Diameter Maintenance and Extensions L. Bertz
Internet-Draft M. Bales
Intended status: Standards Track Sprint
Expires: September 10, 2017 March 9, 2017
Diameter Policy Groups and Sets
draft-bertz-dime-policygroups-03
Abstract
This document defines optional Diameter attributes for efficient
policy provisioning.
Status of This Memo
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1. Introduction
Policy applications often apply common policies to multiple
authorized users. Bulk operations are often applied through the use
of group naming, e.g. 3GPP's use of Base Name.
This document defines a grouping mechanism to apply common operations
to a group of policies and a membership set that can be used to
quickly apply one or more Diameter based policies, e.g. Filter-Rule
[RFC5777] to authorized users.
2. 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 [RFC2119].
3. Terminology
Authorized Users An Entity that has been authorized to use a service
via a Diamater Application.
Base Name An organizational structure used to define a domain for
multiple Policy Groups or Membership Domains.
Determination Type The matching policy applied, e.g. ANDMASK, AND,
etc, for Membership Determination.
Policy Entity A type that may be assigned to a Policy Group or
Membership. This includes but is not limited to Filters [RFC7155]
or Filter-Rules [RFC5777].
Membership Determination The process by which Policy Entities are
selected to be applied to an authorized User.
Membership Domain A name assigned to a Membership Set.
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Membership Value A binary set of values where each bit represents a
specific membership pattern.
4. Concepts
Policy Groups represent a union of Policy Entities. These entities
MUST be of the same type, e.g. Filters [RFC7155] or Filter-Rules
[RFC5777].
When establishing groups and membership Sets an optional Base Name
MAY be used. It identifies the top level grouping. Policy Entity
groups MAY be directly named as well. A Policy Entity's name MUST
contain zero or 1 separator character '/'. The value before the
separator is a Base Name. When no Base Name is provided, i.e. no
separator is present. The value of a policy entity is considered to
be part of the Base Name "" (empty string) for any matching purposes.
Base Name values MUST NOT contain the '/' character.
A Policy Entity can be applied to multiple, distinct sets of
authorized Users. These sets can be based upon their state (paid,
past due, etc.), customer type (pre-paid, post-paid, etc.) or many
other factors. In such cases, a Membership Domain is used.
Membership Domains are named domains (UTF8Strings) with binary values
stored in BitStrings to represent where the Policy Entity is used. A
Policy Entity MAY appear in multiple Membership Domains.
This mechanism creates a compact bit pattern to be used which notes
when a Policy Entity or Policy Group applies to to an Authorized
User.
An Authorized User's memberships are assigned by a Policy-Membership.
A Policy Entity is assigned membership via a Membership-Assignment.
Multiple assignments may be applied to an Authorized User and Policy
Entity but they MUST have unique Membership Domain values. It is
also RECOMMENDED to avoid numerous Policy-Membership assignments for
an Authorized User as it delays computation of the Policy Entities
that should be applied to their Service.
Memberships are matched by understanding the relationship between
their values which are represented as sets of bits. These
relationships are descibed as Match-Types and are specified as set
relations, e.g. subset, superset, etc. Figure 1 shows the reference
model.
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0..1 +-----------+ 0..1
+------------->| Base-Name |<------------+
| +-----+-----+ |
| 0..1 | +-----------+-----------+
| | | Membership-Assignment |
| | +--------+--+-------+---+
| | * ^ | | |
| * | | | | v
| +------+--------+ | | | +------------+
| | Policy Entity +--+ | | | Match-Type |
| +---------------+ | | +------------+
| | |
+---------+---------+0..1 +-----------------+ | |
| Policy-Membership |<-----+ Authorized User | | |
+-----+---+---------+ +-----------------+ | |
| | | |
| | 0..1+-------------------+ | |
| +------------>| Membership Domain |<--+ |
| +-------------------+ 0..1 |
v |
+------------------+ |
| Membership-Value |<------------------------------+
+------------------+
Figure 1: Reference Model
To determine if a Rule is assigned to the User the following
conditions MUST be true at least one Membership-Assignments must
exist where
Policy-Membership's Membership-Domain = Membership-Assignment's
Membership-Domain
Policy-Membership's Membership-Value MUST satisfy the Match-Type
for the Membership-Assignments' Membership-Value
5. Groups and Membership AVPs
5.1. Base-Name AVP
The Base-Name AVP (AVP Code TBD1) is of type UTF8String and defines a
group of Policy Entities, e.g. Filters [RFC7155] or Filter-Rules
[RFC5777].
All Policy Entities with the same Base-Name MUST be of the same AVP
type.
