One document matched: draft-boucadair-mptcp-dhc-00.xml
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<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
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<rfc category="std" docName="draft-boucadair-mptcp-dhc-00" ipr="trust200902">
<front>
<title abbrev="DHCP for MPTCP">DHCP Options for Network-Assisted Multipath
TCP (MPTCP)</title>
<author fullname="Mohamed Boucadair" initials="M." surname="Boucadair">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<region></region>
<code>35000</code>
<country>France</country>
</postal>
<email>mohamed.boucadair@orange.com</email>
</address>
</author>
<author fullname="Christian Jacquenet" initials="C." surname="Jacquenet">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<region></region>
<country>France</country>
</postal>
<email>christian.jacquenet@orange.com</email>
</address>
</author>
<date />
<abstract>
<t>One of the promising deployment scenarios for Multipath TCP (MPTCP)
is to enable a Customer Premises Equipment (CPE) that is connected to
multiple networks (e.g., DSL, LTE, WLAN) to optimize the usage of its
network attachments. Because of the lack of MPTCP support at the server
side, some service providers now consider a “network-assisted
mode” that relies upon the activation of a dedicated function
called: MPTCP Concentrator. This document focuses on the explicit
deployment scheme where the identity of the MPTCP Concentrator(s) is
explicitly configured on connected hosts. </t>
<t>This document specifies DHCP (IPv4 and IPv6) options to configure
hosts with Multipath TCP (MPTCP) parameters.</t>
</abstract>
<note title="Requirements Language">
<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 <xref
target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>One of the promising deployment scenarios for Multipath TCP (MPTCP,
<xref target="RFC6824"></xref>) is to enable a Customer Premises
Equipment (CPE) that is connected to multiple networks (e.g., DSL, LTE,
WLAN) to optimize the usage of such resources, see for example <xref
target="I-D.deng-mptcp-proxy"></xref> or <xref target="RFC4908"></xref>.
This deployment scenario relies on MPTCP Proxy on both the CPE and the
network sides (<xref target="fig"></xref>). The latter plays the role of
traffic concentrator. A concentrator terminates the MPTCP sessions, from
a CPE, before redirecting traffic into a legacy TCP session. </t>
<t><figure align="center" anchor="fig"
title="“Network-Assisted” MPTCP Design">
<artwork><![CDATA[ IP Network #1
+------------+ _--------_ +------------+
| | (e.g., LTE ) | |
| CPE +======================+ |
| (MPTCP | (_ _) |Concentrator|
| Proxy) | (_______) | (MPTCP |
| | | Proxy) |------> Internet
| | | |
| | IP Network #2 | |
| | _--------_ | |
| | ( e.g., DSL ) | |
| +======================+ |
| | (_ _) | |
+-----+------+ (_______) +------------+
|
----CPE network----
|
end-nodes
]]></artwork>
</figure></t>
<t>Both implicit and explicit modes are considered to steer traffic
towards an MPTCP Concentrator. This document focuses on the explicit
mode that consists in configuring explicitly the reachability
information of the MPTCP concentrator on a host. </t>
<t>This document defines DHCPv4 <xref target="RFC2131"></xref> and
DHCPv6 <xref target="RFC3315"></xref> options that can be used to
configure hosts with MPTCP Concentrator IP addresses.</t>
<t>This specification assumes an MPTCP Concentrator is reachable through
one or multiple IP addresses. As such, a list of IP addresses can be
returned in the DHCP MPTCP option.</t>
</section>
<section title="Terminology">
<t>This document makes use of the following terms:<?rfc subcompact="yes" ?></t>
<t><list style="symbols">
<t>MPTCP Concentrator denotes a functional element that terminates
MPTCP connections originated by MPTCP clients. An MPTCP Concentrator
is responsible for transforming an MPTCP connection <xref
target="RFC6824"></xref> into a legacy TCP connection <xref
target="RFC0793"></xref>, and vice versa.</t>
<t>DHCP refers to both DHCPv4 <xref target="RFC2131"></xref> and
DHCPv6 <xref target="RFC3315"></xref>.</t>
<t>DHCP client denotes a node that initiates requests to obtain
configuration parameters from one or more DHCP servers.</t>
<t>DHCP server refers to a node that responds to requests from DHCP
clients.</t>
</list><?rfc subcompact="no" ?></t>
</section>
<section title="DHCPv6 MPTCP Option">
<t></t>
<section title="Format">
<t>The DHCPv6 MPTCP option can be used to configure a list of IPv6
addresses of an MPTCP Concentrator.</t>
<t>The format of this option is shown in <xref
target="dhcpv6_name_option"></xref>.</t>
<t><figure anchor="dhcpv6_name_option" title="DHCPv6 MPTCP option">
<preamble></preamble>
