Diameter Maintenance and                                        M. Jones
Extensions (DIME)                                             M. Liebsch
Internet-Draft                                                 L. Morand
Intended status: Standards Track                           July 15,                        October 21, 2013
Expires: January 16, April 24, 2014

                        Diameter Group Signaling
                 draft-ietf-dime-group-signaling-01.txt
                 draft-ietf-dime-group-signaling-02.txt

Abstract

   In large network deployments, a single Diameter peer can support over
   a million concurrent Diameter sessions.  Recent use cases have
   revealed the need for Diameter peers to apply the same operation to a
   large group of Diameter sessions concurrently.  The Diameter base
   protocol commands operate on a single session so these use cases
   could result in many thousands of command exchanges to enforce the
   same operation on each session in the group.  In order to reduce
   signaling, it would be desirable to enable bulk operations on all (or
   part of) the sessions managed by a Diameter peer using a single or a
   few command exchanges.  This document specifies the Diameter protocol
   extensions to achieve this signaling optimization.

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 January 16, April 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Building and Modifying Session Groups  . . . . . . . . . .  5
     3.2.  Issuing Group Commands . . . . . . . . . . . . . . . . . .  5
   4.  Grouping User Sessions . . . . . . . . . . . . . . . . . . . .  5
     3.1.  6
     4.1.  Group assignment at session initiation . . . . . . . . . .  5
     3.2.  6
     4.2.  Mid-session group assignment modifications . . . . . . . .  5
       3.2.1.  6
       4.2.1.  Client-initiated group assignment changes  . . . . . .  6
       3.2.2.  7
       4.2.2.  Server-initiated group assignment changes  . . . . . .  6
   4.  7
   5.  Protocol Description . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  8
     5.1.  Session Grouping . . . . . . . . . . . . . . . . . . . . .  8
     5.2.  Session Grouping and implicit Capability Discovery  . . . .  7
     4.2. . . . . . .  9
       5.2.1.  Implicit Capability Discovery  . . . . . . . . . . . .  9
       5.2.2.  Explicit Capability Discovery  . . . . . . . . . . . .  9
     5.3.  Performing Group Operations  . . . . . . . . . . . . . . .  8
       4.2.1. 10
       5.3.1.  Sending Group Commands . . . . . . . . . . . . . . . .  8
       4.2.2. 10
       5.3.2.  Receiving Group Commands . . . . . . . . . . . . . . .  8
       4.2.3. 10
       5.3.3.  Single-Session Fallback  . . . . . . . . . . . . . . .  9
     4.3. 11
     5.4.  Session Management . . . . . . . . . . . . . . . . . . . .  9
       4.3.1. 11
       5.4.1.  Authorization Session State Machine  . . . . . . . . .  9
   5. 11
   6.  Commands Formatting  . . . . . . . . . . . . . . . . . . . . . 13
     5.1. 15
     6.1.  Group Re-Auth-Request  . . . . . . . . . . . . . . . . . . 13
   6. 15
   7.  Attribute-Value-Pairs (AVP)  . . . . . . . . . . . . . . . . . 14
     6.1. 16
     7.1.  Session-Group-Info AVP . . . . . . . . . . . . . . . . . . 16
     7.2.  Session-Group-Feature-Vector AVP . . . . . . . . . . . . . 16
     7.3.  Session-Group-Id AVP . . . . . . . . . . . . . . . . . . . 14
     6.2. 16
     7.4.  Session-Group-Action AVP . . . . . . . . . . . . . . . . . 14
   7. 17
   8.  Result-Code AVP Values . . . . . . . . . . . . . . . . . . . . 15
   8. 18
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
     8.1. 19
     9.1.  AVP Codes  . . . . . . . . . . . . . . . . . . . . . . . . 16
   9. 19
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   10. 20
   11. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 18
   11. 21
   12. Normative References . . . . . . . . . . . . . . . . . . . . . 19 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 23

1.  Introduction

   In large network deployments, a single Diameter peer can support over
   a million concurrent Diameter sessions.  Recent use cases have
   revealed the need for Diameter peers to apply the same operation to a
   large group of Diameter sessions concurrently.  For example, a policy
   decision point may need to modify the authorized quality of service
   for all active users having the same type of subscription.  The
   Diameter base protocol commands operate on a single session so these
   use cases could result in many thousands of command exchanges to
   enforce the same operation on each session in the group.  In order to
   reduce signaling, it would be desirable to enable bulk operations on
   all (or part of) the sessions managed by a Diameter peer using a
   single or a few command exchanges.

