I send a message to ::192.31.20.46, will 192.31.20.46 receive my message?
- if I send a message to 192.31.20.46, will ::192.31.20.46 receive my message?
Will ::127.0.0.1 still be a loopback IP address, and if yes, is it
effectively the same address as 127.0.0.1?
No, ::192.31.20.46
is an invalid IPv6 address because the IPv4-Compatible addressing for IPv6 has been deprecated.
IPv4 and IPv6 are two separate, incompatible protocols that can coexist, but cannot directly communicate.
IPv6 has a loopback address of ::1
.
Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
IPv4 and IPv6 have completely separate addressing. IPv4 uses 32-bit addressing that is incompatible with the IPv6 128-bit addressing. The protocol headers are also very different in other ways. IPv6 was created after lessons learned in IPv4. Remember that IPv4 was an academic/government experiment that was never intended to be used the way it is today, and IPv6 is an attempt to correct the deficiencies in IPv4, but it is incompatible with IPv4 because of that.
Are the IPv6 address space and IPv4 address space completely disjoint?
Yes, they are two separate, incompatible protocols with completely different addressing.
That book is out-of-date. The addressing to which it refers was deprecated a long time ago. it is referring to the old IPv4-Compatible addressing for IPv6 that was deprecated. See RFC 5156, Special-Use IPv6 Addresses:
2.3. IPv4-Compatible Addresses
::/96 are the IPv4-compatible addresses [RFC4291].
These addresses are deprecated and should not appear on the public
Internet.
There is IPv4-Mapped addressing for IPv6, but it is not really used as addressing for packets:
2.2. IPv4-Mapped Addresses
::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses
within this block should not appear on the public Internet.
Also see the referenced RFC 4291, IP Version 6 Addressing Architecture:
2.5.5. IPv6 Addresses with Embedded IPv4 Addresses
Two types of IPv6 addresses are defined that carry an IPv4 address in
the low-order 32 bits of the address. These are the "IPv4-Compatible
IPv6 address" and the "IPv4-mapped IPv6 address".
2.5.5.1. IPv4-Compatible IPv6 Address
The "IPv4-Compatible IPv6 address" was defined to assist in the IPv6
transition. The format of the "IPv4-Compatible IPv6 address" is as
follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
Note: The IPv4 address used in the "IPv4-Compatible IPv6 address" must
be a globally-unique IPv4 unicast address.
The "IPv4-Compatible IPv6 address" is now deprecated because the
current IPv6 transition mechanisms no longer use these addresses. New
or updated implementations are not required to support this address
type.
2.5.5.2. IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of IPv4
nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6 address"
is as follows:| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
See [RFC4038] for background on the usage of the "IPv4-mapped
IPv6 address".
Does it mean the IPv4 address space is embedded into the lowest
subrange of the IPv6 address space?
Only under certain circumstances, but this is not normally recommended.
Is such embedding fixed? Can the IPv4 address space be embedded into
any continuous subrange of the IPv6 address space?
Only a couple of IPv6 address ranges are designed for this, and they are not used for sending packets. This is not used in Global IPv6 addressing.
Does it mean that for any IPv4 address, there is some IPv6 address
that refers to the same address as the IPv4 address?
Not really. Conceptually, yes, for IPv4-Mapped addressing for IPv6, but that is not actually used for sending packets.
For example, are
::192.31.20.46
and192.31.20.46
effectively the
same address?
- if I send a message to ::192.31.20.46, will 192.31.20.46 receive my message?
- if I send a message to 192.31.20.46, will ::192.31.20.46 receive my message?
Will ::127.0.0.1 still be a loopback IP address, and if yes, is it
effectively the same address as 127.0.0.1?
No, ::192.31.20.46
is an invalid IPv6 address because the IPv4-Compatible addressing for IPv6 has been deprecated.
IPv4 and IPv6 are two separate, incompatible protocols that can coexist, but cannot directly communicate.
IPv6 has a loopback address of ::1
.
Or are the IPv6 address space and IPv4 address space completely
disjoint (i.e. no overlapping), in the sense that when I communicate
with a IPv6 address, I will not communicate with a IPv4 address?
IPv4 and IPv6 have completely separate addressing. IPv4 uses 32-bit addressing that is incompatible with the IPv6 128-bit addressing. The protocol headers are also very different in other ways. IPv6 was created after lessons learned in IPv4. Remember that IPv4 was an academic/government experiment that was never intended to be used the way it is today, and IPv6 is an attempt to correct the deficiencies in IPv4, but it is incompatible with IPv4 because of that.
edited Mar 23 at 17:36
answered Mar 23 at 17:08
Ron Maupin♦Ron Maupin
68.3k1369126
68.3k1369126
add a comment |
add a comment |
Number 4 is correct. V4 and v6 protocols are completely different with different formats and addressing schemes. The two addresses have the same relationship as telephone numbers and lottery numbers— that is, none.
There have been many proposed methods of mapping v4 to v6 to allow for protocol translation, but most are deprecated today.
add a comment |
Number 4 is correct. V4 and v6 protocols are completely different with different formats and addressing schemes. The two addresses have the same relationship as telephone numbers and lottery numbers— that is, none.
