RADIUS Extensions Working Group S. Winter
Internet-Draft RESTENA
Intended status: Standards Track March 31, 2011
Expires: October 02, 2011

RADIUS Accounting for traffic classes
draft-winter-radext-fancyaccounting-00

Abstract

This document specifies new attributes for RADIUS Accounting to enable NAS reporting of subsets of the total traffic in a user session.

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Table of Contents

1. Introduction

RADIUS Accounting [RFC2866] defines counters for octets and packets, both in the incoming and outgoing direction. Usage of these counters enables an operator create volume-based billing models and to execute proper capacity planning on its infrastructure.

The Accounting model is based on the assumption that all traffic in a user session is treated equally; i.e. that there are no differences in the billing model of one class of traffic over another.

Actual deployments suggest that this assumption is no longer valid. In particular, different traffic classes are defined with DSCP; and billing the use of these traffic classes separately is an understandable request.

Plus, the introduction of dual-stack operation on links creates an understandable interest of getting separate statistics about the amount of IPv4 vs. IPv6 usage on a link; be it for billing or statistical reasons.

This document defines Accounting attributes that supplement (but not replace) the accounting counters in RFC2866. It utilizes the new "extended attributes" in RADIUS to group accounting reports about traffic classes together.

1.1. Requirements Language

In this document, several words are used to signify the requirements of the specification. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. [RFC2119]

2. Definitions

2.1. Unsigned 64-Bit Integer datatype

RADIUS Accounting in RFC2866 uses two distinct attributes, Acct-(Input Output)-Octets and Acct-(Input Output) Gigawords, to transport 64 bit counter values. The reasons for defining a 64 Bit value across two attributes are historic. This specification defines a new datatype, "Unsigned 64 Bit Integer" to convey 64 bit counter values natively.

Type: UINT64 - Length: 8 octets - Value: 64 bit unsigned integer, most significant byte first

2.2. Acct-Traffic-Class attribute

The attribute Acct-Traffic-Group is a container for a group of sub-attributes which specify the class of traffic that is being reported about, and the amount of traffic in a user session that falls into this class.

Attribute: 245.1 Acct-Traffic-Class - Type: TLV - Length: >3 octets

There can be multiple instances of this grouped attribute in a Accounting-Interim-Update or a Accounting-Stop packet. The attribute MUST NOT be present in an Accounting-Start packet.

It is not required that the sum of all traffic in all instances is the total sum of octets and packets in the user's session. I.e. the traffic classes used in the Accounting packet do not need to partition the total traffic in non-overlapping segments.

The total number of octets and packets in a user session continues to be sent in the RFC2866 attributes.

2.2.1. Acct-Traffic-Class-Id attribute

The attribute Acct-Traffic-Class-Id, sub-attribute in the group Acct-Traffic-Class, defines the class of traffic for which the other attributes in the instance of Acct-Traffic-Class count octets and packets.

Every group instance MUST contain exactly one of Acct-Traffic-Class-Id or Acct-Traffic-Class-Name (see below). I.e. if Acct-Traffic-Class-Id is present in the Acct-Traffic-Class instance, then the attribute Acct-Traffic-Class-Name MUST NOT be present.

Attribute: 245.1.1 Acct-Traffic-Class-Id - Type: Enum - Values:

  1. IPv4
  2. IPv6
  3. DSCP 0
  4. DSCP 1
  5. ...

Allocations of new values for this attribute are subject to expert review.

2.2.2. Acct-Traffic-Class-Name attribute

The attribute Acct-Traffic-Class-Name, sub-attribute in the group Acct-Traffic-Class, defines the class of traffic for which the other attributes in the instance of Acct-Traffic-Class count octets and packets.

Every group instance MUST contain exactly one of Acct-Traffic-Class-Id (see above) or Acct-Traffic-Class-Name. I.e. if Acct-Traffic-Class-Name is present in the Acct-Traffic-Class instance, then the attribute Acct-Traffic-Class-Id MUST NOT be present.

Attribute: 245.1.2 Acct-Traffic-Class-Name - Type: STRING - Value: 1-250 octets

2.2.3. Acct-Traffic-Class-Input-Octets attribute

The attribute Acct-Traffic-Class-Input-Octets, sub-attribute in the group Acct-Traffic-Class, carries the number of octets that belong to the class of traffic indicated by Acct-Traffic-Class-Id or Acct-Traffic-Class-Name and have been sent to the entity for which the accounting packet was generated.

Attribute: 245.1.3 Acct-Traffic-Class-Input-Octets - Type: UINT64 - Value: number of octets sent to entity, matching the class of traffic

2.2.4. Acct-Traffic-Class-Output-Octets attribute

The attribute Acct-Traffic-Class-Output-Octets, sub-attribute in the group Acct-Traffic-Class, carries the number of octets that belong to the class of traffic indicated by Acct-Traffic-Class-Id or Acct-Traffic-Class-Name and have been sent from the entity for which the accounting packet was generated.

Attribute: 245.1.4 Acct-Traffic-Class-Output-Octets - Type: UINT64 - Value: number of octets sent from entity, matching the class of traffic

2.2.5. Acct-Traffic-Class-Input-Packets attribute

The attribute Acct-Traffic-Class-Input-Packets, sub-attribute in the group Acct-Traffic-Class, carries the number of packets that belong to the class of traffic indicated by Acct-Traffic-Class-Id or Acct-Traffic-Class-Name and have been sent to the entity for which the accounting packet was generated.

Attribute: 245.1.5 Acct-Traffic-Class-Input-Packets - Type: UINT64 - Value: number of packets sent to entity, matching the class of traffic

2.2.6. Acct-Traffic-Class-Output-Packets attribute

The attribute Acct-Traffic-Class-Output-Packets, sub-attribute in the group Acct-Traffic-Class, carries the number of packets that belong to the class of traffic indicated by Acct-Traffic-Class-Id or Acct-Traffic-Class-Name and have been sent from the entity for which the accounting packet was generated.

Attribute: 245.1.6 Acct-Traffic-Class-Output-Packets - Type: UINT64 - Value: number of packets sent from entity, matching the class of traffic

3. Example

A NAS is configured to create statistics regarding IPv6 usage of CPE for statistical reasons, and of the amount of HTTP traffic sent to the example.com web site for billing reasons.

User john@example.com starts a user session, transfers 1200 Bytes in 10 packets via IPv6 to the internet, and receives 4500 Bytes in 30 packets over IPv6 from the internet.

In the same session, The user visits the IPv4-only example.com web site by sending 6000 bytes in 4 packets to the web site, and receiving 450000 Bytes in 35 packets from the web site.

Then, the user terminates the session and an Accounting-Stop packet is generated.

The NAS sends the recorded octet and packet values to his RADIUS Accounting server. Since there is no ENUM value for "Traffic on TCP/80 to example.com, all IP versions" in Acct-Traffic-Group-Id, the NAS indicates this class of traffic in a corresponding string. The relevant attributes in the Account-Stop packet are:

Accounting-Traffic-Group

Accounting-Traffic-Group

4. Privacy Considerations

Reveals user's traffic usage patterns. Shouldn't be sent unencrpyptedly.

5. IANA Considerations

This document has actions for IANA. TBD later.

6. References

[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

Author's Address

Stefan Winter Fondation RESTENA 6, rue Richard Coudenhove-Kalergi Luxembourg, 1359 LUXEMBOURG Phone: +352 424409 1 EMail: stefan.winter@restena.lu URI: http://www.restena.lu.