One document matched: draft-mdt-softwire-map-dhcp-option-00.xml
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<rfc category="std" docName="draft-mdt-softwire-map-dhcp-option-00.txt"
ipr="trust200902">
<front>
<title abbrev="MAP DHCPv6 Options">DHCPv6 Options for Mapping of Address and Port</title>
<author fullname="Tomasz Mrugalski" initials="T." surname="Mrugalski" role="editor">
<organization abbrev="ISC">Internet Systems Consortium, Inc.
</organization>
<address>
<postal>
<street>950 Charter Street</street>
<city>Redwood City</city>
<region>CA</region>
<code>94063</code>
<country>USA</country>
</postal>
<phone>+1 650 423 1345</phone>
<email>tomasz.mrugalski@gmail.com</email>
</address>
</author>
<author fullname="Mohamed Boucadair" initials="M." surname="Boucadair">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<code>35000</code>
<country>France</country>
</postal>
<email>mohamed.boucadair@gmail.com</email>
</address>
</author>
<author fullname="Ole Troan" initials="O" surname="Troan">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Telemarksvingen 20</street>
<city>Oslo</city>
<code>N-0655</code>
<country>Norway</country>
</postal>
<email>ot@cisco.com</email>
</address>
</author>
<date year="2011" />
<area>Internet</area>
<workgroup>Softwire WG</workgroup>
<keyword>MAP</keyword>
<keyword>DHCPv6</keyword>
<!-- SECTION 0: Abstract -->
<abstract>
<t>Generic mechanism for mapping between an IPv4 prefix, address
or parts of thereof, and transport layer between ports and an
IPv6 prefix or address is specified in <xref
target="map-design"/>. This is a companion document that
specifies provisioning mechanism of MAP rules. It defines DHCPv6
options which are meant to be used between Customer Edge (CE)
devices and DHCPv6 server to obtain necessary parameters to
configure MAP rules. Since specification of MAP
architecture is still expected to evolve, DHCPv6 options may
have to evolve too to fit the revised MAP specification.</t>
<t></t>
</abstract>
</front>
<middle>
<!-- SECTION 1: Introduction -->
<section title="Introduction">
<t>Mapping of Address and Port (MAP) defined in <xref
target="map-design" /> is a mechanism for providing
IPv4 connectivity service to end users over a service provider's
IPv6 network. It defines MAP Border Relay (BR) router that is
located that the edge of a MAP domain. MAP Customer Edge (CE) is
also defined as a device typically deployed at customers'
location. In a residential broadband deployment, this type of
device is sometimes referred to as a Residential Gateway (RG) or
Customer Premises Equipment (CPE). A MAP CE may also be referred
to simply as a "CE" within the context of MAP.</t>
<t>A typical MAP CE adopting MAP rules will serve a residential
site with one WAN side interface, one or more LAN side
interfaces. To operate properly, it requires one or more MAP
rules and additional informations. In larger networks it is
infeasible to configure such parameters manually. Therefore
provisioning mechanism is required. Such mechanism is defined in
this document. It leverages existing DHCPv6 <xref
target="RFC3315"/> protocol to deliver necessary parameters to
CE.</t>
<t>This document defines several DHCPv6 options that allow
delivery of required information to configure CE. Configuration
of the BR is outside of scope of this document. Definitions of
used parameters are provided in <xref target="map-design" />.</t>
<t>Since specification of MAP architecture is still expected to
evolve, DHCPv6 options may have to evolve too to fit the revised
MAP specification.
