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Radext WG Q. Wang
Internet-Draft China Telecom
Intended status: Standards Track W. Meng
Expires: June 4, 2016 C. Wang
ZTE Corporation
M. Boucadair
France Telecom
December 2, 2015


RADIUS Extensions for IPv4-Embedded Multicast and Unicast IPv6 Prefixes
draft-wang-radext-multicast-radius-ext-00

Abstract

This document specifies a new Remote Authentication Dial-In User
Service (RADIUS) attribute to carry the Multicast-Prefixes-64
information, aiming to delivery the Multicast and Unicast IPv6
Prefixes to be used to build multicast and unicast IPv4-Embedded IPv6
addresses. this RADIUS attribute is defined based on the equivalent
DHCPv6 OPTION_v6_PREFIX64 option.

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 June 4, 2016.

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



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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Convention and Terminology . . . . . . . . . . . . . . . . . . 4
3. Multicast-Prefixes-64 Configuration with RADIUS and DHCPv6 . . 5
4. RADIUS Attribute . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Multicast-Prefixes-64 . . . . . . . . . . . . . . . . . . 8
5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
9. Normative References . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16































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1. Introduction

The solution specified in [I-D.ietf-softwire-dslite-multicast] relies
on stateless functions to graft part of the IPv6 multicast
distribution tree and IPv4 multicast distribution tree, also uses
IPv4-in-IPv6 encapsulation scheme to deliver IPv4 multicast traffic
over an IPv6 multicast-enabled network to IPv4 receivers.

To inform the mB4 element of the PREFIX64,a PREFIX64 option may be
used. [I-D.ietf-softwire-multicast-prefix-option] defines a DHCPv6
PREFIX64 option to convey the IPv6 prefixes to be used for
constructing IPv4-embedded IPv6 addresses.

In broadband environments, a customer profile may be managed by
Authentication, Authorization, and Accounting (AAA) servers, together
with AAA for users. The Remote Authentication Dial-In User Service
(RADIUS) protocol [RFC2865] is usually used by AAA servers to
communicate with network elements. Since the Multicast-Prefixes-64
information can be stored in AAA servers and the client configuration
is mainly provided through DHCP running between the NAS and the
requesting clients, a new RADIUS attribute is needed to send
Multicast-Prefixes-64 information from the AAA server to the NAS.

This document defines a new RADIUS attribute to be used for carrying
the Multicast-Prefixes-64, based on the equivalent DHCPv6 option
already specified in [I-D.ietf-softwire-multicast-prefix-option].

This document makes use of the same terminology defined in
[I-D.ietf-softwire-dslite-multicast].

This attribute can be in particular used in the context of DS-Lite
Mulitcast, MAP-E Multicast and other IPv4-IPv6 Multicast techniques.
However it is not limited to DS-Lite Multicast.

DS-Lite unicast RADIUS extentions are defined in [RFC6519] .
















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2. Convention and Terminology

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 [RFC2119].

The terms DS-Lite multicast Basic Bridging BroadBand element (mB4)
and the DS-Lite multicast Address Family Transition Router element
(mAFTR) are defined in [I-D.ietf-softwire-dslite-multicast]










































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3. Multicast-Prefixes-64 Configuration with RADIUS and DHCPv6

Figure 1 illustrates in DS-Lite scenario how the RADIUS protocol and
DHCPv6 work together to accomplish Multicast-Prefixes-64
configuration on the mB4 element for multicast service when an IP
session is used to provide connectivity to the user.


mB4 NAS AAA
| | Server
|------ DHCPv6 Solicit ---------> | |
| | |
| |----Access-Request ---->|
| | |
| |<---Access-Accept-------|
| |(Multicast-Prefixes-64) |
| | |
|<------- DHCPv6 Advertise ------| |
| (DHCPv6 OPTION_V6_PREFIX64 ) | |
| | |
|------- DHCPv6 Request -------->| |
| | |
| | |
|<----- DHCPv6 Reply ------------- | |
| (DHCPv6 OPTION_V6_PREFIX64 ) | |

DHCPv6 RADIUS

Figure 1: RADIUS and DHCPv6 Message Flow for an IP Session

The NAS operates as a client of RADIUS and as a DHCP Server/Relay for
mB4. When the mB4 sends a DHCPv6 Solicit message to NAS(DHCP Server/
Relay). The NAS sends a RADIUS Access-Request message to the RADIUS
server, requesting authentication. Once the RADIUS server receives
the request, it validates the sending client, and if the request is
approved, the AAA server replies with an Access-Accept message
including a list of attribute-value pairs that describe the
parameters to be used for this session. This list MAY contain the
Multicast-Prefixes-64 attribute (asm-length,ASM_PREFIX64,ssm-length,
SSM_PREFIX64,unicast-length,U_PREFIX64). Then, when the NAS receives
the DHCPv6 Request message containing the OPTION_V6_PREFIX64 option
in its Option Request option,the NAS SHALL use the prefixes returned
in the RADIUS Multicast-Prefixes-64 attribute to populate the DHCPv6
OPTION_V6_PREFIX64 option in the DHCPv6 reply message.