<artwork><![CDATA[ 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_V6_MPTCP | Option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| ipv6-address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| ipv6-address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>The fields of the option shown in <xref
target="dhcpv6_name_option"></xref> are as follows:<?rfc subcompact="yes" ?></t>
<t><list style="symbols">
<t>Option-code: OPTION_V6_MPTCP (TBA, see <xref
target="iana6"></xref>)</t>
<t>Option-length: Length of the 'MPTCP Concentrator IP
Address(es)' field in octets. MUST be a multiple of 16.</t>
<t>MPTCP Concentrator IPv6 Addresses: Includes one or more IPv6
addresses <xref target="RFC4291"></xref> of the MPTCP Concentrator
to be used by the MPTCP client. Note, IPv4-mapped IPv6 addresses
(Section 2.5.5.2 of <xref target="RFC4291"></xref>) are allowed to
be included in this option.</t>
</list></t>
<t><?rfc subcompact="no" ?>To return more than one MPTCP concentrators
to the DHCPv6 client, the DHCPv6 server returns multiple instances of
OPTION_V6_MPTCP.</t>
</section>
<section title="DHCPv6 Client Behavior">
<t>To discover one or more MPTCP Concentrators, the DHCPv6 client
requests MPTCP Concentrator IP addresses by including OPTION_V6_MPTCP
in an Option Request Option (ORO), as described in Section 22.7 of
<xref target="RFC3315"></xref>.</t>
<t>The DHCPv6 client MUST be prepared to receive multiple instances of
OPTION_V6_MPTCP; each instance is to be treated separately as it
corresponds to a given MPTCP Concentrator: there are as many
concentrators as instances of the OPTION_V6_MPTCP option. </t>
<t>If an IPv4-mapped IPv6 address is received in OPTION_V6_MPTCP, it
indicates that the MPTCP Concentrator has the corresponding IPv4
address.</t>
<t>The DHCPv6 client MUST silently discard multicast and host loopback
addresses <xref target="RFC6890"></xref> conveyed in
OPTION_V6_MPTCP.</t>
</section>
</section>
<section title="DHCPv4 MPTCP Option">
<t></t>
<section title="Format">
<t>The DHCPv4 MPTCP option can be used to configure a list of IPv4
addresses of an MPTCP Concentrator. The format of this option is
illustrated in <xref target="dhcppcp"></xref>.</t>
<t><figure anchor="dhcppcp" title="DHCPv4 MPTCP option">
<preamble></preamble>
<artwork><![CDATA[ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| List-Length | List of |
+-+-+-+-+-+-+-+-+ MPTCP |
/ Concentrator IPv4 Addresses /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---
| List-Length | List of | |
+-+-+-+-+-+-+-+-+ MPTCP | |
/ Concentrator IPv4 Addresses / |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. ... . optional
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| List-Length | List of | |
+-+-+-+-+-+-+-+-+ MPTCP | |
/ Concentrator IPv4 Addresses / |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---
]]></artwork>
<postamble></postamble>
</figure></t>
<t>The description of the fields is as follows:<?rfc subcompact="yes" ?><list
style="symbols">
<t>Code: OPTION_V4_MPTCP (TBA, see <xref
target="iana4"></xref>);</t>
<t>Length: Length of all included data in octets. The minimum
length is 5.</t>
<t>List-Length: Length of the "List of MPTCP Concentrator IPv4
Addresses" field in octets; MUST be a multiple of 4.</t>
<t>List of MPTCP Concentrator IPv4 Addresses: Contains one or more
IPv4 addresses of the MPTCP Concentrator to be used by the MPTCP
client. The format of this field is shown in <xref
target="list"></xref>.</t>
<t>OPTION_V4_MPTCP can include multiple lists of MPTCP
Concentrator IPv4 addresses; each list is treated separately as it
corresponds to a given MPTCP Concentrator. When several lists of
MPTCP Concentrator IPv4 addresses are to be included,
"List-Length" and "MPTCP Concentrator IPv4 Addresses" fields are
repeated.</t>
</list><figure anchor="list"
title="Format of the List of MPTCP Concentrator IPv4 Addresses">
<artwork><![CDATA[ 0 8 16 24 32 40 48
+-----+-----+-----+-----+-----+-----+--
| a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+--
IPv4 Address 1 IPv4 Address 2 ...]]></artwork>
<postamble>This format assumes that an IPv4 address is encoded as
a1.a2.a3.a4.</postamble>
</figure></t>
<t><?rfc subcompact="no" ?>OPTION_V4_MPTCP is a
concatenation-requiring option. As such, the mechanism specified in
<xref target="RFC3396"></xref> MUST be used if OPTION_V4_MPTCP exceeds
the maximum DHCPv4 option size of 255 octets.</t>
</section>
<section title="DHCPv4 Client Behavior">
<t>To discover one or more MPTCP Concentrators, the DHCPv4 client
requests MPTCP Concentrator’s IP addresses by including
OPTION_V4_MPTCP in a Parameter Request List Option <xref
target="RFC2132"></xref>.</t>
<t>The DHCPv4 client MUST be prepared to receive multiple lists of
MPTCP Concentrator IPv4 addresses in the same OPTION_V4_MPTCP; each
list is to be treated as a separate MPTCP Concentrator instance.</t>
<t>The DHCPv4 client MUST silently discard multicast and host loopback
