draft-ietf-6man-rfc3484bis-00.txt   draft-ietf-6man-rfc3484bis-01.txt 
Network Working Group D. Thaler, Ed. Network Working Group D. Thaler, Ed.
Internet-Draft Microsoft Internet-Draft Microsoft
Obsoletes: 3484 (if approved) R. Draves Obsoletes: 3484 (if approved) R. Draves
Intended status: Standards Track Microsoft Research Intended status: Standards Track Microsoft Research
Expires: August 26, 2012 T. Chown Expires: September 6, 2012 A. Matsumoto
NTT
T. Chown
University of Southampton University of Southampton
February 23, 2012 March 5, 2012
Default Address Selection for Internet Protocol version 6 (IPv6) Default Address Selection for Internet Protocol version 6 (IPv6)
draft-ietf-6man-rfc3484bis-00.txt draft-ietf-6man-rfc3484bis-01.txt
Abstract Abstract
This document describes two algorithms, for source address selection This document describes two algorithms, for source address selection
and for destination address selection. The algorithms specify and for destination address selection. The algorithms specify
default behavior for all Internet Protocol version 6 (IPv6) default behavior for all Internet Protocol version 6 (IPv6)
implementations. They do not override choices made by applications implementations. They do not override choices made by applications
or upper-layer protocols, nor do they preclude the development of or upper-layer protocols, nor do they preclude the development of
more advanced mechanisms for address selection. The two algorithms more advanced mechanisms for address selection. The two algorithms
share a common context, including an optional mechanism for allowing share a common context, including an optional mechanism for allowing
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 26, 2012. This Internet-Draft will expire on September 6, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conventions Used in This Document . . . . . . . . . . . . 5 1.1. Conventions Used in This Document . . . . . . . . . . . . 5
2. Context in Which the Algorithms Operate . . . . . . . . . . . 5 2. Context in Which the Algorithms Operate . . . . . . . . . . . 5
2.1. Policy Table . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Policy Table . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Common Prefix Length . . . . . . . . . . . . . . . . . . . 8 2.2. Common Prefix Length . . . . . . . . . . . . . . . . . . . 8
3. Address Properties . . . . . . . . . . . . . . . . . . . . . . 8 3. Address Properties . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Scope Comparisons . . . . . . . . . . . . . . . . . . . . 8 3.1. Scope Comparisons . . . . . . . . . . . . . . . . . . . . 8
3.2. IPv4 Addresses and IPv4-Mapped Addresses . . . . . . . . . 9 3.2. IPv4 Addresses and IPv4-Mapped Addresses . . . . . . . . . 9
3.3. Other IPv6 Addresses with Embedded IPv4 Addresses . . . . 9 3.3. Other IPv6 Addresses with Embedded IPv4 Addresses . . . . 9
3.4. IPv6 Loopback Address and Other Format Prefixes . . . . . 9 3.4. IPv6 Loopback Address and Other Format Prefixes . . . . . 9
3.5. Mobility Addresses . . . . . . . . . . . . . . . . . . . . 9 3.5. Mobility Addresses . . . . . . . . . . . . . . . . . . . . 10
4. Candidate Source Addresses . . . . . . . . . . . . . . . . . . 10 4. Candidate Source Addresses . . . . . . . . . . . . . . . . . . 10
5. Source Address Selection . . . . . . . . . . . . . . . . . . . 11 5. Source Address Selection . . . . . . . . . . . . . . . . . . . 11
6. Destination Address Selection . . . . . . . . . . . . . . . . 13 6. Destination Address Selection . . . . . . . . . . . . . . . . 14
7. Interactions with Routing . . . . . . . . . . . . . . . . . . 16 7. Interactions with Routing . . . . . . . . . . . . . . . . . . 16
8. Implementation Considerations . . . . . . . . . . . . . . . . 16 8. Implementation Considerations . . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17 9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Default Source Address Selection . . . . . . . . . . . . . 18 10.1. Default Source Address Selection . . . . . . . . . . . . . 18
10.2. Default Destination Address Selection . . . . . . . . . . 18 10.2. Default Destination Address Selection . . . . . . . . . . 18
10.3. Configuring Preference for IPv6 or IPv4 . . . . . . . . . 20 10.3. Configuring Preference for IPv6 or IPv4 . . . . . . . . . 20
10.3.1. Handling Broken IPv6 . . . . . . . . . . . . . . . . 20 10.3.1. Handling Broken IPv6 . . . . . . . . . . . . . . . . 20
10.4. Configuring Preference for Link-Local Addresses . . . . . 21 10.4. Configuring Preference for Link-Local Addresses . . . . . 21
10.5. Configuring a Multi-Homed Site . . . . . . . . . . . . . . 21 10.5. Configuring a Multi-Homed Site . . . . . . . . . . . . . . 21
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2002::/16 30 2 2002::/16 30 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13 fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
An implementation MAY automatically add additional site-specific rows An implementation MAY automatically add additional site-specific rows
to the default table based on its configured addresses, such as for to the default table based on its configured addresses, such as for
ULAs and 6to4 addresses for instance (see Section 10.6 and ULAs and 6to4 addresses for instance (see Section 10.6 and
Section 10.7 for examples). Section 10.7 for examples). Any such rows automatically added by the
implementation as a result of address acquisition MUST NOT override a
row for the same prefix configured via other means. That is, rows
can be added but never updated automatically. An implementation
SHOULD provide a means for an administrator to disable automatic row
additions.
