Internet DRAFT - draft-boucadair-mptcp-radius
draft-boucadair-mptcp-radius
Network Working Group M. Boucadair
Internet-Draft C. Jacquenet
Intended status: Standards Track Orange
Expires: April 11, 2018 October 8, 2017
RADIUS Extensions for Network-Assisted Multipath TCP (MPTCP)
draft-boucadair-mptcp-radius-05
Abstract
Because of the lack of Multipath TCP (MPTCP) support at the server
side, some service providers now consider a network-assisted model
that relies upon the activation of a dedicated function called MPTCP
Conversion Point (MCP). Network-assisted MPTCP deployment models are
designed to facilitate the adoption of MPTCP for the establishment of
multi-path communications without making any assumption about the
support of MPTCP by the communicating peers. MCPs located in the
network are responsible for establishing multi-path communications on
behalf of endpoints, thereby taking advantage of MPTCP capabilities
to achieve different goals that include (but are not limited to)
optimization of resource usage (e.g., bandwidth aggregation), of
resiliency (e.g., primary/backup communication paths), and traffic
offload management.
This document specifies a new Remote Authentication Dial-In User
Service (RADIUS) attributes that carry the IP addresses that will be
returned to authorized users to reach one or multiple MCPs.
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
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 April 11, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. MPTCP RADIUS Attributes . . . . . . . . . . . . . . . . . . . 4
2.1. MPTCP-MCP-IPv4 . . . . . . . . . . . . . . . . . . . . . 4
2.2. MPTCP-MCP-IPv6 . . . . . . . . . . . . . . . . . . . . . 5
3. Sample Use Case . . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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 [RFC4908].
Network-assisted MPTCP deployment models are designed to facilitate
the adoption of MPTCP for the establishment of multi-path
communications without making any assumption about the support of
MPTCP by the communicating peers. This deployment scenario relies on
MPTCP proxies located on both the CPE and network sides (Figure 1).
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MPTCP proxies are responsible for establishing multi-path
communications on behalf of endpoints, thereby taking advantage of
MPTCP capabilities to optimize resource usage to achieve different
goals that include (but are not limited to) bandwidth aggregation,
primary/backup communication paths, and traffic offload management.
+------------+ _--------_ +----------------+
| | ( LTE ) | |
| CPE +=======+ +===+ Backbone |
| (MCP) | (_ _) | Network |
| | (_______) |+--------------+|
| | IP Network #1 || Concentrator ||------> Internet
| | || (MCP) ||
| | |+--------------+|
| | IP Network #2 | |
| | _--------_ | |
| | ( DSL ) | |
| +=======+ +==+ |
| | (_ _) | |
+-----+------+ (_______) +----------------+
|
---- LAN ----
|
end-nodes
Figure 1: Network-Assisted MPTCP: Reference Architecture
Within this document, an MPTCP Conversion Point (MCP) refers to a
functional element that is responsible for aggregating the traffic
originated by a group of CPEs. This element is located in the
network. One or multiple MCPs can be deployed in the network to
assist MPTCP-enabled CPEs to establish MPTCP connections via their
available network attachments. On the uplink path, the MCP
terminates the MPTCP connections received from its customer-facing
interfaces and transforms these connections into legacy TCP
connections [RFC0793] towards upstream servers. On the downlink
path, the MCP turns the legacy server's TCP connection into MPTCP
connections towards its customer-facing interfaces.
This document specifies two new Remote Authentication Dial-In User
Service (RADIUS, [RFC2865]) attributes that carry the MCP IP address
list (Section 2). In order to accommodate both IPv4 and IPv6
deployment contexts, and given the constraints in Section 3.4 of
[RFC6158], two attributes are specified. Note that one or multiple
IPv4 and/or IPv6 addresses may be returned to a requesting CPE. A
sample use case is described in Section 3.
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This document assumes that the MCP(s) reachability information can be
stored in Authentication, Authorization, and Accounting (AAA) servers
while the CPE configuration is usually provided by means of DHCP
([RFC2131][RFC3315]). Further Network-Assisted MPTCP deployment and
operational considerations are discussed in
[I-D.nam-mptcp-deployment-considerations].
This specification assumes an MCP is reachable through one or
multiple IP addresses. As such, a list of IP addresses can be
communicated via RADIUS. Also, it assumes the various network
attachments provided to an MPTCP-enabled CPE are managed by the same
administrative entity.
This document adheres to [RFC8044] for defining the new attributes.
2. MPTCP RADIUS Attributes
2.1. MPTCP-MCP-IPv4
Description
The RADIUS MPTCP-MCP-IPv4 attribute contains the IPv4 address of
an MCP that is assigned to a CPE.
Because multiple MCP IP addresses may be provisioned to an
authorised CPE (that is a CPE entitled to solicit the resources of
an MCP to establish MPTCP connections), multiple instances of the
MPTCP-MCP-IPv4 attribute MAY be included; each instance of the
attribute carries a distinct IP address.
