draft-ietf-6man-text-addr-representation-03.txt   draft-ietf-6man-text-addr-representation-04.txt 
IPv6 Maintenance Working Group S. Kawamura IPv6 Maintenance Working Group S. Kawamura
Internet-Draft NEC BIGLOBE, Ltd. Internet-Draft NEC BIGLOBE, Ltd.
Intended status: Standards Track M. Kawashima Intended status: Standards Track M. Kawashima
Expires: May 29, 2010 NEC AccessTechnica, Ltd. Expires: July 18, 2010 NEC AccessTechnica, Ltd.
November 25, 2009 January 14, 2010
A Recommendation for IPv6 Address Text Representation A Recommendation for IPv6 Address Text Representation
draft-ietf-6man-text-addr-representation-03 draft-ietf-6man-text-addr-representation-04
Abstract Abstract
As IPv6 network grows, there will be more engineers and also non- As IPv6 network grows, there will be more engineers and also non-
engineers who will have the need to use an IPv6 address in text. engineers who will have the need to use an IPv6 address in text.
While the IPv6 address architecture RFC 4291 section 2.2 depicts a While the IPv6 address architecture RFC 4291 section 2.2 depicts a
flexible model for text representation of an IPv6 address, this flexible model for text representation of an IPv6 address, this
flexibility has been causing problems for operators, system flexibility has been causing problems for operators, system
engineers, and users. This document will describe the problems that engineers, and users. This document will describe the problems that
a flexible text representation has been causing. This document also a flexible text representation has been causing. This document also
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on May 29, 2010. This Internet-Draft will expire on July 18, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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3.1.4. Searching for an Address in a Network Diagram . . . . 7 3.1.4. Searching for an Address in a Network Diagram . . . . 7
3.2. Parsing and Modifying . . . . . . . . . . . . . . . . . . 7 3.2. Parsing and Modifying . . . . . . . . . . . . . . . . . . 7
3.2.1. General Summary . . . . . . . . . . . . . . . . . . . 7 3.2.1. General Summary . . . . . . . . . . . . . . . . . . . 7
3.2.2. Logging . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. Logging . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.3. Auditing: Case 1 . . . . . . . . . . . . . . . . . . . 7 3.2.3. Auditing: Case 1 . . . . . . . . . . . . . . . . . . . 7
3.2.4. Auditing: Case 2 . . . . . . . . . . . . . . . . . . . 8 3.2.4. Auditing: Case 2 . . . . . . . . . . . . . . . . . . . 8
3.2.5. Verification . . . . . . . . . . . . . . . . . . . . . 8 3.2.5. Verification . . . . . . . . . . . . . . . . . . . . . 8
3.2.6. Unexpected Modifying . . . . . . . . . . . . . . . . . 8 3.2.6. Unexpected Modifying . . . . . . . . . . . . . . . . . 8
3.3. Operating . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3. Operating . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3.1. General Summary . . . . . . . . . . . . . . . . . . . 8 3.3.1. General Summary . . . . . . . . . . . . . . . . . . . 8
3.3.2. Customer Calls . . . . . . . . . . . . . . . . . . . . 9 3.3.2. Customer Calls . . . . . . . . . . . . . . . . . . . . 8
3.3.3. Abuse . . . . . . . . . . . . . . . . . . . . . . . . 9 3.3.3. Abuse . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4. Other Minor Problems . . . . . . . . . . . . . . . . . . . 9 3.4. Other Minor Problems . . . . . . . . . . . . . . . . . . . 9
3.4.1. Changing Platforms . . . . . . . . . . . . . . . . . . 9 3.4.1. Changing Platforms . . . . . . . . . . . . . . . . . . 9
3.4.2. Preference in Documentation . . . . . . . . . . . . . 9 3.4.2. Preference in Documentation . . . . . . . . . . . . . 9
3.4.3. Legibility . . . . . . . . . . . . . . . . . . . . . . 9 3.4.3. Legibility . . . . . . . . . . . . . . . . . . . . . . 9
4. A Recommendation for IPv6 Text Representation . . . . . . . . 10 4. A Recommendation for IPv6 Text Representation . . . . . . . . 9
4.1. Handling Leading Zeros in a 16 Bit Field . . . . . . . . . 10 4.1. Handling Leading Zeros in a 16 Bit Field . . . . . . . . . 10
4.2. "::" Usage . . . . . . . . . . . . . . . . . . . . . . . . 10 4.2. "::" Usage . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2.1. Shorten As Much As Possible . . . . . . . . . . . . . 10 4.2.1. Shorten As Much As Possible . . . . . . . . . . . . . 10
4.2.2. Handling One 16 Bit 0 Field . . . . . . . . . . . . . 10 4.2.2. Handling One 16 Bit 0 Field . . . . . . . . . . . . . 10
4.2.3. Choice in Placement of "::" . . . . . . . . . . . . . 10 4.2.3. Choice in Placement of "::" . . . . . . . . . . . . . 10
