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Versions: 00 01 02 03 04 05 06 07 08 RFC 6142

Network Working Group                                           A. Moise
Internet-Draft                                                J. Brodkin
Intended Status: Informational                       Future DOS R&D Inc.
Expires: February 7, 2011                                 August 7, 2010

          ANSI C12.22, IEEE 1703 and MC12.22 Transport Over IP

               draft-c1222-transport-over-ip-05.txt

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on February 7, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   to this document.

Abstract

   This RFC provides a framework for transporting ANSI C12.22/IEEE 1703/
   MC12.22 Advanced Metering Infrastructure (AMI) Application-Layer
   Messages on an IP network.



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Table of Contents

   1. Introduction.....................................................3
      1.1. Terminology.................................................3
      1.2. Definitions.................................................3
   2. The C12.22 IP Network Segment....................................7
      2.1. Composition of a C12.22 IP Network Segment..................7
      2.2. Native IP Address...........................................7
      2.3. Encoding of Native IP Addresses.............................8
      2.4. Standardized Port Numbers...................................9
      2.5. Use of UDP Source Port 0....................................9
      2.6. IP Multicast................................................9
      2.7. IP Broadcast...............................................12
      2.8. Encoding of Multicast and Broadcast Addresses..............12
   3. IP Message Transport............................................14
      3.1. C12.22 Connection Types and TCP/UDP Transport Modes........14
      3.2. IP Message Transport Details...............................15
         3.2.1. TCP and UDP Port Use..................................15
         3.2.2. Active-OPEN UDP (CL=1, CL Accept=0)...................15
         3.2.3. Passive-OPEN UDP (CL=1, CL Accept=1)..................16
         3.2.4. Active-OPEN TCP Mode (CO=1, CO Accept=0)..............16
         3.2.5. Passive-OPEN TCP Mode (CO=1, CO Accept=1).............17
         3.2.6. TCP and C12.22 Message Directionality.................17
      3.3. Using IP Broadcast/Multicast...............................18
      3.4. Transport Protocol Decisions...............................18
         3.4.1. Unicast Versus Multicast Versus Broadcast.............19
         3.4.2. Sending Large C12.22 APDUs Using UDP..................19
         3.4.3. Choice of Protocol for C12.22 Response APDUs..........19
      3.5. Quality of Service.........................................19
      3.6. Congestion Control.........................................20
   4. Security Considerations.........................................20
   5. IANA Considerations.............................................21
   6. References......................................................21
      6.1. Normative References.......................................21
   7. Acknowledgments.................................................23
   8. Authors' Addresses..............................................24















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1. Introduction

   The ANSI C12.22 standard [1] provides a set of application layer
   messaging services that are applicable for the enterprise and End
   Device components of an Advanced Metering Infrastructure (AMI) for
   the Smart Grid.  The messaging services are tailored for, but not
   limited to, the exchange of the data Tables Elements defined and co-
   published in ANSI C12.19 [2], IEEE P1377 [3], and MC12.19 [4].  These
   standards were developed jointly by ANSI (ANSI C12.22 and ANSI
   C12.19), by IEEE (IEEE 1377 and IEEE 1703) and Measurement Canada
   (MC12.19 and MC12.22).

   ANSI C12.22, which is an application-level messaging protocol, may be
   transported over any underlying transport network.  This RFC defines
   the requirements governing the transmission of ANSI C12.22 Messages
   via the TCP and UDP transports and the IP networking protocol.

1.1. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [5].

   Throughout this document we use terms like ANSI C12.22 or ANSI
   C12.19, as in C12.22 Relay or ANSI C12.19 Device.  These terms are
   interchangeable with the terms IEEE 1703 Relay and IEEE 1377 Device,
   respectively.  However, the recent versions of the Utility End Device
   communication standards were developed under the auspices of ANSI C12
   SC17 WG1 and ANSI C12 SC17 WG2.  For that reason, the terminology
   used in this document expands on the ANSI C12.22-2008 [1] and ANSI
   C12.19-2008 [2] definitions as revised by IEEE 1703-2009 [6] and IEEE
   1377-2010 [3].

1.2. Definitions

   This specification uses a number of terms to refer to the roles
   played by participants (actors) in, and objects of, the ANSI C12.22
   [1], IEEE 1703 [6], and MC12.22 [7] protocol.

   Terms prefixed by C12.22 or C12.19, which are not defined here, can
   be resolved in [1] [6] [7] or [2] [3] [4].

   ACSE

      Association Control Service Element.  In the context of this
      specification and of [1], ACSEs are encoded per ISO/IEC 10035-1
      [8] using the ASN.1 BER [9].




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   Active-OPEN UDP

      Active-OPEN UDP is a state used by a local C12.22 IP Node to
      expect and receive incoming C12.22 Messages from a foreign C12.22
      IP Node using the UDP protocol.  The local C12.22 IP Node SHALL
      solicit the incoming C12.22 Messages from the foreign C12.22 IP
      Node using the foreign C12.22 IP Node's registered Native IP
      Address.  The local C12.22 IP Node MAY exit Active-OPEN UDP state
      when it has received all of the expected C12.22 Messages or a
      C12.22 Message timeout has occurred.  The local C12.22 IP Node
      SHALL receive all C12.22 Response Messages solicited from the
      foreign C12.22 IP Node that arrive at the local port number that
      matches the source port number used to solicit the C12.22
      Messages from the foreign C12.22 IP Node.

