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Versions: 00 01 02 03                                                   
Internet Engineering Task Force                   Tsunemasa Hayashi, NTT
Internet Draft                                        Daisuke Andou, NTT
March, 2003                                 Haixiang He, Nortel Networks
Expires: September, 2003                   Wassim Tawbi, Nortel Networks
                             Teruki Niki, Matsushita Electric Industrial


              IGMP for user Authentication Protocol (IGAP)
                     <draft-hayashi-igap-01.txt>


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 except that the right to
   produce derivative works is not granted.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt
   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


Abstract

   This memo documents the IGMP for user Authentication Protocol (IGAP),
   a protocol developed by NTT, Nortel Networks and Panasonic. IGAP
   extends the existing IGMPv2 protocol to add user authentication
   functionality, accounting functionality and status notification
   functionality. IGAP is only used in IPv4 environment. In a controlled
   or managed multicast environment, IGAP can be used to replace IGMP
   for group membership communication between hosts and their associated
   first hop routers. The user authentication information in IGAP can
   enable a provider to control the distribution of the multicast
   traffic as well as collecting real time user accounting information
   in an environment where the last hop access networks are not shared.

1. Introduction

   IP multicast provides an efficient mechanism for delivering packets
   to multiple destinations. Unfortunately, IP multicast services,
   especially commercial IP multicast services, are not widely
   deployed. One of the important reasons that discourage the deployment
   is related to the current IP multicast model.




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   The current IP multicast model provides by nature a non-secure
   non-controlled way for end systems attached to a network to access
   multicast traffic. Lack of access control in this model makes it
   difficult for a service provider to generate enough revenue to
   sustain multicast services such as IP multicast based Internet TV.

   A provider can enforce such access control through static
   configuration on the last hop network devices including Ethernet
   switches or routers. However, the rules to control the access to
   multicast data may change dynamically or the rules may be very
   specific such as user-based rules instead of end system based rules
   that a network device is not always able to enforce. This leads to
   the need for a comprehensive way to authenticate and authorize end
   systems before they are granted access to some multicast groups.

   The IGMP for user Authentication Protocol (IGAP) is designed to
   facilitate the last hop network devices to enforce the dynamic
   multicast receiver access control in a non-shared access networks
   environment. IGAP extends the existing IGMPv2 [IGMPv2] protocol to
   add authentication functionality via permitting known authentication
   mechanisms such as password mechanism and challenge-response
   mechanism to be incorporated into IGMP protocol sequences. IGAP is
   used only in IPv4 environment. IGAP enables an IP multicast service
   provider to authenticate and authorize a host's requests to join a
   specific multicast group based on its user's authentication
   information and then to control the user's access to the multicast
   traffic accordingly.

   IGAP uses a user-based authentication model versus IP or MAC address
   based authentication model. The benefits of a user-based model are
   well known. It offers operational simplicity and flexibility, in
   particular with respect to adds, moves, and changes.

   Another issue that discourages the wide deployment of IP multicast
   services is the lack of multicast network management functions
   especially an effective multicast accounting function. Effective
   user-based accounting information is critical in two aspects. On one
   hand network providers who provide commercial multicast services need
   to accurately identify the users and collect their usage information
   to generate correct billing information. One the other hand some
   content providers need to learn the content usage information. For
   example, in IP multicast based Internet TV services, network
   providers need to know which TV program and how long a user watches
   so that they can charge the user differently based on the values of
   the TV programs. In such services, content providers, TV programs
   owners, need to know how many viewers for a TV program and how long
   they watch the TV program so they can generate appropriate
   advertisement revenue.

   IGAP combines the user information including user ID with the
   multicast group addresses that reflect the different contents.



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   Authenticated and authorized group join requests enable providers to
   effectively collect the user usage information for different content.

   IGAP not only encourages the wide deployment of new commercial IP
   multicast services, but also can be used in non-commercial
   environments such as enterprises. For example, IGAP can be used for
   closed video broadcasting. IGAP provides a mechanism to allow the
   access to the video broadcasting, only if the user is an
   authenticated user who is allowed to join the video broadcasting.

   IGAP is designed to add authentication capability to IGMP
   transactions controlling multicast group membership. The transactions
   flow between an IGAP host client and an IGAP router. The IGAP router
   is assumed to be 1 hop from the IGAP host, such that the host does
   not have a route that bypasses the IGAP router. An IGAP host MUST
   authenticate itself to an IGAP router in order to join a multicast
   group.


2. IGAP Message Format

   Similar to IGMP, IGAP messages are encapsulated in IP datagrams, with
   an IP protocol number of 2. All IGAP messages described in this
   document are sent with IP TTL 1, and contain the IP Router Alert
   option [RFC 2113] in their IP header.