One effect of the default policy table is to prefer using native One effect of the default policy table is to prefer using native
source addresses with native destination addresses, 6to4 [RFC3056] source addresses with native destination addresses, 6to4 [RFC3056]
source addresses with 6to4 destination addresses, etc. Another source addresses with 6to4 destination addresses, etc. Another
effect of the default policy table is to prefer communication using effect of the default policy table is to prefer communication using
IPv6 addresses to communication using IPv4 addresses, if matching IPv6 addresses to communication using IPv4 addresses, if matching
source addresses are available. source addresses are available.
Policy table entries for scoped address prefixes MAY be qualified Policy table entries for scoped address prefixes MAY be qualified
with an optional zone index. If so, a prefix table entry only with an optional zone index. If so, a prefix table entry only
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The default policy table gives IPv6 addresses higher precedence than The default policy table gives IPv6 addresses higher precedence than
IPv4 addresses. This means that applications will use IPv6 in IPv4 addresses. This means that applications will use IPv6 in
preference to IPv4 when the two are equally suitable. An preference to IPv4 when the two are equally suitable. An
administrator can change the policy table to prefer IPv4 addresses by administrator can change the policy table to prefer IPv4 addresses by
giving the ::ffff:0.0.0.0/96 prefix a higher precedence: giving the ::ffff:0.0.0.0/96 prefix a higher precedence:
Prefix Precedence Label Prefix Precedence Label
::1/128 50 0 ::1/128 50 0
::/0 40 1 ::/0 40 1
fc00::/7 35 13
::ffff:0:0/96 100 4 ::ffff:0:0/96 100 4
2002::/16 7 2 2002::/16 30 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
This change to the default policy table produces the following This change to the default policy table produces the following
behavior: behavior:
Candidate Source Addresses: 2001::2 or fe80::1 or 169.254.13.78 Candidate Source Addresses: 2001::2 or fe80::1 or 169.254.13.78
Destination Address List: 2001::1 or 198.51.100.121 Destination Address List: 2001::1 or 198.51.100.121
Unchanged Result: 2001::1 (src 2001::2) then 198.51.100.121 (src Unchanged Result: 2001::1 (src 2001::2) then 198.51.100.121 (src
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The destination address selection rules give preference to The destination address selection rules give preference to
destinations of smaller scope. For example, a link-local destination destinations of smaller scope. For example, a link-local destination
will be sorted before a global scope destination when the two are will be sorted before a global scope destination when the two are
otherwise equally suitable. An administrator can change the policy otherwise equally suitable. An administrator can change the policy
table to reverse this preference and sort global destinations before table to reverse this preference and sort global destinations before
link-local destinations: link-local destinations:
Prefix Precedence Label Prefix Precedence Label
::1/128 50 0 ::1/128 50 0
::/0 40 1 ::/0 40 1
fc00::/7 35 13 ::ffff:0:0/96 35 4
fe80::/10 33 1 fe80::/10 33 1
::ffff:0:0/96 10 4 2002::/16 30 2
2002::/16 7 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
This change to the default policy table produces the following This change to the default policy table produces the following
behavior: behavior:
Candidate Source Addresses: 2001::2 or fe80::2 Candidate Source Addresses: 2001::2 or fe80::2
Destination Address List: 2001::1 or fe80::1 Destination Address List: 2001::1 or fe80::1
New Result: 2001::1 (src 2001::2) then fe80::1 (src fe80::2) (prefer New Result: 2001::1 (src 2001::2) then fe80::1 (src fe80::2) (prefer
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However, the administrators of sites A and B can achieve their However, the administrators of sites A and B can achieve their
desired behavior via policy table configuration. For example, they desired behavior via policy table configuration. For example, they
can use the following policy table: can use the following policy table:
Prefix Precedence Label Prefix Precedence Label
::1/128 50 0 ::1/128 50 0
2001:aaaa:aaaa::/48 43 6 2001:aaaa:aaaa::/48 43 6
2001:bbbb:bbbb::/48 43 6 2001:bbbb:bbbb::/48 43 6
::/0 40 1 ::/0 40 1
fc00::/7 35 13 ::ffff:0:0/96 35 4
::ffff:0:0/96 10 4 2002::/16 30 2
2002::/16 7 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
This policy table produces the following behavior: This policy table produces the following behavior:
Candidate Source Addresses: 2001:aaaa:aaaa::a or 2007:0:aaaa::a or Candidate Source Addresses: 2001:aaaa:aaaa::a or 2007:0:aaaa::a or
fe80::a fe80::a
Destination Address List: 2001:bbbb:bbbb::b or 2007:0:bbbb::b Destination Address List: 2001:bbbb:bbbb::b or 2007:0:bbbb::b
New Result: 2001:bbbb:bbbb::b (src 2001:aaaa:aaaa::a) then 2007:0: New Result: 2001:bbbb:bbbb::b (src 2001:aaaa:aaaa::a) then 2007:0:
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Result: 2001:db8:2::2 (src 2001:db8:1::1) then fd22:2222:2222:2::2 Result: 2001:db8:2::2 (src 2001:db8:1::1) then fd22:2222:2222:2::2
(src fd11:1111:1111:1::1) (prefer higher precedence) (src fd11:1111:1111:1::1) (prefer higher precedence)
However, a site-specific policy entry can be used to cause ULAs However, a site-specific policy entry can be used to cause ULAs
within a site to be preferred over global addresses as follows. within a site to be preferred over global addresses as follows.
