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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 5678

Internet Engineering Task force                            Gabor Bajko
Internet Draft                                                   Nokia
Intended Status: Proposed Standard                           Subir Das
Expires: May 17, 2009                           Telcordia Technologies
                                                     November 17, 2008


 Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Options for
                    IEEE 802.21 Mobility Server (MoS) discovery
                    draft-ietf-mipshop-mos-dhcp-options-08

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
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   This Internet-Draft will expire on May 17, 2009.

Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document defines a number of Dynamic Host Configuration Protocol
  (DHCPv4 and DHCPv6) options that contain a list of domain names
   or IP addresses that can be mapped to servers providing IEEE 802.21
   type of Mobility Services [MSFD]. These Mobility Services are used
   to assist an MN in handover preparation (network discovery) and
   handover decision (network selection). The services addressed
   in this document are the Media Independent Handover Services
   defined in [IEEE802.21].

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 (1) Conventions used in this document

   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.

 (2) Terminology and abbreviations used in this document

   Mobility Services: a set of different services provided by the
   network to mobile nodes to facilitate handover preparation
   and handover decision. In this document, Mobility Services refer to
   the services defined in IEEE 802.21 specifications [IEEE802.21]

   Mobility Server: a network node providing Mobility Support Services.

   MIH: Media Independent Handover, as defined in [IEEE802.21].

   MIH Service: IS, ES or CS type of service, as defined in
   [IEEE802.21]

Table of Contents

   1. Introduction .................................................2
   2. DHCPv4 Options for MoS Discovery..............................3
        2.1 Domain Name List........................................5
        2.2 IPv4 Address List.......................................6
   3. DHCPv6 Options for MoS Discovery..............................6
   4. Option Usage..................................................8
        4.1 Usage of DHCPv4 Options for MoS Discovery...............8
        4.2 Usage of DHCPv6 Options for MoS Discovery...............9
   5. Security Considerations .....................................10
   6. IANA Considerations .........................................10
   7. Acknowledgements ............................................11
   8. References ..................................................11
       8.1 Normative References ...................................11
       8.2 Informative References .................................12
   Author's Addresses .............................................12
   Intellectual Property and Copyright Statements .................13

1. Introduction

   IEEE 802.21 [IEEE802.21] defines three distinct service types to
   facilitate link layer handovers across heterogeneous technologies:

   a) Information Services (IS)
        IS provides a unified framework to the higher layer entities
   across the heterogeneous network environment to facilitate discovery
   and selection of multiple types of networks existing within a
   geographical area, with the objective to help the higher layer

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   mobility protocols to acquire a global view of heterogeneous
   networks and perform seamless handover across these networks.

     b) Event Services (ES)
        Events may indicate changes in state and transmission behavior
   of the physical, data link and logical link layers, or predict state
   changes of these layers. The Event Service may also be used to
   indicate management actions or command status on the part of the
   network or some management entity.

   c) Command Services (CS)
        The command service enables higher layers to control the
   physical, data link, and logical link layers. The higher layers may
   control the reconfiguration or selection of an appropriate link
   through a set of handover commands.

   In IEEE terminology these services are called Media Independent
   Handover (MIH) services. While these services may be co-located,
   the different pattern and type of information they provide does not
   necessitate the co-location.

   An MN may make use of any of these MIH service types separately or
   any combination of them [MSFD]. In practice a Mobility Server may
   not necessarily host all three of these MIH services together, thus
   there is a need to discover the MIH services types separately.

   This document defines a new DHCPv4 option called the MoS option,
   which allows the MN to locate a Mobility Server which hosts the
   desired service type (i.e. IS, ES or CS) as defined in [IEEE802.21].
   The MoS information type defines sub-options for different services.
   This document also defines DHCPv6 options that allow the MN to
   discover Mobility Servers hosting MIH services in different
   deployment scenarios. Apart from manual configuration, this is one
   of the possible solutions for locating a server providing Mobility
   Services.

2. DHCPv4 Option for MoS Discovery

   This section describes the MoS option for DHCPv4. Whether the MN
   receives an MoS address from local or home network will depend on
   the actual network deployment [MSFD]. The MoS option begins with a
   option code followed by a length and sub-options. The value of the
   length octet does not include itself or the option code. The option
   layout is depicted below:

     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
                                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                     | Option Code   |    length     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Sub-Option 1                              |

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     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                       ...                                     |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Sub-Option n                              |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


         Option Code

                OPTION-IPv4-MoS (To Be Assigned) - 1 byte

         Length

                An 8-bit field indicating the length of the option
                excluding the 'Option Code' and the 'Length' fields

         Sub-options

                A series of DHCPv4 sub-options.

