[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-xie-rserpool-enrp) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 RFC 5353

Network Working Group                                              Q. Xie
INTERNET-DRAFT                                                   Motorola
                                                            R. R. Stewart
                                                            Cisco Systems


Expires in six months                                       Nov. 20, 2001


                 Endpoint Name Resolution Protocol (ENRP)
                  <draft-ietf-rserpool-enrp-01.txt>

Status of This Memo

    This document is an Internet-Draft and is in full conformance with
    all provisions of Section 10 of RFC 2026. 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.

    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

    Endpoint Name Resolution Protocol (ENRP) is designed to work in
    conjunction with the Aggregate Server Access Protocol (ASAP) [ASAP]
    to accomplish the functionality of the Reliable Server Pooling
    (Rserpool) requirements and architecture as defined in [RSERPOOL1]
    and [RSERPOOL2].

    Within the operational scope of Rserpool, ENRP defines the
    procedures and message formats of a distributed fault-tolerant
    registry service for storing, bookkeeping, retrieving, and
    distributing pool operation and membership information.


Table Of Contents

    1. Introduction...............................................2
       1.2 Definitions............................................2
    2. Conventions................................................3
    3. Message Definitions........................................4
       3.1 ENRP Parameter Formats.................................4
           3.1.1 IPv4 Address Parameter...........................5
           3.1.2 IPv6 Address Parameter ..........................5
           3.1.3 Pool Element Parameter...........................6
           3.1.4 Pool Handle Parameter............................6
           3.1.5 Authorization Parameter..........................7

Xie, Stewart                                                    [Page 1]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

           3.1.6 Name Server Identifier Parameter.................7
       3.2  ENRP Message Formats..................................7
            3.2.1 PEER_PRESENCE message...........................8
            3.2.2 PEER_NAME_TABLE_REQUEST message.................9
            3.2.3 PEER_NAME_TABLE_RESPONSE message................9
            3.2.4 PEER_NAME_UPDATE message........................10
            3.2.5 PEER_LIST_REQUEST message.......................11
            3.2.6 PEER_LIST_RESPONSE message......................11
    4. ENRP Operation Procedures..................................12
       4.1 Basic ENRP Operations..................................12
           4.1.1 PE Registration..................................12
           4.1.2 PE De-registration...............................13
           4.1.3 PE Re-registration...............................13
           4.1.4 Name Translation.................................14
           4.1.5 Server Namespace Update..........................15
                 4.1.5.1 Add/Update a PE..........................15
                 4.1.5.2 Remove a PE..............................15
           4.1.6 Server Download Namespace from a Peer Server.....16
           4.1.7 Server Monitor Peer Status.......................17
           4.1.8 Server Download Peer List from a Peer Server.....17
           4.1.9 Server Initialization............................17
       4.2 Fault Management Operations............................18
           4.2.1 Detect and Remove an Unreachable PE..............18
           4.2.2 Server Failure Detection by Heartbeat............19
           4.2.3 PE or PU Discover Home ENRP Server...............19
    5. Variables and Timer Constants..............................20
       5.1 Variables..............................................20
       5.2 Timer Constants........................................20
    6. Security COnsiderations....................................20
    7. References.................................................20
    8. Acknowledgements...........................................21
    9. Authors' Addresses.........................................21


1. Introduction

    Endpoint Name Resolution Protocol (ENRP) is designed to work in
    conjunction with the Aggregate Server Access Protocol (ASAP) [ASAP]
    to accomplish the functionality of the Reliable Server Pooling
    (Rserpool) requirements and architecture as defined in [RSERPOOL1]
    and [RSERPOOL2].

    Within the operation scope of Rserpool, ENRP defines the procedures
    and message formats of a distributed fault-tolerant registry service
    for storing, bookkeeping, retrieving, and distributing pool
    operation and membership information.

    Whenever appropriate, in the rest of this document we will refer to
    this Rserpool registry service as ENRP namespace, or simply
    namespace.


1.2 Definitions


Xie, Stewart                                                    [Page 2]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    This document uses the following terms:

     Operation scope:
          The part of the network visible to pool users by a specific
          instance of the reliable server pooling protocols.

     Pool (or server pool):
          A collection of servers providing the same application
          functionality.