   Active-OPEN TCP

      Active-OPEN TCP is a state used by a local C12.22 IP Node to
      establish a TCP connection with a fully-specified foreign C12.22
      IP Node using the TCP protocol and the foreign C12.22 IP Node's
      registered Native IP Address.  The Active-OPEN TCP state is
      identical to "local active OPEN" defined in [11].

   APDU

      Application Protocol Data Unit.  In the context of the ANSI
      C12.22 Application, it is an ACSE C12.22 Message.

   ACSE PDU

      ACSE Protocol Data Unit; same as APDU.

   ApTitle

      An ANSI C12.22 Application-process Title.  An ApTitle is a name
      for a system-independent application activity that exposes
      application services to the application agent; e.g., a set of
      application service elements that together perform all or part of
      the communication aspects of an application process.  An ApTitle
      is encoded as a unique registered (as per [1]) object identifier.

   C12.22 IP Node

      A C12.22 Node that is located on a C12.22 IP Network Segment and
      communicates using the IP protocol.






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   C12.22 IP Network Segment

      A collection of all C12.22 IP Nodes that implement the IP-based
      protocols, as defined in this specification, and can communicate
      with each other using IP routers, switches, and bridges and
      without the use of a C12.22 Relay.

   C12.22 IP Relay

      A C12.22 IP Node that performs the functions of a C12.22 Relay.
      A C12.22 IP Relay acts as a bridge between a C12.22 IP Network
      Segment and an adjacent, C12.22 Network Segment.

   C12.22 Message

      An APDU that is also a fully assembled or a segment of a C12.22
      Request Message or a C12.22 Response Message.  The C12.22 Message
      described in this specification MUST be encoded using [9].

   C12.22 Request Message

      A fully assembled C12.22 APDU that contains an ACSE user
      information element, which includes one or more EPSEM service
      requests.

   C12.22 Response Message

      A fully assembled C12.22 Message APDU that contains an ACSE user
      information element, which includes one or more EPSEM service
      responses.

   Connection

      A logical and physical binding between two or more users of a
      service (ref. [1]).

   EPSEM

      Extended Protocol Specification for Electronic Metering.  EPSEM
      defines structures and services used to encode multiple requests
      and responses for use by devices such as gas, water, electricity,
      and related electronic modules or appliances.

   Initiating C12.22 IP Node

      A role of a C12.22 IP Node in which it initiates the transmission
      of a C12.22 Request Message.




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   Native Address

      The term Native Address refers to the network address of a C12.22
      Node on its C12.22 Network Segment.  In this specification, the
      Native Address is the IP address plus the associated port number
      used in communications by a C12.22 IP Node on the C12.22 IP
      Network Segment.

   Native IP Address

      The binary IP address and the OPTIONAL port number used by a
      C12.22 IP Node to encode a Native Address in a C12.22 Message or
      in a C12.19 Table Element of an IP Node interface.

   Passive-OPEN UDP

      Passive-OPEN UDP is a state used by a local C12.22 IP Node to
      expect and receive incoming C12.22 Messages from any foreign
      C12.22 IP Node using the UDP protocol.  When the Passive-OPEN UDP
      state is active, the local C12.22 IP Node SHALL accept all C12.22
      Messages that arrive at the local port number that was registered
      by the local C12.22 IP Node.

   Passive-OPEN TCP

      Passive-OPEN TCP is a state used by a local C12.22 IP Node that
      wants to establish a TCP connection with an unspecified foreign
      C12.22 IP Node using the TCP protocol.  In this case any foreign
      C12.22 IP Node MAY connect to the local C12.22 IP Node as long as
      the local port matches the port used by the foreign C12.22 IP
      Node.  The Passive-OPEN TCP state is identical to "local passive
      OPEN" defined in [11].

   Responding C12.22 IP Node

      A role of a C12.22 IP Node in which it responds to the reception
      of a C12.22 Request Message.

   Target C12.22 IP Node

      The C12.22 IP Node that is the destination for a C12.22 Message.










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2. The C12.22 IP Network Segment

   This section defines the characteristics of the C12.22 IP Network
   Segment.

2.1. Composition of a C12.22 IP Network Segment

   A C12.22 Network Segment is a collection of C12.22 Nodes that can
   communicate with each other directly - without having to forward
   C12.22 Messages through a C12.22 Relay.

   A C12.22 IP Network Segment comprises C12.22 IP Nodes and the network
   infrastructure that enables any one node to reach all other nodes on
   the same segment.  All C12.22 IP Nodes on the C12.22 IP Network
   Segment employ the same IP address encoding scheme (per Figures 1 and
   2) and the same network and transport protocols in accordance with
   this specification.

   There is no restriction on the size of a C12.22 IP Network Segment.
   It MAY be as small as a single LAN or subnet, or it MAY include
   numerous, heterogeneous LANs and WANs connected by routers, bridges,
   and switches.  The C12.22 IP Network Segment MAY be completely
   private, or include communication across the global Internet.

2.2. Native IP Address

   The IP address and the port number of a C12.22 IP Node on a C12.22 IP
   Network Segment are collectively referred to as the Native IP
   Address.

   When the Native Address of a C12.22 IP Node is communicated within
   the payload of a C12.22 Message it SHALL be encoded as described in
   Section 2.3. Encoding of Native IP Addresses.