   When the total length of a MoS option exceeds 254 octets, the
   procedure outlined in [RFC3396] MUST be employed to split the
   option into multiple, smaller options.

   A sub-option begins with a sub-option Type followed by a length
   and a `enc` field. The value of the length octet does not include
   itself or the Sub-opt Type field. There are two types of encodings,
   specified by the encoding byte ('enc') that follows the code byte.
   If the encoding byte has the value 0, it is followed by a list of
   domain names, as described below (Section 2.1). If the encoding byte
   has the value 1, it is followed by one or more IPv4 addresses
   (Section 2.2).

   All implementations MUST support both encodings. A DHCP server MUST
   NOT mix the two encodings in the same DHCP message, even if it sends
   two different instances of the same option. Attempts to do so would
   result in incorrect client behavior as DHCP processing rules call
   for the concatenation of multiple instances of an option into a
   single option prior to processing the option [RFC3396].

   The sub-option layout is depicted below:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Sub-opt Type  |    length     |    enc        | FQDN or      .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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      +---------------------------------------------------------------+
      .              IP Address                                       .
      .                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The sub-option Types are summarized below.
      +--------------+---------------+
      |  Sub-opt     | Service       |
      |   Type*      | Name          |
      +==============+===============+
      |    1         |   IS          |
      +--------------+---------------+
      |    2         |   ES          |
      +--------------+---------------+
      |    3         |  IS and ES    |
      +--------------+---------------+
      |    4         |   CS          |
      +--------------+---------------+
      |    5         |  IS and CS    |
      +--------------+---------------+
      |    6         |  ES and CS    |
      +--------------+---------------+
      |    7         | IS, CS and ES |
      +--------------+---------------+

*Note: The values `0` '8' to '255' are reserved and MUST NOT be used.


    2.1 Domain Name List

   If the 'enc' byte has a value of 0, the encoding byte is followed by
   a sequence of labels, encoded according to Section 8 of [RFC3315],
   quoted below:

       So that domain names may be encoded uniformly, a domain name
       or a list of domain names is encoded using the technique
       described in section 3.1 of [RFC1035]. A domain name, or list
       of domain names, in DHCP MUST NOT be stored in compressed form,
       as described in section 4.1.4 of [RFC1035].

   [RFC1035] encoding was chosen to accommodate future international-
   lized domain name mechanisms. The minimum length for this encoding
   is 3.

   The option MAY contain multiple domain names, but these SHOULD refer
   to different NAPTR records, rather than different A records. The
   client MUST try the records in the order listed, applying the
   mechanism described in [MoS-DNS] for each. The client only resolves


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   the subsequent domain names if attempts to contact the first one
   failed or yielded no common transport protocols between the MN and
   the server.

   Use of multiple domain names is not meant to replace NAPTR and SRV
   records, but rather to allow a single DHCP server to indicate MIH
   servers operated by multiple providers.


  The sub-option for this encoding has the following format:


           Type Len enc DNS name of MoS server
         +-----+---+---+-----+-----+-----+-----+-----+--
         |1..7 | n | 0 |  s1 |  s2 |  s3 |  s4 | s5  |  ...
         +-----+---+---+-----+-----+-----+-----+-----+--

   As an example, consider the case where the server wants to offer
   two MIH IS servers, "example.com" and "example.net".  These would
   be encoded as follows:
   +----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   |1..7|27 | 0 | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'c'|'o'|'m'| 0 |
   +----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   +---+---+---+---+---+---+---+---+---+---+---+---+---+
   | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'n'|'e'|'t'| 0 |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+


2.2 IPv4 Address List

   If the 'enc' byte has a value of 1, the encoding byte is followed by
   a list of IPv4 addresses indicating appropriate MIH servers
   available to the MN. Servers MUST be listed in order of preference.

   Its minimum length is 5, and the length MUST be a multiple of 4 plus
   one. The sub-option for this encoding has the following format:

           Code Len enc IPv4 Address 1 IPv4 Address 2
         +-----+---+---+-----+----+---+----+----+--
         |1..7 | n | 1 | a1  | a2 |a3 | a4 | a1 |  ...
         +-----+---+---+-----+----+---+----+----+--


3.  DHCPv6 Option for MoS discovery

   This section introduces new DHCPv6 option used for MoS discovery.