   IGAP adopts and extends the IGMPv2 packet format. All IGAP messages
   of concern have the following packet format:

   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 (bit)
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      | Max Resp Time |           Checksum            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Group Address                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |    Subtype    |  Reserved-1   | Challenge ID  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Account Size  | Message Size  |          Reserved-2           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                     User Account (16 bytes)                   .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                     Message (64 bytes)                        .
   .                                                               .
   |                                                               |



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


2.1 Type

   There are three types of IGAP messages of concern.

   0x40 = IGAP Membership Report (IGAP Join)

   0x41 = IGAP Membership Query  (IGAP Query)

   0x42 = IGAP Leave Group       (IGAP Leave)

   Unrecognized message types should be silently ignored.


2.2 Max Response Time

   The meaning and the usage of Max Response Time are the same as those
   of the IGMP messages as described in RFC 2236 [IGMPv2].


2.3 Checksum

   Checksum covers the IGAP message (the entire IPv4 payload). The
   algorithm is the same as described in RFC2236 [IGMPv2].


2.4 Group Address

   In a Basic Query message described in section 2.6, the group address
   field is set zero. In both Authentication Message and Accounting
   Message described in section 2.6, the group address field holds the
   IP multicast address of an IGAP Join. In a Membership Report or Leave
   Group message, the group address field holds the IP multicast group
   address of interest or the group being left.


2.5 Version

   This field indicates the version of IGAP. It is set to 0x10 to
   indicate the IGAP version 1.


2.6 Subtype

   This field indicates the subtype of message transferred within the
   IGAP packet. Usage of this field is described later.

   The following 3 Subtypes are only used in IGAP join (Type 0x40).




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       0x02 : Password Mechanism Join
              (Password-Join)
       0x03 : Challenge-Response Mechanism Join Challenge Request
              (Challenge-Request-Join)
       0x04 : Challenge-Response Mechanism Join Response
              (Challenge-Response-Join)

   The following 4 Subtypes are only used in IGAP Query (Type 0x41).

       0x21 : Basic Query
       0x23 : Challenge-Response Mechanism Challenge
              (Challenge)
       0x24 : Authentication Message
       0x25 : Accounting Message

   The following 4 Subtypes are used in IGAP Leave (Type 0x42).

       0x41 : Basic Leave
       0x42 : Password Mechanism Leave
              (Password-Leave)
       0x43 : Challenge-Response Mechanism Leave Challenge Request
              (Challenge-Request-Leave)
       0x44 : Challenge-Response Mechanism Leave Response
              (Challenge-Response-Leave)


2.7 Reserved-1

   This field should be set to 0x00. It is ignored when received.


2.8 Challenge ID

   This field is meaningful only when Challenge-Response authentication
   mechanism is used. The value is set according to the
   Challenge-Response protocol. If this field is not used, it is set to
   the default value of 0x00.


2.9 Account Size

   This field indicates the valid length in units of bytes of the User
   Account field described in section 2.12. The value must be less than
   or equal to 16. If this field is not used, it is set to the default
   value of 0x00.


2.10 Message Size

   This field indicates the valid length in units of bytes of the
   Message field described in section 2.13. The value must be less than



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   or equal to 64. If this field is not used, it is set to the default
   value of 0x00.


2.11 Reserved-2

   This field should be set to 0x00. It is ignored when received.


2.12 User Account

   This field contains the user account information. The size of this
   field is 16 bytes. The length of the valid information is decided by
   the Account Size field described in section 2.9. If the user account
   occupies less than 16 bytes, the field is padded with 0x00.

2.13 Message

   This field contains certain information such as password. Different
   IGAP messages contain different Message information. The size of this
   field is 64 bytes. The length of the valid information is decided by
   the Message Size field described in section 2.10. If message
   information occupies less than 64 bytes, the field is padded with
   0x00.


3. Protocol Description

   IGAP is used for controlled or managed multicast services. A user
   must use IGAP to access such multicast services. IGMP is not needed
   when IGAP is used. An IGAP router will ignore all IGMP messages.

   Different from IGMPv2, IGAP tracks individual host's group membership
   information. This feature allows an IGAP router to implement fast
   leave feature. In another word, IGAP does NOT implement
   Group-Specific Query feature that IGMPv2 has. When an IGAP router
   receives an IGAP Leave message, it will not send Group-Specific
   Query. Instead it will just delete corresponding state information.
   To facilitate tracking individual host's group membership, Host
   Suppression feature is NOT allowed in IGAP.

   IGAP specifies different behaviors for IGAP hosts and for IGAP
   routers. If an IGAP router attempts to join some multicast groups, it
   can perform both parts of the protocol.


