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Versions: (draft-howlett-eap-gss) 00 01 02 03 04 05 06 07 08 09 RFC 7055

Network Working Group                                         S.  Wadhwa
Internet-Draft                                            Alcatel-Lucent
Intended status: Standards Track                              J. Moisand
Expires: August 6, 2011                                 Juniper Networks
                                                                T.  Haag
                                                        Deutsche Telekom
                                                                N. Voigt
                                                  Nokia Siemens Networks
                                                          T. Taylor, Ed.
                                                     Huawei Technologies
                                                        February 2, 2011


    Protocol for Access Node Control Mechanism in Broadband Networks
                      draft-ietf-ancp-protocol-15

Abstract

   This document describes the Access Node Control Protocol (ANCP).
   ANCP operates between a Network Access Server (NAS) and an Access
   Node (e.g., a Digital Subscriber Line Access Multiplexer (DSLAM)) in
   a multi-service reference architecture in order to perform QoS-
   related, service-related and subscriber-related operations.  Use
   cases for ANCP are documented in RFC 5851.  As well as describing the
   base ANCP protocol, this document specifies capabilities for Digital
   Subscriber Line (DSL) topology discovery, line configuration, and
   remote line connectivity testing.  The design of ANCP allows for
   protocol extensions in other documents if they are needed to support
   other use cases and other access technologies.

   ANCP is based on GSMPv3 (RFC 3292), but with many modifications and
   extensions, to the point that the two protocols are not
   interoperable.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on August 6, 2011.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  6
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  7
   2.  Broadband Access Aggregation . . . . . . . . . . . . . . . . .  8
     2.1.  ATM-based Broadband Aggregation  . . . . . . . . . . . . .  8
     2.2.  Ethernet-Based Broadband Aggregation . . . . . . . . . . . 10
   3.  Access Node Control Protocol -- General Aspects  . . . . . . . 10
     3.1.  Protocol Version . . . . . . . . . . . . . . . . . . . . . 10
     3.2.  ANCP Transport . . . . . . . . . . . . . . . . . . . . . . 11
     3.3.  Encoding of Text Fields  . . . . . . . . . . . . . . . . . 12
     3.4.  Treatment of Reserved and Unused Fields  . . . . . . . . . 12
     3.5.  Use of the GSMPv3 Adjacency Protocol . . . . . . . . . . . 12
       3.5.1.  ANCP Adjacency Message Format  . . . . . . . . . . . . 12
       3.5.2.  ANCP Adjacency Procedures  . . . . . . . . . . . . . . 15
     3.6.  ANCP General Message Formats . . . . . . . . . . . . . . . 17
       3.6.1.  The ANCP Message Header  . . . . . . . . . . . . . . . 17
       3.6.2.  The ANCP Message Body  . . . . . . . . . . . . . . . . 25
     3.7.  General Principles for the Design of ANCP Messages . . . . 26
   4.  Generally Useful ANCP Messages and TLVs  . . . . . . . . . . . 27
     4.1.  Provisioning Message . . . . . . . . . . . . . . . . . . . 27
     4.2.  Generic Response Message . . . . . . . . . . . . . . . . . 28
     4.3.  Target TLV . . . . . . . . . . . . . . . . . . . . . . . . 30
     4.4.  Command TLV  . . . . . . . . . . . . . . . . . . . . . . . 30
     4.5.  Status-Info TLV  . . . . . . . . . . . . . . . . . . . . . 31
   5.  Introduction To ANCP Capabilities For Digital Subscriber
       Lines (DSL)  . . . . . . . . . . . . . . . . . . . . . . . . . 32
     5.1.  DSL Access Line Identification . . . . . . . . . . . . . . 33
       5.1.1.  Control Context (Informative)  . . . . . . . . . . . . 33
       5.1.2.  TLVs For DSL Access Line Identification  . . . . . . . 34
   6.  ANCP Based DSL Topology Discovery  . . . . . . . . . . . . . . 37
     6.1.  Control Context (Informative)  . . . . . . . . . . . . . . 37
     6.2.  Protocol Requirements  . . . . . . . . . . . . . . . . . . 39
       6.2.1.  Protocol Requirements On the AN Side . . . . . . . . . 39
       6.2.2.  Protocol Requirements On the NAS Side  . . . . . . . . 40
     6.3.  ANCP Port UP and Port DOWN Event Message Descriptions  . . 40
     6.4.  Procedures . . . . . . . . . . . . . . . . . . . . . . . . 42
       6.4.1.  Procedures On the AN Side  . . . . . . . . . . . . . . 42
       6.4.2.  Procedures On the NAS Side . . . . . . . . . . . . . . 43
     6.5.  TLVs For DSL Line Attributes . . . . . . . . . . . . . . . 43
       6.5.1.  DSL-Line-Attributes TLV  . . . . . . . . . . . . . . . 43
       6.5.2.  DSL-Type TLV . . . . . . . . . . . . . . . . . . . . . 44
       6.5.3.  Actual-Net-Data-Rate-Upstream TLV  . . . . . . . . . . 44
       6.5.4.  Actual-Net-Data-Rate-Downstream TLV  . . . . . . . . . 44
       6.5.5.  Minimum-Net-Data-Rate-Upstream TLV . . . . . . . . . . 45
       6.5.6.  Minimum-Net-Data-Rate-Downstream TLV . . . . . . . . . 45
       6.5.7.  Attainable-Net-Data-Rate-Upstream TLV  . . . . . . . . 45