   This document describes mechanisms for grouping Diameter sessions and
   applying Diameter commands, such as performing re-authentication, re-
   authorization, termination and abortion of sessions to a group of
   sessions.  This document does not define a new Diameter application.
   Instead it defines mechanisms, commands and AVPs that may be used by
   any Diameter application that requires management of groups of
   sessions.

   These mechanisms take the following design goals and features into
   account:

   o Minimal impact to existing applications

   o Extension of existing commands' CCF with optional AVPs to enable
   grouping and group operations

   o Fallback to single session operation

   o Implicit discovery of capability to support grouping and group
   operations

2.  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 RFC 2119 [RFC2119].

   This document uses terminology defined [RFC3588].

3.  Grouping User Sessions

   Either Diameter peer may assign  Use Cases

3.1.  Building and Modifying Session Groups

   Client and Server can add a new Diameter session to a group.  Diameter AAA
   applications typically assign client and server roles to the Diameter group, e.g. in
   case the subscription profile of the associated user has similar
   characteristics as the profile of other users whose Diameter session
   has been added to one or multiple groups.  Such similarities can be
   for example maximum bandwidth bounds of each user in the a group.
   These users may share resources of, e.g., an access multiplexer,
   together with other users.  Runtime adjustments in the granted
   bandwidth bounds or other Quality of Service related attributes can
   be accomplished for the whole group by identifying the group in the
   Diameter group command.

   In case a user's subscription profile changes during runtime, either
   node, a Diameter Server or Diameter client, may decide to remove this
   user's Diameter session from the session group.  The user's Diameter
   session can be assigned to a different group, whose adjusted profile
   matches the one of the different group.  Both groups, the user's
   previous group and its new group, will be modified mid-session.

   In case of mobile users, a change in the node implementing the
   Diameter client can happen, which has impact to a group of sessions a
   particular pair of Diameter client and server has in common.  Due to
   mobility, the mobile user's session may get transferred to a new
   Diameter client during runtime without mandating from-scratch
   authorization.  Such scenario necessitates mid-session modification.

3.2.  Issuing Group Commands

   A policy decision point may decide to terminate a group of sessions,
   e.g. based on previous agreement for temporary authorization to
   access a system.  All Diameter sessions of associated users with such
   temporarily granted access will be added to a single Diameter session
   group.  After the time limit for the temporary authorization has been
   reached, the policy decision point can issue a single Session
   Termination Request (STR) to the policy enforcement point.  The STR
   command identifies the group of Diameter sessions which are to be
   terminated.  The policy enforcement point treats the STR as group
   command and initiates termination of all sessions in the group.
   Subsequently, the policy enforcement point confirms successful
   termination of these sessions to the policy decision point by sending
   a single Session Termination Answer (STA) command which includes the
   identifier of the group.

4.  Grouping User Sessions

   Either Diameter peer may assign a session to a group.  Diameter AAA
   applications typically assign client and server roles to the Diameter
   peers.

3.1.

4.1.  Group assignment at session initiation

   Assignment of a new session to a group is accomplished by the
   Diameter server when requested by the Diameter client.  Without being
   explicitly requested by the client, the Diameter server can assign a
   new session to a server-assigned group based on its own decision.
   When a new session is to be assigned to a group by the Diameter
   server, the server assigns a new session to at least one server-
   assigned group.  To complement server-assigned grouping, a Diameter
   client can assign a session to a client-assigned group.

   To assign a session to a group at session initiation, a Diameter
   client sends a service specific request, e.g.  NASREQ AAR [RFC4005],
   containing one or more group identifiers.  The Diameter client can
   assign the session to a client-assigned group and identify the
   associated group with an appended client-assigned group identifier.
   The client can append multiple client-assigned group identifiers if
   the client assigns the new session to more than one group.  If the
   Diameter client does not send a client-assigned group identifier, the
   client may receive one or multiple server-assigned group identifiers
   in the server's response, which identify the server-assigned groups
   to which the new session has been assigned.  The Diameter client can
   explicitly request the Diameter server to perform grouping of the new
   session.