There have been many proposed methods of mapping v4 to v6 to allow for protocol translation, but most are deprecated today.
add a comment |
Number 4 is correct. V4 and v6 protocols are completely different with different formats and addressing schemes. The two addresses have the same relationship as telephone numbers and lottery numbers— that is, none.
There have been many proposed methods of mapping v4 to v6 to allow for protocol translation, but most are deprecated today.
Number 4 is correct. V4 and v6 protocols are completely different with different formats and addressing schemes. The two addresses have the same relationship as telephone numbers and lottery numbers— that is, none.
There have been many proposed methods of mapping v4 to v6 to allow for protocol translation, but most are deprecated today.
answered Mar 23 at 17:07
Ron TrunkRon Trunk
39.6k33781
39.6k33781
add a comment |
add a comment |
I'm somewhat surprised that no existing answer mentioned 6to4.
It allows to send an IPv6 packet to an IPv4 host, encapsulated within IPv4 packet of protocol type 41.
6to4 addresses are of the type 2002:AABB:CCDD:suffix corresponding to IPv4 address A.B.C.D where A,B,C,D are decimal and AA,BB,CC,DD are hexadecimal. So, each IPv4 address actually has a whole /48 block of IPv6 addresses.
6to4 is not just some notation mechanism allowing IPv4 addresses to be notated using IPv6 addresses, it's a real and working IPv6 transition mechanism.
The performance and latency of 6to4 connectivity will be poor, however, so native IPv6 is preferred where such connectivity is available.
So, my answer to IPv4 and IPv6 spaces being disjoint: not really, each IPv4 address has a /48 block of IPv6 addresses.
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
add a comment |
I'm somewhat surprised that no existing answer mentioned 6to4.
It allows to send an IPv6 packet to an IPv4 host, encapsulated within IPv4 packet of protocol type 41.
6to4 addresses are of the type 2002:AABB:CCDD:suffix corresponding to IPv4 address A.B.C.D where A,B,C,D are decimal and AA,BB,CC,DD are hexadecimal. So, each IPv4 address actually has a whole /48 block of IPv6 addresses.
6to4 is not just some notation mechanism allowing IPv4 addresses to be notated using IPv6 addresses, it's a real and working IPv6 transition mechanism.
The performance and latency of 6to4 connectivity will be poor, however, so native IPv6 is preferred where such connectivity is available.
So, my answer to IPv4 and IPv6 spaces being disjoint: not really, each IPv4 address has a /48 block of IPv6 addresses.
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
add a comment |
I'm somewhat surprised that no existing answer mentioned 6to4.
It allows to send an IPv6 packet to an IPv4 host, encapsulated within IPv4 packet of protocol type 41.
6to4 addresses are of the type 2002:AABB:CCDD:suffix corresponding to IPv4 address A.B.C.D where A,B,C,D are decimal and AA,BB,CC,DD are hexadecimal. So, each IPv4 address actually has a whole /48 block of IPv6 addresses.
6to4 is not just some notation mechanism allowing IPv4 addresses to be notated using IPv6 addresses, it's a real and working IPv6 transition mechanism.
The performance and latency of 6to4 connectivity will be poor, however, so native IPv6 is preferred where such connectivity is available.
So, my answer to IPv4 and IPv6 spaces being disjoint: not really, each IPv4 address has a /48 block of IPv6 addresses.
I'm somewhat surprised that no existing answer mentioned 6to4.
It allows to send an IPv6 packet to an IPv4 host, encapsulated within IPv4 packet of protocol type 41.
6to4 addresses are of the type 2002:AABB:CCDD:suffix corresponding to IPv4 address A.B.C.D where A,B,C,D are decimal and AA,BB,CC,DD are hexadecimal. So, each IPv4 address actually has a whole /48 block of IPv6 addresses.
6to4 is not just some notation mechanism allowing IPv4 addresses to be notated using IPv6 addresses, it's a real and working IPv6 transition mechanism.
The performance and latency of 6to4 connectivity will be poor, however, so native IPv6 is preferred where such connectivity is available.
So, my answer to IPv4 and IPv6 spaces being disjoint: not really, each IPv4 address has a /48 block of IPv6 addresses.
answered Mar 24 at 11:48
juhistjuhist
37217
37217
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
add a comment |
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
The problem with your answer is that it leads people to believe that you can have an IPv6-only host directly communicate with an IPv4-only host or vice versa, and that simply isn't true. There is a lot more to it than that, including relay routers to translate the protocols, so, yes, the address space is still separate, but you have something that can talk in both protocols to do translation.
– Ron Maupin♦
Mar 24 at 15:03
add a comment |
Thanks for contributing an answer to Network Engineering Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fnetworkengineering.stackexchange.com%2fquestions%2f57903%2fare-the-ipv6-address-space-and-ipv4-address-space-completely-disjoint%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
3
Beware of outdated textbooks. IPv4-compatible IPv6 addresses have been deprecated for almost 15 years, replaed by IPv4-mapped IPv6 addresses. Modern operating systems may not recognize them. See RFC 4291.
– Michael Hampton
Mar 23 at 23:45