4.3. Lower Case . . . . . . . . . . . . . . . . . . . . . . . . 10 4.3. Lower Case . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Text Representation of Special Addresses . . . . . . . . . . . 11 5. Text Representation of Special Addresses . . . . . . . . . . . 10
6. Notes on Combining IPv6 Addresses with Port Numbers . . . . . 11 6. Notes on Combining IPv6 Addresses with Port Numbers . . . . . 11
7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. Prefix Representation . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 13 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . . 13 12.1. Normative References . . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. For Developers . . . . . . . . . . . . . . . . . . . 13 Appendix A. For Developers . . . . . . . . . . . . . . . . . . . 13
Appendix B. Prefix Issues . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
A single IPv6 address can be text represented in many ways. Examples A single IPv6 address can be text represented in many ways. Examples
are shown below. are shown below.
2001:db8:0:0:1:0:0:1 2001:db8:0:0:1:0:0:1
2001:0db8:0:0:1:0:0:1 2001:0db8:0:0:1:0:0:1
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it was better, a simple diff will tell you that a different address it was better, a simple diff will tell you that a different address
was configured. If this was done on a wide scale network, people was configured. If this was done on a wide scale network, people
will be focusing on 'why the extra zeros were put in' instead of will be focusing on 'why the extra zeros were put in' instead of
doing any real auditing. Lots of tools are just plain 'diff's that doing any real auditing. Lots of tools are just plain 'diff's that
do not take into account address representation rules. do not take into account address representation rules.
3.2.4. Auditing: Case 2 3.2.4. Auditing: Case 2
Node configurations will be matched against an information system Node configurations will be matched against an information system
that manages IP addresses. If output notation is different, there that manages IP addresses. If output notation is different, there
will need to be a script that is implemented to cover for this. An will need to be a script that is implemented to cover for this. The
SNMP GET of an interface address and text representation in a humanly result of an SNMP GET operation, converted to text and compared to a
written text file is highly unlikely to match on first try. textual address written by a human is highly unlikely to match on
first try.
3.2.5. Verification 3.2.5. Verification
Some protocols require certain data fields to be verified. One Some protocols require certain data fields to be verified. One
example of this is X.509 certificates. If an IPv6 address was example of this is X.509 certificates. If an IPv6 address field in a
embedded in one of the fields in a certificate, and the verification certificate was incorrectly verified by converting it to text and
was done by just a simple textual comparison, the certificate may be making a simple textual comparison to some other address, the
mistakenly shown as being invalid due to a difference in text certificate may be mistakenly shown as being invalid due to a
representation methods. difference in text representation methods.
3.2.6. Unexpected Modifying 3.2.6. Unexpected Modifying
Sometimes, a system will take an address and modify it as a Sometimes, a system will take an address and modify it as a
convenience. For example, a system may take an input of convenience. For example, a system may take an input of
2001:0db8:0::1 and make the output 2001:db8::1 (which is seen in some 2001:0db8:0::1 and make the output 2001:db8::1. If the zeros were
RIR databases). If the zeros were input for a reason, the outcome input for a reason, the outcome may be somewhat unexpected.
may be somewhat unexpected.
3.3. Operating 3.3. Operating
3.3.1. General Summary 3.3.1. General Summary
When an operator sets an IPv6 address of a system as 2001:db8:0:0:1: When an operator sets an IPv6 address of a system as 2001:db8:0:0:1:
0:0:1, the system may take the address and show the configuration 0:0:1, the system may take the address and show the configuration
result as 2001:DB8::1:0:0:1. A distinguished engineer will know that result as 2001:DB8::1:0:0:1. Someone familiar with IPv6 address
the right address is set, but an operator, or a customer that is representation will know that the right address is set, but not
communicating with the operator to solve a problem, is usually not as everyone may understand this.
distinguished as we would like.