   Assuming the user has been successfully authenticated and/or
   authorized, the Diameter server responds with service-specific auth
   response, e.g.  NASREQ AAA [RFC4005], containing both the client-
   assigned group identifiers (if sent with the request) and one or more
   server-assigned group identifiers.

   Both peers, the Diameter client and the Diameter server, must keep a
   list of all group identifiers which identify all client- and server-
   assigned groups to which the session has been assigned.

3.2.

4.2.  Mid-session group assignment modifications

   Either Diameter peer may modify the group membership of an active
   Diameter session.  A Diameter client MAY remove the group(s) assigned
   to the active session by the Diameter server and vice versa.

   This document does not define a permission model that limits removal
   of a session from a group by the same peer that added the session to
   the group.  However, applications which re-use the commands and
   methods defined in this document may impose their own permission
   model.  For example, an application could require that the server
   MUST NOT remove a session from a group assigned by the client.

3.2.1.

4.2.1.  Client-initiated group assignment changes

   To update the assigned groups mid-session, a Diameter client sends a
   service specific re-authorization request containing the updated list
   of group identifiers.  Assuming the user is successfully
   authenticated and/or authorized, the Diameter server responds with a
   service-specific auth response containing the updated list of group
   identifiers received in the request.

3.2.2.

4.2.2.  Server-initiated group assignment changes

   To update the assigned groups mid-session, a Diameter server sends a
   Re-authorization Request (RAR) message requesting re-authorization
   and the client responds with a Re-authorization Answer (RAA) message.
   The Diameter client sends a service specific re-authorization request
   containing the current list of group identifiers and the Diameter
   server responds with a service-specific auth response containing the
   updated list of group identifiers.

4.

5.  Protocol Description

4.1.

5.1.  Session Grouping and implicit Capability Discovery

   Either Diameter peer, a Diameter client or server, can initiate
   assigning a session to a single or multiple session groups according
   to the procedure described in Section 3. 4.  Modification of a group by
   removing or adding a single or multiple user sessions can be
   initiated and performed at runtime by either Diameter peer.

   A Diameter client as sender of a command for session initiation can
   determine one or multiple groups to which the new session should be
   assigned.  Each of these groups need to be identified by a unique
   Session-Group-Id contained in a separate
   Session-Group-Id Session-Group-Info AVP as
   specified in Section 6. 7.

   In each appended
   Session-Group-Id Session-Group-Info AVP which carries a client-assigned group
   identifier, a the SESSION_GROUP_ALLOCATION_MODE flag must of the Session-
   Group-Feature-Vector AVP MUST be:

   o  set (1) to indicate that the carried group identifier is
   not a server-assigned but server-
      assigned group;

   o  cleared (0) to indicate that the carried group identifier is a
      client-assigned one.  If the group.

   A Diameter client does not determine the group to which the new session should
   be assigned, the client can set a flag in an appended
   Session-Group-Id AVP to explicitly request the Diameter server as
   recipient of the message to assign the new session to one or multiple
   groups.

   By
   server-assigned groups by appending at least one a Session-Group-Info AVP with no
   Session-Group-Id AVP, the Diameter client
   announces its capability to support group operations according to AVP and the
   specification in this document to Session-Group-Feature-Vector AVP with
   the addressed Diameter server. SESSION_GROUP_ALLOCATION_MODE flag set (1).

   If the Diameter client supports group operations, it MUST append at
   least one Session-Group-Id AVP to announce its capability to support
   group operations.

   A Diameter server receiving receives a command for session initiation which
   includes at least one Session-Group-Id Session-Group-Info AVP learns about the sender's
   capability to support group operations.  If a flag in the appended
   Session-Group-Id AVPs identifies a client-assigned group, the server
   must store the one or multiple identifiers and associate the new
   session with these groups.

   If a flag in a received no
   Session-Group-Id AVP indicates that the
   Diameter client explicitly requests and the Diameter server to assign Session-Group-Feature-Vector AVP with
   the
   new session to a server-assigned group, SESSION_GROUP_ALLOCATION_MODE flag set (1), the Diameter server should
   SHOULD assign the new session to one or multiple server-assigned
   groups.  The Diameter server identifies each of these server-assigned
   groups in a Session-
   Group-Id Session-Group-Id AVP contained in a Session-Group-Info
   AVP, which are appended to the response to the received command.
   Each of these Session-Group-Id Session-Group-Info AVPs must indicate in a have the
   SESSION_GROUP_ALLOCATION_MODE flag of the Session-Group-Feature-
   Vector AVP set to indicate that the carried identifier is a server-assigned server-
   assigned group identifier.