   The IP address of the C12.22 IP Node MUST be configured before the
   C12.22 IP Node attempts to send or receive any C12.22 Message on its
   C12.22 IP Network Segment.  If the port number is not explicitly
   configured by the controlling application, it SHALL be set to the
   default port number, 1153 (see Section 2.4. Standardized Port
   Numbers).

   It is beyond the scope of this specification to define the method of
   configuration, the configuration parameters, or any administrative
   controls that the system administrator may wish to implement to
   assign an IP address.






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2.3. Encoding of Native IP Addresses

   ANSI C12.22 defines binary fields for encoding a C12.22 Native
   Address for transport within C12.22 Messages.  In this RFC the fields
   SHALL contain an IPv4 or an IPv6 binary native IP network address
   that is followed by an OPTIONAL two-byte TCP or UDP port number.
   ANSI C12.22 allows these fields to be conveyed in select ANSI C12.22
   service elements (e.g., ANSI C12.22 Registration Service <native-
   address> parameter, ANSI C12.22 Resolve Service response <local-
   address>, and ANSI C12.19 INTERFACE_CTRL_TBL Element NATIVE_ADDRESS).
   The length of the C12.22 Native Address is qualified by an ANSI
   C12.22 address length field (e.g., ANSI C12.22 Registration Service
   <address-length> parameter, ANSI C12.22 Resolve Service response
   <local-address-length>, and ANSI C12.19 ACT_NETWORK_TBL Element
   NATIVE_ADDRESS_LEN).

   The binary Native IP Address fields SHALL be encoded in network byte
   order as shown in Figure 1.

               Actual     Native IP Address (ADDR) and Port (P)
               Length                   Octet
                           0                   1
                           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-
   IPv4          4        | ADDR4 |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   IPv4 + port   6        | ADDR4 | P |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   IPv6         16        |             ADDR6             |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   IPv6 + port  18        |             ADDR6             | P |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 1:  Encoding of the Native IP Addresses for ANSI C12.22

   When an ANSI C12.22 Native Address is encoded in ANSI C12.19 Tables'
   BINARY data Elements then the size of the native address Element is
   defined by ACT_NETWORK_TBL.NATIVE_ADDRESS_LEN (See [1] [2] Table
   121).  This is the actual number of octets that are placed inside the
   C12.19 BINARY Element.  This value is common to all of the C12.22
   Node's interfaces, including those that are not IP based (thus not
   conforming to this specification).  For this reason the



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   ACT_NETWORK_TBL.NATIVE_ADDRESS_LEN MAY be greater than, and SHALL NOT
   be smaller than, the actual length needed to encode a Native IP
   Address per Figure 1.  When this is the case, the C12.22 Native IP
   Address SHALL be padded with zero (0) to fill the Table's BINARY data
   Element.

2.4. Standardized Port Numbers

   IANA (Internet Assigned Numbers Authority) has assigned port 1153 for
   UDP [10] and TCP [11] C12.22 IP Messages.

   By default, C12.22 IP Nodes SHALL send all C12.22 Application
   Association initiation message requests set with 1153 as the
   destination port number.

   To ensure interoperability among C12.22 IP Nodes, all C12.22 IP
   Relays and Master Relays SHALL monitor and accept UDP and TCP
   messages destined to port 1153.

   Any IP firewalls or Access Control Lists (ACLs) shielding a C12.22
   device MUST be configured to forward UDP and TCP traffic destined to
   port 1153 and other ports that are assigned and registered by the
   Network administrator, in order to maintain the continuity of the
   C12.22 IP Network Segment.

2.5. Use of UDP Source Port 0

   Although [10] allows for a source port number of zero (0), C12.22 IP
   Nodes SHALL NOT send datagrams on UDP with the source port set to
   zero.  A C12.22 IP Node SHALL ignore and SHALL NOT respond to any
   C12.22 Message that it receives from source port 0.

   Further details of C12.22 IP Node's use of UDP, and of TCP, are given
   in Section 3. IP Message Transport.

2.6. IP Multicast

   In addition to unicast, the ANSI C12.22 protocol requires the support
   of a multicast message delivery service from the network.  In cases
   where C12.22 IP Nodes MUST perform Native IP Address discovery (e.g.,
   the discovery of the Native IP Address of C12.22 IP Relays that
   provide a route out of the C12.22 IP Network Segment, or the
   discovery of the Native IP Address of a C12.22 IP Master Relay on the
   C12.22 IP Network), the C12.22 IP Nodes uses IP Multicast to send a
   C12.22 Message that contains an EPSEM Resolve Service Request on the
   IP LAN.





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   IP multicast is also desirable, for example, when a C12.22 Host needs
   to read a multitude of C12.22 Nodes (e.g., meters) that are
   configured with a common C12.22 multicast group ApTitle.  Using IP
   multicast, the C12.22 Host MAY send a C12.22 Message containing an
   EPSEM Read Service Request that reaches all C12.22 Nodes on the
   C12.22 IP Network Segment.

   For these reasons, all C12.22 IP Relays and Master Relays SHALL
   support IP multicast and it is RECOMMENDED that all C12.22 Nodes
   support IP multicast.  Any IPv4 C12.22 IP Node that supports IP
   multicast SHALL use the Internet Group Management Protocol IGMP
   version 1 (IGMPv1) [12] as a minimum, to report (i.e., request)
   membership in the C12.22 multicast group to its local router(s).
   It is RECOMMENDED that C12.22 IP Nodes implement IGMPv3 [13].