     Pool handle (or pool name):
          A logical pointer to a pool. Each server pool will be
          identifiable in the operation scope of the system by a unique
          pool handle or "name".

     ENRP namespace (or namespace):
          A cohesive structure of pool names and relations that may be
          queried by an internal or external agent.

     Pool element (PE):
          A server entity that runs ASAP and has registered to a pool.

     Pool user (PU):
          A server pool user that runs ASAP. Note, a PU can also be a
          PE if it has registered itself to a pool.

     ENRP namespace server (or ENRP server):
          Entity which runs ENRP and is responsible for managing and
          maintaining the namespace within the operation scope.

     ENRP client channel:
          The communication channel through which a PE requests for
          ENRP namespace service. The ENRP client channel is usually
          defined by the transport address of the home ENRP server and
          a well known port number.

     ENRP server channel:
          Defined by a well known multicast IP address and a well
          known port number. All ENRP servers in an operation scope
          can send multicast messages to other servers through this
          channel. PEs are also allowed to multicast on this channel
          occasionally.

     Network Byte Order:
          Most significant byte first, a.k.a Big Endian.


2. Conventions

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when
   they appear in this document, are to be interpreted as described in
   [RFC2119].


Xie, Stewart                                                    [Page 3]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001


3. Message Definitions

   All messages as well as their fields described below shall be in
   Network Byte Order during transmission. For fields with a length
   bigger than 4 octets, a number in a pair of parentheses may follow
   the filed name to indicate the length of the field in number of
   octets.


3.1 ENRP Parameter Formats

   ENRP parameters are defined in a Type-length-value (TLV) format as
   shown below.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Parameter Type       |       Parameter Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      :                       Parameter Value                         :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameter Type:  16 bits (unsigned integer)

      The Type field is a 16 bit identifier of the type of parameter.
      It takes a value of 0 to 65534.

      The value of 65535 is reserved for IETF-defined extensions. Values
      other than those defined in specific SCTP chunk description are
      reserved for use by IETF.

   Parameter Length:  16 bits (unsigned integer)

      The Parameter Length field contains the size of the parameter in
      bytes, including the Parameter Type, Parameter Length, and
      Parameter Value fields.  Thus, a parameter with a zero-length
      Parameter Value field would have a Length field of 4.  The
      Parameter Length does not include any padding bytes.

   Parameter Value: variable-length.

      The Parameter Value field contains the actual information to be
      transferred in the parameter.

   The total length of a parameter (including Type, Parameter Length and
   Value fields) MUST be a multiple of 4 bytes.  If the length of the
   parameter is not a multiple of 4 bytes, the sender pads the Parameter
   at the end (i.e., after the Parameter Value field) with all zero
   bytes.  The length of the padding is not included in the parameter
   length field.  A sender SHOULD NOT pad with more than 3 bytes.  The
   receiver MUST ignore the padding bytes.

Xie, Stewart                                                    [Page 4]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001


   The Parameter Types are encoded such that the highest-order two bits
   specify the action that must be taken if the processing endpoint does
   not recognize the Parameter Type.

   00 - Stop processing this ENRP message and discard it, do not process
        any further parameters within it.

   01 - Stop processing this ENRP message and discard it, do not process
        any further parameters within it, and report the unrecognized
        parameter in an 'Unrecognized Parameter Type' error.

   10 - Skip this parameter and continue processing.

   11 - Skip this parameter and continue processing but report the
        unrecognized parameter in an 'Unrecognized Parameter Type'
        error.

   In the following sections, we define the common parameter formats
   used in ENRP.


3.1.1 IPv4 Address Parameter

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Type = 0x1             |      Length = 8               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        IPv4 Address                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   IPv4 Address: 32 bits (unsigned integer)

      Contains an IPv4 address of the sending endpoint.  It is binary
      encoded.


3.1.2 IPv6 Address Parameter

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Type = 0x2         |          Length = 20          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                         IPv6 Address                          |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv6 Address: 128 bit (unsigned integer)


Xie, Stewart                                                    [Page 5]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

      Contains an IPv6 address of the sending endpoint.  It is binary
      encoded.