   If the Diameter server receives a flag in Session-Group-Info AVP with a received
   Session-Group-Id AVP indicates that the
   Diameter client does not explicitly request and the Session-Group-Feature-Vector AVP with
   the SESSION_GROUP_ALLOCATION_MODE flag cleared (0), the Diameter server to
   assign must
   store the one or multiple group identifiers and associate the new
   session to a server-assigned group, the with these client-assigned groups.  The Diameter server may
   still assign the new session to one or multiple server-assigned
   groups.  The Diameter server identifies each of these server-assigned
   groups in a Session-Group-Id AVP contained in a Session-Group-Info
   AVP, which are appended to the response to the received command. command, in
   addition to the those related to the client-assigned groups received
   in the request.  Each of these Session-Group-Id Session-Group-Info AVPs must indicate
   in a have the
   SESSION_GROUP_ALLOCATION_MODE flag that of the Session-Group-Feature-
   Vector AVP set to indicate that this carried identifier is a server-assigned server-
   assigned group identifier.

   A Diameter server receiving a command for session initiation which
   includes at least one Session-Group-Info AVP but the server does not
   understand the semantics of this optional AVP because it does not
   support group operations according to the specification in this
   document, MUST ignore the optional group operations specific AVPs and
   proceed with processing the command for a single session.

   A Diameter client, which sent a request for session initiation to a
   Diameter server and appended a single or multiple Session-Group-Id
   AVPs but cannot find any Session-Group-Info AVP in the associated
   response from the Diameter server proceeds with processing the
   command for a single session.  Furthermore, the client keeps a log to
   remember that the server is not able to perform group operations.

5.2.  Session Grouping Capability Discovery

5.2.1.  Implicit Capability Discovery

   By appending at least one Session-Group-Id Session-Group-Info AVP, the Diameter server client
   announces its capability to support group operations according to the
   specification in this document to the addressed Diameter client. server.  If
   the Diameter client supports group operations, it MUST append at
   least one Session-Group-Info AVP to announce its capability to
   support group operations.

   A session-group aware Diameter server receiving a command for session
   initiation which includes at least one Session-Group-Id Session-Group-Info AVP but learns
   about the server does not
   understand sender's capability to support group operations.

   By appending at least one Session-Group-Id AVP, the semantics of this optional AVP because it does not Diameter server
   announces its capability to support group operations according to the
   specification in this
   document, MUST ignore the optional group operations specific AVPs and
   proceed with processing document to the command for a single session.

   A addressed Diameter client, which sent a request client.

5.2.2.  Explicit Capability Discovery

   New Diameter applications may consider support for session initiation to a Diameter server session
   grouping and appended a single or multiple Session-Group-Id
   AVPs but cannot find any Session-Group-Id AVP in the associated
   response from the Diameter server proceeds with processing the
   command for a single session.  Furthermore, performing group commands during the client keeps a log to
   remember that standardization
   process.  Such applications provide intrinsic support for the server is not able to perform support
   of group operations.

4.2. commands and announce this capability through the assigned
   application ID.

5.3.  Performing Group Operations

4.2.1.

5.3.1.  Sending Group Commands

   Either Diameter peer can request the recipient of a request to
   process an associated command for all sessions being assigned to one
   or multiple groups by identifying these groups in the request.  The
   sender of the request appends for each group, to which the command
   applies, a Session-Group-Info AVP including the Session-Group-Id AVP
   and indicates in a the SESSION_GROUP_ALLOCATION_MODE flag of the
   Session-Group-Feature-Vector AVP whether the identifier represents a
   server- or a client-assigned group.  If the CCF of the request
   mandates a Session-Id AVP, the Session-Id AVP MUST identify a single
   session which is assigned to at least one of the groups being
   identified in the appended Session-Group-Id AVPs.