   Whether the MN receives an MoS address from local or home network
   will depend on the actual network deployment [MSFD].

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   The MoS option begins with a option code followed by a length and
   sub-options. The value of the length octet does not include itself
   or the option code. The option layout is depicted below:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       Option Code             |           length              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Sub-Option 1                              |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                       ...                                     |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Sub-Option n                              |
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Option Code

             OPTION-IPv6-MoS (To Be Assigned) - 2 bytes

       Length

             A 16-bit field indicating the length of the option
             excluding the 'Option Code' and the 'Length' fields.

       Sub-options

             A series of DHCPv6 sub-options.


   The sub-options follow the same format (except the Sub-opt Type and
   Length value) and 'enc' rules as described in Section 2. The value of
   the Sub-opt Type and Length are 2-octets and the Length does not
   include itself or the Sub-opt Type field. The sub-option layout is
   depicted below:

       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

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | sub-opt Type                  |     Length                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     enc       |                FQDN or IP Address             |
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


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  The sub-option Types are summarized below.
      +--------------+---------------+
      |  Sub-opt     | Service       |
      |   Type*      | Name          |
      +==============+===============+
      |    1         |   IS          |
      +--------------+---------------+
      |    2         |   ES          |
      +--------------+---------------+
      |    3         |  IS and ES    |
      +--------------+---------------+
      |    4         |   CS          |
      +--------------+---------------+
      |    5         |  IS and CS    |
      +--------------+---------------+
      |    6         |  ES and CS    |
      +--------------+---------------+
      |    7         | IS, CS and ES |
      +--------------+---------------+

*Note: The values `0` '8' to '65535' are reserved and MUST NOT be
used.

4. Option Usage

4.1 Usage of DHCPv4 Options for MoS Discovery

   The requesting and sending of the proposed DHCPv4 option follow the
   rules for DHCP options in [RFC2131].

4.1.1 Mobile Node behavior

   The mobile node may perform the MoS information discovery procedure
   either during initial association with a network or when the
   mobility service is required. It may also try to perform the MoS
   information discovery when it lacks the network information for MoS
   or needs to change the  MoS for some reasons, for instance, to
   recover from the single point of failure of the existing MoS.

   In order to acquire the MoS information, the mobile node MUST send
   either a DHCPDISCOVER or DHCPINFORM message to a subnet broadcast or
   a unicast server address, respectively. In this message the mobile
   node (DHCP client) MUST include the sub-opt Type for the MoS
   Discovery in the sub-options field.






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4.1.2 DHCP Server behavior

   When the DHCP server receives the DHCPDISCOVER or DHCPINFORM message
   with the MoS Discovery option in the options field, the DHCP server
   MUST follow the [RFC2131] logic to construct either a DHCPOFFER or
   DHCPACK message including the MoS Discovery option. The reply
   message may contain the IP address or the FQDN of the MoS Server.

   The DHCP server MUST always construct the response according to
   the Sub-opt Type requested by the DHCP client. If set of FQDNs
   in the response message turns out to be more than 256 bytes,
   the DHCP server should send a reduced list of FQDNs so that they
   fit into one sub option.

   In case that the server cannot find any MoS information for a
   specific MoS sub-opt Type, it MUST return the MoS option with a
   sub-option by setting the sub-opt Type to the requested
   sub-opt Type and the length of the sub-option to 1.


4.2 DHCPv6 Options for MoS discovery

   The requesting and sending of the proposed DHCPv6 options follow the
   rules for DHCP options in [RFC3315].

4.2.1 Mobile node behavior

   The mobile node may perform the MoS information discovery procedure
   either during initial association with a network or when the
   mobility service is required. It may also try to perform the MoS
   information discovery when it lacks the network information for MoS
   or needs to change the  MoS for some reasons, for instance, to
   recover from the single point of failure of the existing MoS

   In order to acquire the MoS address, the mobile node MUST send either
   a REQUEST or INFORMATION_REQUEST message to the All_DHCP_Servers
   multicast address. In this message the mobile node (DHCP client)
   MUST include the Option Code for the MoS Discovery option in the
   option_code.