3.1 User Authentication Mechanisms

   Currently IGAP supports two user authentication mechanisms for Join
   operation: simple and basic password authentication mechanism [PAP],
   and more advanced challenge-response authentication mechanism



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   [CHAP]. These mechanisms are not used at the same time. Only one
   mechanism is configured to be used in a network. An IGAP
   implementation MUST support password authentication mechanism.
   Challenge-response authentication mechanism is optional.

   IGAP is intended for use with standard AAA servers such as RADIUS
   [RADIUS] servers that with necessary extensions can be used to
   achieve the authentication, authorization and accounting functions
   described in this document. However, IGAP is not limited for use with
   only standard AAA servers. It can be used with any back-end
   Authentication, Authorization, and Accounting functions or
   mechanisms. These functions or mechanisms can be located in different
   servers, within one server, or even within the IGAP routers. In this
   document, we use AAA servers as an example for these functions or
   mechanisms.


3.2 IGAP Host side Protocol Description

   This section describes the IGAP host behavior. Based on the
   configured authentication mechanism, an IGAP host behaves
   differently.


3.2.1 Password Authentication Mechanism

   When an IGAP host joins a multicast group, it should immediately
   transmit an unsolicited IGAP Membership Report that has a Subtype
   field of 0x02 (Password Mechanism Join) to the corresponding
   group. The User Account field is filled with the user account (user
   ID) while the Account Size field is set to the length of the user
   account. The Message field is filled with the user password while the
   Message Size field is set to the length of the password.

   When a host receives an IGAP Query, it sets delay timers as described
   in RFC2236 [IGMPv2]. If a timer for the group is already running, it
   is reset to the random value only if the requested Max Response Time
   is less than the remaining value of the running timer. When a group's
   timer expires, the host sends  a Membership Report that has a Subtype
   field of 0x02. In this message, the User Account field is filled with
   the user account (user ID) while the Account Size field is set to the
   length of the user account.

   When an IGAP host leaves from a multicast group, it sends an IGAP
   Leave Group message to the all-routers multicast group
   (224.0.0.2). Normally an IGAP host sends a Leave message that has a
   Subtype field of 0x41 (Basic Leave). In Basic Leave, the User Account
   field is filled with the user account (user ID) while the Account
   Size field is set to the length of the user account. In scenarios
   where Leave message authentication is required, an IGAP host can send
   a Leave message that has a Subtype field of 0x42 (Password Mechanism



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   Leave). In Password Mechanism Leave, the User Account and Account
   Size fields are set to the values as in Basic Leave. The Message
   field is filled with the user password while the Message Size field
   is set to the length of the password. An IGAP implementation MUST
   support Basic Leave. Password Mechanism Leave is optional.


3.2.2 Challenge-Response Authentication Mechanism

   When an IGAP host joins a multicast group, it sends a
   Challenge-Request-Join that has a Subtype field of 0x03
   (Challenge-Response Mechanism Join Challenge Request) to the
   corresponding group. The user Account field is filled with the user
   account (user ID) while the Account Size field is set to the length
   of the user account. The message field is not used.

       When the IGAP host receives a Challenge that has a Subtype of
       0x23 (Challenge-Response Mechanism Challenge) as a response to
       the Challenge-Request-Join, the IGAP host sends a
       Challenge-Response-Join that has a Subtype of 0x04
       (Challenge-Response Mechanism Join Response). The Challenge ID
       field is set to the same value of Challenge ID on the Challenge
       packet. The user Account field is filled with the user account
       (user ID) while the Account Size field is set to the length of
       the user account. The Message field is set the results of MD5
       calculation. The Message Size field is set to 0x10.

   When a host receives an IGAP Query, it follows the behavior described
   above to set the delay timer. When a group's timer expires, the host
   sends a Membership Report that has a Subtype field of 0x03. In this
   message, the User Account field is filled with the user account (user
   ID) while the Account Size field is set to the length of the user
   account.

   When an IGAP host leaves from a multicast group, it sends an IGAP
   Leave Group message to the all-routers multicast group
   (224.0.0.2). Normally an IGAP host sends a Basic Leave message as
   described above. In scenarios where Leave message authentication is
   required, an IGAP host can send a Leave message that has a Subtype
   field of 0x43 (Challenge-Response Mechanism Leave Challenge
   Request). The User Account field is filled with the user account
   (user ID) while the Account Size field is set to the length of the
   user account. The other fields are not used. When the IGAP host
   receives a Challenge that has a Subtype of 0x23 (Challenge-Response
   Mechanism Challenge) as a response to the Challenge-Response Leave,
   it sends a Leave message that has a Subtype field of 0x44
   (Challenge-Response Mechanism Leave Response). The User Account field
   and Account Size field are the same. The Message field is set to the
   results of MD5 calculation. The Message Size field is set to 0x10.
   An IGAP implementation MUST support Basic Leave. Challenge-Response
   Authentication Mechanism Leave is optional.