   Any IPv6 C12.22 IP Node that supports IP multicast SHALL use
   Multicast Listener Discovery version 2 (MLDv2) (RFC 3810 [14]
   possibly within ICMPv6 RFC 4443 [15]) to report membership.

   Routers that interconnect C12.22 IP Nodes on the C12.22 IP Network
   Segment, MUST support Protocol Independent Multicast Sparse Mode (PIM
   SM) (RFC 4601 [16]) along with IGMPv1 (RFC 1112 [12]) as a minimum
   for IPv4, or MLDv2 for IPv6 (RFC 3810 [14]).  It is RECOMMENDED that
   they implement IGMPv3 [13].  It is beyond the scope of this
   specification to define the mechanism for selecting an initial
   Rendezvous Point (RP) for the C12.22 multicast group, the use of
   shared versus source trees, or the mechanism for inter-domain
   multicast routing.

   IANA has registered the "All C1222 Nodes" multicast group, and has
   assigned the IPv4 multicast address of 224.0.2.4 and the IPv6
   multicast address of FF0X::204, where X represents the Scope field as
   defined in RFC 4291, the IP Version 6 Addressing Architecture [17].

   For IPv6, all C12.22 IP Relays, C12.22 IP Master Relays, and all
   C12.22 IP Nodes configured to support broadcast and multicast (see
   Section 3.3. Using IP Broadcast/Multicast) SHALL join the global
   scope multicast address, FF0E::204, as well as all of the assigned,
   reduced scope, multicast addresses:

       link-local         - FF02::204;
       admin-local        - FF04::204;
       site-local         - FF05::204; and
       organization-local - FF08::204.

   IPv6 C12.22 IP Nodes SHOULD use the minimum scope needed, when
   initiating IP multicast messages to reach another C12.22 IP Node on




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   the C12.22 Network.  This practice allows the sender to limit
   unnecessary propagation of C12.22 IP multicast Messages.

   To determine the minimum scope required to reach the closest C12.22
   IP Relay on the C12.22 Node's IP Network Segment, this specification
   RECOMMENDS the following simple steps:

     1. Starting with the smallest (local-most) scope, link-local (or a
        pre-configured scope), send the C12.22 EPSEM Resolve Service
        Request for C12.22 IP Relay discovery.
     2. Listen for a response from a C12.22 IP Relay; then:
          a. If no response is received, assign the next wider scope
             level, then repeat steps (1) and (2) at the newly
             assigned scope.
          b. If a response is received then record the scope level as
             the minimum scope to use on the node's C12.22 IP Network
             Segment.

   A C12.22 IPv6 Node that initiates any EPSEM Service Request SHOULD
   use the minimum scope necessary to reach its target C12.22 IP Nodes.
   A C12.22 IPv6 Relay SHALL use the global scope for any C12.22 message
   destined for the global Internet.

   This specification does not preclude the use of the unassigned scope
   values defined in [17]; those scope values MAY be used on a private
   basis, or through mutual operating agreements.

   For IPv4, all C12.22 IP Relays, C12.22 IP Master Relays, and all
   C12.22 IP Nodes configured to support broadcast/multicast SHALL join
   the assigned multicast address of 224.0.2.4.  This global address
   does not provide for the type of scoping discussed above for IPv6,
   nor is it compatible with the administratively scoped IP multicast
   specification in RFC 2365 [18].  Therefore, a different technique to
   limit the propagation of C12.22 IP multicast Messages is needed.  One
   available technique to control IPv4 multicast scope is through the
   use of the Time-to-Live (TTL) attribute in the IP packet header.
   This attribute is not managed by the C12.22 protocol.

   In the implementation of this technique, an administrative domain
   MUST include at least one C12.22 IP Relay, and all C12.22 IP Nodes in
   the administrative domain SHOULD be configured with a TTL
   sufficiently large to reach that C12.22 IP Relay.  A TTL threshold
   SHOULD be defined and configured on all border routers linking the
   administrative domain to the global Internet such that the routers
   forward on their Internet interfaces only those 224.0.2.4 multicast
   packets that have a TTL exceeding the threshold value.





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   A C12.22 IPv4 Node that initiates any C12.22 Request Message SHOULD
   use the minimum TTL needed to reach its target C12.22 IP Nodes.  A
   C12.22 IPv4 Relay SHOULD use a TTL that exceeds the threshold for any
   C12.22 message destined for the global Internet.

2.7. IP Broadcast

   IP broadcast is not generally suitable as a replacement for, or an
   alternative to multicast in a C12.22 IP Network Segment.  IP
   broadcast is not supported in IPv6 and it suffers from limited scope
   in IPv4.  This specification, however, does not preclude the use of
   IP network directed or limited/local scope (address 255.255.255.255)
   broadcast, and specifies a minimum requirement in Section 2.8.
   Encoding of Multicast and Broadcast Addresses.

2.8. Encoding of Multicast and Broadcast Addresses

   ANSI C12.22 Tables provide binary Elements for encoding a Native
   Broadcast or Multicast Address for transport within a C12.22 Message.
   The encoding of these Table Elements is identical to that defined is
   Section 2.3. Encoding of Native IP Addresses.  These fields SHALL be
   used as shown in Figure 2.





