   The sender of the request can indicate to the receiver how follow up
   message exchanges should be performed by appending a Session-Group-
   Action AVP.  If the sender wants the receiver to perform follow up
   exchanges with a single command for all impacted groups, the sender
   sets the value of the Session-Group-Action AVP to ALL_GROUPS (1).  If
   follow up message exchanges should be performed on a per-group basis
   in case multiple groups are identified in the group command, the
   value of the Session-Group-Action AVP is set to PER_GROUP (2).  A
   value set to PER_SESSION (3) indicates to the receiver that all
   follow up exchanges should be performed using a single message for
   each impacted session.

   If the sender wants the receiver of the request to process the
   associated command solely for a single session does not append any
   group identifier, but identifies the relevant session in the
   Session-Id AVP.

4.2.2.

5.3.2.  Receiving Group Commands

   A Diameter peer receiving a request to process a command for a group
   of sessions identifies the relevant groups according to the appended
   Session-Group-Id AVP in the Session-Group-Info AVP.  If the received
   request identifies multiple groups in multiple appended Session-Group-Id Session-
   Group-Id AVPs, the receiver should process the associated command for
   each of these groups. if a session has been assigned to more than one
   of the identified groups, the receiver must process the associated command only once per
   session.

4.2.3. associated
   command only once per session.

   The Diameter peer receiving a request which requests performing the
   command to at least on session group SHOULD perform follow up message
   exchanges according to the value identified in the Session-Group-Info
   AVP.

5.3.3.  Single-Session Fallback

   Either Diameter peer, a Diameter client or a Diameter server, can
   fall back to single session operation by ignoring and omitting the
   optional and group session-specific AVPs.  Fallback to single-session
   operation is performed by processing the Diameter command solely for
   the session identified in the mandatory Session-Id AVP.  The response
   to the group command must not identify any group but identify solely
   the single session for which the command has been processed.

4.3.

5.4.  Session Management

   Editor's note: This first document revision adopts the WG's current view on
   how Diameter commands can be formatted to enable group signaling.
   The required change in the formatting and protocol operation has not
   yet been considered in this Section 4.3 5.4 , which still reflects the
   formatting as per version 0 of this specification.  The described
   session state machines still need revision to reflect the generalized
   formatting and the adopted protocol operation.

4.3.1.

5.4.1.  Authorization Session State Machine

   Section 8.1 in [RFC3588] defines a set of finite state machines,
   representing the life cycle of Diameter sessions, and which MUST be
   observed by all Diameter implementations that make use of the
   authentication and/or authorization portion of a Diameter
   application.  This section defines the additional state transitions
   related to the processing of the new commands which may impact
   multiple sessions.

   The group membership is session state and therefore only those state
   machines from [RFC3588] in which the server is maintaining session
   state are relevant in this document.  As in [RFC3588], the term
   Service-Specific below refers to a message defined in a Diameter
   application (e.g., Mobile IPv4, NASREQ).

   The following state machine is observed by a client when state is
   maintained on the server.  State transitions which are unmodified
   from [RFC3588] are not repeated here.

                              CLIENT, STATEFUL
      State     Event                          Action       New State
      ---------------------------------------------------------------
      Idle      Client or Device Requests      Send         Pending
                access                         service
                                               specific
                                               auth req
                                               optionally
                                               including
                                               groups

      Open      GASR received with             Send GASA    Discon
                Session-Group-Action           with
                = ALL_GROUPS,                  Result-Code
                session is assigned to         = SUCCESS,
                received group(s) and          Send GSTR.
                client will comply with
                request to end the session

      Open      GASR received with             Send GASA    Discon
                Session-Group-Action           with
                = PER_GROUPS,                  Result-Code
                session is assigned to         = SUCCESS,
                received group(s) and          Send GSTR
                client will comply with        per group
                request to end the session

      Open      GASR received with             Send GASA    Discon
                Session-Group-Action           with
                = PER_SESSION,                 Result-Code
                session is assigned to         = SUCCESS,
                received group(s) and          Send STR
                client will comply with        per session
                request to end the session

      Open      GASR received,                 Send GASA    Open
                client will not comply with    with
                request to end all session     Result-Code
                in received group(s)           != SUCCESS

      Discon    GSTA Received                  Discon.      Idle
                                               user/device