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3.3 IGAP Router side Protocol Description

   IGAP routers use IGAP to learn which groups have members on each
   of their interfaces. They can be physical interfaces or virtual
   interfaces such as VLANs. Same as IGMP, an IGAP router keeps a list
   of multicast group memberships for each attached network, and a timer
   for each membership. Each group membership state has the conceptual
   following format:

        (group address, user-id, host IP, timer)

   IGAP routers periodically [Query Interval] send an IGAP Membership
   Query on each attached network to solicit membership information. On
   startup, a router SHOULD send [Startup Query Count] IGAP Membership
   Queries spaced closely together [Startup Query Interval] in order to
   quickly and reliably determine membership information. [Query
   Interval], [Startup Query Count] and [Startup Query Interval] are
   same as RFC 2236 [IGMPv2].

   An IGAP Membership Query is addressed to the all-systems multicast
   group (224.0.0.1), has a Group Address field of 0, has a Max Response
   Time of [Query Response Interval], and has a IGAP Type field of 0x21
   (Basic Query). Other fields are not used. [Query Response Interval]
   is same as RFC 2236 [IGMPv2].

   When an IGAP router receives an IGAP Membership Report or an IGAP
   Group Leave, it takes different actions based on the configured
   authentication mechanism.


3.3.1 Password Authentication Mechanism

   When an IGAP router receives a Password Mechanism Join (an IGAP join
   that has a Subtype field of 0x02), if the router already has the
   corresponding group membership state, it refreshes the associate
   timer.

   If the router does not have the group membership state, it forwards
   the user's group join request information as well as its user
   authentication information including its user account and password to
   the back-end AAA server. Based on the AAA server's results of
   authentication and authorization processes, the IGAP router grants or
   denies the user's access request. When the IGAP router grants the
   request, it adds the group being reported to the list of multicast
   group memberships on the interface on which it received the Report
   and sets the timer for the membership to the [User Membership
   Interval].

   When an IGAP router receives an IGAP Leave message for a group that
   has group members on the reception interface, it deletes the
   corresponding group membership state.



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   If Leave message authentication is required, an IGAP Leave
   (Password-Leave) MUST have a Subtype field of 0x42, and includes a
   user authentication information which is same to a user

   authentication on Password-Join, and the router forwards the user's
   group leave information as well as the user authentication
   information to the back-end AAA server. If the group leave request is
   authenticated and authorized, the router deletes the corresponding
   group membership state. Otherwise, the leave request is ignored.


3.3.2 Challenge-Response Authentication Mechanism

   When an IGAP router receives a Challenge-Response Mechanism Join
   Challenge Request Mechanism Join (a Challenge-Request-Join that has
   a Subtype field of 0x03), the router tries to establish
   Challenge-Response communication for a Join process, then the router
   sends a Challenge-Response Mechanism Challenge (a Challenge that
   has a Type field of 0x41, a Subtype field of 0x23, a Challenge ID
   field of an ID [CHAP], a User Account set to the same user ID in the
   Challenge-Response-Join, and a Message set to a Challenge value
   [CHAP]).

   When the IGAP router receives a Challenge-Response Mechanism Join
   Response (a Challenge-Response-Join that has a Subtype field of
   0x04), if the router already has the corresponding group membership
   state, it refreshes the associate timer.

   If the router does not have the group membership state, it forwards
   the user's group join request information as well as its user
   authentication information including its user account and password to
   the back-end AAA server. Based on the AAA server's results of
   authentication and authorization processes, the IGAP router grants or
   denies the user's access request. When the IGAP router grants the
   request, it adds the group being reported to the list of multicast
   group memberships on the interface on which it received the Report
   and sets the timer for the membership to the [User Membership
   Interval].

   When an IGAP router receives an IGAP Leave message for a group that
   has group members on the reception interface, it deletes the
   corresponding group membership state.

   If Leave message authentication is required, a host oriented
   Challenge-Response communication is establish between a host and the
   IGAP router. When a IGAP router receives an Challenge-Response
   Mechanism Leave (Challenge-Request-Leave that has a Subtype field of
   0x43), the router sends a Challenge-Response Mechanism Challenge (a
   Challenge that has a Type field of 0x41, a Subtype field of 0x23, a
   Challenge ID field of an ID [CHAP], a User Account set to the same
   user ID in the Challenge-Request-Leave, and a Message set to a



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   Challenge value [CHAP]).

   When the IGAP router receives a Challenge-Response Mechanism Leave
   Response (a Challenge-Response-Leave that has a Subtype field of
   0x44, the User Account field and Account Size field are the same. The
   Message field is set to the results of MD5 calculation. The Message
   Size field is set to 0x10), and the router forwards the user's
   group leave information as well as the user authentication
   information to the back-end AAA server. If the group leave request is
   authenticated and authorized, the router deletes the corresponding
   group membership state. Otherwise, the leave request is ignored.

