draft-ietf-6man-reserved-iids-01.txt   draft-ietf-6man-reserved-iids-02.txt 
Network Working Group S. Krishnan Network Working Group S. Krishnan
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track July 14, 2008 Intended status: Standards Track December 2, 2008
Expires: January 15, 2009 Expires: June 5, 2009
Reserved IPv6 Interface Identifiers Reserved IPv6 Interface Identifiers
draft-ietf-6man-reserved-iids-01 draft-ietf-6man-reserved-iids-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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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 January 15, 2009. This Internet-Draft will expire on June 5, 2009.
Abstract Abstract
Interface Identifiers in IPv6 unicast addresses are used to identify Interface Identifiers in IPv6 unicast addresses are used to identify
interfaces on a link. They are required to be unique within a interfaces on a link. They are required to be unique within a
subnet. Several RFCs have specified interface identifiers or subnet. Several RFCs have specified interface identifiers or
identifier ranges that have a special meaning attached to them. An identifier ranges that have a special meaning attached to them. An
IPv6 node autoconfiguring an interface identifier in these ranges IPv6 node autoconfiguring an interface identifier in these ranges
will encounter unexpected consequences. Since there is no will encounter unexpected consequences. Since there is no
centralized repository for such reserved identifiers, this document centralized repository for such reserved identifiers, this document
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1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Issues with reusing reserved Interface Identifiers . . . . . . 5 3. Issues with reusing reserved Interface Identifiers . . . . . . 5
3.1. Possible solutions . . . . . . . . . . . . . . . . . . . . 5 3.1. Possible solutions . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Appendix A. List of potentially affected RFCs . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 12
1. Requirements notation 1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
An IPv6 unicast address is composed of two parts : A subnet prefix An IPv6 unicast address is composed of two parts : A subnet prefix
and an interface identifier (IID) that identifies an unique interface and an interface identifier (IID) that identifies an unique interface
within the subnet prefix. The structure of an IPv6 unicast address within the subnet prefix. The structure of an IPv6 unicast address
is depicted in the IPv6 Addressing Architecture [RFC4291] and is is depicted in the IPv6 Addressing Architecture [RFC4291] and is
replicated here for clarity. replicated here for clarity.
| n bits | 128-n bits | | n bits | 128-n bits |
+------------------------------------------------+----------------+ +-------------------------------+---------------------------------+
| subnet prefix | interface ID | | subnet prefix | interface ID |
+------------------------------------------------+----------------+ +-------------------------------+---------------------------------+
Figure 1: IPv6 Unicast Address Format Figure 1: IPv6 Unicast Address Format
For all unicast addresses, except those that start with binary value For all unicast addresses, except those that start with the binary
000, interface identifiers are required to be 64 bits long (i.e. value 000, Interface IDs are required to be 64 bits long and to be
n==64) . If the interface identifiers are generated from an unique constructed in Modified EUI-64 format. If the interface identifiers
token like an ethernet MAC address, they need to set bit 6 of the are generated from an unique token like an ethernet MAC address, they
first octet to one. If they are not generated from an unique token need to set bit 6 of the first octet to one. If they are not
they need to set bit 6 to zero. Examples of mechanisms that generate generated from an unique token they need to set bit 6 to zero.
interface identifiers without an unique token include Examples of mechanisms that generate interface identifiers without an
Cryptographically Generated Addresses [RFC3972], Privacy Addresses unique token include Cryptographically Generated Addresses [RFC3972],
[RFC4941], Hash Based Addresses [HBA] etc. Non-unique interface Privacy Addresses [RFC4941], Hash Based Addresses [HBA] etc. Non-
identifiers can also be allocated using managed address assignment unique interface identifiers can also be allocated using managed
mechanisms like DHCPv6 [RFC3315]. address assignment mechanisms like DHCPv6 [RFC3315].