      Open      GRAR received with             Send GRAA,   Pending
                Session-Group-Action           Send
                = ALL_GROUPS,                  service
                session is assigned to         specific
                received group(s) and          group
                client will perform            re-auth req
                subsequent re-auth

      Open      GRAR received with             Send GRAA,   Pending
                Session-Group-Action           Send
                = PER_GROUP,                   service
                session is assigned to         specific
                received group(s) and          group
                client will perform            re-auth req
                subsequent re-auth             per group

      Open      GRAR received with             Send GRAA,   Pending
                Session-Group-Action           Send
                = PER_SESSION,                 service
                session is assigned to         specific
                received group(s) and          re-auth req
                client will perform            per session
                subsequent re-auth

      Open      GRAR received and client will  Send GRAA    Idle
                not perform subsequent         with
                re-auth                        Result-Code
                                               != SUCCESS,
                                               Discon.
                                               user/device

      Pending   Successful service-specific    Provide      Open
                group re-authorization answer  service
                received.

      Pending   Failed service-specific        Discon.      Idle
                group re-authorization answer  user/device
                received.

   The following state machine is observed by a server when it is
   maintaining state for the session.  State transitions which are
   unmodified from [RFC3588] are not repeated here.

                                SERVER, STATEFUL
      State     Event                          Action       New State
      ---------------------------------------------------------------

      Idle      Service-specific authorization Send         Open
                request received, and user     successful
                is authorized                  service
                                               specific
                                               answer
                                               optionally
                                               including
                                               groups

      Open      Server wants to terminate      Send GASR    Discon
                group(s)

      Discon    GASA received                  Cleanup      Idle

      Any       GSTR received                  Send GSTA,   Idle
                                               Cleanup

      Open      Server wants to reauth         Send GRAR    Pending
                group(s)

      Pending   GRAA received with Result-Code Update       Open
                = SUCCESS                      session(s)

      Pending   GRAA received with Result-Code Cleanup      Idle
                != SUCCESS                     session(s)

      Open      Service-specific group         Send         Open
                re-authoization request        successful
                received and user is           service
                authorized                     specific
                                               group
                                               re-auth
                                               answer

      Open      Service-specific group         Send         Idle
                re-authorization request       failed
                received and user is           service
                not authorized                 specific
                                               group
                                               re-auth
                                               answer,
                                               cleanup

5.

6.  Commands Formatting

   This document does not specify new Diameter commands to enable group
   operations, but relies on command extensibility capability provided
   by the Diameter Base protocol.  This section provides the guidelines
   to extend the CCF of existing Diameter commands with optional AVPs to
   enable the recipient of the command to perform the command to all
   sessions associated with the identified group(s).

5.1.

6.1.  Group Re-Auth-Request

   A request that one or more groups of users are re-authentication is
   issues by appending one or multiple Session-Group-Id AVP(s) to the
   Re-Auth-Request (RAR).  The one or multiple Session-Group-Id AVP(s)
   identify the associated group(s) for which the group re-
   authentication has been requested.  The recipient of the group
   command initiates re-authentication for all users associated with the
   identified group(s).  Furthermore, the sender of the group re-
   authentication request appends a Session-Group-Action AVP to provide
   more information to the receiver of the command about how to
   accomplish the group operation.

   The value of the mandatory Session-Id AVP MUST identify a session
   associated with a single user, which is assigned to at least one of
   the groups being identified in the appended Session-Group-Id AVPs.

         <RAR>  ::= < Diameter Header: 258, REQ, PXY >
                    < Session-Id >
                    { Origin-Host }
                    { Origin-Realm }
                    { Destination-Realm }
                    { Destination-Host }
                    { Auth-Application-Id }
                    { Re-Auth-Request-Type }
                    [ User-Name ]
                    [ Origin-State-Id ]
                  * [ Proxy-Info ]
                  * [ Route-Record ]
                  * [ Session-Group-Id ]
                    [ Session-Group-Action ]
                  * [ AVP ]

6.