4.2.2 DHCP Server behavior

   When the DHCP Server receives either REQUEST or INFORMATION-REQUEST
   message the DHCP server MUST follow the following logic to construct
   a REPLY message with the MoS Information option.

   If the DHCP server has the requested MoS information, it MUST
   include the information in the MoS Information option. The server


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   may provide the matching information from the preconfigured
   information available locally. The DHCP server MUST always
   construct the response according to the Sub-Opt Type requested
   by the DHCP client.

   In case that the server cannot find any MoS information for a
   specific MoS type, it MUST return the MoS option with
   a sub-option by setting the Sub-opt Type to the requested Sub-opt
   Type and the length of the sub-option to 1.


5. Security Considerations

   The security considerations in [RFC2131] apply. If an adversary
   manages to modify the response from a DHCP server or insert its own
   response, an MN could be led to contact a rogue Mobility Server,
   possibly one that then would provide wrong information, event or
   command for handover.

   It is recommended to use either DHCP authentication option described
   in [RFC3118] where available, or rely upon link layer security.

   This will also protect the denial of service attacks to DHCP
   servers. [RFC3118] provides mechanisms for both entity authentication
   and message authentication.


6. IANA Considerations

  This document defines one new DHCPv4 option as described in section
  2.

   MoS Option for DHCPv4 (OPTION-IPv4-MoS)             To Be Assigned

   This document creates a new registry for the Sub-Option field in the
   MoS DHCPv4 option called the "IEEE 802.21 Service Type" (Section 2).
      IS                       1
      ES                       2
      IS and ES                3
      CS                       4
      IS and CS                5
      ES and CS                6
      IS, CS and ES            7

  The values '0', '8' to '255' are reserved and MUST NOT be used. New
  values can be allocated by Standards Action or IESG approval.

  This document also defines new DHCPv6 options as described in
  section 3.

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   MoS Option for DHCPv6 (OPTION-IPv6-MoS)          To Be Assigned

   This document creates a new registry for the sub-option field in
   the MoS DHCPv6 option called the "IEEE 802.21 Service Type"
   (section 3).

        IS                       1
        ES                       2
        IS and ES                3
        CS                       4
        IS and CS                5
        ES and CS                6
        IS, CS and ES            7

  The values '0', '8' to '65535' are reserved and MUST NOT be used. New
  Values can be allocated by Standards Action or IESG approval.


7. Acknowledgements

   Authors would like to acknowledge the following individuals for
   their valuable comments.
   Bernie Volz, Vijay Devarapalli, Alfred Hoenes, Telemaco Melia, and
   Yoshihiro Ohba


8. References

    8.1 Normative References

   [RFC1035] Mockapetris, P., "Domain names - implementation and
      specification", STD 13, RFC 1035, November 1987.

   [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
      2131, March 1997.

   [RFC3315] Dynamic Host Configuration Protocol for IPv6 (DHCPv6),
      Droms et al, July 2003

   [RFC3118] Authentication for DHCP Messages, Droms et al, June 2001

   [RFC3396] Lemon, T. and S. Cheshire, "Encoding Long DHCP Options",
      RFC3396, November 2002.

   [MSFD] T Melia, Ed., " Mobility Services Framework Design (MSFD)",
      draft-ietf-mipshop-mstp-solution-09.txt (Work in Progress).




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[MoS-DNS] Bajko, G., "Locating Mobility Servers",
      draft-ietf-mipshop-mos-dns-discovery-04.txt (Work in Progress),



8.2 Informative References

   [IEEE802.21] IEEE 802.21 Standard for Local and Metropolitan Area
      Networks: Media Independent Handover Services





 Authors' Addresses

   Gabor Bajko
   Nokia
   e-mail: gabor.bajko@nokia.com

   Subir Das
   Telcordia Technologies Inc.
   e-mail: subir@research.telcordia.com


  Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.


   This document and the information contained herein are provided on
   an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
   IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
   WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
   ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
   FOR A PARTICULAR PURPOSE.







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Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed
   to pertain to the implementation or use of the technology described
   in this document or the extent to which any license under such
   rights might or might not be available; nor does it represent that
   it has made any independent effort to identify any such rights.
   Information on the procedures with respect to rights in RFC
   documents can be found in BCP 78 and BCP 79.


   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use
   of such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository
   at http://www.ietf.org/ipr.


   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at ietf-
   ipr@ietf.org.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).


















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