draft-ietf-softwire-ds-lite-tunnel-option-04.txt   draft-ietf-softwire-ds-lite-tunnel-option-05.txt 
Softwires D. Hankins Softwires D. Hankins
Internet-Draft ISC Internet-Draft ISC
Intended status: Standards Track T. Mrugalski Intended status: Standards Track T. Mrugalski
Expires: March 19, 2011 Gdansk University of Technology Expires: March 31, 2011 Gdansk University of Technology
September 15, 2010 September 27, 2010
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Options for Dual- Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-
Stack Lite Stack Lite
draft-ietf-softwire-ds-lite-tunnel-option-04 draft-ietf-softwire-ds-lite-tunnel-option-05
Abstract Abstract
This document specifies two DHCPv6 options which are meant to be used This document specifies single DHCPv6 option which is meant to be
by a Dual-Stack Lite client (Basic Bridging BroadBand element, B4) to used by a Dual-Stack Lite client (Basic Bridging BroadBand element,
discover its Address Family Transition Router (AFTR) address. B4) to discover its Address Family Transition Router (AFTR) address.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 19, 2011. This Internet-Draft will expire on March 31, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 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
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skipping to change at page 2, line 10 skipping to change at page 2, line 10
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3 1. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The Dual-Stack Lite Address DHCPv6 Option . . . . . . . . . . . 3 3. The Dual-Stack Lite Address DHCPv6 Option . . . . . . . . . . . 3
4. The Dual-Stack Lite Name DHCPv6 Option . . . . . . . . . . . . 4 4. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . . 4
5. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . . 6 5. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . . 5
6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 9. Normative References . . . . . . . . . . . . . . . . . . . . . 6
10. Normative References . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Requirements Language 1. Requirements Language
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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Introduction 2. Introduction
Dual-Stack Lite [I-D.softwire-ds-lite] is a solution to offer both Dual-Stack Lite [I-D.softwire-ds-lite] is a solution to offer both
IPv4 and IPv6 connectivity to customers which are addressed only with IPv4 and IPv6 connectivity to customers which are addressed only with
an IPv6 prefix (no IPv4 address is assigned to the attachment an IPv6 prefix (no IPv4 address is assigned to the attachment
device). One of its key components is an IPv4-over-IPv6 tunnel, device). One of its key components is an IPv4-over-IPv6 tunnel,
commonly referred to as a Softwire, but a DS-Lite Basic Bridging commonly referred to as a Softwire. DS-Lite Basic Bridging BroadBand
BroadBand (B4) will not know if the network it is attached to offers (B4) will not know if the network it is attached to offers Dual-Stack
Dual-Stack Lite support, and if it did would not know the remote end Lite support, and if it did would not know the remote end of the
of the tunnel to establish a connection. tunnel to establish a connection.
To inform the B4 of the Address Family Transition Router's (AFTR) To inform the B4 of the Address Family Transition Router's (AFTR)
location, either an IPv6 address, Fully Qualified Domain Name (FQDN) location, an option containing a single IPv6 address may be used.
or both may be used. Once this information is conveyed, the presence Once this information is conveyed, the presence of the configuration
of the configuration indicating the AFTR's location also informs a indicating the AFTR's location also informs a host to initiate Dual-
host to initiate Dual-Stack Lite (DS-Lite) service and become a Stack Lite (DS-Lite) service and become a Softwire Initiator.
Softwire Initiator.
To provide the conveyance of the configuration information, two To provide the conveyance of the configuration information, a single
DHCPv6 [RFC3315] options are used; one in the case where the host DHCPv6 [RFC3315] option is used.
receives an IPv6 address, and one in the case where the host receives
an FQDN in order to derive an IPv6 address.
The details of how the B4 establishes an IPv4-in-IPv6 tunnel to the The details of how the B4 establishes an IPv4-in-IPv6 tunnel to the
AFTR are out of scope for this document. AFTR are out of scope for this document.
3. The Dual-Stack Lite Address DHCPv6 Option 3. The Dual-Stack Lite Address DHCPv6 Option
The Dual-Stack Lite Address option consists of option-code and The Dual-Stack Lite Address option consists of option-code and
option-len fields (common for all DHCPv6 options), and a 128 bit option-len fields (common for all DHCPv6 options), and a 128 bit
tunnel-endpoint-addr field, containing one IPv6 address. The tunnel- tunnel-endpoint-addr field, containing one IPv6 address. The tunnel-
endpoint-addr specifies the location of the remote tunnel endpoint, endpoint-addr specifies the location of the remote tunnel endpoint,
expected to be located at an AFTR. expected to be located at an AFTR.