   An IGAP implementation MUST support Basic Leave. Challenge-Response
   Authentication Mechanism Leave is optional.


3.4 Status Notifications

   In controlled or managed multicast environments, it is very important
   to notify a user of its service statuses. IGAP supports the following
   status notifications.


3.4.1 Authentication Result Notification

   When an IGAP router receives the authentication result from the
   back-end AAA server, it notifies the user of the result by unicasting
   an Authentication message to the host.

   The Authentication message has a Type field of 0x41 (IGAP Query) and
   a Subtype field of 0x24. The Group Address field contains the
   corresponding group address for authentication. The Max Resp Time
   field is not used and is ignored by IGAP hosts. It can be set to any
   value or set to the default value 0x64. The User Account contains the
   user account (user ID) for authentication and the Account Size field
   is set the length of the user account.

   The Message Size field is set to 0x01. The Message field has the
   following values:

    0x11: Authentication success.
    0x21: Authentication failure.

   An IGAP implementation MUST support the above mandatory values. It
   supports the any other vendor specific values. Appropriate value is
   chosen to reflect the result from the AAA server as well as other
   vendor specific processes. The process adopted by the IGAP hosts upon
   receiving this packet type is up to implementation. However, it must
   not affect other IGAP process.





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3.4.2 Accounting Status Notification

   An IGAP router informs the accounting server to start accounting when
   it starts forwarding related multicast traffic into the host's
   network. When the IGAP host leaves the multicast group (either via
   silent departure or an explicit leave), the router informs the
   accounting server to stop accounting. Once it receives the response
   from the accounting server, it notifies the IGAP host by unicasting
   an Accounting message.

   The Accounting message has a Type field of 0x41 (IGAP Query) and a
   Subtype field of 0x25. The Group Address field, the Max Resp Time
   field, the User Account field, and the Account Size field are the
   same as those in the Authentication message described in section
   3.4.1.

   The Message Size field is set to 0x01. The Message field has the
   following values:

    0x11: Accounting start
    0x12: Accounting stop

   An IGAP implementation MUST support the above mandatory values. It
   supports the any other vendor specific values. The process adopted by
   the IGAP host upon receiving this packet type is up to
   implementation. However, it must not affect other IGAP process.


3.5 Validity Period

   For each group membership state, an IGAP router MAY maintain another
   timer: Validity Period timer. This timer indicates the valid period
   of an accounting to a group membership. When the timer is expired, an
   IGAP router needs to re-authenticate the group membership. The value
   of the "Validity Period" can be statically configured or dynamically
   set based on the results from the AAA server.

   When "Validity Period" is enforced, an IGAP router checks this timer
   when it receives an IGAP Join. If the timer does not expire, the IGAP
   router does not ask the AAA server a user authentication by a IGAP
   Join response. If the timer expires, it follows the procedures for
   initial authentication described above to re-authenticate the join
   request. During the re-authentication period, an IGAP router
   continues forwarding the multicast traffic and does not stop
   accounting. If the re-authentication succeeds, an IGAP router resets
   the group timer and the Validity Period timer. If the
   re-authentication fails, an IGAP router stops accounting and deletes
   the group membership state.


4. Security Considerations



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   IGAP is based around an asymmetrical trust model in which the IGAP
   router does not trust the IGAP host, but the IGAP host trusts the
   IGAP router therefore may not be suitable for use in isolation where
   mutual authentication is required.

   IGAP supports password and challenge-response authentication
   mechanisms and inherits the security concerns of each. For multicast
   content encryption related technology, please refer to other IETF
   work. IGAP does not obstruct snooping of multicast traffic by
   unauthorized host that have access to media shared with multicast
   traffic.

   Some of the security issues discussed in IGMPv2 document also apply
   here. Please refer to IGMPv2 document [IGMPv2] for details.


5. IANA Considerations

   This document introduces the following new Types of IGMP that require
   allocation by IANA:

       0x40: IGAP Membership Report (IGAP Join)
       0x41: IGAP Membership Query  (IGAP Query)
       0x42: IGAP Leave Group       (IGAP Leave)


Acknowledgments

   Portions of this document are copied from RFC 2236 [IGMPv2]. The
   authors would like to thank Daphne Tong, Dave Allen, Abbie Barbir,
   Ghassem Koleyni ,Paul Knight, Kaori Izutsu, Akihiro Tanabe, Takashi
   Shimizu, and Atsushi Takahara for their kindness, patience, and time
   to review the document and to provide their valuable suggestions.


Normative References

[IGMPv2]
   W. Fenner, "Internet Group Management Protocol, Version 2", RFC 2236,
   Xerox PARC, November 1997.

[IPRA]
   D. Katz, "IP Router Alert Option", RFC 2113, Cisco Systems,
   February 1997.