</t>
</section>
<!-- SECTION 2: REQUIREMENTS LANGUAGE -->
<section anchor="conventions" title="Conventions">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 <xref
target="RFC2119"></xref>.</t>
</section>
<!-- conventions -->
<!-- SECTION 3: DESCRIPTION -->
<section anchor="description" title="Provisioning mechanism">
<t>A typical MAP CE usually acts as a DHCPv6 client and requests
options that are being provided by a DHCPv6 server located
somewhere in ISP network. It would adopt three kinds of
parameters independently:</t>
<t>
<list style="symbols">
<t>MAP mapping rules are defined in <xref
target="map-design"/>, including Rule IPv6 prefix/length,
Rule IPv4 prefix and BR IPv6 prefix. One MAP CE can receive
one or more MAP mapping rules from the DHCPv6 server, the
first of which should be the default MAP mapping rule for the
initiated CE of its own, followed by other mapping rules
within the MAP domain if necessary.</t>
<t>Transport mode indicates encapsulation or translation mode for MAP
approach. It should be conducted on interface-by-interface
basis</t>
<t>Discussion: Qiong also proposed to add deployment mode
here. Jacni Qin recommends against it. Deployment mode is to
notify whether CE is in Hub and spoke mode or mesh. In Hub and
spoke mode, only the first default MAP mapping rule is needed
in the following MAP procedure. While in mesh mode, all MAP
mapping rules are included to achieve CE-CE traffic
optimization.</t>
</list>
</t>
</section>
<section title="DHCPv6 Options Format">
<t>DHCPv6 protocol is used for CE provisioning. Several new
options are defined for conveying MAP-specific parameters. Their
format and usage is defined in the following sections.</t>
<t>Discussion: As the exact parameters required to configure MAP
rules and MAP in general are expected to change, this section
is expected to be updated or even rewritten completely.</t>
<t>Discussion: Proposed layout assumes that several simple
options are used. Such approach simplifies implementation as it
is much easier for implementors to reuse existing code handling
such options. This design choice comes at a cost,
however. Clients must perform checks if provided set of options
is complete. Alternatively, it would be possible to define one
complex option that contains all mandatory
parameters. </t>
<t>Discussion: It should be noted that initial concept of 4rd
provisioning was presented in DHC working group meeting. It used
one complex option to convey all required parameters. Strong
suggestion from DHC WG was to use several simpler
options. Options (possibly nested) are preferred over
conditional option formatting. See DHCP option guidelines
document <xref target="I-D.ietf-dhc-option-guidelines"/>).</t>
<section title="MAP Options Cardinality">
<t>MAP rule is defined in <xref target="map-design"/>, Section 4.</t>
<t>Discussion: If you want additional parameter added to the
OPTION_MAP_RULE option, please update <xref
target="map-design"/> first.</t>
<t>In each REPLY message, server that supports MAP configuration
MUST include exactly one OPTION_MAP_FLAGS option.</t>
<t>MAP_FLAGS option MUST include one or more OPTION_MAP_RULE options.</t>
<t>For proper operation, additional parameters obtained via
other options are necessary. In particular, L parameter is equal
to a length of a prefix delegated to CE, conveyed in OPTION_IA_PD
and IAPREFIX, as defined in <xref target="RFC3633"/>.</t>
</section>
<section anchor="option-flags" title="MAP Flags Option">
<t>. This option specifies MAP
flags. Currently the only defined flag is T - transport
mode. 0 designates translation and 1 designates encapsulation.
</t>
<t>Each MAP_FLAGS option MUST contain one or more MAP Rule
Options.</t>
<figure align="center" anchor="img-option-flags" title="MAP Flags Option">
<preamble></preamble>
<artwork align="center"><![CDATA[
TODO: Add format here later
]]>
</artwork>
</figure>
<t>option-code: OPTION_MAP_FLAGS (TBD)</t>
</section>
<section title="MAP Rule Option">
<t>This option represents a single MAP Rule. Depending on
deployment mode, each CE may require one or more MAP Rules to
operate properly.</t>
<t>Server includes one or more MAP Rule Options in MAP Flags option.</t>
<t>Discussion: Do we need to distinguish or reference rules?