3.1.3 Pool Element Parameter

    This parameter is used in multiple ENRP message to represent an ASAP
    endpoint (i.e., a PE in a pool) and the associated information, such
    as its transport address(es), load control, and other operational
    status information of the PE.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Type = 0x3            |       Length=variable         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          SCTP Port            |    Number of IP addrs=k       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                        IP addr param #0                       :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                        IP addr param #1                       :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                             .....                             :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                        IP addr param #k                       :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Load Policy Type        |        Policy Value           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Registration Life                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Each of the IP address parameters in a PE parameter can be either
    an IPv4 or IPv6 address parameter.


3.1.4 Pool Handle Parameter

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Type = 0x4            |       Length=variable         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                         Pool Handle                           :
    :                                                               :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    This parameter holds a pool handle (i.e., a pool name), defined as
    a NULL terminated ASCII string.



Xie, Stewart                                                    [Page 6]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

3.1.5 Authorization Parameter

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Type = 0x5            |       Length=variable         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                   Authorization Signature                     :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    This parameter is used to hold an authorization signature. The
    signature is signed over the entire ASAP message and uses a
    preconfigured public/private key pair. The receiver of a message
    which includes this parameter can validate the message is
    from the sender by comparing the signature to one generated
    using the peers public key.


3.1.6 Name Server Identifier Parameter

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Type = 0x7            |          Length=variable      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Name Server SCTP Port   |          (reserved)           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                   IPv4 or IPv6 Addr Param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    When a name server is multi-homed, any one of its IP addresses can
    be used in its Server Identifier Parameter. This is because the
    combination of any one of its IP addresses and its SCTP port
    number always uniquely identifies the server.

3.2  ENRP Message Formats

   The figure below illustrates the common format for all ENRP
   messages. Each message is formatted with a Message
   Type field, a message-specific Flag field, a Message Length field, and a
   Value field.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Message Type  |   Msg Flags   |        Message Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      :                                                               :
      :                        Message Value                          :
      :                                                               :
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Xie, Stewart                                                    [Page 7]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001


   Message Type: 8 bits (unsigned integer)

      This field identifies the type of information contained in the
      Message Value field. It takes a value from 0 to 254.  The value
      of 255 is reserved for future use as an extension field.

      Message Types are encoded such that the highest-order two bits
      specify the action that must be taken if the message receiver
      does not recognize the Message Type.

      00 - Stop processing this message and discard it.

      01 - Stop processing this message and discard it, and report the
           unrecognized message in an 'Unrecognized Parameter Type'
           error.

      10 - reserved.

      11 - reserved.

   Message Flags: 8 bits

      The usage of these bits depends on the message type as given by
      the Message Type. Unless otherwise specified, they are set to
      zero on transmit and are ignored on receipt.

   Message Length: 16 bits (unsigned integer)

      This value represents the size of the message in bytes including
      the Message Type, Message Flags, Message Length, and Message
      Value fields. Therefore, if the Message Value field is
      zero-length, the Length field will be set to 4.  The Message
      Length field does not count any padding.

   Message Value: variable length

      The Message Value field contains the actual information to be
      transferred in the message.  The usage and format of this field
      is dependent on the Message Type.

   The total length of a message (including Type, Length and Value
   fields) MUST be a multiple of 4 bytes.  If the length of the
   message is not a multiple of 4 bytes, the sender MUST pad the
   message with all zero bytes and this padding is not included in the
   message length field. The sender should never pad with more than 3
   bytes.  The receiver MUST ignore the padding bytes.


3.2.1 PEER_PRESENCE message

     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

Xie, Stewart                                                    [Page 8]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x1  |0|0|0|0|0|0|0|R|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID param (optional)            :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    The receiving server's ID does not need to be included if the
    message is being multicasted.

    "Reply_required" (R) flag shall be set to '1' if response to this
    message is required, otherwise set to '0'.


3.2.2 PEER_NAME_TABLE_REQUEST message

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x2  |0|0|0|0|0|0|0|0|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID param (optional)            :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    The receiving server's ID does not need to be included if the
    message is being multicasted.

    (Editor's note: we may not support multicast of this message).