3.3.2. Customer Calls 3.3.2. Customer Calls
When a customer calls to inquire about a suspected outage, IPv6 When a customer calls to inquire about a suspected outage, IPv6
address representation should be handled with care. Not all address representation should be handled with care. Not all
customers are engineers nor have the same skill in IPv6 technology. customers are engineers nor have the same skill in IPv6 technology.
The NOC will have to take extra steps to humanly parse the address to The network operations center will have to take extra steps to
avoid having to explain to the customers that 2001:db8:0:1::1 is the humanly parse the address to avoid having to explain to the customers
same as 2001:db8::1:0:0:0:1. This is one thing that will never that 2001:db8:0:1::1 is the same as 2001:db8::1:0:0:0:1. This is one
happen in IPv4 because IPv4 address cannot be abbreviated. thing that will never happen in IPv4 because IPv4 address cannot be
abbreviated.
3.3.3. Abuse 3.3.3. Abuse
Network abuse is reported along with the abusing IP address. This Network abuse is reported along with the abusing IP address. This
'reporting' could take any shape or form of the flexible model. A 'reporting' could take any shape or form of the flexible model. A
team that handles network abuse must be able to tell the difference team that handles network abuse must be able to tell the difference
between a 2001:db8::1:0:1 and 2001:db8:1::0:1. Mistakes in the between a 2001:db8::1:0:1 and 2001:db8:1::0:1. Mistakes in the
placement of the "::" will result in a critical situation. A system placement of the "::" will result in a critical situation. A system
that handles these incidents should be able to handle any type of that handles these incidents should be able to handle any type of
input and parse it in a correct manner. Also, incidents are reported input and parse it in a correct manner. Also, incidents are reported
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information. information.
3.4. Other Minor Problems 3.4. Other Minor Problems
3.4.1. Changing Platforms 3.4.1. Changing Platforms
When an engineer decides to change the platform of a running service, When an engineer decides to change the platform of a running service,
the same code may not work as expected due to the difference in IPv6 the same code may not work as expected due to the difference in IPv6
address text representation. Usually, a change in a platform (e.g. address text representation. Usually, a change in a platform (e.g.
Unix to Windows, Cisco to Juniper) will result in a major change of Unix to Windows, Cisco to Juniper) will result in a major change of
code, but flexibility in address representation will increase the code anyway, but flexibility in address representation will increase
work load. the work load.
3.4.2. Preference in Documentation 3.4.2. Preference in Documentation
A document that is edited by more than one author, may become harder A document that is edited by more than one author, may become harder
to read. to read.
3.4.3. Legibility 3.4.3. Legibility
Capital case D and 0 can be quite often misread. Capital B and 8 can Capital case D and 0 can be quite often misread. Capital B and 8 can
also be misread. also be misread.
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by various operating systems, and is human friendly. The by various operating systems, and is human friendly. The
recommendation in this document SHOULD be followed by systems when recommendation in this document SHOULD be followed by systems when
generating an address to represent as text, but all implementations generating an address to represent as text, but all implementations
MUST accept any legitimate [RFC4291] format. It is advised that MUST accept any legitimate [RFC4291] format. It is advised that
humans also follow these recommendations when spelling an address. humans also follow these recommendations when spelling an address.
4.1. Handling Leading Zeros in a 16 Bit Field 4.1. Handling Leading Zeros in a 16 Bit Field
Leading zeros should be chopped for human legibility and easier Leading zeros should be chopped for human legibility and easier
searching. Also, a single 16 bit 0000 field should be represented as searching. Also, a single 16 bit 0000 field should be represented as
just 0. Place holder zeros are often cause of misreading. just 0.
4.2. "::" Usage 4.2. "::" Usage
4.2.1. Shorten As Much As Possible 4.2.1. Shorten As Much As Possible
The use of "::" should be used to its maximum capability (i.e. 2001: The use of "::" should be used to its maximum capability (i.e. 2001:
db8::0:1 is not considered as clean representation). db8::0:1 is not considered as clean representation).
4.2.2. Handling One 16 Bit 0 Field 4.2.2. Handling One 16 Bit 0 Field
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Recent implementations tend to represent IPv6 address as lower case. Recent implementations tend to represent IPv6 address as lower case.