(i.e. Is some kind of ID field required?)</t>
<t>Server MAY send more than one MAP Rule Option, if it is
configured to do so. Clients MUST NOT send MAP Rule
Option.</t>
<figure align="center" anchor="img-option-rule" title="MAP Rule Option">
<preamble></preamble>
<artwork align="center"><![CDATA[
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_MAP_RULE | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| rule IPv6 prefix |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rule IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| BR prefix (IPv6 prefix) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rule-pref6-len|
+-+-+-+-+-+-+-+-+]]>
</artwork>
</figure>
<t>
<list style="symbols">
<t>option-code: OPTION_MAP_RULE (TBD)</t>
<t>option-length: 37 in octets</t>
<t>rule-pref6-len: length for the rule IPv6 prefix in bits</t>
<t>rule IPv6 prefix: an IPv6 prefix that appears in a MAP rule.</t>
<t>rule IPv4 prefix: an IPv4 prefix that appears in a MAP rule.</t>
<t>BR prefix: the IPv6 prefix of BR that appears in a MAP rule</t>
</list>
</t>
</section>
<section anchor="example" title="MAP Options Example">
<t>DHCPv6 server provisioning a single MAP Rule to a CE
(DHCPv6 client) will convey the following MAP options in its
messages:</t>
<figure align="center" anchor="img-example" title="MAP Options Example">
<preamble></preamble>
<artwork align="center"><![CDATA[
<MAP_FLAGS>
<MAP_RULE1/>
<MAP_RULE2/>
...
<MAP_RULEN/>
</MAP_FLAGS>
]]></artwork>
</figure>
</section>
</section>
<section title="DHCPv6 Server Behavior">
<t><xref target="RFC3315">RFC 3315 Section 17.2.2</xref>
describes how a DHCPv6 client and server negotiate configuration
values using the ORO. As a convenience to the reader, we
mention here that a server will not reply with a MAP Rule Option
if the client has not explicitly enumerated it on its Option
Request Option.</t>
<t>Server conformant to this specification MUST allow
configuration of one or more MAP Rule Options.</t>
<t>Server MUST transmist all configured instances of the Mapping
Rule Options with all sub-options, if client requested it using
OPTION_MAP_RULE in its Option Request Option (ORO). Server MUST
transmit MAP Flags Option if client requested OPTION_MAP_FLAGS
in its ORO.</t>
<t>Rules assignment is a stateless process from the server's
perspective. Server does not need to maintain a state of rules
provisioned to clients, track lifetimes, expire outdated rules
etc. Server SHOULDs assign the same set of rules to all CEs in
one MAP Domain, unless there are several classes of CEs defined,
e.g. regular and premium users. In such case, each class of CEs
is expected to get the same set of rules. Server is not expected
to track MAP rules on a per CE basis. Exact assignment of
specific rules to a specific CEs is outside of scope of this
document.</t>
</section>
<section title="DHCPv6 Client Behavior">
<t>Although other use cases are allowed, in typical use case CE
will act as DHCPv6 client and will request MAP configuration to
be assigned by the DHCPv6 server located in the ISP network. A
client that supports MAP CE functionality and conforms to this
specfication MUST include OPTION_MAP_RULE and OPTION_MAP_FLAGS
in its ORO.</t>
<t>For proper operation, MAP CE client MUST also request IPv6
address (OPTION_IA_NA, defined in <xref target="RFC3315"/>) and
prefix delegation (OPTION_IA_PD, defined in <xref
target="RFC3633"/>). MAP CE client SHOULD NOT initiate DHCPv4
configuration as all parameters are delivered over DHCPv6.</t>
<t>Client SHOULD request OPTION_MAP_RULE and OPTION_MAP_FLAGS
options in SOLICIT, REQUEST, RENEW, REBIND and
INFORMATION-REQUEST messages.</t>
<t>If client receives more than one OPTION_MAP_RULE option, it
MUST use all received instances. It MUST NOT use only the first
one, while discarding remaining ones.</t>
<t>Note that system implementing MAP CE functionality may have