Prefix Precedence Label Prefix Precedence Label
::1/128 50 0 ::1/128 50 0
fd11:1111:1111::/48 45 14 fd11:1111:1111::/48 45 14
::/0 40 1 ::/0 40 1
fc00::/7 35 13 ::ffff:0:0/96 35 4
::ffff:0:0/96 10 4 2002::/16 30 2
2002::/16 7 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
Such a configuration would have the following effect: Such a configuration would have the following effect:
Candidate Source Addresses: 2001:db8:1::1 or fd11:1111:1111:1::1 Candidate Source Addresses: 2001:db8:1::1 or fd11:1111:1111:1::1
Destination Address List: 2001:db8:2::2 or fd22:2222:2222:2::2 Destination Address List: 2001:db8:2::2 or fd22:2222:2222:2::2
Unchanged Result: 2001:db8:2::2 (src 2001:db8:1::1) then fd22:2222: Unchanged Result: 2001:db8:2::2 (src 2001:db8:1::1) then fd22:2222:
2222:2::2 (src fd11:1111:1111:1::1) (prefer higher precedence) 2222:2::2 (src fd11:1111:1111:1::1) (prefer higher precedence)
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However, NAT'ed IPv4 is now also preferred over 6to4-to-6to4 However, NAT'ed IPv4 is now also preferred over 6to4-to-6to4
connectivity by default. Since a 6to4 prefix might be used natively connectivity by default. Since a 6to4 prefix might be used natively
within an organization, a site-specific policy entry can be used to within an organization, a site-specific policy entry can be used to
cause native IPv6 communication (using a 6to4 prefix) to be preferred cause native IPv6 communication (using a 6to4 prefix) to be preferred
over NAT'ed IPv4 as follows. over NAT'ed IPv4 as follows.
Prefix Precedence Label Prefix Precedence Label
::1/128 50 0 ::1/128 50 0
2002:836b:4179::/48 45 14 2002:836b:4179::/48 45 14
::/0 40 1 ::/0 40 1
fc00::/7 35 13 ::ffff:0:0/96 35 4
::ffff:0:0/96 10 4 2002::/16 30 2
2002::/16 7 2
2001::/32 5 5 2001::/32 5 5
fc00::/7 3 13
::/96 1 3 ::/96 1 3
fec0::/10 1 11 fec0::/10 1 11
3ffe::/16 1 12 3ffe::/16 1 12
Such a configuration would have the following effect: Such a configuration would have the following effect:
Candidate Source Addresses: 2002:836b:4179:1::1 or 10.1.2.3 Candidate Source Addresses: 2002:836b:4179:1::1 or 10.1.2.3
Destination Address List: 2002:836b:4179:2::2 or 203.0.113.1 Destination Address List: 2002:836b:4179:2::2 or 203.0.113.1
New Result: 2002:836b:4179:2::2 (src 2002:836b:4179:1::1) then New Result: 2002:836b:4179:2::2 (src 2002:836b:4179:1::1) then
203.0.113.1 (sec 10.1.2.3) (prefer higher precedence) 203.0.113.1 (sec 10.1.2.3) (prefer higher precedence)
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Phone: +1 425 703 8835 Phone: +1 425 703 8835
Email: dthaler@microsoft.com Email: dthaler@microsoft.com
Richard Draves Richard Draves
Microsoft Research Microsoft Research
One Microsoft Way One Microsoft Way
Redmond, WA 98052 Redmond, WA 98052
Phone: +1 425 706 2268 Phone: +1 425 706 2268
Email: richdr@microsoft.com Email: richdr@microsoft.com
Arifumi Matsumoto
NTT SI Lab
Midori-Cho 3-9-11
Musashino-shi, Tokyo 180-8585
Japan
Phone: +81 422 59 3334
Email: arifumi@nttv6.net
Tim Chown Tim Chown
University of Southampt on University of Southampt on
Southampton, Hampshire SO17 1BJ Southampton, Hampshire SO17 1BJ
United Kingdom United Kingdom
Email: tjc@ecs.soton.ac.uk Email: tjc@ecs.soton.ac.uk
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