3.2.3 PEER_NAME_TABLE_RESPONSE message

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x3  |0|0|0|0|0|0|0|M|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID parameter                   :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                     Pool entry #1 (see below)                 :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                              ...                              :

Xie, Stewart                                                    [Page 9]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                     Pool entry #n (see below)                 :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    "More_to_send" (M) flag:

       shall be set to '1' if there are more pool entries to be sent
       in subsequent PEER_NAME_TABLE_RESPONSE messages. Otherwise, it
       shall be set to '0'.

    Pool entries:

       At least one pool entry MUST be present in the message. Each
       pool entry MUST start with a pool handle parameter, followed by
       one or more pool element (PE) parameters, i.e.:

                 +---------------------------+
                 :      Pool handle          :
                 +---------------------------+
                 :         PE #1             :
                 +---------------------------+
                 :         PE #2             :
                 +---------------------------+
                 :          ...              :
                 +---------------------------+
                 :         PE #n             :
                 +---------------------------+


3.2.4 PEER_NAME_UPDATE message

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x4  |0|0|0|0|0|0|0|0|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID param (optional)            :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                        Pool handle                            :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                                                               :
    :                        Pool Element                           :
    :                                                               :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Update action                           |

Xie, Stewart                                                   [Page 10]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    The receiving server's ID does not need to be included if the
    message is being multicasted.

    "Update_action" field:

       shall take one of the following values:

       0x0 - ADD_PE: add the PE as a new member to or update the PE in
             the named pool in the namespace.
       0x1 - DELETE_PE: delete the specified PE from the namespace.


3.2.5 PEER_LIST_REQUEST message

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x5  |0|0|0|0|0|0|0|0|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID param (optional)            :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    The receiving server's ID does not need to be included if the
    message is being multicasted.


3.2.6 PEER_LIST_RESPONSE message

    This message shall contain all the peer information of the sending
    server.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Type = 0x6  |0|0|0|0|0|0|0|R|        Message Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                  Sender's Server ID param                     :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :              Receiver's Server ID parameter                   :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                   ID of Peer Server #1                        :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                           ...                                 :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    :                   ID of Peer Server #n                        :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Xie, Stewart                                                   [Page 11]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    :                Authorization Parameter (optional)             :
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    "Reject" (R) flag:

        shall be set to '1' if the sender of this message is rejecting
        a peer list request. In such a case, this message MUST be sent
        with no peer server ID included.


4. ENRP Operation Procedures

    In this section, we discuss the procedures defined by ENRP. The
    procedures are divided into two groups, namely the basic ENRP
    operations and fault management procedures.

    Many of the Rserpool events call for message exchange and other
    activities between both a PE and an ENRP server and the ENRP server
    and its peers. But only the message exchange and activities between
    the ENRP server and its peers are considered within the ENRP
    protocol definition scope

    Procedures and message formats for communications between the PE
    and ENRP servers are defined in [ASAP]. However, in order to put
    our discussion in context, we will give brief description of the
    ASAP activities whenever appropreate.


4.1 Basic ENRP Operations

4.1.1 PE Registration

    ENRP server <-> PE:

    This action is part of the ASAP protocol and is defined in [ASAP].

    To register itself with the name space, a PE sends a REGISTRATION
    message over the ENRP client channel to its home ENRP server.

    In the REGISTRATION message, the PE indicates the name of the pool
    it wishes to join in a pool handle parameter, and its port number
    and network access address(es) and any load control information in
    a PE parameter.

    The ENRP server handles the REGISTRATION message according to the
    following rules:

    1) If the named pool does not exist in the namespace, the ENRP
    server will creates a new pool with that name in the namespace and
    add the PE to the pool as its first PE;

    2) If the named pool already exists in the namespace, but the
    requesting PE is not currently a member of the pool, ENRP server
    will add the PE as a new member to the pool;

Xie, Stewart                                                   [Page 12]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001


    3) If the named pool already exists in the namespace AND the
    requesting PE is already a member of the pool, the ENRP server
    shall consider this as a re-registration case. The ENRP Server
    shall replace the attributes of the existing PE with the
    information carried in the received REGISTRATION message.

    4) The ENRP server may reject the registration due to reasons such
    as invalid values, lack of resource, etc.