NAS MAY be configured to return the configured Multicast-Prefixes-64
by the AAA Server to any requesting client without relaying each
received request to the AAA Server.



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Figure 2 describes another scenario, which accomplish DS-Lite
Multicast-Prefixes-64 configuration on the mB4 element for multicast
service when a PPP session is used to provide connectivity to the
user. Once the NAS obtains the Multicast-Prefixes-64 attribute from
the AAA server through the RADIUS protocol, the NAS MUST store the
received Multicast-Prefixes-64 locally. When a user is online and
sends a DHCPv6 Request message containing the OPTION_V6_PREFIX64
option in its Option Request option, the NAS retrieves the previously
stored Multicast-Prefixes-64 and uses it as OPTION_V6_PREFIX64 option
in DHCPv6 Reply message.

mB4 NAS AAA
| | Server
| | |
|----PPP LCP Config-Request------> | |
| | |
| |----Access-Request ---->|
| | |
| |<---- Access-Accept-----|
| | (Multicast-Prefixes-64)|
|<-----PPP LCP Config-ACK ------- | |
| | |
| | |
|--- PPP IPv6CP Config-Request --->| |
| | |
|<----- PPP IPv6CP Config-ACK -----| |
| | |
|------- DHCPv6 Solicit -------->| |
| | |
|<------- DHCPv6 Advertise -----| |
| (DHCPv6 OPTION_V6_PREFIX64 ) | |
| | |
|------- DHCPv6 Request -------->| |
| | |
| | |
|<-------- DHCPv6 Reply ---------- | |
| (DHCPv6 OPTION_V6_PREFIX64) | |

DHCPv6 RADIUS


Figure 2: RADIUS and DHCPv6 Message Flow for a PPP Session

According to [RFC3315], after receiving the Multicast-Prefixes-64
attribute in the initial Access-Accept packet, the NAS MUST store the
received V6_PREFIX64 locally. When the mB4 sends a DHCPv6 Renew
message to request an extension of the lifetimes for the assigned
address or prefix, the NAS does not have to initiate a new Access-



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Request packet towards the AAA server to request the Multicast-
Prefixes-64. The NAS retrieves the previously stored Multicast-
Prefixes-64 and uses it in its reply.

Also, if the DHCPv6 server to which the DHCPv6 Renew message was sent
at time T1 has not responded, the DHCPv6 client initiates a Rebind/
Reply message exchange with any available server. In this scenario,
the NAS receiving the DHCPv6 Rebind message MUST initiate a new
Access-Request message towards the AAA server. The NAS MAY include
the Multicast-Prefixes-64 attribute in its Access-Request message.









































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4. RADIUS Attribute

This section specifies the format of the new RADIUS attribute.

4.1. Multicast-Prefixes-64

The Multicast-Prefixes-64 attribute conveys the IPv6 prefixes to be
used in [I-D.ietf-softwire-dslite-multicast] to synthesize IPv4-
embedded IPv6 addresses. The NAS SHALL use the IPv6 prefixes
returned in the RADIUS Multicast-Prefixes-64 attribute to populate
the DHCPv6 PREFIX64 Option
[I-D.ietf-softwire-multicast-prefix-option] .

This attribute MAY be used in Access-Request packets as a hint to the
RADIUS server, for example, if the NAS is pre-configured with
Multicast-Prefixes-64, these prefixes MAY be inserted in the
attribute. The RADIUS server MAY ignore the hint sent by the NAS,
and it MAY assign a different Multicast-Prefixes-64 attribute.

If the NAS includes the Multicast-Prefixes-64 attribute, but the AAA
server does not recognize this attribute, this attribute MUST be
ignored by the AAA server.

NAS MAY be configured with both ASM_PREFIX64 and SSM_PREFIX64 or only
one of them. Concretely, AAA server MAY return ASM_PREFIX64 or
SSM_PREFIX64 based on the user profile and service policies. AAA MAY
return both ASM_PREFIX64 and SSM_PREFIX64. When SSM_PREFIX64 is
returned by the AAA server, U_PREFIX64 MUST also be returned by the
AAA server.

If the NAS does not receive the Multicast-Prefixes-64 attribute in
the Access-Accept message, it MAY fall back to a pre-configured
default Multicast-Prefixes-64, if any. If the NAS does not have any
pre-configured, the delivery of multicast traffic is not supported.

If the NAS is pre-provisioned with a default Multicast-Prefixes-64
and the Multicast-Prefixes-64 received in the Access-Accept message
are different from the configured default, then the Multicast-
Prefixes-64 attribute received in the Access-Accept message MUST be
used for the session.

A summary of the Multicast-Prefixes-64 RADIUS attribute format is
shown Figure 3. The fields are transmitted from left to right.