The DS-Lite Address option MAY appear in the root scope of a DHCPv6 The DS-Lite Address option MAY appear in the root scope of a DHCPv6
packet. It MUST NOT appear inside any IA_NA, IA_TA, IA_PD, IAADDR, packet. It MUST NOT appear inside any IA_NA, IA_TA, IA_PD, IAADDR,
or similar. Any DS-Lite Address option received inside any other or similar. Any DS-Lite Address option received inside any other
option MUST be ignored. option MUST be ignored.
The DS-Lite Address option MUST NOT appear more than once in a The DS-Lite Address option MUST NOT appear more than once in a
message. Client that receives more than one DS-Lite Address option message.
MUST discard all instances of that option.
The format of the Dual-Stack Lite Address option is shown in the The format of the Dual-Stack Lite Address option is shown in the
following figure: following figure:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
| OPTION_DS_LITE_ADDR (TBD) | option-len: 16 | | OPTION_DS_LITE_ADDR (TBD) | option-len: 16 |
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
| | | |
skipping to change at page 4, line 33 skipping to change at page 4, line 29
option-len: Length of the tunnel-endpoint-addr field, option-len: Length of the tunnel-endpoint-addr field,
which is precisely 16 octets. which is precisely 16 octets.
tunnel-endpoint-addr: A single IPv6 address in binary tunnel-endpoint-addr: A single IPv6 address in binary
representation of the remote tunnel representation of the remote tunnel
endpoint, located at the DS-Lite AFTR. endpoint, located at the DS-Lite AFTR.
Figure 1: DS-Lite IPv6 Address DHCPv6 Option Format Figure 1: DS-Lite IPv6 Address DHCPv6 Option Format
The client validates the DS-Lite Address option by confirming the The client validates the DS-Lite Address option by confirming the
option length is exaclty 16 octets. The client MUST ignore any DS- option length is exactly 16 octets. The client MUST ignore any DS-
Lite Address option that has length other than 16 octets. Lite Address option that has length other than 16 octets.
Because this option conveys the tunnel-endpoint-addr value, no Because this option conveys the tunnel-endpoint-addr value, no
further processing is required of the client. further processing is required of the client.
This option conveys a single IPv6 address, as the Dual-Stack Lite This option conveys a single IPv6 address, as the Dual-Stack Lite
specification [I-D.softwire-ds-lite] defines only one Softwire specification [I-D.softwire-ds-lite] defines only one Softwire
connection between a B4 and any AFTR. Multiple connections or connection between a B4 and any AFTR. Multiple connections or
endpoints are undefined. For more information, see Section 7.2 "High endpoints are undefined. It is expected that Service Provider (SP)
Availability" of [I-D.softwire-ds-lite]. will deal with load balancing and high availability, not the client.
For more information, see Section 12.3 "High Availability" of
4. The Dual-Stack Lite Name DHCPv6 Option [I-D.softwire-ds-lite].
The Dual-Stack Lite Name option consists of option-code and option-
len fields (common for all DHCPv6 options), and a variable length
tunnel-endpoint-name field, containing a Fully Qualified Domain Name
that refers to the AFTR the client is requested to establish a
connection with.
The DS-Lite Name option MAY appear in the root scope of a DHCPv6
packet. It MUST NOT appear inside any IA_NA, IA_TA, IA_PD, IAADDR,
or similar. Any DS-Lite Name option received inside any other option
MUST be ignored.
The DS-Lite Name option MUST NOT appear more than once in a message.
Client that receives more than one DS-Lite Name option MUST discard
all instances of that option.
The format of the Dual-Stack Lite Name option is shown in the
following figure:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| OPTION_DS_LITE_NAME (TBD) | option-len |
+-------------------------------+-------------------------------+
| tunnel-endpoint-name (FQDN) |
+---------------------------------------------------------------+
option-code: OPTION_DS_LITE_NAME (TBD)
option-len: Length in octets of the tunnel-endpoint-
name field.
tunnel-endpoint-name: A single Fully Qualified Domain Name of the
remote tunnel endpoint, located at the
DS-Lite AFTR.