It is better to use lower case to avoid problems such as described in It is better to use lower case to avoid problems such as described in
section 3.3.3 and 3.4.3. section 3.3.3 and 3.4.3.
5. Text Representation of Special Addresses 5. Text Representation of Special Addresses
Addresses such as IPv4-Mapped IPv6 addresses, ISATAP [RFC5214], and Addresses such as IPv4-Mapped IPv6 addresses, ISATAP [RFC5214], and
IPv4-translatable addresses [I-D.ietf-behave-address-format] have IPv4-translatable addresses [I-D.ietf-behave-address-format] have
IPv4 addresses embedded in the low-order 32 bits of the address. IPv4 addresses embedded in the low-order 32 bits of the address.
These addresses have special representation that may mix hexadecimal These addresses have special representation that may mix hexadecimal
and decimal notations. The decimal notation may be used only for the and dot decimal notations. The decimal notation may be used only for
last 32 bits of the address. For these addresses, mixed notation is the last 32 bits of the address. For these addresses, mixed notation
recommended if either of the below conditions are met. is recommended if the following condition is met: The address can be
distinguished as having IPv4 addresses embedded in the lower 32 bits
(1) The address can be distinguished as having IPv4 addresses solely from the address field through the use of a well known prefix.
embedded in the lower 32 bits solely from the address field. (e.g. If it is known by some external method that a given prefix includes
Well Known Prefixes) an IPv4 address, it MAY be represented as mixed notation. Tools that
provide options to specify prefixes that is (or is not) to be
(2) An external mechanism such as prefix learning or pre- represented as mixed notation may be useful.
configuration helps in recognizing the address as having IPv4
addresses embedded in the lower 32 bits.
However, there may be situations where full hexadecimal The text representation method noted in Section 4 should be applied
representation is chosen to meet certain needs. Addressing those for the leading hexadecimal part (i.e. ::ffff:192.0.2.1 instead of
needs is out of the scope of this document. The text representation 0:0:0:0:0:ffff:192.0.2.1).
method noted in Section 4 should be applied for the leading
hexadecimal part (i.e. ::ffff:192.0.2.1 instead of 0:0:0:0:0:ffff:
192.0.2.1).
6. Notes on Combining IPv6 Addresses with Port Numbers 6. Notes on Combining IPv6 Addresses with Port Numbers
When IPv6 addresses and port numbers are represented in text combined When IPv6 addresses and port numbers are represented in text combined
together, there seems to be many different ways to do so. Examples together, there are many different ways to do so. Examples are shown
are shown below. below.
o [2001:db8::1]:80 o [2001:db8::1]:80
o 2001:db8::1:80 o 2001:db8::1:80
o 2001:db8::1.80 o 2001:db8::1.80
o 2001:db8::1 port 80 o 2001:db8::1 port 80
o 2001:db8::1p80 o 2001:db8::1p80
o 2001:db8::1#80 o 2001:db8::1#80
The situation is not much different in IPv4, but the most ambiguous The situation is not much different in IPv4, but the most ambiguous
case with IPv6 is the second bullet. This is due to the "::"usage in case with IPv6 is the second bullet. This is due to the "::"usage in
IPv6 addresses. This style is not recommended for its ambiguity. IPv6 addresses. This style is not recommended for its ambiguity.
The [] style as expressed in [RFC3986] is recommended. Other styles The [] style as expressed in [RFC3986] should be employed, and is the
are acceptable when cross-platform portability does not become an default unless otherwise specified. Other styles are acceptable when
issue. there is exactly one style for the given context and cross-platform
portability does not become an issue.
7. Conclusion 7. Prefix Representation
Problems with prefixes are just the same as problems encountered with
addresses. Text representation method of IPv6 prefixes should be no
different from that of IPv6 addresses.
8. Conclusion
The recommended format of text representing an IPv6 address is The recommended format of text representing an IPv6 address is
summarized as follows. summarized as follows.
(1) omit leading zeros in a 16 bit field (1) omit leading zeros in a 16 bit field
(2) when using "::", shorten consecutive zero fields to their (2) when using "::", shorten consecutive zero fields to their
maximum extent (leave no zero fields behind). maximum extent (leave no zero fields behind).