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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| asm-length | |
+-+-+-+-+-+-+-+-+ :
: ASM_PREFIX64 (variable) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ssm-length | |
+-+-+-+-+-+-+-+-+ :
: SSM_PREFIX64 (variable) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| unicast-length| |
+-+-+-+-+-+-+-+-+ :
: U_PREFIX64 (variable) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Figure 3: RADIUS attribute format for Multicast-Prefixes-64

Type:

145 for Multicast-Prefixes-64

Length:

This field indicates the total length in octets of this attribute
including the Type and Length fields, and the length in octets of all
PREFIX fields.

asm-length:

the prefix-length for the ASM IPv4-embedded prefix, as an 8-bit
unsigned integer (0 to 128). This field represents the number of
valid leading bits in the prefix.

ASM_PREFIX64:

this field identifies the IPv6 multicast prefix to be used to
synthesize the IPv4-embedded IPv6 addresses of the multicast groups
in the ASM mode. It is a variable size field with the length of the
field defined by the asm-length field and is rounded up to the
nearest octet boundary. In such case any additional padding bits
must be zeroed. The conveyed multicast IPv6 prefix MUST belong to
the ASM range. This prefix is likely to be a /96.

ssm-length:




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the prefix-length for the SSM IPv4-embedded prefix, as an 8-bit
unsigned integer (0 to 128). This field represents the number of
valid leading bits in the prefix.

SSM_PREFIX64:

this field identifies the IPv6 multicast prefix to be used to
synthesize the IPv4-embedded IPv6 addresses of the multicast groups
in the SSM mode. It is a variable size field with the length of the
field defined by the ssm-length field and is rounded up to the
nearest octet boundary. In such case any additional padding bits
must be zeroed. The conveyed multicast IPv6 prefix MUST belong to
the SSM range. This prefix is likely to be a /96.

unicast-length:

the prefix-length for the IPv6 unicast prefix to be used to
synthesize the IPv4-embedded IPv6 addresses of the multicast sources,
as an 8-bit unsigned integer (0 to 128). This field represents the
number of valid leading bits in the prefix.

U_PREFIX64:

this field identifies the IPv6 unicast prefix to be used in SSM
mode for constructing the IPv4-embedded IPv6 addresses representing
the IPv4 multicast sources in the IPv6 domain. U_PREFIX64 may also
be used to extract the IPv4 address from the received multicast data
flows. It is a variable size field with the length of the field
defined by the unicast-length field and is rounded up to the nearest
octet boundary. In such case any additional padding bits must be
zeroed. The address mapping MUST follow the guidelines documented in
[RFC6052].



















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5. Table of Attributes

The following tables provide a guide to which attributes may be found
in which kinds of packets, and in what quantity.

The following table defines the meaning of the above table entries.

Access- Access- Access- Challenge Accounting- # Attribute
Request Accept Reject Request
0-1 0-1 0 0 0-1 145 Multicast-Prefixes-64

CoA- CoA- CoA- # Attribute
Request ACK NACK
0-1 0 0 145 Multicast-Prefixes-64

0 This attribute MUST NOT be present in the packet.
0+ Zero or more instances of this attribute MAY be present in the
packet.
0-1 Zero or one instances of this attribute MAY be present in the
packet.
1 Exactly one instances of this attribute MAY be present in the
packet.





























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6. Security Considerations

This document has no additional security considerations beyond those
already identified in [RFC2865] for the RADIUS protocol and in
[RFC5176] for CoA messages.

The security considerations documented in [RFC3315] and [RFC6052] are
to be considered.











































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7. IANA Considerations

Per this document, IANA has allocated a new RADIUS attribute type
from the IANA registry "Radius Attribute Types" located at
http://www.iana.org/assignments/radius-types.

Multicast-Prefixes-64 - 145












































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8. Acknowledgments

The authors would like to thank Ian Farrer, Chongfen Xie, Qi Sun,
Linhui Sun and Hao Wang for their contributions to this work.















































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9. Normative References

[I-D.ietf-softwire-dslite-multicast]
Qin, J., Boucadair, M., Jacquenet, C., Lee, Y., and Q.
Wang, "Delivery of IPv4 Multicast Services to IPv4 Clients
over an IPv6 Multicast Network",
draft-ietf-softwire-dslite-multicast-10 (work in
progress), August 2015.

[I-D.ietf-softwire-multicast-prefix-option]
Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
Option for IPv4-Embedded Multicast and Unicast IPv6
Prefixes", draft-ietf-softwire-multicast-prefix-option-09
(work in progress), August 2015.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
.

[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,
.

[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, .

[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,
.

[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010,
.

[RFC6519] Maglione, R. and A. Durand, "RADIUS Extensions for Dual-
Stack Lite", RFC 6519, DOI 10.17487/RFC6519,
February 2012, .







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Authors' Addresses

Qian Wang
China Telecom
No.118, Xizhimennei
Beijing 100035
China

Email: wangqian@ctbri.com.cn


Wei Meng
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China

Email: meng.wei2@zte.com.cn,vally.meng@gmail.com


Cui Wang
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China

Email: wang.cui1@zte.com.cn


Mohamed Boucadair
France Telecom
Rennes, 35000
France

Email: mohamed.boucadair@orange.com
















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