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               Actual           IP Address (ADDR) and Port (P)
               Length                     Octet
                           0                   1
                           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
   IPv4                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Broadcast     4        |BADDR4 |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv4                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Broadcast     6        |BADDR4 | P |
   +Port                  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv4                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Multicast     4        |MADDR4 |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv4                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Multicast     6        |MADDR4 | P |
   +Port                  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv6                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Multicast    16        |            MADDR6             |
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv6                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Multicast    18        |            MADDR6             | P |
   +Port                  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2:  Encoding of broadcast/multicast native IP addresses

   The IPv4 and IPv6 multicast addresses, MADDR4 and MADDR6,
   respectively, are those assigned by IANA for use by ANSI C12.22.

   When a broadcast/multicast Native IP Address is encoded in ANSI
   C12.19 Tables' BINARY data Elements the size of the Native Address
   Element transmitted is defined by ACT_NETWORK_TBL.NATIVE_ADDRESS_LEN
   (See [1] [2] Table 121).  This is the actual number of octets that
   are placed inside the C12.19 BINARY Element.  This value is common to
   all of the C12.22 Node's interfaces, including those that are not IP
   based (thus not conforming to this specification).  For this reason
   the ACT_NETWORK_TBL.NATIVE_ADDRESS_LEN MAY be greater than, and SHALL
   NOT be smaller than, the actual length needed to encode a native IP
   broadcast/multicast address per Figure 2.  When this is the case, the
   C12.22 Native IP Address SHALL be padded with zero (0) to fill the
   Table's BINARY data Element.

   The IPv4 network directed broadcast address can be computed by
   performing a bitwise OR between the bit complement of the subnet mask



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   of the target IP subnet and the IP address of any host on that IP
   subnet.

3. IP Message Transport

   This section defines a C12.22 Node's usage of the Connection-Oriented
   (CO) and Connectionless (CL) transport layer protocols, TCP and UDP,
   respectively.

3.1. C12.22 Connection Types and TCP/UDP Transport Modes

   A C12.22 IP Node's use of TCP and UDP is based on its registered
   capabilities as defined in its configuration parameters (flags) and
   as expressed in the Node's accepted registration attributes [1]:

       CL Flag = <connection-type>.CONNECTIONLESS_MODE_SUPPORTED;
       CL Accept Flag = <connection-type>.ACCEPT_CONNECTIONLESS;
       CO Flag = <connection-type>.CONNECTION_MODE_SUPPORTED; and
       CO Accept Flag = <connection-type>.ACCEPT_CONNECTIONS.

   The mapping of the connection-type parameters to the type of TCP and
   UDP transports that a C12.22 Node MAY support is defined in Table 1.

        Table 1:  C12.22 Node Parameters to IP Transport Mapping

    CL   CO   CL Accept  CO Accept
   Flag Flag    Flag      Flag        IP Transport Mode Supported
   ---- ----    ----      ----   --------------------------------------
    0    0       x         x     Invalid
    0    1       0         0     TCP, Active-OPEN
    0    1       0         1     TCP, Passive- and Active-OPEN
    0    1       1         0     Invalid
    0    1       1         1     Invalid
    1    0       0         0     UDP, Active-OPEN
    1    0       0         1     Invalid
    1    0       1         0     UDP, Passive- and Active-OPEN
    1    0       1         1     Invalid
    1    1       0         0     UDP, Active-OPEN; TCP Active-OPEN
    1    1       0         1     UDP, Active-OPEN;
                                 TCP, Passive- and Active-OPEN
    1    1       1         0     UDP, Passive- and Active-OPEN;
                                 TCP, Active-OPEN
    1    1       1         1     UDP, Passive- and Active-OPEN;
                                 TCP, Passive- and Active-OPEN
   --------------------------------------------------------------------

   Every C12.22 IP Node MUST support at least one of unicast CO or CL
   operating capabilities (as advertized in Decade 12, Network Tables



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   [1], where available, and as registered using the C12.22 Registration
   Service [1]).

3.2. IP Message Transport Details

3.2.1. TCP and UDP Port Use

   General rules:

      1. A C12.22 IP Node that implements [CL Accept=1] SHALL receive
        incoming UDP C12.22 Messages on its registered Native IP
        Address (IP address and port number).

      2. A C12.22 IP Node that implements [CO Accept=1] SHALL receive
        incoming TCP connections on its registered Native IP Address
        (IP address and port number).

      3. A C12.22 IP Relay that forwards a UDP C12.22 Message to a
        C12.22 IP Node on the C12.22 IP Network Segment SHALL send the
        C12.22 Message to the C12.22 IP Node's registered Native IP
        Address (IP address and port number).

      4. A C12.22 IP Relay that forwards a TCP C12.22 Message to a
        C12.22 IP Node on the C12.22 IP Network Segment MAY use an
        established TCP connection to that C12.22 IP Node, or it SHALL
        establish a new TCP connection to the C12.22 IP Node's
        registered Native IP Address (IP address and port number).

      5. A C12.22 IP Node that implements [CL=1] SHOULD set the source
        port number in outbound UDP C12.22 Messages to its registered
        port number.  When the target UDP C12.22 IP Node is reachable
        using direct messaging (as defined in [1]), the C12.22 IP Node
        MAY set the source port number to a UDP port number that is
        difference than the its registered port number.

      6. When the registered Native IP Address of a C12.22 IP Node does
        not include the OPTIONAL port number, then port 1153 SHALL be
        assumed and used as the registered port number.