Figure 2: DS-Lite Name DHCPv6 Option Format
The tunnel-endpoint-name field is formatted as required in DHCPv6
[RFC3315] Section 8 ("Representation and Use of Domain Names").
Briefly, the format described is using a single octet noting the
length of one DNS label (limited to at most 64 octets), followed by
the label. This repeats until all labels in the FQDN are exhausted.
The root label (or the end of the FQDN) is denoted as a zero length
label. Any possible updates to Section 8 of DHCPv6 [RFC3315] also
apply to encoding of this FQDN field. An example FQDN format for
this option is shown in Figure 3.
+------+------+------+------+------+------+------+------+------+
| 0x07 | e | x | a | m | p | l | e | 0x03 |
+------+------+------+------+------+------+------+------+------+
| i | s | c | 0x03 | o | r | g | 0x00 |
+------+------+------+------+------+------+------+------+
Figure 3: Example tunnel-endpoint-name.
Note that in the specific case of the example tunnel-endpoint-name,
(Figure 3) the length of the option is 17 octets, and so an option-
len field value of 17 would be used.
The client (B4) validates the option in this format by first
confirming that the option length is greater than 3, that the option
data can be contained by the option length (that the option length
does not run off the end of the packet), and that the tunnel-
endpoint-name is of valid format as described in DHCPv6 Section 8
[RFC3315]; there are no compression tags, there is at least one label
of nonzero length.
The client (B4) determines a value for the tunnel-endpoint-addr from
the tunnel-endpoint-name using standard DNS resolution, as defined in
[RFC3596]. If the DNS response contains more than one IPv6 address,
the client picks only one IPv6 address and uses it as a remote tunnel
endpoint. The client MUST NOT establish more than one DS-Lite tunnel
at the same time. For a redundancy and high availability discussion,
see Section 7.2 "High availability" of [I-D.softwire-ds-lite].
5. DHCPv6 Server Behavior 4. DHCPv6 Server Behavior
DHCP servers must translate user input from their own specific and Following requirements are result of applying behaviors defined in
unique operator's interfaces into configuration state for the client. RFC 3315 Section 17.2.2 [RFC3315] to the DS-Lite Address option.
The server MUST provide a way to configure the OPTION_DS_LITE_ADDR. They do not change default DHCPv6 operation, but rather are
As a convenience to the operator, the server MAY allow the operator enumerated here as a convenience for the reader.
to enter a Fully Qualified Domain Name, upon which the server
performs DNS Resolution to assemble its OPTION_DS_LITE_ADDR contents.
The server MAY either provide the same Fully Qualified Domain Name as
OPTION_DS_LITE_NAME contents, or simply provide a distinct method of
configuring it.
If configured with values, DHCPv6 servers will include the DS-Lite If configured to offer DS-Lite Address information, DHCPv6 server
Address and/or Name options if either or both appear on the client's will include the DS-Lite Address option if such option appears on the
Option Request Option (OPTION_ORO). RFC 3315 Section 17.2.2 client's Option Request Option (OPTION_ORO). RFC 3315 Section 17.2.2
[RFC3315] describes how a DHCPv6 client and server negotiate [RFC3315] describes how a DHCPv6 client and server negotiate
configuration values using the ORO. configuration values using the ORO.
A DHCPv6 server MUST NOT send either option if it has not been A DHCPv6 server MUST NOT send DS-Lite Address option if it has not
explicitly requested by the client. been explicitly requested by the client.
A DHCPv6 server MUST NOT send more than one DS-Lite Address option. A DHCPv6 server MUST NOT send more than one DS-Lite Address option.
A DHCPv6 server MUST NOT send more than one DS-Lite Name option.
A DHCPv6 server MUST NOT send DS-Lite Address or DS-Lite Name options
as suboptions in other options.
If the server is configured with an FQDN as the tunnel endpoint A DHCPv6 server MUST NOT send DS-Lite Address as suboption in other
locator, the configured FQDN value MUST contain a resolvable Fully options.
Qualified Domain Name, having appropriate delegations from the root,
and having a AAAA record locating the Softwire Concentrator.
If OPTION_DS_LITE_NAME is being configured, the server MUST be
configured to provide OPTION_DNS_SERVERS defined in [RFC3646]
together with the DS-Lite Name option, so that clients will be able
to ask for DNS servers locations to resolve the domain name provided
in the DS-Lite Name option.