[MD5]
   R. Rivest, S. Dusse, "The MD5 Message-Digest Algorithm", RFC 1321,
   April 1992.

[RADIUS]
   C. Rigney, S. Willens, A. Rubens, W. Simpson, "Remote Authentication



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   Dial In User Service (RADIUS)", RFC 2865, June 2000.

[PAP]
   B. Lloyd and W. Simpson, "PPP Authentication Protocols", RFC1334,
   October 1992.

[CHAP]
   W. Simpson, "PPP Challenge Handshake Authentication Protocol (CHAP)",
   RFC 1994, August 1996.


Author's Addresses

        Tsunemasa Hayashi
        NTT Network Innovation Laboratories
        1-1 Hikari-no-oka, Yokosuka-shi, Kanagawa, 239-0847 Japan
        Phone : +81 468 59 8790
        Email : hayashi@exa.onlab.ntt.co.jp


        Daisuke Andou
        NTT Access Network Service Systems Laboratories
        1-6 Nakase Mihiama-ku, Chiba-shi, Chiba, 261-0023 Japan
        Phone : +81 43 211 2115
        Email : dandou@ansl.ntt.co.jp


        Haixiang He
        Nortel Networks
        600 Technology Park Drive
        Billerica, MA 01801, USA
        Phone : 1 978 288 7482
        Email : haixiang@nortelnetworks.com

        Wassim Tawbi
        Nortel Networks
        4655 Great America Parkway
        Santa Clara, CA 95054, USA
        Email : wtawbi@nortelnetworks.com


        Teruki Niki
        Matsushita Electric Industrial Co.,Ltd
        Multimedia Systems Research-Laboratory
        4-5-15 Higashi-Shinagawa Shinagawa-ku, Tokyo, 140-8632 Japan
        Phone : +81 3 5460 2741
        Email : niki.teruki@jp.panasonic.com


Appendix 1. IGAP State Machines on Password authentication




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   This Section describes an example of IGAP State Machines. The example
   of FSM on Password authentication mechanism with a infinity value of
   Validity-Period is shown about each pattern as follows.
   Authentication and Accounting packets are operated between IGAP
   routers and AAA servers. In this example, Basic-Leave is used,
   although there is another alternative for Leave operation (Password
   Mechanism Leave). The choice is depends on the strategy of a network
   service provider.

   Here, we define a vendor specific Message "Error-Message" in
   Authentication Message. The Message field has 0x25.


A.1.1. FSM for Host

   PH1[Non Member]:
     if join group{
         send Password-Join;
         start Authentication-Timer;
         transition PC2;
     }

   PH2[Waiting Authentication Message Member]:
     if Authentication-Message(Reject) received
       or Error-Message(Response time out) received
       or Authenticated-Timer expired{
         stop Authenticated-Timer;
         transition PC1;
     }
     else if Authentication-Message(Success) received{
         stop Authenticated-Timer;
         transition PC3;
     }

   PH3[Idle Member]:
     if Basic-Query received{
         start Delaying-Timer;
         transition PC4;
     }
     else if leave group{
         send Basic-Leave;
         transition PC5;
     }

   PH4[Delaying Member]:
     if leave group{
         send Basic-Leave;
         stop Delaying-Timer;
         start Accounted-Timer;
         transition PC5;
     }



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     else(Delaying-Timer expired){
         send Password-Join;
         stop Delaying-Timer;
         transition PC2;
     }

   PH5[Waiting Accounting Message Member]:
     if Accounting-Message(Stop) received{
         stop Accounted-Timer;
         transition PC1;
     }
     else if Basic-Query received{
         send Basic-Leave;
         continue(no transition);
     }
     else(Accounted-Timer expired){
         send Basic-Leave;
         restart Accounted-Timer;
         continue(no transition);
     }


A1.2. FSM for IGAP router

   PR1[No Transfer Present]:
     if Password-Join received{
         send Authentication Request;
         start Authentication-Timer;
         transition PR2;
     }
     else if Basic-Leave received{
         send Accounting-Request(Stop);
         transition PR5;
     }

   PR2[Waiting Authentication-Response]:
     if Access-Reject received{
         send Authentication-Message(Reject);
         stop Authentication-Timer;
         transition PR1;
     }
     else if Access-Accept received{
         send Accounting-Request(Start);
         send Authentication-Message(Success);
         stop Authentication-Timer;
         start Accounting-Timer;
         transition PR3;
     }
     else(Authentication-Timer expired){
         send Error-Message(Response time out);
         stop Authentication-Timer;



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         start User-Membership-Interval-Timer;
         transition PR4;
     }

