DHCP Options for Network-Assisted Multipath TCP (MPTCP)
draft-boucadair-mptcp-dhc-00
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Mohamed Boucadair , Christian Jacquenet | ||
| Last updated | 2015-07-02 | ||
| Replaced by | draft-boucadair-tcpm-dhc-converter | ||
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draft-boucadair-mptcp-dhc-00
Network Working Group M. Boucadair
Internet-Draft C. Jacquenet
Intended status: Standards Track France Telecom
Expires: January 3, 2016 July 2, 2015
DHCP Options for Network-Assisted Multipath TCP (MPTCP)
draft-boucadair-mptcp-dhc-00
Abstract
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.
This document specifies DHCP (IPv4 and IPv6) options to configure
hosts with Multipath TCP (MPTCP) parameters.
Requirements Language
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 3, 2016.
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Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. DHCPv6 MPTCP Option . . . . . . . . . . . . . . . . . . . . . 4
3.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . 4
4. DHCPv4 MPTCP Option . . . . . . . . . . . . . . . . . . . . . 5
4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. DHCPv4 Client Behavior . . . . . . . . . . . . . . . . . 6
5. DHCP Server Configuration Guidelines . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7.1. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . 8
7.2. DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
One of the promising deployment scenarios for Multipath TCP (MPTCP,
[RFC6824]) 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 [I-D.deng-mptcp-proxy] or
[RFC4908]. This deployment scenario relies on MPTCP Proxy on both
the CPE and the network sides (Figure 1). 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.
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IP Network #1
+------------+ _--------_ +------------+
| | (e.g., LTE ) | |
| CPE +======================+ |
| (MPTCP | (_ _) |Concentrator|
| Proxy) | (_______) | (MPTCP |
| | | Proxy) |------> Internet
| | | |
| | IP Network #2 | |
| | _--------_ | |
| | ( e.g., DSL ) | |
| +======================+ |
| | (_ _) | |
+-----+------+ (_______) +------------+
|
----CPE network----
|
end-nodes
Figure 1: "Network-Assisted" MPTCP Design
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.
This document defines DHCPv4 [RFC2131] and DHCPv6 [RFC3315] options
that can be used to configure hosts with MPTCP Concentrator IP
addresses.
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.
2. Terminology
This document makes use of the following terms:
o MPTCP Concentrator denotes a functional element that terminates
MPTCP connections originated by MPTCP clients. An MPTCP
Concentrator is responsible for transforming an MPTCP connection
[RFC6824] into a legacy TCP connection [RFC0793], and vice versa.
o DHCP refers to both DHCPv4 [RFC2131] and DHCPv6 [RFC3315].
o DHCP client denotes a node that initiates requests to obtain
configuration parameters from one or more DHCP servers.
o DHCP server refers to a node that responds to requests from DHCP
clients.
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3. DHCPv6 MPTCP Option
3.1. Format
The DHCPv6 MPTCP option can be used to configure a list of IPv6
addresses of an MPTCP Concentrator.
The format of this option is shown in Figure 2.
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 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DHCPv6 MPTCP option
The fields of the option shown in Figure 2 are as follows:
o Option-code: OPTION_V6_MPTCP (TBA, see Section 7.1)
o Option-length: Length of the 'MPTCP Concentrator IP Address(es)'
field in octets. MUST be a multiple of 16.
o MPTCP Concentrator IPv6 Addresses: Includes one or more IPv6
addresses [RFC4291] of the MPTCP Concentrator to be used by the
MPTCP client. Note, IPv4-mapped IPv6 addresses (Section 2.5.5.2
of [RFC4291]) are allowed to be included in this option.
To return more than one MPTCP concentrators to the DHCPv6 client, the
DHCPv6 server returns multiple instances of OPTION_V6_MPTCP.
3.2. DHCPv6 Client Behavior
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
[RFC3315].
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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.