      7. All C12.22 IP Nodes SHOULD use port 1153 in their Native IP
        Address when registering.

3.2.2. Active-OPEN UDP (CL=1, CL Accept=0)

   A C12.22 IP Node that supports this mode SHALL NOT monitor for
   unsolicited incoming C12.22 Messages via UDP.  As a result, the
   C12.22 IP Node is incapable of receiving unsolicited C12.22 Messages
   using UDP.



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   The C12.22 IP Node MAY enter the Active-OPEN UDP state by initiating
   an unsolicited UDP transmission to a Target C12.22 IP Node, which is
   expected to implement the Passive-OPEN UDP mode.

   C12.22 IP Nodes SHOULD use their registered UDP port number, or if
   not yet registered then they SHOULD use port 1153, as the source port
   number for all UDP C12.22 IP Messages.


3.2.3. Passive-OPEN UDP (CL=1, CL Accept=1)

   A C12.22 IP Node that operates in this mode SHALL be capable of
   receiving solicited and unsolicited C12.22 Messages from other C12.22
   IP Nodes.  The C12.22 Node MAY change the port number that it
   monitors by using the <native-address> parameter of the ANSI C12.22
   Registration Service.  The C12.22 IP Node MAY initiate unsolicited
   Active-OPEN UDP transmissions to other C12.22 IP Nodes that implement
   the Passive-OPEN UDP mode.

   When operating in this mode, the C12.22 IP Nodes SHALL use their
   registered UDP port number as the source port number for all UDP
   C12.22 IP Messages.

   All C12.22 IP Relays SHALL support the Passive-OPEN UDP mode.  C12.22
   Authentication Hosts and C12.22 Notification Hosts that implement UDP
   SHALL support Passive-OPEN UDP mode.  For all other C12.22 IP Nodes,
   Passive-OPEN UDP mode is the RECOMMENDED mode when implementing UDP.

3.2.4. Active-OPEN TCP Mode (CO=1, CO Accept=0)

   A C12.22 IP Node that supports this mode SHALL NOT monitor for
   inbound TCP connections.  As a result, the node is incapable of
   accepting incoming connections via TCP.  The C12.22 IP Node MAY
   initiate TCP connections to Target C12.22 IP Nodes, which are
   expected to implement the Passive-OPEN TCP mode.

   In this mode, C12.22 Messages exchanged by a pair of associated
   C12.22 IP Nodes can only be communicated through any of the TCP
   connections that were initiated by the C12.22 IP Node that implements
   this mode.  The loss or closure of a connection SHALL NOT
   automatically result in the termination of the C12.22 associations
   between the peer nodes.  In order to continue exchanging C12.22
   Messages without loss of association, the initiating C12.22 IP Node
   MAY re-establish new TCP connections with the peer node, or use
   existing connections to the peer node.  The termination of the C12.22
   Application associations is dependent upon C12.22 application timeout




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   attributes and C12.22 link management services (such as Procedure 25
   Network Interface Control [1]).

3.2.5. Passive-OPEN TCP Mode (CO=1, CO Accept=1)

   A C12.22 IP Node that operates in this mode SHALL monitor and accept
   incoming TCP connections.  The C12.22 Node May change the port number
   that it monitors by using the <native-address> parameter of the ANSI
   C12.22 Registration Service.  The C12.22 IP Node MAY initiate Active-
   OPEN TCP connections to other C12.22 IP Nodes that implement the
   Passive-OPEN TCP mode.

   In this mode, C12.22 Messages exchanged by a pair of associated
   C12.22 IP Nodes can arrive through any of the TCP connections that
   were established by either node.  The loss or closure of a connection
   SHALL NOT automatically result in the termination of the C12.22
   associations between the peer nodes.  In order to continue exchanging
   C12.22 Messages without loss of association, either C12.22 IP Node
   MAY re-establish new TCP connections with the peer node, or use
   existing connections to the peer node.  The termination of the C12.22
   Application associations is dependent upon C12.22 application timeout
   attributes and C12.22 link management services (such as Procedure 25
   Network Interface Control [1]).

   All C12.22 IP Relays SHALL support the Passive-OPEN TCP mode.  C12.22
   Authentication Hosts and C12.22 Notification Hosts that implement TCP
   SHALL support Passive-OPEN TCP mode.  For all other C12.22 IP Nodes,
   Passive-OPEN TCP mode is the RECOMMENDED mode when implementing TCP.

3.2.6. TCP and C12.22 Message Directionality

   C12.22 IP Nodes MAY use TCP in one of two ways: bi-directional
   traffic flow or uni-directional traffic flow.

   When TCP connections are used, any new or established TCP connection
   between the two C12.22 IP Nodes MAY be used equivalently by the
   C12.22 IP Nodes to send and to receive C12.22 Messages.  This is the
   RECOMMENDED and default mode of operation, because ANSI C12.22
   requires the transport network to be reliable and connectionless (per
   connectionless-mode ACSE).  For this reason ANSI C12.22 defines peer-
   to-peer application associations and not peer-to-peer connections.

   It is known that some C12.22 implementations have been deployed in
   which TCP is used for uni-directional traffic flow.  For these types
   of implementations, an established TCP connection SHALL be used by
   the initiator of that connection to send C12.22 Messages and by the
   target node (who accepted the connection) to receive C12.22 Messages.
   If a C12.22 IP Node wishes to send a C12.22 Message to a peer C12.22



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   IP Node, it MUST establish and use a new TCP connection or use an
   existing TCP connection that it had previously initiated, for its
   outbound uni-directional traffic flow.