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A Base-Name MAY be assigned at the creation of the Policy Entity or
in a subsequent update but MUST only be assigned once, i.e. re-
assignment of the Base-Name MUST NOT be allowed.
5.2. Policy-Membership AVP
The Policy-Membership AVP (AVP Code TBD2) is of type Grouped and
specifies the Membership-Value and optionally the Membership-Domain
and Base-Name for an Authorized User. It is defined as follows (per
the grouped-avp-def of [RFC6733]):
Policy-Membership ::= < AVP Header: TBD2 >
{ Membership-Value }
[ Membership-Domain ]
[ Base-Name ]
Multiple Policy-Membership values MAY be assigned to an Authorzied
User. However, assigning multiple Policy-Memberships to an
Authorized Users MAY delay policy enforcement as membership
determination time is increased and SHOULD be avoided.
If multiple Policy-Memberships are assigned to an Authorized User,
the Membership-Domain of each Policy-Membership value MUST be unique.
5.3. Membership-Assignment AVP
The Membership-Assignment AVP (AVP Code TBD3) is of type Grouped and
specifies the Membership-Value and optionally the Membership-Domain
and Base-Name for a Policy-Entity. It is defined as follows (per the
grouped-avp-def of [RFC6733]):
Membership-Assignment ::= < AVP Header: TBD3 >
{ Membership-Value }
{ Match-Type }
[ Membership-Domain ]
[ Base-Name ]
Multiple Policy-Membership values MAY be assigned to a Policy Entity.
If multiple Policy-Memberships are assigned, the Membership-Domain of
each Membership-Assignment MUST be unique.
5.4. Membership-Domain AVP
The Membership-Domain AVP (AVP Code TBD4) is of type UTF8String and
defines a membership set for a group of Policy Entities, e.g.
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Filters [RFC7155] or Filter-Rules [RFC5777], that are commonly
applied to a set of Authorized Users.
5.5. Membership-Value AVP
The Membership-Value AVP (AVP Code TBD5) is of type OctetString and
defines a membership of a Policy Entity or Authorized User.
Each bit of the OctetString represents a single position in the
Membership-Domain set.
When two Membership-Values of different lengths are compared, the
smaller Membership-Value is padded with '0' valued bits until it is
the same length as the longer Membership-Value.
5.6. Match-Type AVP
The Match-Type AVP (AVP Code TBD6) is of type Enumerated and defines
the type of Matching algorithm used for the Policy Entity.
When applying the Match-Type between the Membership-Value of
Membership-Assignment (Policy Entity) and a Policy-Membership
(Authorized User), the Membership-Domain MUST be the same, i.e. they
are omitted or both MUST be present and have the same value.
Match-Types can be one of the following:
EQ 0
The Membership-Values are equal.
SUPER 1
The Membership-Assignment's Membership-Value is a superset of the
Policy-Membership's Membership-Value, i.e. the may be equal.
PSUPER 2
The Membership-Assignment's Membership-Value is a proper superset of
the Policy-Membership's Membership-Value.
SUB 3
The Membership-Assignment's Membership-Value is a subset of the
Policy-Membership's Membership-Value, i.e. the may be equal.
PSUB 4
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The Membership-Assignment's Membership-Value is a proper subset of
the Policy-Membership's Membership-Value.
OVERLAP 5
The Membership-Assignment's Membership-Value has overlap with the
Policy-Membership's Membership-Value. They may be equal or have some
form of subset / superset relationship.
NONOVERLAP 6
The Membership-Assignment's Membership-Value has no intersection with
the Policy-Membership's Membership-Value.
6. Lifecycle Considerations
Base Names are typically assigned when a Policy Entity is installed
on the Diameter Client. Assignment MAY occur after installation but
the impact of this is outside of the scope of this document.
Membership-Assignments MAY occur at any time in the lifecycle of the
Policy Entity. However, there is no guarantee that resources exist
on the Diameter Client to perform a re-evualation of the membership
of all Authorized Users. A Diameter Server MUST NOT assume that re-
evaluation will occur or that an evaluation will occur immediately.
Policy-Memberships MAY change at any time in the lifecycle of the
Authorized User's session. It is expected that sufficient resources
exist to perform a re-evaluation of applicable Policy Entities based
upon Membership testing. If this cannot be done a Diameter
Applicaiton level appropriate message MUST be sent to the Diamater
Server.
Generally, Base-Names assignment SHOULD occur upon creation of a
Policy Entity or the authorization of a User. Membership-Assignments
SHOULD occur prior to an Authorized User being created with a Policy-
Membership that would apply the Policy Entity to the Authorized
User's session.