Both MPTCP-MCP-IPv4 and MPTCP-MCP-IPv6 attributes MAY be present
in a RADIUS message.
The MPTCP-MCP-IPv4 Attribute MAY appear in a RADIUS Access-Accept
packet. It MAY also appear in a RADIUS Access-Request packet as a
hint to the RADIUS server to indicate a preference, although the
server is not required to honor such a hint.
The MPTCP-MCP-IPv4 Attribute MAY appear in a CoA-Request packet.
The MPTCP-MCP-IPv4 Attribute MAY appear in a RADIUS Accounting-
Request packet.
The MPTCP-MCP-IPv4 Attribute MUST NOT appear in any other RADIUS
packet.
Type
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TBA (see Section 6).
Length
6
Data Type
The attribute MPTCP-MCP-IPv4 is of type ip4addr (Section 3.3 of
[RFC8044]).
Value
This field includes an IPv4 address (32 bits) of the MCP.
The MPTCP-MCP-IPv4 attribute MUST NOT include multicast and host
loopback addresses [RFC6890]. Anycast addresses are allowed to be
included in an MPTCP-MCP-IPv4 attribute.
2.2. MPTCP-MCP-IPv6
Description
The RADIUS MPTCP-MCP-IPv6 attribute contains the IPv6 address of
an MCP that is assigned to a CPE.
Because multiple MCP IP addresses may be provisioned to an
authorised CPE (that is a CPE entitled to solicit the resources of
an MCP to establish MPTCP connections), multiple instances of the
MPTCP-MCP-IPv6 attribute MAY be included; each instance of the
attribute carries a distinct IP address.
Both MPTCP-MCP-IPv4 and MPTCP-MCP-IPv6 attributes MAY be present
in a RADIUS message.
The MPTCP-MCP-IPv6 Attribute MAY appear in a RADIUS Access-Accept
packet. It MAY also appear in a RADIUS Access-Request packet as a
hint to the RADIUS server to indicate a preference, although the
server is not required to honor such a hint.
The MPTCP-MCP-IPv6 Attribute MAY appear in a CoA-Request packet.
The MPTCP-MCP-IPv6 Attribute MAY appear in a RADIUS Accounting-
Request packet.
The MPTCP-MCP-IPv6 Attribute MUST NOT appear in any other RADIUS
packet.
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Type
TBA (see Section 6).
Length
18
Data Type
The attribute MPTCP-MCP-IPv6 is of type ip6addr (Section 3.9 of
[RFC8044]).
Value
This field includes an IPv6 address (128 bits) of the MCP.
The MPTCP-MCP-IPv6 attribute MUST NOT include multicast and host
loopback addresses [RFC6890]. Anycast addresses are allowed to be
included in an MPTCP-MCP-IPv6 attribute.
3. Sample Use Case
This section does not aim to provide an exhaustive list of deployment
scenarios where the use of the RADIUS MPTCP-MCP-IPv6 and MPTCP-MCP-
IPv4 attributes can be helpful. Typical deployment scenarios are
described, for instance, in [RFC6911].
Figure 2 shows an example where a CPE is assigned an MCP. This
example assumes that the Network Access Server (NAS) embeds both
RADIUS client and DHCPv6 server capabilities.
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CPE NAS AAA
DHCPv6 client DHCPv6 server server
| | |
|---------DHCPv6 Solicit-------->| |
| |----Access-Request ---->|
| | |
| |<----Access-Accept------|
| | MPTCP-MCP-IPv6 |
|<-------DHCPv6 Advertisement----| |
| (OPTION_V6_MPTCP) | |
| | |
|---------DHCPv6 Request-------->| |
| | |
|<---------DHCPv6 Reply----------| |
| (OPTION_V6_MPTCP) | |
DHCPv6 RADIUS
Figure 2: Sample Flow Example (1)
Upon receipt of the DHCPv6 Solicit message from a CPE, the NAS sends
a RADIUS Access-Request message to the AAA server. Once the AAA
server receives the request, it replies with an Access-Accept message
(possibly after having sent a RADIUS Access-Challenge message and
assuming the CPE is entitled to connect to the network) that carries
a list of parameters to be used for this session, and which include
MCP reachability information (namely a list of IP addresses).
The content of the MPTCP-MCP-IPv6 attribute is then used by the NAS
to complete the DHCPv6 procedure that the CPE initiated to retrieve
information about the MCP it has been assigned.
Upon change of the MCP assigned to a CPE, the RADIUS server sends a
RADIUS CoA message [RFC5176] that carries the RADIUS MPTCP-MCP-IPv6
attribute to the NAS. Once that message is accepted by the NAS, it
replies with a RADIUS CoA ACK message. The NAS replaces the old MCP
with the new one.
Figure 3 shows another example where a CPE is assigned an MCP, but
the CPE uses DHCPv6 to retrieve a list of IP addresses of an MCP.