addresses <xref target="RFC6890"></xref> conveyed in
OPTION_V4_MPTCP.</t>
</section>
</section>
<section title="DHCP Server Configuration Guidelines">
<t>DHCP servers that support the DHCP MPTCP Concentrator option can be
configured with a list of IP addresses of the MPTCP Concentrator(s). If
multiple IP addresses are configured, the DHCP server MUST be explicitly
configured whether all or some of these addresses refer to:</t>
<t><list style="numbers">
<t>the same MPTCP Concentrator: the DHCP server returns multiple
addresses in the same instance of the DHCP MPTCP Concentrator
option.</t>
<t>distinct MPTCP Concentrators : the DHCP server returns multiple
lists of MPTCP Concentrator IP addresses to the requesting DHCP
client (encoded as multiple OPTION_V6_MPTCP or in the same
OPTION_V4_MPTCP); each list refers to a distinct MPTCP
Concentrator.</t>
</list></t>
<t>Precisely how DHCP servers are configured to separate lists of IP
addresses according to which MPTCP Concentrator they refer to is out of
scope for this document. However, DHCP servers MUST NOT combine the IP
addresses of multiple MPTCP Concentrators and return them to the DHCP
client as if they were belonging to a single MPTCP Concentrator, and
DHCP servers MUST NOT separate the addresses of a single MPTCP
Concentrator and return them as if they were belonging to distinct MPTCP
Concentrators. For example, if an administrator configures the DHCP
server by providing a Fully Qualified Domain Name (FQDN) for a MPTCP
Concentrator, even if that FQDN resolves to multiple addresses, the DHCP
server MUST deliver them within a single server address block.</t>
<t>DHCPv6 servers that implement this option and that can populate the
option by resolving FQDNs will need a mechanism for indicating whether
to query A records or only AAAA records. When a query returns A records,
the IP addresses in those records are returned in the DHCPv6 response as
IPv4-mapped IPv6 addresses. <list style="empty">
<t>Discussion: The motivation for this design is to accommodate
deployment cases where an IPv4 connectivity service is provided
while only DHCPv6 is in use (e.g., DS-Lite context <xref
target="RFC6333"></xref>).</t>
</list></t>
<t>Since this option requires support for IPv4-mapped IPv6 addresses, a
DHCPv6 server implementation will not be complete if it does not query A
records and represent any that are returned as IPv4-mapped IPv6
addresses in DHCPv6 responses. The mechanism whereby DHCPv6
implementations provide this functionality is beyond the scope of this
document.</t>
<t>For guidelines on providing context-specific configuration
information (e.g., returning a regional-based configuration), and
information on how a DHCP server might be configured with FQDNs that get
resolved on demand, see <xref
target="I-D.ietf-dhc-topo-conf"></xref>.</t>
</section>
<section anchor="Security" title="Security Considerations">
<t>The security considerations in <xref target="RFC2131"></xref> and
<xref target="RFC3315"></xref> are to be considered. MPTCP-related
security considerations are discussed in <xref
target="RFC6824"></xref>.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t></t>
<section anchor="iana6" title="DHCPv6 Option">
<t>IANA is requested to assign the following new DHCPv6 Option Code in
the registry maintained in
http://www.iana.org/assignments/dhcpv6-parameters:</t>
<texttable style="headers">
<ttcol align="right">Option Name</ttcol>
<ttcol>Value</ttcol>
<c>OPTION_V6_MPTCP</c>
<c>TBA</c>
</texttable>
</section>
<section anchor="iana4" title="DHCPv4 Option">
<t>IANA is requested to assign the following new DHCPv4 Option Code in
the registry maintained in
http://www.iana.org/assignments/bootp-dhcp-parameters/:</t>
<texttable style="headers">
<ttcol align="right">Option Name</ttcol>
<ttcol>Value</ttcol>
<ttcol>Data length</ttcol>
<ttcol>Meaning</ttcol>
<c>OPTION_V4_MPTCP</c>
<c>TBA</c>
<c>Variable; the minimum length is 5.</c>
<c>Includes one or multiple lists of MPTCP Concentrator IP
addresses; each list is treated as a separate MPTCP
Concentrator.</c>
</texttable>
<t></t>
</section>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>TBC.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include='reference.RFC.6824'?>
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.3315'?>
<?rfc include='reference.RFC.2131'?>
<?rfc include='reference.RFC.4291'?>
<?rfc include='reference.RFC.2132'?>
<?rfc include='reference.RFC.6890'?>
<?rfc include='reference.RFC.3396'?>
</references>
<references title="Informative References">
<?rfc include='reference.I-D.deng-mptcp-proxy'?>
<?rfc include='reference.I-D.ietf-dhc-topo-conf'?>
<?rfc include='reference.RFC.4908'?>
<?rfc include='reference.RFC.6333'?>
<?rfc include='reference.RFC.0793'?>
</references>
</back>
</rfc>
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