7. Examples
7.1. Rule Sets
A policy administrator has defined three 'default rule sets' based
upon various product options selected by a Customer. Each rule set
consists of twenty Filter-Rules as defined in [RFC5777].
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Rules that are part of Rule Set 1 are given a Membership-Value of 1,
Rule Set 2 members are given the value 2 and Rule Set three members
have a value of 4 in their respective Membership-Assignment values.
All Membership-Assignments have the Membership-Domain of "Product X"
and a Match-Type of EQ (Equals).
When a User is Authorized for service usage, a Policy-Membership
value is provided with the appropriate Membership-Value set to 1, 2
or 4 and a Membership-Domain of "Product X". The Diameter Client can
then appropriately the correct 20 Filter-Rules.
7.2. Rule in multiple sets (1 Domain)
Expanding upon our example from above Section 7.1, a new Filter-Rule
is added that is part of both Rule Set 1 and Rule Set 2.
According, the Membership-Assignment has a Membership-Domain of
"Product X", a Membership-Value of 3 and a Match-Type of OVERLAP.
Thus, any Policy-Membership whose Membership-Value is set to 1 or 2
will have this Filter-Rule applied.
7.3. Default Route (Overlapping) Rules
A common traffic rule is the default (all traffic) rule. It is often
used as the lowest priority rule in a policy enforcement session.
Even though the rule is typically the same, e.g. "any any", the
actions taken may vary, e.g. deny traffic, permit traffic, set
quality of service. To distinguish the rules the use of the
Membership-Domain in the Membership-Assignment even when the
Membership-Value MAY be the same.
8. IANA Considerations
IANA allocated AVP codes in the IANA-controlled namespace registry
specified in Section 11.1.1 of [RFC6733] for the following AVPs that
are defined in this document.
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+-----------------------+----------+-----------------+-------------+
| AVP | AVP Code | Section Defined | Data Type |
+-----------------------+----------+-----------------+-------------+
| Base-Name | TBD1 | Section 5.1 | UTF8String |
| | | | |
| Policy-Membership | TBD2 | Section 5.2 | GROUPED |
| | | | |
| Membership-Assignment | TBD3 | Section 5.3 | GROUPED |
| | | | |
| Membership-Domain | TBD4 | Section 5.4 | UTF8String |
| | | | |
| Membership-Value | TBD5 | Section 5.5 | OctetString |
| | | | |
| Match-Type | TBD6 | Section 5.6 | Enumerated |
+-----------------------+----------+-----------------+-------------+
9. Security Considerations
The use of Base-Names and Membership-Domain can unintentionally
provide user information if it is too explicit, e.g. "Bobs'
Policies". It is RECOMMENDED that an operator consider the values it
assigns and ensure they provide no user or group speicific
information.
As bit and test patterns the data provided by the Membership-
Assignment and Policy-Membership AVPs provide more clues between an
Operator and Authorized User's policy relationship. However, it is
no different than if one has access to the information transmitted
between the Diameter Client and Server today (if the Base-Names and
Membership-Domains) follow the reommendations in this section.
In either case, access to the Diameter communications is still
required.
The Security Considerations of the Diameter protocol itself have been
discussed in [RFC6733]. The Diameter base protocol [RFC6733]
requires that each Diameter implementation use underlying security;
i.e., TLS/TCP, DTLS/SCTP or IPsec. Use of the AVPs defined in this
document MUST take into consideration the security issues and
requirements of the Diameter base protocol.
10. References
10.1. Normative References
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[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>.
[RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
Ed., "Diameter Base Protocol", RFC 6733,
DOI 10.17487/RFC6733, October 2012,
<http://www.rfc-editor.org/info/rfc6733>.
10.2. Informative References
[RFC5777] Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
Ed., and A. Lior, "Traffic Classification and Quality of
Service (QoS) Attributes for Diameter", RFC 5777,
DOI 10.17487/RFC5777, February 2010,
<http://www.rfc-editor.org/info/rfc5777>.
[RFC7155] Zorn, G., Ed., "Diameter Network Access Server
Application", RFC 7155, DOI 10.17487/RFC7155, April 2014,
<http://www.rfc-editor.org/info/rfc7155>.
Authors' Addresses
Lyle Bertz
Sprint
6220 Sprint Parkway
Overland Park, KS 66251
United States
Email: lylebe551144@gmail.com
Mark Bales
Sprint
6220 Sprint Parkway
Overland Park, KS 66251
United States
Email: yellowjeep2017@gmail.com
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