3. Issues with reusing reserved Interface Identifiers 3. Issues with reusing reserved Interface Identifiers
Let us assume a node comes up with an interface identifier that has Let us assume a node comes up with an interface identifier that has
been reserved for use in some other capacity. e.g. An IPv6 node that been reserved for use in some other capacity. e.g. An IPv6 node that
uses temporary IPv6 addresses [RFC4941] comes up with an IID of fdff: uses temporary IPv6 addresses [RFC4941] comes up with an IID of fdff:
ffff:ffff:fff . This node will receive requests from all nodes that ffff:ffff:fff . This node will receive requests from all nodes that
are requesting a service from a MobileIPv6 home agent since the above are requesting a service from a MobileIPv6 home agent since the above
mentioned interface identifier has been reserved in [RFC2526] to mentioned interface identifier has been reserved in [RFC2526] to
serve as a MIPv6 home agents anycast address. At best this is an serve as a MIPv6 home agents anycast address. At best this is an
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configuration or for managed address configuration. configuration or for managed address configuration.
3.1. Possible solutions 3.1. Possible solutions
There are two possible ways to go about avoiding usage of these There are two possible ways to go about avoiding usage of these
reserved interface identifiers. One of them would be to add reserved interface identifiers. One of them would be to add
normative reference to each specification that reserves an interface normative reference to each specification that reserves an interface
identifier. The other one would be to create an IANA registry for identifier. The other one would be to create an IANA registry for
such interface identifiers. There are two disadvantages to the such interface identifiers. There are two disadvantages to the
normative reference approach. Firstly, this approach does not scale normative reference approach. Firstly, this approach does not scale
well. This is because the number of such specifications can need to well. This is because the number of such specifications that need to
be updated is large. Secondly, the maturity level of the document be updated is large. Secondly, the maturity level of the document
reserving the IID might be lower than the one prohibited from using reserving the IID might be lower than the one prohibited from using
it. This will cause a downward reference problem. Therefore the it. This will cause a downward reference problem. Therefore the
better solution is to create an IANA registry for this purpose. e.g. better solution is to create an IANA registry for this purpose.
Reserving certain identifiers may be useful in certain protocols such
as PMIP in order to avoid duplicate address detection on point to
point links, but PMIP will be at a lower standardization level than
the address sutoconfiguration standards and hence not referable from
them.
4. IANA Considerations 4. IANA Considerations
This document requests the creation of an IANA registry for reserved This document requests the creation of an IANA registry for reserved
IPv6 Interface Identifiers. Initial values for the reserved IPv6 IPv6 Interface Identifiers. Initial values for the reserved IPv6
Interface Identifiers are given below. Interface Identifiers are given below.
+-----------------------------------------+-------------------------+ +-----------------------------------------+-------------------------+
| Interface Identifier Range | Description | | Interface Identifier Range | Description |
+-----------------------------------------+-------------------------+ +-----------------------------------------+-------------------------+
| 0000:0000:0000:0000-0000:0000:0000:0000 | Subnet-Router Anycast | | 0000:0000:0000:0000-0000:0000:0000:0000 | Subnet-Router Anycast |
| | [RFC4291] | | | [RFC4291] |
| | | | | |
| fdff:ffff:ffff:ff80-fdff:ffff:ffff:fffd | Reserved Subnet Anycast | | FDFF:FFFF:FFFF:FF80-FDFF:FFFF:FFFF:FFFF | Reserved Subnet Anycast |
| | [RFC2526] | | | Addresses[RFC2526] |
| | |
| fdff:ffff:ffff:fffe-fdff:ffff:ffff:fffe | MobileIPv6 Home Agents |
| | Anycast [RFC2526] |
| | |
| fdff:ffff:ffff:ffff-fdff:ffff:ffff:ffff | Reserved Subnet Anycast |
| | [RFC2526] |
+-----------------------------------------+-------------------------+ +-----------------------------------------+-------------------------+
Table 1: Current Assignments Table 1: Current Assignments
It is possible that implementations might predate a specific It is possible that implementations might predate a specific
assignment from this registry and hence not be cognizant of the assignment from this registry and hence not be cognizant of the
reserved nature of the interface identifier. Hence. future reserved nature of the interface identifier. Hence. future
assignments from this registry are discouraged but in exceptional assignments from this registry are discouraged but in exceptional
circumstances are to be made through Standards Action [RFC5226]. circumstances are to be made through Standards Action [RFC5226].
Assignments consist of a single interface identifier or a range of Assignments consist of a single interface identifier or a range of
interface identifiers. interface identifiers.