(3) "::" used where shortens address the most (3) "::" used where shortens address the most
(4) "::" used in the former part in case of a tie breaker (4) "::" used in the former part in case of a tie breaker
(5) do not shorten one 16 bit 0 field, but always shorten when (5) do not shorten one 16 bit 0 field, but always shorten when
there are two or more consecutive 16 bit 0 fields there are two or more consecutive 16 bit 0 fields
(6) use lower case (6) use lower case
Hints for developers are written in the Appendix section. Hints for developers are written in the Appendix section.
8. Security Considerations 9. Security Considerations
None. None.
9. IANA Considerations 10. IANA Considerations
None. None.
10. Acknowledgements 11. Acknowledgements
The authors would like to thank Jan Zorz, Randy Bush, Yuichi Minami, The authors would like to thank Jan Zorz, Randy Bush, Yuichi Minami,
Toshimitsu Matsuura for their generous and helpful comments in kick Toshimitsu Matsuura for their generous and helpful comments in kick
starting this document. We also would like to thank Brian Carpenter, starting this document. We also would like to thank Brian Carpenter,
Akira Kato, Juergen Schoenwaelder, Antonio Querubin, Dave Thaler, Akira Kato, Juergen Schoenwaelder, Antonio Querubin, Dave Thaler,
Brian Haley, Suresh Krishnan, Jerry Huang, Roman Donchenko, Heikki Brian Haley, Suresh Krishnan, Jerry Huang, Roman Donchenko, Heikki
Vatiainen ,Dan Wing for their input. Also a very special thanks to Vatiainen ,Dan Wing for their input. Also a very special thanks to
Ron Bonica, Fred Baker, Brian Haberman, Robert Hinden, Jari Arkko, Ron Bonica, Fred Baker, Brian Haberman, Robert Hinden, Jari Arkko,
and Kurt Lindqvist for their support in bringing this document to the and Kurt Lindqvist for their support in bringing this document to the
light of IETF working groups. light of IETF working groups.
11. References 12. References
11.1. Normative References 12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006. Architecture", RFC 4291, February 2006.
11.2. Informative References 12.2. Informative References
[I-D.ietf-behave-address-format] [I-D.ietf-behave-address-format]
Huitema, C., Bao, C., Bagnulo, M., Boucadair, M., and X. Huitema, C., Bao, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", Li, "IPv6 Addressing of IPv4/IPv6 Translators",
draft-ietf-behave-address-format-01 (work in progress), draft-ietf-behave-address-format-03 (work in progress),
October 2009. December 2009.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005. RFC 3986, January 2005.
[RFC4038] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E. [RFC4038] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E.
Castro, "Application Aspects of IPv6 Transition", Castro, "Application Aspects of IPv6 Transition",
RFC 4038, March 2005. RFC 4038, March 2005.
[RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
skipping to change at page 13, line 44 skipping to change at page 14, line 5
Appendix A. For Developers Appendix A. For Developers
We recommend that developers use display routines that conform to We recommend that developers use display routines that conform to
these rules. For example, the usage of getnameinfo() with flags these rules. For example, the usage of getnameinfo() with flags
argument NI_NUMERICHOST in FreeBSD 7.0 will give a conforming output, argument NI_NUMERICHOST in FreeBSD 7.0 will give a conforming output,
except for the special addresses notes in Section 5. The function except for the special addresses notes in Section 5. The function
inet_ntop() of FreeBSD7.0 is a good C code reference, but should not inet_ntop() of FreeBSD7.0 is a good C code reference, but should not
be called directly. See [RFC4038] for details. be called directly. See [RFC4038] for details.
Appendix B. Prefix Issues
Problems with prefixes are just the same as problems encountered with
addresses. Text representation method of IPv6 prefixes should be no
different from that of IPv6 addresses.
Authors' Addresses Authors' Addresses
Seiichi Kawamura Seiichi Kawamura
NEC BIGLOBE, Ltd. NEC BIGLOBE, Ltd.
14-22, Shibaura 4-chome 14-22, Shibaura 4-chome
Minatoku, Tokyo 108-8558 Minatoku, Tokyo 108-8558
JAPAN JAPAN
Phone: +81 3 3798 6085 Phone: +81 3 3798 6085
Email: kawamucho@mesh.ad.jp Email: kawamucho@mesh.ad.jp
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