7.  Attribute-Value-Pairs (AVP)

                                                  +--------------------+
                                                  |   AVP Flag rules   |
                                                  +----+---+------+----+
                               AVP                |    |   |SHOULD|MUST|
 Attribute Name                Code   Value Type  |MUST|MAY| NOT  | NOT|
   +---------------------------------------+----+---+------+----+
+-------------------------------------------------+----+---+------+----+
|Session-Group-Info            TBD1   Grouped     |    | P |      | V  |
|Session-Group-Feature-Vector  TBD2   Unsigned32  |    | P |      | V  |
|Session-Group-Id     TBD              TBD3   OctetString |    | P |      | V  |
|Session-Group-Action TBD   Enumerated          TBD4   Unsigned32  |    | P |      | V  |
   +---------------------------------------+----+---+------+----+
+-------------------------------------------------+----+---+------+----+

                   AVPs for the Diameter Group Signaling

6.1.  Session-Group-Id

7.1.  Session-Group-Info AVP

   The Session-Group-Info AVP (AVP Code TBD1) is of type Grouped.  It
   contains the identifier of the session group as well as an indication
   of the node responsible for session group identifier assignment.
      Session-Group-Info ::= < AVP Header: TBD1 >
                             < Session-Group-Feature-Vector >
                             [ Session-Group-Id ]
                           * [ AVP ]

7.2.  Session-Group-Feature-Vector AVP

   The Session-Group-Feature-Vector AVP (AVP Code TBD) TBD2) is of type OctetString
   Unsigned32 and
   identifies and contains a group 32-bit flags field of sessions. capabilities
   supported by the session-group aware node.

   The following capabilities are defined in this document:

   SESSION_GROUP_ALLOCATION_MODE (0x00000001)

      This uniqueness scope flag indicates the mode of allocation of session group
      identifier.  When this flag is set, it indicates that Diameter
      server is responsible for the allocation of the session group
      identifier.  When this flag is not set, it indicates that the
      session group identifier is allocated by the client.

7.3.  Session-Group-Id AVP

   The Session-Group-Id AVP (AVP Code TBD3) is of type UTF8String and
   identifies a group of sessions.

   The Session-Group-Id MUST be globally and eternally unique, as it is
   meant to uniquely identify a group of Diameter sessions without
   reference to any other information.

   Unless stated otherwise, the default format of the Session-Group-id
   SHOULD comply to the format recommended for a Session-Id, as defined
   in the section 8.8 of the RFC6733 [RFC6733].  However, the exact
   format of the Session-Group-Id MAY be specified by the Diameter application
   applications which makes make use of group signaling commands.

6.2.

7.4.  Session-Group-Action AVP

   The Session-Group-Action AVP (AVP Code TBD) TBD4) is of type Enumerated Unsigned32
   and
   specifies contains a 32-bit address space representing values indicating
   how the peer SHOULD issue follow up exchanges in response to a
   command which impacts mulitple sessions.  The following values are supported:
   defined by this application:

   ALL_GROUPS (0) (1)
      Follow up exchanges should be performed with a single message
      exchange for all impacted groups.

   PER_GROUP (1) (2)
      Follow up exchanges should be performed with a message exchange
      for each impacted group.

   PER_SESSION (2) (3)
      Follow up exchanges should be performed with a message exchange
      for each impacted session.

7.

8.  Result-Code AVP Values

   This section defines document does not define new Result-Code [RFC3588] values that MUST be
   supported by all Diameter implementations that conform for
   existing applications, which are extended to this
   specification.

   [Editor's Note: Group specific error values support group commands.
   Specification documents of new applications, which will have
   intrinsic support for group commands, may need to be added
   here.]

8. specify new Result-Codes.

9.  IANA Considerations

   This section contains the namespaces that have either been created in
   this specification or had their values assigned to existing
   namespaces managed by IANA.

8.1.

9.1.  AVP Codes

   This specification requires IANA to register the following new AVPs
   from the AVP Code namespace defined in [RFC3588].

   o  Session-Group-Info

   o  Session-Group-Feature-Vector

   o  Session-Group-Id

   o  Session-Group-Action

   The AVPs are defined in Section 6.

9. 7.

10.  Security Considerations

   TODO

10.  Acknowledgments

11.  Acknowledgments
12.  Normative References

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

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

   [RFC4005]  Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
              "Diameter Network Access Server Application", RFC 4005,
              August 2005.

Authors' Addresses

   Mark Jones

   Email: mark@azu.ca

   Marco Liebsch

   Email: marco.liebsch@neclab.eu

   Lionel Morand

   Email: lionel.morand@orange.com