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CPE NAS AAA
DHCPv4 client DHCPv4 server server
| | |
|-----------DHCPDISCOVER---------->| |
| |----Access-Request ---->|
| | |
| |<----Access-Accept------|
| | MPTCP-MCP-IPv4 |
|<------------DHCPOFFER------------| |
| (OPTION_V4_MPTCP) | |
| | |
|------------DHCPREQUEST---------->| |
| (OPTION_V4_MPTCP) | |
| | |
|<-----------DHCPACK---------------| |
| (OPTION_V4_MPTCP) | |
DHCPv4 RADIUS
Figure 3: Sample Flow Example (2)
Some deployments may rely on the mechanisms defined in [RFC4014] or
[RFC7037], which allows a NAS to pass attributes obtained from a
RADIUS server to a DHCP server.
4. Security Considerations
RADIUS-related security considerations are discussed in [RFC2865].
MPTCP-related security considerations are discussed in [RFC6824] and
[RFC6181].
Traffic theft is a risk if an illegitimate MCP is inserted in the
path. Indeed, inserting an illegitimate MCP in the forwarding path
allows to intercept traffic and can therefore provide access to
sensitive data issued by or destined to a host. To mitigate this
threat, secure means to discover an MCP should be enabled.
5. Table of Attributes
The following table provides a guide as what type of RADIUS packets
that may contain these attributes, and in what quantity.
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Access- Access- Access- Challenge Acct. # Attribute
Request Accept Reject Request
0+ 0+ 0 0 0+ TBA MPTCP-MCP-IPv4
0+ 0+ 0 0 0+ TBA MPTCP-MCP-IPv6
CoA-Request CoA-ACK CoA-NACK # Attribute
0+ 0 0 TBA MPTCP-MCP-IPv4
0+ 0 0 TBA MPTCP-MCP-IPv6
The following table defines the meaning of the above table entries:
0 This attribute MUST NOT be present in packet.
0+ Zero or more instances of this attribute MAY be present in packet.
6. IANA Considerations
IANA is requested to assign two new RADIUS attribute types from the
IANA registry "Radius Attribute Types" located at
http://www.iana.org/assignments/radius-types:
MPTCP-MCP-IPv4 (TBA)
MPTCP-MCP-IPv6 (TBA)
7. Acknowledgements
Thanks to Alan DeKok for the comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, DOI 10.17487/RFC2865, June 2000,
<https://www.rfc-editor.org/info/rfc2865>.
[RFC6158] DeKok, A., Ed. and G. Weber, "RADIUS Design Guidelines",
BCP 158, RFC 6158, DOI 10.17487/RFC6158, March 2011,
<https://www.rfc-editor.org/info/rfc6158>.
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[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<https://www.rfc-editor.org/info/rfc6890>.
[RFC8044] DeKok, A., "Data Types in RADIUS", RFC 8044,
DOI 10.17487/RFC8044, January 2017,
<https://www.rfc-editor.org/info/rfc8044>.
8.2. Informative References
[I-D.nam-mptcp-deployment-considerations]
Boucadair, M., Jacquenet, C., Bonaventure, O., Henderickx,
W., and R. Skog, "Network-Assisted MPTCP: Use Cases,
Deployment Scenarios and Operational Considerations",
draft-nam-mptcp-deployment-considerations-01 (work in
progress), December 2016.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/info/rfc793>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997,
<https://www.rfc-editor.org/info/rfc2131>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <https://www.rfc-editor.org/info/rfc3315>.
[RFC4014] Droms, R. and J. Schnizlein, "Remote Authentication Dial-
In User Service (RADIUS) Attributes Suboption for the
Dynamic Host Configuration Protocol (DHCP) Relay Agent
Information Option", RFC 4014, DOI 10.17487/RFC4014,
February 2005, <https://www.rfc-editor.org/info/rfc4014>.
[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,
DOI 10.17487/RFC4908, June 2007,
<https://www.rfc-editor.org/info/rfc4908>.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176,
DOI 10.17487/RFC5176, January 2008,
<https://www.rfc-editor.org/info/rfc5176>.
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[RFC6181] Bagnulo, M., "Threat Analysis for TCP Extensions for
Multipath Operation with Multiple Addresses", RFC 6181,
DOI 10.17487/RFC6181, March 2011,
<https://www.rfc-editor.org/info/rfc6181>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<https://www.rfc-editor.org/info/rfc6824>.
[RFC6911] Dec, W., Ed., Sarikaya, B., Zorn, G., Ed., Miles, D., and
B. Lourdelet, "RADIUS Attributes for IPv6 Access
Networks", RFC 6911, DOI 10.17487/RFC6911, April 2013,
<https://www.rfc-editor.org/info/rfc6911>.
[RFC7037] Yeh, L. and M. Boucadair, "RADIUS Option for the DHCPv6
Relay Agent", RFC 7037, DOI 10.17487/RFC7037, October
2013, <https://www.rfc-editor.org/info/rfc7037>.
Authors' Addresses
Mohamed Boucadair
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Christian Jacquenet
Orange
Rennes
France
Email: christian.jacquenet@orange.com
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