    In all cases, the ENRP server will reply to the requesting PE with
    a REGISTRATION_RESPONSE message, and will indicate in the message
    body whether the registration is granted or rejected.

    ENRP server <-> Its peers:

    If the registration request is granted (i.e., cases 1-3 above),
    the ENRP server MUST take the namespace modification action as
    described in section 4.1.5.1?. Otherwise, no message shall be
    exchanged with its peers.


4.1.2 PE De-registration

    ENRP server <-> PE:

    This action is part of the ASAP protocol and is defined in [ASAP].

    To remove itself from a pool, a PE sends a DEREGISTRATION message
    over the ENRP client channel to its home ENRP server.

    In response, the home ENRP server sends a REGISTRATION_RESPONSE
    message to the PE and indicates in the message body whether the
    request is granted or rejected.

    If the PE is the last one of the named pool, the home ENRP server
    will remove the pool from the namespace as well.

    The ENRP server may reject the de-registration request due to
    reasons such as invalid parameters, etc.

    It should be noted that de-registration does not stop the PE from
    sending or receiving application messages.

    ENRP server <-> peers:

    Once the de-registration request is granted and the PE removed from
    its local copy of the namespace, the home ENRP server MUST take the
    namespace modification action described in Section 4.1.5.2.


4.1.3 PE Re-registration

    A PE may re-register itself to the namespace with a new set of

Xie, Stewart                                                   [Page 13]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    attributtes in order to, for example, extend its registration
    life, change its load policy value.

    However, an existing PE MUST NOT change its access address list
    via re-registration. Instead, to change its address list a PE
    shall de-register itself first and then register with the
    namespace as a new PE.

    A PE can modify its load policy value at any time via
    re-registration. Based on the number of PEs in the pool and the
    pool's load distrbution policy, this operation allows the PE to
    dynamically control its share of inbound messages received by the
    pool (also see Section 4.5.2 in [ASAP] for more on load control).

    ENRP server <-> PE:

    This action is part of the ASAP protocol and is defined in [ASAP].

    To perform a re-registration, a registered PE shall simply send
    a new REGISTRATION message with a new set of attributes over the
    ENRP client channel to its home ENRP server.

    Upon the reception of this REGISTRATION message, the home ENRP
    server shall follow the same procedures described in Section
    4.1.1.

    ENRP server <-> peers:

    If the REGISTRATION message is accepted, the home ENRP server
    shall take the action described in Section 4.1.5.1?. Otherwise, no
    message shall be exchanged with its peers.


4.1.4 Name Translation

    ENRP server <-> PE or PU:

    This action is part of the ASAP protocol and is defined in [ASAP].

    A PE or PU can use the name translation service provided by the ENRP
    server to resolve a pool name to a list of accessible transport
    addresses of existing PEs.

    This requires the PE or PU to send a NAME_RESOLUTION messages to its
    home ENRP server and in the NAME_RESOLUTION message specify the pool
    name to be translated in a Pool Handle parameter.

    If the named pool exits in the namespace, the home ENRP server will
    send back a NAME_RESOLUTION_RESPONSE message that shall carry a
    list of PE parameters containing all information of the PEs
    currently registered under that pool name. This information may
    include the current load control policy of the pool, policy value
    of each PE, transport address(es) for each PE, etc.


Xie, Stewart                                                   [Page 14]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    Otherwise, the ENRP server shall respond with a NAME_UNKNOWN
    message.

    ENRP server <-> peers:

    None.


4.1.5 Server Namespace Update

    This includes a set of update operations used by an ENRP server to
    inform its peer(s) about the addition of a new PE, removal of an
    existing PE, or change of pool or PE properties.


4.1.5.1 Add/Update a PE

    When a new PE is granted registration to the namespace or an
    existing PE is granted a re-registration, the home ENRP server
    uses this procedure to inform all its peers.

    An ENRP server shall multicast over the ENRP server channel a
    PEER_NAME_UPDATE message with the Update_action field set to
    ADD_PE, indicating the addition of the new PE or the update of an
    existing PE to the namespace. The PE and the pool its belongs to
    shall be indicated in the message with a PE parameter and a Pool
    Handle parameter, respectively (see Section 3.2.4).