NOTE: Please note that the address ::/128 (all zeros in the interface NOTE: Please note that the address :: (all zeros in the interface
identifier field) is used as an unspecified address and ::/0 (again identifier field) is used as the unspecified address. In addition,
all zeros in the interface identifier field) is used as a default many IETF protocols and data formats prescribe that the unused bits
route indicator as specified in [RFC5156]. These do not necessarily in prefixes be set to 0. Hence, prefixes with prefix lengths up to
conflict with the reserved interface identifiers defined here, since 64 are usually stored and transmitted with an interface identifier
the reserved identifiers defined in this document are used for part of all zeros. This includes ::/0, used as a default route
avoiding conflicts with stateless address autoconfiguration that uses indicator, as specified in [RFC5156]. These uses do not conflict
a 64 bit prefix length. with the reserved interface identifiers defined here, since the
reserved identifiers defined in this document are used for avoiding
conflicts with stateless address autoconfiguration that utilizes a 64
bit prefix length.
5. Acknowledgements 5. Acknowledgements
The author would like to thank Alain Durand, Alex Petrescu, Bernie The author would like to thank Alain Durand, Alex Petrescu, Bernie
Volz, Bob Hinden, Christian Huitema, Fred Templin, Jordi Palet Volz, Bob Hinden, Christian Huitema, Fred Templin, Jordi Palet
Martinez, Pekka Savola, Remi Denis-Courmount, Tim Enos, Alex Martinez, Pekka Savola, Remi Denis-Courmount, Tim Enos, Alex
Petrescu, Ed Jankiewicz and Brian Carpenter for reviewing this Petrescu, Ed Jankiewicz, Brian Carpenter, Alfred Hoenes, Jari Arkko,
document and suggesting changes. Pasi Eronen, Tim Polk, Lars Eggert, Derek Atkins and Robert Sparks
for reviewing this document and suggesting changes.
6. Security Considerations 6. Security Considerations
Information that creates or updates a registration needs to be By utilizing one of the reserved interface identifiers, an IPv6 node
authenticated and authorized. By utilizing one of the reserved might receive requests that it is not authorized to receive.
interface identifiers an IPv6 node might receive requests that it is Information that creates or updates a registration in this registry
not authorized to receive. needs to be authenticated and authorized by the IANA based on the
instructions set forth by [RFC5226].
7. References 7. References
7.1. Normative References 7.1. 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.
[RFC2526] Johnson, D. and S. Deering, "Reserved IPv6 Subnet Anycast [RFC2526] Johnson, D. and S. Deering, "Reserved IPv6 Subnet Anycast
Addresses", RFC 2526, March 1999. Addresses", RFC 2526, March 1999.
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[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.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
7.2. Informative References 7.2. Informative References
[HBA] Bagnulo, M., "Hash Based Addresses (HBA)", [HBA] Bagnulo, M., "Hash Based Addresses (HBA)",
draft-ietf-shim6-hba-02 (work in progress), October 2006. draft-ietf-shim6-hba-05 (work in progress), October 2006.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005. RFC 3972, March 2005.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, September 2007. IPv6", RFC 4941, September 2007.
[RFC5156] Blanchet, M., "Special-Use IPv6 Addresses", RFC 5156, [RFC5156] Blanchet, M., "Special-Use IPv6 Addresses", RFC 5156,
April 2008. April 2008.
Appendix A. List of potentially affected RFCs
The following RFCs that generate interface identifiers need to be
updated if they wish to avoid conflicts with the reserved interface
identifier ranges.
o RFC2590 - Transmission of IPv6 Packets over Frame Relay Networks
o RFC3315 - Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
o RFC3972 - Cryptographically Generated Addresses (CGA)
o RFC4489 - A Method for Generating Link-Scoped IPv6 Multicast
Addresses
o RFC4862 - IPv6 Stateless Address Autoconfiguration
o RFC4941 - Privacy Extensions for Stateless Address
Autoconfiguration in IPv6
o RFC5072 - IP Version 6 over PPP
o RFC4982 - Support for Multiple Hash Algorithms in CGAs
Author's Address Author's Address
Suresh Krishnan Suresh Krishnan
Ericsson Ericsson
8400 Decarie Blvd. 8400 Decarie Blvd.
Town of Mount Royal, QC Town of Mount Royal, QC
Canada Canada
Phone: +1 514 345 7900 x42871 Phone: +1 514 345 7900 x42871
Email: suresh.krishnan@ericsson.com Email: suresh.krishnan@ericsson.com
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