Internet DRAFT - draft-chen-radext-identifier-attr
draft-chen-radext-identifier-attr
Network Working Group E. Chen
Internet Draft N. Shen
Intended Status: Standards Track Cisco Systems
Expiration Date: April 21, 2018 October 20, 2017
RADIUS Extended Identifier Attribute
draft-chen-radext-identifier-attr-02.txt
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Internet Draft draft-chen-radext-identifier-attr-02.txt October 2017
Abstract
The limitation with the one-octet "Identifier" field in the RADIUS
packet is well known. In this document we propose extensions to the
RADIUS protocol to address this fundamental limitation, and thus
allowing for more efficient and more scalable implementations.
1. Introduction
The "Identifier" field in the RADIUS packet [RFC2865] is used to
match outstanding requests and replies. As the field is one octet in
size, only 256 requests can be in progress between two endpoints,
which would present a significant bottleneck for performance. The
workaround for this limitation is to use multiple source ports as
documented and discussed in [RFC2865], [RFC3539], and [RFC6613].
Currently it is quite common to have hundreds of parallel connections
between a RADIUS client and a server, especially in the deployment of
controllers for wireless clients. As the scale requirement continues
to increase, the number of "parallel connections" is expected to grow
(perhaps reaching thousands), which will undoubtedly create a number
of challenges with resource utilization, efficiency, and connection
management (with RADIUS over TCP [RFC6613] in particular) on both the
client and the server.
In this document we propose extensions to the RADIUS protocol to
address this fundamental limitation and thus allowing for more
efficient and more scalable implementations. More specifically, a new
attribute ("Extended Identifier Attribute") is defined that can be
used to discover the support of this specification between a client
and a server using the Status-Server message [RFC5997]. Once the
support is confirmed, the attribute can then be used to carry the
extended identifier parameter in subsequent RADIUS packets. The
extended identifier parameter can be used together with the
Identifier to match outstanding requests and replies.
For brevity the extensions specified in this document are referred to
as "the Extended Identifier feature" hereafter.
1.1. Specification of Requirements
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].
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2. Protocol Extensions
2.1. The Extended Identifier Attribute
A new attribute, termed "Extended Identifier Attribute", is specified
which can be used to discover the support for the Extended Identifier
feature between a client and a server. It can also be used to carry
the "extended identifier" parameter in a RADIUS packet after the
support is confirmed. The attribute number is TBD. The value of the
attribute has 4 octets, and consists of the following fields:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sta| Extended Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where the 2-bit Status field is to be used in a Status-Server message
to discover the support for the Extended Identifier feature. The
following settings are defined:
o It is set to 1 (for "request") when a client sends the
Status-Server request to a server indicating its support for
the Extended Identifier feature.
o It is set to 2 (for "accept") or 3 (for "reject") by the
server in its response to indicate whether it supports the
Extended Identifier feature.
The 30-bit "Extended Identifier" field is an unsigned integer. It is
to be used together with the Identifier field to match outstanding
requests and replies.
When the "Extended Identifier Attribute" is used in a Status-Server
request or reply, only the Status field is used. All other fields
SHOULD be set to zero by the sender and MUST be ignored by the
receiver.
When the "Extended Identifier Attribute" is used in a message other
than the Status-Server request or reply, the Status field is unused,
and SHOULD be set to zero by the sender and MUST be ignored by the
receiver.
To simplify packet processing and for consistency, the "Extended
Identifier Attribute" MUST be encoded as the very first attribute in
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the attribute list of a RADIUS packet. If the attribute does not
appear as the first one in the attribute list of a RADIUS packet, the
RADIUS packet MUST be treated as invalid and the packet be discarded
according to [RFC2865].
Due to the hop-by-hop nature of RADIUS packet transmission between
RADIUS devices, a PROXY server MUST strip the "Extended Identifier
Attribute" (and reconstruct if appropriate) before sending the packet
over a different session.
2.2. Status-Server Considerations
This section extends processing of Status-Server messages as
described in Sections 4.1 and 4.2 of [RFC5997].
Prior to sending a RADIUS packet (other than the Status-Server
request) with the "Extended Identifier Attribute", a client
implementing this specification SHOULD first send a Status-Server
request with the "Extended Identifier Attribute" to indicate its
support for the Extended Identifier feature.
When a server implementing this specification receives a Status-
Server request with the "Extended Identifier Attribute", it MUST
include the "Extended Identifier Attribute" in its response to
indicate whether it supports the Extended Identifier feature. If the
Status-server reply from a server does not contain the "Extended
Identifier Attribute", the client MUST treat this case as "reject" by
the server for the Extended Identifier feature.
Unless specified by configuration, a client MUST NOT send a RADIUS
packet (other than the Status-Server request) with the "Extended
Identifier Attribute" to a server until it has received a response
from the server confirming its support for the Extended Identifier
feature using the "Extended Identifier Attribute".
When TCP is used as the transport protocol for RADIUS [RFC6613]
between a client and a server, the Extended Identifier feature SHOULD
be discovered each time the TCP session is established.
2.3. Use of the Extended Identifier Field
After the functionality defined in this specification is discovered
between the client and the server, the Extended Identifier field can
be carried using the "Extended Identifier Attribute" in a RADIUS
packet. The Extended Identifier is to be used together with the
Identifier to identify requests and replies. The assignment of these
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parameters is left to implementation.
When the "Extended Identifier Attribute" is present in a RADIUS
packet other than the Status-Server request or reply, the Extended
Identifier field in the attribute MUST be used together with the
Identifier field to identify requests and replies.
In response to a request from a client that contains the Extended
Identifier field, the server MUST include the Extended Identifier
field with an identical value in its reply.
3. IANA Considerations
A new attribute ("Extended Identifier Attribute") is defined for the
RADIUS protocol. The type value [RFC3575] needs to be assigned using
the assignment rules in section 10.3 of [RFC6929].
4. Security Considerations
This document defines a new RADIUS attribute, which does not affect
the security considerations of the RADIUS protocol [RFC2865].
The new RADIUS attribute and the procedures described in this
document helps eliminate the need for "parallel connections" between
a RADIUS client and a server due to the limitation with the
"Identifier" field. Thus the resource utilization (such as the
number of UDP/TCP ports) on a RADIUS device is expected to be reduced
significantly in large scale deployment.
5. Acknowledgments
We would like to thank Alan DeKok for useful discussions and
suggestions.
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6. References
6.1. 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,
<http://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, June 2000.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575, July
2003.
6.2. Informative References
[RFC3539] Aboba, B. and J. Wood, "Authentication, Authorization
and Accounting (AAA) Transport Profile", RFC 3539, June
2003.
[RFC6613] DeKok, A., "RADIUS over TCP", RFC 6613, May 2012.
[RFC5997] DeKok, A., "Use of Status-Server Packets in the Remote
Authentication Dial In User Service (RADIUS) Protocol",
RFC 5997, August 2010.
[RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User
Service (RADIUS) Protocol Extensions", RFC 6929, April
2013.
7. Authors' Addresses
Enke Chen
Cisco Systems
560 McCarthy Blvd.
Milpitas, CA 95035
USA
Email: enkechen@cisco.com
Naiming Shen
Cisco Systems
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560 McCarthy Blvd.
Milpitas, CA 95035
USA
Email: naiming@cisco.com
Chen & Shen [Page 7]