    Upon the reception of this PEER_NAME_UPDATE message, each of the
    peer ENRP servers shall take the following actions:

    1) If the named pool under which the PE has been registered (or
    re-registered) does not exist in the peer's local copy of the
    namespace, the peer ENRP server shall create the named pool in its
    local namespace copy and add the PE to it as the first PE. It then
    shall copy in all other attributes of the PE carried in the
    message.

    2) If the named pool already exists in the peer's local copy of the
    namespace AND the PE does not exist, the peer shall add the PE to
    the pool as a new PE and copy in all attributes of the PE carried
    in the message.

    3) If the named pool exists AND the PE is already a member of the
    pool in its the local copy of the namespace, the peer ENRP server
    shall replace the attributes of the PE with the new information
    carried in the message.


4.1.5.2 Remove a PE

    This procedure is used by an ENRP server to inform its peer(s) to
    remove an existing PE.


Xie, Stewart                                                   [Page 15]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    An ENRP server shall multicast over the ENRP server channel a
    PEER_NAME_UPDATE message with the Update_action field set to
    DELETE_PE, indicating the removal of an existing PE from the
    namespace. The PE and the pool its belongs to shall be indicated
    in the message with a PE parameter and a Pool Handle parameter,
    respectively.

    On the reception of this PEER_NAME_UPDATE message, each peer ENRP
    server shall find and remove the PE from its local copy of the
    namespace. If the peer does not find the PE in its local copy of
    the namespace, it SHOULD take no action.


4.1.6 Server Download Namespace from a Peer Server

    This operation allows an ENRP server to request and receive a copy
    of the current namespace from one of its peer ENRP servers.

    This operation is especially useful for a newly started ENRP server
    to initiate its local copy of the namespace, as well as for an
    existing ENRP server to correct namespace inconsistency found during
    its operation.

    1) An ENRP server shall first send a PEER_NAME_TABLE_REQUEST message
    directly to one of its peers.

    2) Upon the reception of this message, the peer server shall
    initiate a download session in which the namespace shall be sent
    to the requesting ENRP server in one or more
    PEER_NAME_TABLE_RESPONSE messages.

    If the sending ENRP server determines that multiple
    PEER_NAME_TABLE_RESPONSE messages are needed for the session, it
    shall use the M flag in each PEER_NAME_TABLE_RESPONSE message to
    inform the receiving ENRP server whether or not the data
    in this message is the last piece of the namespace transfer.

    3) During the downloading, every time the requesting ENRP server
    receives a PEER_NAME_TABLE_RESPONSE message, it shall transfer the
    data entries carried in the message into its local namespace
    database, and then check whether or not the data in this message is
    the last piece being transfered. If more data transfer is indicated,
    the requesting ENRP server shall send another
    PEER_NAME_TABLE_REQUEST message to the same peer to request for the
    next piece whenever it is ready.

    When unpacking the data entries from a PEER_NAME_TABLE_RESPONSE
    message into its local namespace database, the requesting ENRP
    server shall handle each PE by the following steps:

    1) If the named pool does not exist in the local namespace, the
    ENRP server will creates a new pool with that name in the
    namespace and add the PE to the pool as the first PE;


Xie, Stewart                                                   [Page 16]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    2) If the named pool already exists in the local namespace, but
    the PE is not currently a member of the pool, ENRP server shall
    add the PE as a new member to the pool;

    3) If the named pool already exists in the local namespace AND
    the requesting PE is already a member of the pool, the ENRP
    server may skip this PE.


4.1.7 Server Monitor Peer Status

    An ENRP server shall keep a record on the status of each of its
    known peers. This record is referred to as the "Peer list" of the
    server.

    An interanl variable <Peer-last-heared> is kept for each peer on
    the peer list and its value updated to the current local time each
    time a message of any type is received from the peer.

    If a message of any type is received from a peer previously
    unknown, the ENRP server shall create a record for the new peer
    and add it to the peer list.


4.1.8 Server Download Peer List from a Peer Server

    This operation allows an ENRP server to request from a peer server
    a copy of its peer list. This is useful for a new ENRP server to
    initiate its own peer list at startup.

    An ENRP server shall send a PEER_LIST_REQUEST message to a peer to
    request a copy of the peer list.