multiple network interfaces, and these interfaces may be
configured differently; some may be connected to networks that
call for MAP, and some may be connected to networks that are
using normal dual stack or other means. The MAP CE system
should approach this specification on an interface-by-interface
basis. For example, if the CE system is attached to multiple
networks that provide the MAP Mapping Rule Option, then the CE
system MUST configure a MAP connection (i.e. a translation or
encapsulation) for each interface separately as each MAP
provides IPv4 connectivity for each distinct interface. Means to
bind a MAP configuration to a given interface in a multiple
interfaces device are out of scope of this document.</t>
</section>
<!-- SECTION 4: IANA Considerations -->
<section title="IANA Considerations">
<t>This specification does not require any IANA actions.</t>
</section>
<!-- SECTION 6: Acknowledgements -->
<!-- SECTION 5: Security Considerations -->
<section title="Security Considerations">
<t>Implementation of this document does not present any new
security issues, but as with all DHCPv6-derived configuration
state, it is completely possible 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 over the MAP can be
trusted, and it should not therefore bypass any security
mechanisms such as IP firewalls.</t>
<t>Readers concerned with security of MAP provisioning over
DHCPv6 are encouraged to familiarize with <xref
target="I-D.ietf-dhc-secure-dhcpv6"/>.</t>
<t>Section XX of <xref target="map-design"/> discusses security
issues of the MAP mechanism.</t>
<t>Section 23 of <xref target="RFC3315"/> discusses
DHCPv6-related security issues.</t>
<t>Section 6 of <xref target="I-D.murakami-softwire-4rd"/> discusses 4rd
related security issues that are partially applicable to MAP mechanism.</t>
</section>
<section title="IANA Considerations">
<t>IANA is requested to allocate DHCPv6 option codes referencing
this document, delineating OPTION_MAP_RULE, OPTION_MAP_BR_PREFIX6,
OPTION_MAP_PREFIX6, OPTION_MAP_PREFIX4 and OPTION_MAP_FLAGS
option names.</t>
</section>
<section title="Contributors">
<t>The members of the MAP design team are:
<list style="numbers">
<t>Mohamed Boucadair</t>
<t>Gang Chen</t>
<t>Wojciech Dec</t>
<t>Xiaohong Deng</t>
<t>Jouni Korhonen</t>
<t>Xing Li</t>
<t>Maoke</t>
<t>Satoru Matsushima</t>
<t>Tomasz Mrugalski</t>
<t>Jacni Qin</t>
<t>Tina Tsou</t>
<t>Ole Troan</t>
<t>Dan Wing</t>
<t>Leaf Yeh</t>
<t>Jan Zorz</t>
</list></t>
</section>
<section title="Acknowledgements">
<t>Authors would like to thank Xiaohong Deng, Congxiao Bao,
Jacni Qin, Qiong Sun for their comments and suggestions.</t>
</section>
</middle>
<back>
<!-- SECTION 8.1: Normative References -->
<references title="Normative References">
&rfc2119;
<reference anchor="map-design" target="">
<front>
<title>Mapping of Address and Port (MAP)</title>
<author initials="O." surname="Troan" fullname="Ole Troan" role="editor">
<organization>Cisco</organization>
</author>
<date day="24" month="10" year="2011" />
</front>
<seriesInfo name="draft-ietf-softwire-mapping-address-and-port" value="00" />
</reference>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.3315"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.3633"?>
</references>
<references title="Informative References">
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-dhc-option-guidelines.xml" ?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.mrugalski-dhc-dhcpv6-4rd.xml" ?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.boucadair-dhcpv6-shared-address-option.xml" ?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-dhc-secure-dhcpv6.xml" ?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.murakami-softwire-4rd.xml" ?>
</references>
<!-- SECTION 8.2: Informative References -->
</back>
</rfc>
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