   For increased interoperability, the initiator of the connection
   SHOULD accept incoming C12.22 Messages on that connection in case the
   target node attempts to use the connection for bi-directional traffic
   flow.

   Uni-directional use of TCP is a special mode of operation; it is NOT
   RECOMMENDED because multiple one-way channel communication is not
   described by ANSI C12.22, and it utilizes one-half of the TCP
   connection capability.  As a result it doubles the number of TCP
   connections used to communicate C12.22 Messages, and thus could
   become a burden when a large number of connections is required.

3.3. Using IP Broadcast/Multicast

   A C12.22 IP Node's use of Broadcast/Multicast is based on its
   capabilities as defined in its configuration parameters (flags) and
   as expressed in the Node's accepted registration attributes [1]
   (<connection-type>.BROADCAST_AND_MULTICAST_SUPPORTED).  The mapping
   of the C12.22 IP Node's Broadcast/Multicast parameter (flag) to IP
   Broadcast/Multicast usage is defined in Table 2.

        Table 2:  C12.22 to IP Broadcast/Multicast Mapping

   C12.22 Broadcast and
   Multicast Supported
          Flag                  IP Broadcast/Multicast Supported
          ----         -------------------------------------------------
           0           The C12.22 IP Node does not accept IP broadcast
                       and it does not accept IP multicast messages.
           1           The C12.22 IP Node accepts both IP broadcast
                       (IPv4 only) and IP multicast messages (IPv4 and
                       IPv6).

   If a C12.22 IP Node is configured to accept IP broadcast and
   multicast messages, it SHALL join the "All C1222 Nodes" multicast
   group (see Section 2.6. IP Multicast), and SHALL use the default port
   1153.  In addition it SHALL accept IP Network directed or limited
   (local scope) broadcast messages sent to port 1153.  Note that
   successful communication using network directed broadcast requires
   configuration of network routers, which by default SHALL NOT forward
   directed broadcasts as per RFC 2644 [19].

3.4. Transport Protocol Decisions




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3.4.1. Unicast Versus Multicast Versus Broadcast

   An initiating C12.22 IP Node MAY send any C12.22 Message using UDP or
   TCP.  However, in accordance with Section 5.3.2.4.12, Resolve
   Service, of ANSI C12.22, it is RECOMMENDED that the C12.22 Resolve
   Request message be transported using UDP/IP multicast when the Native
   IP Address of the Target C12.22 Node is not known.  Use of UDP/IP
   multicast is preferred over the use of IP network directed or limited
   broadcast; therefore when UDP/IP multicast is supported its use is
   RECOMMENDED over network broadcast.

3.4.2. Sending Large C12.22 APDUs Using UDP

   When sending a large C12.22 Message that exceed the path MTU via UDP,
   the sender SHALL segment the ACSE PDU in accordance with ANSI C12.22
   Datagram Segmentation and Reassembly algorithm, such that the size of
   resulting IP datagram does not exceed the path MTU, thus avoiding UDP
   packet fragmentation.  The fundamental issue with fragmentation
   exists for both IPv4 and IPv6.  Section 3.2 of RFC 5405 [20] provides
   additional guidelines for determining the appropriate UDP message
   side.  When path MTU is not known, the sender SHALL follow the
   guidelines stipulated in Section 3.2 of RFC 5405 [20]: for IPv4 use
   the smaller of 576 bytes and the first-hop MTU [21], and for IPv6 use
   1280 bytes [22]. Sending large APDUs via UDP may lead to network
   congestion. For more information on avoiding network congestion see
   Section 3.6. Congestion Control.

3.4.3. Choice of Protocol for C12.22 Response APDUs

   When a Target C12.22 IP Node receives a C12.22 Request Message from
   an initiating C12.22 IP Node, it SHALL send a C12.22 Response Message
   using the same transport protocol (i.e., TCP to TCP, UDP to UDP).

   In the case of UDP, the target SHALL send the C12.22 Response Message
   to the source IP address and port number.

3.5. Quality of Service

   The ANSI C12.22 standard provides a configuration parameter in the
   APDU's <calling-AE-qualifier>.URGENT to mark a message as urgent.
   There are numerous IP-based technologies that enable enhanced levels
   of message delivery and quality of service.  This specification does
   not define the technology to be used to send urgent messaged over IP.








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3.6. Congestion Control

   Designers of unicast applications that implement the upper-layers of
   C12.22 Messaging over UDP SHOULD follow the congestion control
   guidelines in Section 3.1 of RFC 5405 [20].

   For the transmission of C12.22 Messages that are greater than the TCP
   initial window would be over a given Internet path, TCP SHOULD be
   used rather than UDP as the transport protocol.  TCP's initial window
   depends on the MSS, which in turn depends on the path MTU, and is
   computed according to formula (1) in RFC 3390 [23]. For unknown path
   MTUs, the minimum-sized MSS MUST be used and the C12.22 Application
   SHOULD assume the maximum C12.22 Message size to be 2048 bytes. By
   using TCP the C12.22 Application benefits from the built-in TCP
   congestion control mechanism.

   When UDP is the preferred transport mechanism or when UDP multicast
   or broadcast are the preferred modes of communication, then the
   C12.22 application SHOULD use C12.22 acknowledged Messages that are
   smaller than TCP's initial window over the return path, as computed
   by formula (1) in [23] and described above. The size of the C12.22
   Message MAY be managed through the use of ANSI C12.22 EPSEM Partial
   Table Read/Write service requests and responses.

