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Diameter Maintenance and Extensions                             L. Bertz
Internet-Draft                                                  M. Bales
Intended status: Standards Track                                  Sprint
Expires: December 20, 2018                                 June 18, 2018


                    Diameter Policy Groups and Sets
                    draft-bertz-dime-policygroups-06

Abstract

   This document defines optional Diameter attributes for efficient
   policy provisioning.

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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   working documents as Internet-Drafts.  The list of current Internet-
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 20, 2018.

Copyright Notice

   Copyright (c) 2018 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
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   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November



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   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

1.  Introduction

   As Users connect to a network, policy applications often apply common
   policies to them.  In some cases policies are grouped and applied
   through the use of AVPs, e.g. 3GPP Base Name.  Other options include
   sending identifiers, usually a list of integers, associated with
   rules to apply a group to a single user.  This compacts the over the
   wire representation but requires strong coordination between policy
   based Clients and Servers.

   Application of common policy if further limited when the filters
   overlap.  This requires partitioning policies into non-overlapping
   namespaces, e.g. tables in a Software Defined Networking (SDN)
   switch.  To reduce the need to partition sets of policies some SDN
   technologies, e.g.  OpenFlow, rely on metadata that is applied as
   part of the filter or metadata that is specific to the packet, e.g.
   OpenFlow Registers.

   This document defines grouping mechanisms to allow users or groups of
   users to share policies or groups of policies.  The mechanism also
   extends filters to include a metadata matching field that permits
   filters that overlap at the protocol level to coexist in the same
   policy enforcement space.

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 Diameter Application.

   Base Name  An organizational structure used to define a domain for
      multiple Policy Groups or Membership Domains.




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   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.

   Membership Value  A binary set of values where each bit represents a
      specific membership pattern.  This metadata is used as part of the
      filter or as user information when policy application occurs.

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 bit strings to represent where the Policy Entity is used.
   A Policy Entity MAY appear in multiple Membership Domains.

   Membership-Value is 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



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   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 described as Match-Types and are specified as set
   relations, e.g. subset, superset, etc.  Figure 1 shows the reference
   model.

              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







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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.

   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 Authorized
   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]):









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               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.
   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




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   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

   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-evaluation 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
   Application level appropriate message MUST be sent to the Diameter
   Server.




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   Generally, Base-Name 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 defines Product X with 3 separate rules sets.
   The administrator creates the Membership-Domain "Product X" and
   Membership-Values of 1, 2 and 4 representing separate rule sets.  For
   this example each rule set consists of twenty Filter-Rules as defined
   in [RFC5777].

   Each Rule Set is assigned a Membership-Value.  Rule Set 1 is assigned
   a Membership-Value of 1, Rule Set 2 members is assigned the value 2
   and Rule Set three members are assigned a value of 4.  All
   Membership-Assignments have the Membership-Domain of "Product X" and
   a Match-Type of EQ (Equals).

   The policy administrator defines three users.  User 1 is assigned the
   Membership-Domain of "Product X"" and Membership-Value of 1.  User 2
   is assigned a Membership-Domain of "Product X" and a Membership-Value
   of 2.  User 3 is assigned a Membership-Domain of "Product X"" and
   Membership-Value of 4.

7.2.  Rule in multiple sets (1 Domain)

   Expanding upon our example from above Section 7.1, a new Filter-Rule
   is added that shall be part of Users with either Rule Set 1 or Rule
   Set 2 of Product X.

   Accordingly, the policy administrator defines the Membership-
   Assignment having 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




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   Membership-Domain in the Membership-Assignment even when the
   Membership-Value MAY be the same.

   Within the enforcement point, for each overlapping Match-Type can be
   set to OVERLAP and contain all bits where the rule applies in its
   Membership-Value.  In general, the Membership-Value MUST be NOT
   overlap with other default rules or a Precedence MUST be followed.

   In the case where a Filter-Rule [RFC5777] is used, the Match-Type and
   Membership-Value can be used as part of the Classifier AVP.

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.

   +-----------------------+----------+-----------------+-------------+
   | 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 specific
   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 recommendations in this section.




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   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

   [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>.

   [RFC6733]  Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
              Ed., "Diameter Base Protocol", RFC 6733,
              DOI 10.17487/RFC6733, October 2012,
              <https://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,
              <https://www.rfc-editor.org/info/rfc5777>.

   [RFC7155]  Zorn, G., Ed., "Diameter Network Access Server
              Application", RFC 7155, DOI 10.17487/RFC7155, April 2014,
              <https://www.rfc-editor.org/info/rfc7155>.

Authors' Addresses

   Lyle Bertz
   Sprint
   6220 Sprint Parkway
   Overland Park, KS  66251
   United States

   Email: lylebe551144@gmail.com






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   Mark Bales
   Sprint
   6220 Sprint Parkway
   Overland Park, KS  66251
   United States

   Email: yellowjeep2017@gmail.com












































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