   PR3[Waiting Accounting-Response(Start)]:
     if Accounting-Response received{
         send Accounting-Message(Start);
         stop Accounting-Timer;
         start User-Membership-Interval-Timer;
         transition PR4;
     }
     else(Accounting-Timer expired){
         send Error-Message(Response time out);
         stop Accounting-Timer;
         start User-Membership-Interval-Timer;
         transition PR4;
     }

   PR4[Transfer Present]:
     if Password-Join received{
         restart User-Membership-Interval-Timer;
         continue(no transition);
     }
     else if Basic-Leave received{
         send Accounting-Request(Stop);
         stop User-Membership-Interval-Timer;
         start Accounting-Timer;
         transition PR5;
     }
     else(User-Membership-Interval-Timer expired){
         send Accounting-Request(Stop);
         start Accounting-Timer;
         transition PR5;
     }

   PR5[Waiting Accounting-Response(Stop) for Leave]:
     if Accounting-Response received{
         send Accounting-Message(stop);
         stop Accounting-Timer;
         transition PR1;
     }
     else(Accounting-Timer expired){
         send Error-Message(Response time out);
         transition PR1;
     }


Appendix 2. IGAP State Machines on Challenge-Response

   This Section describes an example of IGAP State Machines. The example
   of FSM on Challenge-Response with a finite value of Validity-Period



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   is shown about each pattern as follows. Authentication and Accounting
   packets are operated between IGAP routers and AAA servers. In this
   example, Basic-Leave is used, although there is another alternative
   for Leave operation (Challenge-Response Mechanism Leave). The choice
   is depends on the strategy of a network service provider.

   Here, we define a vendor specific Message "Error-Message" in
   Authentication Message. The Message field has 0x25.


A2.1. FSM for Host

   CH1[Non Member]:
     if join group{
         send Challenge-Request-Join;
         start Challenge-Timer;
         transition CC2;
     }

   CH2[Waiting Challenge Member]:
     if Challenge received{
         send Challenge-Response-Join;
         stop Challenge-Timer;
         start Authenticated-Timer;
         transition CC3;
     }
     else(Challenge-Timer expired){
         stop Challenge-Timer;
         transition CC1;
     }

   CH3[Waiting Authentication Message Member]:
     if Authentication-Message(Reject) received
       or Error-Message(Response time out) received
       or Authenticated-Timer expired{
         stop Authenticated-Timer;
         transition CC1;
     }
     else if Authentication-Message(Success) received
         stop Authenticated-Timer;
         transition CC4;
     }

   CH4[Idle Member]:
     if Basic-Query received{
         start Delaying-Timer;
         transition CC5;
     }
     else if leave group{
         send Basic-Leave;
         start Accounted-Timer;



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         transition CC6;
     }

   CH5[Delaying Member]:
     if leave group{
         send Basic-Leave;
         stop Delaying-Timer;
         start Accounted-Timer;
         transition CC6;
     }
     else(Delaying-Timer expired){
         send Challenge-Request-Join;
         stop Delaying-Timer;
         start Challenge-Timer;
         transition CC2;
     }

   CH6[Waiting Accounting Message Member]:
     if Accounting-Message(Stop) received{
         stop Accounted-Timer;
         transition CC1;
     }
     else if Basic-Query received{
         send Basic-Leave;
         continue(no transition);
     }
     else(Accounted-Timer expired){
         send Basic-Leave;
         restart Accounted-Timer;
         continue(no transition);
     }


A2.2. FSM for IGAP router

   CR1[No Transfer Present]:
     if Challenge-Request-Join received{
         send Challenge;
         start Response-Timer;
         transition CR2;
     }
     else if Basic-Leave received{
         send Accounting-Request(Stop);
         transition CR7;
     }

   CR2[Waiting Challenge-Response]:
     if Challenge-Response-Join received{
         send Authentication Request;
         stop Response-Timer;
         start Authentication-Timer;



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         transition CR3;
     }
     else(Response-Timer expired){
         stop Response-Timer;
         transition CR1;
     }

   CR3[Waiting Authentication-Response]:
     if Access-Reject received{
         send Authentication-Message(Reject);
         stop Authentication-Timer;
         transition CR1;
     }
     else if Access-Accept received{
         send Accounting-Request(Start);
         send Authentication-Message(Success);
         stop Authentication-Timer;
         start Accounting-Timer;
         transition CR4;
     }
     else(Authentication-Timer expired){
         send Error-Message(Response time out);
         stop Authentication-Timer;
         start User-Membership-Interval-Timer;
         start Validity-Timer;
         transition CR5;
     }

   CR4[Waiting Accounting-Response(Start)]:
     if Accounting-Response received{
         send Accounting-Message(Start);
         stop Accounting-Timer;
         start User-Membership-Interval-Timer;
         start Validity-Timer;
         transition CR5;
     }
     else(Accounting-Timer expired){
         send Error-Message(Response time out);
         stop Accounting-Timer;
         start User-Membership-Interval-Timer;
         start Validity-Timer;
         transition CR5;
     }