6. DHCPv6 Client Behavior 5. DHCPv6 Client Behavior
A client that supports B4 functionality of DS-Lite (defined in A client that supports B4 functionality of DS-Lite (defined in
[I-D.softwire-ds-lite]) and conforms to this specification MUST [I-D.softwire-ds-lite]) and conforms to this specification MUST
include OPTION_DS_LITE_ADDR on its OPTION_ORO, and MAY include include OPTION_DS_LITE_ADDR on its OPTION_ORO.
OPTION_DS_LITE_NAME at its option and ability.
If requesting the OPTION_DS_LITE_NAME option, the client also SHOULD
request OPTION_DNS_SERVERS defined in [RFC3646] to be able to resolve
any received domain name.
If the client receives either DS-Lite option, it MUST verify the If the client receives DS-Lite Address option, it MUST verify the
option contents as described in Section 3 and Section 4. The client option contents as described in Section 3. The client (B4) is
(B4) is expected to establish a softwire tunnel to the tunnel- expected to establish a softwire tunnel to the tunnel-endpoint-addr
endpoint-addr IPv6 address it determines from either of these IPv6 address it determines from DS-Lite Address option.
options.
If the client requests and receives both the OPTION_DS_LITE_ADDR and Client that receives more than one DS-Lite Address option MUST
the OPTION_DS_LITE_NAME options, it MUST proceed with resolving the discard all instances of that option.
OPTION_DS_LITE_NAME.
7. Security Considerations 6. Security Considerations
This document does not present any new security issues, but as with This document does not present any new security issues, but as with
all DHCPv6-derived configuration state, it is completely possible all DHCPv6-derived configuration state, it is completely possible
that the configuration is being delivered by a third party (Man In that the configuration is being delivered by a third party (Man In
The Middle). As such, there is no basis to trust that the access the The Middle). As such, there is no basis to trust that the access the
DS-Lite Softwire connection represents can be trusted, and it should DS-Lite Softwire connection represents can be trusted, and it should
not therefore bypass any security mechanisms such as IP firewalls. not therefore bypass any security mechanisms such as IP firewalls.
RFC 3315 [RFC3315] discusses DHCPv6-related security issues. RFC 3315 [RFC3315] discusses DHCPv6-related security issues.
[I-D.softwire-ds-lite] discusses DS-Lite related security issues. [I-D.softwire-ds-lite] discusses DS-Lite related security issues.
8. IANA Considerations 7. IANA Considerations
IANA is requested to allocate two DHCPv6 option codes referencing IANA is requested to allocate single DHCPv6 option code referencing
this document. One delineating OPTION_DS_LITE_ADDR, and one this document, delineating OPTION_DS_LITE_ADDR name.
delineating OPTION_DS_LITE_NAME.
9. Acknowledgements 8. Acknowledgements
Authors would like to thank Alain Durand, Rob Austein, Dave Thaler Authors would like to thank Alain Durand, Rob Austein, Dave Thaler,
and Paul Selkirk for their valuable feedback and suggestions. Paul Selkirk and Ralph Droms for their valuable feedback and
suggestions.
10. Normative References This work has been partially supported by the Polish Ministry of
Science and Higher Education under the European Regional Development
Fund, Grant No. POIG.01.01.02-00-045/09-00 (Future Internet
Engineering Project).
9. Normative References
[I-D.softwire-ds-lite] [I-D.softwire-ds-lite]
Durand, A., Ed., "Dual-stack lite broadband deployments Durand, A., Ed., "Dual-stack lite broadband deployments
post IPv4 exhaustion", draft-ietf-softwire-dual-stack-lite post IPv4 exhaustion", draft-ietf-softwire-dual-stack-lite
(work in progress). (work in progress).
[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.
[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.
[RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
"DNS Extensions to Support IP Version 6", RFC 3596,
October 2003.
[RFC3646] Droms, R., "DNS Configuration options for Dynamic Host
Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
December 2003.
Authors' Addresses Authors' Addresses
David W. Hankins David W. Hankins
Internet Systems Consortium, Inc. Internet Systems Consortium, Inc.
950 Charter Street 950 Charter Street
Redwood City, CA 94063 Redwood City, CA 94063
US US
Phone: +1 650 423 1307 Phone: +1 650 423 1307
Email: David_Hankins@isc.org Email: David_Hankins@isc.org
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