    Upon the reception of this message, the peer server shall reply
    with a PEER_LIST_RESPONSE message and include in the message body
    a list of server IDs of all known peers.

    If the peer itself is in the process of startup and not ready to
    provide a good peer list, it shall response with a
    PEER_LIST_RESPONSE message but set the R flag in the message to
    '1' to indicate that it can not grant the PEER_LIST_REQUEST. In
    such a case, the requesting ENRP server shall select another peer
    and repeat the peer list request with the new peer at a later
    time.


4.1.9 Server Initialization

    This section describes the steps a new ENRP server needs to take in
    order to join the other existing ENRP servers for providing the
    namespace service in the operation scope, or initiating the
    namespace service if this is the first ENRP server starting in the
    operation scope.


Xie, Stewart                                                   [Page 17]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    1) At startup, before getting into service, the ENRP server
    (initiating server) shall multicast a PEER_PRESENCE message with
    'Reply_required' flag set over the ENRP server channel. This is to
    inform any other existing peers in the operation scope about the
    initiating peer's presence.

    2) Upon the reception of this message, a peer shall send a
    PEER_PRESENCE without 'Reply_required' flag back to the initiating
    server, in order to help the initiating server to build a peer list.

    3) If no response to its PEER_PRESENCE message are received after
    <MAX-TIME-SERVER-HUNT> seconds, the initiating server shall assume
    that it is alone in the operation scope and shall mark the
    initialization process as completed. The initiation server shall
    skip the remaining steps and start to offer the namespace
    services.

    4) If there are responses to its PEER_PRESENCE message, the
    initiating server shall then take the actions described in 4.1.8 to
    request a peer list from one of the peers that have responded.

    5) Upon the reception of the PEER_LIST_RESPONSE message from the
    peer, the initiating server shall use the information carried in the
    message to build a complete peer list.

    6) Then, the initiating server shall request to download a copy of
    the namespace from one of the peer, as described in 4.1.6.

    At this point, the initialization process is completed and the
    initiating server shall start to provide namespace services.


4.2 Fault Management Operations

    The following operations are used to detect and recover from
    various system faults.


4.2.1 Detect and Remove an Unreachable PE

    Whenever a PE finds a peer PE unreachable (e.g., via an SCTP
    SEND.FAILURE Notification, see section 10.2 of [RFC2960]), the
    former shall send an ENDPOINT_UNREACHABLE message over the ENRP
    client channel to its home ENRP server. The message shall contain
    the pool handle and one of the transport addresses of the
    unreachable peer PE in a PE parameter.

    Note: The definition and procedure of ENDPOINT_UNREACHABLE message
    are part of ASAP and are described in [ASAP].

    Upon the reception of the ENDPOINT_UNREACHABLE message, the home
    ENRP server shall immediately send an ENDPOINT_KEEP_ALIVE message
    to the PE that is reported as unreachable. If this
    ENDPOINT_KEEP_ALIVE fails (i.e., it results in an SCTP

Xie, Stewart                                                   [Page 18]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    SEND.FAILURE notification), the ENRP server shall consider the PE
    as truly unreachable and shall remove the PE from its local copy
    of the namespace and take actions described in 4.1.5.2.

    Note: The definition and handling of the ENDPOINT_KEEP_ALIVE
    message by the PE are part of ASAP and are described in Sections
    3.2.8? and 4.9.3? in [ASAP].


4.2.2 Server Failure Detection by Heartbeat

    An ENRP server shall multicast, in every <PEER-HEARTBEAT-CYCLE>
    seconds, a PEER_PRESENCE message over the ENRP server channel to
    inform its peers that it is still operational. In the multicasted
    PEER_PRESENCE message, the sending ENRP server shall set the
    'Replay_required' flag to '0' indicating that no response is
    required.

    An ENRP server shall keep track the time when the last message
    (multicast or point-to-point) was received from each known peer in
    the internal variable <Peer-last-heared>.

    If a peer has not been heard for more than <MAX-TIME-LAST-HEARD>
    seconds, the ENRP server shall send a point-to-point PEER_PRESENCE
    with 'Reply_request' flag set to '1' to that peer.