4. Security Considerations

   The ANSI C12.22 Application layer security is defined in Section
   5.3.4.13, C12.22 Security Mechanism, of the ANSI C12.22 standard.
   The security mechanisms include provisions for AES-128/EAX message
   privacy and authentication, playback rejection, and message
   acceptance windows as well as ANSI C12.19 [2] role-based data access
   and secured register mechanisms.  Additional Transport or Network
   layer security protocols are not required but MAY be provided
   transparently by network integrators.  However, any added Transport
   or IP Network security features SHALL act only to enhance and
   preserve (i.e., not be a substitute for, or an alteration of) the
   ANSI C12.22 and ANSI C12.19 (interoperable) security provisions.














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5. IANA Considerations

   UDP and TCP port 1153, which is used for C12.22 communication over
   IP, is registered with IANA.

   Section 2.6. IP Multicast defines the use of multicast.  The
   following multicast addresses have been registered by IANA for use by
   the ANSI C12.22 standard:

      IPv4 - "All C1222 Nodes" address 224.0.2.4

      IPv6 - "All C1222 Nodes" address FF0X::204

6. References

6.1. Normative References

   [1]   ANSI, "Protocol Specification for Interfacing to Data
         Communication Networks", ANSI C12.22-2008, approved January
         9, 2009.

   [2]   ANSI, "Utility Industry End Device Data Tables", ANSI C12.19-
         2008, approved February 24, 2009.

   [3]   IEEE, "Draft Standard for Utility Industry Metering
         Communication Protocol Application Layer (End Device Data
         Tables)", IEEE P1377/D6, May 2010.

   [4]   Measurement Canada, "Draft Specification for Utility Industry
         Metering Communication Protocol Application Layer (End Device
         Data Tables)", MC12.19, 2010.

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

   [6]   IEEE, "Standard for Local Area Network/Wide Area Network
         (LAN/WAN) Node Communication Protocol to Complement the
         Utility Industry End Device Data Tables", IEEE 1703/D5,
         revised May 2010.

   [7]   Measurement Canada, "Draft Specification for Local Area
         Network/Wide Area Network (LAN/WAN) Node Communication
         Protocol to Complement the Utility Industry End Device Data
         Tables", MC12.22, 2010.







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   [8]   ISO/IEC, "Information Technology-Open Systems
         Interconnection-Connectionless Protocol for the Association
         Control Service Element: Protocol Specification", ISO/IEC
         10035-1, 1995.

   [9]   ISO/IEC, "Information Technology-ASN.1 Encoding Rules:
         Specification of Basic Encoding Rules (BER), Canonical
         Encoding Rules (CER) and Distinguished Encoding Rules (DER)",
         ISO/IEC 8825-1, 2002.

   [10]  Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
         1980.

   [11]  Postel, J., "Transmission Control Protocol", STD 7, RFC 793,
         September 1981.

   [12]  Deering, S.E., "Host extensions for IP multicasting", STD 5,
         RFC 1112, August 1989.

   [13]  Cain, B., Deering, S., Kouvelas, I., Fenner, B., Thyagarajan,
         A., "Internet Group Management Protocol, Version 3", RFC
         3376, October 2002.

   [14]  Vida, R., Costa, L., "Multicast Listener Discovery Version 2
         (MLDv2) for IPv6", RFC 3810, June 2004.

   [15]  Conta, A., Deering, S., Gupta, M., "Internet Control Message
         Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6)
         Specification", RFC 4443, March 2006.

   [16]  Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
         "Protocol Independent Multicast - Sparse Mode (PIM-SM):
         Protocol Specification (Revised)", RFC 4601, August 2006.

   [17]  Hinden, R., Deering, S., "IP Version 6 Addressing
         Architecture", RFC 4291, February 2006.

   [18]  Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
         RFC 2365, July 1998.

   [19]  Senie, D., "Changing the Default for Directed Broadcasts in
         Routers", BCP 34, RFC 2644, August 1999.

   [20]  Eggert, L., Fairhurst, G., "Unicast Usage Guidelines for
         Application Designers", BCP 145, RFC 5405, November 2008.

   [21]  Braden, R., "Requirements for Internet Hosts -- Communication
         Layers", RFC 1122, October 1989.



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   [22]  Deering, S., Hinden, R., "Internet Protocol, Version 6 (IPv6)
         Specification", RFC 2460, December 1998.

   [23]  Allman, M., Floyd, S., Partridge, C., "Increasing TCP's
         Initial Window", RFC 3390, October 2002.

7. Acknowledgments

   The authors wish to recognize Alexander Shulgin for providing
   valuable comments and for conducting feasibility testing in support
   of this work.

   The following people have improved this document through thoughtful
   comments and suggestions: Fred Baker, Ralph Droms, Vijay Gurbani,
   Michael Stuber, Spencer Dawkins, Alfred Hoenes, Russ Housley, Paul
   Hoffman, Lars Eggert and Sean Turner.


































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8. Authors' Addresses

   Avygdor Moise
   Future DOS R&D Inc.
   #303 - 6707 Elbow Drive SW
   Calgary, Alberta, T2V 0E5
   Canada

   Email:  avy@fdos.ca


   Jonathan Brodkin
   Future DOS R&D Inc.
   #303 - 6707 Elbow Drive SW
   Calgary, Alberta, T2V 0E5
   Canada

   Email:  jonathan.brodkin@fdos.ca

































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