   CR5[Transfer Present]:
     if Challenge-Request-Join received{
         if Validity-Timer < Validity-Period{
             restart User-Membership-Interval-Timer;
             continue(no transition);
         }
         else(Validity-Timer expired){



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             send Accounting-Request(Stop);
             stop Validity-Timer;
             stop User-Membership-Interval-Timer;
             start Accounting-Timer
             transition CR6;
         }
     }
     else if Basic-Leave received{
         send Accounting-Request(Stop);
         stop User-Membership-Interval-Timer;
         stop Validity-Timer;
         start Accounting-Timer;
         transition CR7;
     }
     else(User-Membership-Interval-Timer expired){
         send Accounting-Request(Stop);
         stop Validity-Timer;
         start Accounting-Timer;
         transition CR7;
     }

   CR6[Waiting Accounting-Response(Stop)]:
     if Accounting-Response received{
         send Accounting-Message(Stop);
         send Challenge;
         stop Accounting-Timer;
         start Response-Timer;
         transition CR2;
     }
     else(Accounting-Timer expired){
         send Error-Message(Response time out);
         stop Accounting-Timer;
         start Validity-Timer;
         transition CR5;
     }

   CR7[Waiting Accounting-Response(Stop) for Leave]:
     if Accounting-Response received{
         send Accounting-Message(stop);
         stop Accounting-Timer;
         transition CR1;
     }
     else(Accounting-Timer expired){
         send Error-Message(Response time out);
         stop Accounting-Timer;
         transition CR1;
     }


Appendix 3. IGAP State Machines of Query Process




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   This Section describes an example of IGAP State Machines on Query
   Process.

   QR1[Initial]:
     start IGAP{
         send Basic-Query;
         start Startup-Query-Interval-Timer;
         start Startup-Query-Counter;
         transition QR2;
     }

   QR2[Startup]
     if Startup-Query-Interval-Timer expired{
         if Startup-Query-Counter < Startup-Query-Count{
             send Basic-Query;
             restart Startup-Query-Interval-Timer;
             continue(no transition)
         }
         else{
             send Basic-Query;
             stop Startup-Query-Counter;
             start Query-Interval-Timer;
             transition QR3;
         }
     }

   QR3[Affirmed Connection]:
     if Query-Interval-Timer expired{
         send Basic-Query;
         restart Query-Interval-Timer;
         continue(no transition);
   }


Appendix 4. List of Timers, Counters

   This section describes the parameters set in IGAP router and Host
   when supporting IGAP processes.

A4.1. Robustness Variable

   It is the same meaning as IGMPv2.


A4.2. Timers for Host

A4.2.1. Challenge-Timer

   It controls waiting time from sending Join message to receiving
   Challenge Message.




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A4.2.2. Authenticated-Timer

   It controls waiting time from sending Response Message to receiving
   Authentication Message (accept or reject) from IGAP router.

A4.2.3. Accounted-Timer

   It controls waiting time from sending Response Message to receiving
   Accounting Message (start or stop) from IGAP router.

A4.2.4. Delaying-Timer

   It controls waiting time from receiving Query to sending Join Message
   to IGAP router. It is calculated from Max Resp Time.


A4.3. Timers and Counters for IGAP router

A4.3.1. Response-Timer

   It controls waiting time from sending Challenge Message to receiving
   Response Message.

A4.3.2. Authentication-Timer

   It controls waiting time from sending Authentication request to
   receiving Authentication Response.

A4.3.3. Accounting-Timer

   It controls waiting time from sending Accounting request to receiving
   Accounting Response.

A4.3.4. Validity-Timer

   This is an integer multiple of Basic-Query Interval in units of
   second, and used by IGAP router to determine whether user
   authentication is necessary or not.

A4.3.5. Query-Interval-Timer

   It is the same meaning as IGMPv2. The Query Interval is the interval
   between Basic Queries.

A4.3.6. Query-Response-Interval-Timer

   It is the same meaning as IGMPv2. The Max Response Time inserted into
   the periodic Basic Queries.

A4.3.7. User-Membership-Interval-Timer




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   The User Membership Interval is the amount of time that must pass
   before a IGAP router decides there are no more users of a
   group on a network. This value MUST be ((the Robustness Variable)
   times (the Query Interval)) plus (one Query Response Interval).

A4.3.8.  Startup-Query-Interval-Timer

   It is the same meaning as IGMPv2.
   The Startup Query Interval is the interval between General Queries
   sent by a Querier on startup.

A4.3.9.  Startup-Query-Counter

   It is the same meaning as IGMPv2.
   The Startup Query Count is the number of Queries sent out on startup,
   separated by the Startup Query Interval.






































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