    If the send fails or the peer does not reply after
    <MAX-TIME-NO-RESPONSE> seconds, the ENRP server shall consider
    the peer server dead and shall remove the peer from its peer list.

    When an ENRP server receives a PEER_PRESENCE message with
    'Reply_request' flag set to '1', it MUST immediately respond to
    the sender with its own point-to-point PEER_PRESENCE message
    without setting the 'Replay_required' flag.


4.2.3 PE or PU Discover Home ENRP Server

    This action is part of ASAP protocol and is defined in [ASAP].

    At its startup, or when it fails to send to (i.e., timed-out on a
    service request) with its current home ENRP server, a PE or PU shall
    initiate the following procedure to find a new home server.

    In the home server hunt procedure, the PE or PU shall multicast a
    SERVER_HUNT message over the ENRP client channel, and shall repeat
    sending this message every <TIMEOUT-SERVER-HUNT> seconds until a
    SERVER_HUNT_RESPONSE message is received from an ENRP server.

    Then the PE or PU shall pick one of the ENRP servers that have
    responded as its new home ENRP server, and send all its subsequent
    the namespace service requests to this new home server.

    Upon the reception of the SERVER_HUNT message, an ENRP server shall

Xie, Stewart                                                   [Page 19]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    reply to the PE with a SERVER_HUNT_RESPONSE message.


5.  Variables and Time Constants

5.1 Variables

    <Peer-last-heared> - the local time that a peer server was last
                         heard (via receiving either a multicast or
                         point-to-point message from the peer).

5.2 Timer Constants

    <PEER-HEARTBEAT-CYCLE> - the period for an ENRP server to send out a
                             heartheat message to its known peers.
                             (Default=30 secs.)

    <MAX-TIME-LAST-HEARD> - pre-set threshold for how long an ENRP
                            server will wait before considering a
                            silent peer server potentially dead.
                            (Default=61 secs.)

    <MAX-TIME-NO-RESPONSE> - pre-set threshold for how long a message
                             sender will wait for a response after
                             sending out a message. (Default=5 secs.)

    <TIMEOUT-SERVER-HUNT> - pre-set threshold for how long a sender
                            will wait before sending another
                            SERVER_HUNT message out. (Default=5 secs.)


6. Security COnsiderations

   [TBD]

7. References

    [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
    3", BCP 9, RFC 2026, October 1996.

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

    [ASAP] R. R. Stewart, Q. Xie: "Aggregate Server Access Protocol
    (ASAP)", <draft-ietf-rserpool-asap-00.txt>, work in progress.

    [RSERPOOL1] M. Tuexen, Q. Xie, R. R. Stewart, E. Lear, M. Shore,
    L. Ong, J. Loughney, M. Stillman: "Requirements for Reliable Server
    Pooling," <draft-ietf-rserpool-reqts-03.txt>, work in progress.

    [RSERPOOL2] M. Tuexen, Q. Xie, R. R. Stewart, E. Lear, M. Shore,
    L. Ong, J. Loughney, M. Stillman: "Architecture for Reliable Server
    Pooling," <draft-ietf-rserpool-arch-00.txt>, work in progress.


Xie, Stewart                                                   [Page 20]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001

    [RFC2960] R. R. Stewart, Q. Xie, K. Morneault, C. Sharp,
    H. J. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang, and,
    V. Paxson: "Stream Control Transmission Protocol," RFC 2960, October
    2000.


8. Acknowledgements

   The authors wish to thank John Loughney, Lyndon Ong, and Maureen
   Stillman and many others for their invaluable comments.

9.  Authors' Addresses

   Randall R. Stewart
   24 Burning Bush Trail.
   Crystal Lake, IL 60012
   USA

   Phone: +1-815-477-2127
   EMail: rrs@cisco.com


   Qiaobing Xie
   Motorola, Inc.
   1501 W. Shure Drive, #2309
   Arlington Heights, IL 60004
   USA

   Phone: +1-847-632-3028
   EMail: qxie1@email.mot.com



                    Expires in six months from Nov. 2001





















Xie, Stewart                                                   [Page 21]


Internet Draft      Endpoint Name Resoluton Protocol       November 2001
























































Xie, Stewart                                                   [Page 22]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/