If an IPv4-mapped IPv6 address is received in OPTION_V6_MPTCP, it
indicates that the MPTCP Concentrator has the corresponding IPv4
address.
The DHCPv6 client MUST silently discard multicast and host loopback
addresses [RFC6890] conveyed in OPTION_V6_MPTCP.
4. DHCPv4 MPTCP Option
4.1. Format
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 Figure 3.
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 / |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---
Figure 3: DHCPv4 MPTCP option
The description of the fields is as follows:
o Code: OPTION_V4_MPTCP (TBA, see Section 7.2);
o Length: Length of all included data in octets. The minimum length
is 5.
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o List-Length: Length of the "List of MPTCP Concentrator IPv4
Addresses" field in octets; MUST be a multiple of 4.
o 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 Figure 4.
o 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.
0 8 16 24 32 40 48
+-----+-----+-----+-----+-----+-----+--
| a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+--
IPv4 Address 1 IPv4 Address 2 ...
This format assumes that an IPv4 address is encoded as a1.a2.a3.a4.
Figure 4: Format of the List of MPTCP Concentrator IPv4 Addresses
OPTION_V4_MPTCP is a concatenation-requiring option. As such, the
mechanism specified in [RFC3396] MUST be used if OPTION_V4_MPTCP
exceeds the maximum DHCPv4 option size of 255 octets.
4.2. DHCPv4 Client Behavior
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 [RFC2132].
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.
The DHCPv4 client MUST silently discard multicast and host loopback
addresses [RFC6890] conveyed in OPTION_V4_MPTCP.
5. DHCP Server Configuration Guidelines
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:
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1. the same MPTCP Concentrator: the DHCP server returns multiple
addresses in the same instance of the DHCP MPTCP Concentrator
option.
2. 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.
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.
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.
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 [RFC6333]).
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.
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 [I-D.ietf-dhc-topo-conf].
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6. Security Considerations
The security considerations in [RFC2131] and [RFC3315] are to be
considered. MPTCP-related security considerations are discussed in
[RFC6824].
7. IANA Considerations
7.1. DHCPv6 Option
IANA is requested to assign the following new DHCPv6 Option Code in
the registry maintained in http://www.iana.org/assignments/
dhcpv6-parameters:
Option Name Value
--------------- -----
OPTION_V6_MPTCP TBA
7.2. DHCPv4 Option
IANA is requested to assign the following new DHCPv4 Option Code in
the registry maintained in http://www.iana.org/assignments/bootp-
dhcp-parameters/:
Option Name Value Data length Meaning
--------------- ----- ----------- -----------------------------------
OPTION_V4_MPTCP TBA Variable; Includes one or multiple lists of
the minimum MPTCP Concentrator IP addresses;
length is each list is treated as a separate
5. MPTCP Concentrator.
8. Acknowledgements
TBC.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
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[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the
Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
November 2002.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, January 2013.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153, RFC
6890, April 2013.
9.2. Informative References
[I-D.deng-mptcp-proxy]
Lingli, D., Liu, D., Sun, T., Boucadair, M., and G.
Cauchie, "Use-cases and Requirements for MPTCP Proxy in
ISP Networks", draft-deng-mptcp-proxy-01 (work in
progress), October 2014.
[I-D.ietf-dhc-topo-conf]
Lemon, T. and T. Mrugalski, "Customizing DHCP
Configuration on the Basis of Network Topology", draft-
ietf-dhc-topo-conf-04 (work in progress), January 2015.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[RFC4908] Nagami, K., Uda, S., Ogashiwa, N., Esaki, H., Wakikawa,
R., and H. Ohnishi, "Multi-homing for small scale fixed
network Using Mobile IP and NEMO", RFC 4908, June 2007.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
Authors' Addresses
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Mohamed Boucadair
France Telecom
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Christian Jacquenet
France Telecom
Rennes
France
Email: christian.jacquenet@orange.com
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