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       6.5.8.  Attainable-Net-Data-Rate-Downstream TLV  . . . . . . . 45
       6.5.9.  Maximum-Net-Data-Rate-Upstream TLV . . . . . . . . . . 46
       6.5.10. Maximum-Net-Data-Rate-Downstream TLV . . . . . . . . . 46
       6.5.11. Minimum-Net-Low-Power-Data-Rate-Upstream TLV . . . . . 46
       6.5.12. Minimum-Net-Low-Power-Data-Rate-Downstream TLV . . . . 46
       6.5.13. Maximum-Interleaving-Delay-Upstream TLV  . . . . . . . 47
       6.5.14. Actual-Interleaving-Delay-Upstream TLV . . . . . . . . 47
       6.5.15. Maximum-Interleaving-Delay-Downstream TLV  . . . . . . 47
       6.5.16. Actual-Interleaving-Delay-Downstream . . . . . . . . . 47
       6.5.17. DSL-Line-State TLV . . . . . . . . . . . . . . . . . . 47
       6.5.18. Access-Loop-Encapsulation TLV  . . . . . . . . . . . . 48
   7.  ANCP based DSL Line Configuration  . . . . . . . . . . . . . . 49
     7.1.  Control Context (Informative)  . . . . . . . . . . . . . . 49
     7.2.  Protocol Requirements  . . . . . . . . . . . . . . . . . . 50
       7.2.1.  Protocol Requirements On the NAS Side  . . . . . . . . 51
       7.2.2.  Protocol Requirements On the AN Side . . . . . . . . . 51
     7.3.  ANCP Port Management (Line Configuration) Message
           Format . . . . . . . . . . . . . . . . . . . . . . . . . . 51
     7.4.  Procedures . . . . . . . . . . . . . . . . . . . . . . . . 54
       7.4.1.  Procedures On the NAS Side . . . . . . . . . . . . . . 54
       7.4.2.  Procedures On the AN Side  . . . . . . . . . . . . . . 54
     7.5.  TLVs For DSL Line Configuration  . . . . . . . . . . . . . 55
       7.5.1.  Service-Profile-Name TLV . . . . . . . . . . . . . . . 55
   8.  ANCP-Based DSL Remote Line Connectivity Testing  . . . . . . . 55
     8.1.  Control Context (Informative)  . . . . . . . . . . . . . . 55
     8.2.  Protocol Requirements  . . . . . . . . . . . . . . . . . . 56
       8.2.1.  Protocol Requirements On the NAS Side  . . . . . . . . 56
       8.2.2.  Protocol Requirements On the AN Side . . . . . . . . . 57
     8.3.  Port Management (OAM) Message Format . . . . . . . . . . . 57
     8.4.  Procedures . . . . . . . . . . . . . . . . . . . . . . . . 58
       8.4.1.  NAS-Side Procedures  . . . . . . . . . . . . . . . . . 58
       8.4.2.  AN-Side Procedures . . . . . . . . . . . . . . . . . . 59
     8.5.  TLVs For the DSL Line Remote Connectivity Testing
           Capability . . . . . . . . . . . . . . . . . . . . . . . . 60
       8.5.1.  OAM-Loopback-Test-Parameters TLV . . . . . . . . . . . 60
       8.5.2.  Opaque-Data TLV  . . . . . . . . . . . . . . . . . . . 61
       8.5.3.  OAM-Loopback-Test-Response-String TLV  . . . . . . . . 61
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 61
     9.1.  Summary  . . . . . . . . . . . . . . . . . . . . . . . . . 61
     9.2.  IANA Actions . . . . . . . . . . . . . . . . . . . . . . . 62
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 67
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 69
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 69
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 69
     12.2. Informative References . . . . . . . . . . . . . . . . . . 69
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 70





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1.  Introduction

   This draft defines a new protocol, the Access Node Control Protocol
   (ANCP), to realize a control plane between a service-oriented layer 3
   edge device (the Network Access Server, NAS) and a layer 2 Access
   Node (e.g., Digital Subscriber Line Access Module, DSLAM) in order to
   perform QoS-related, service-related and subscriber-related
   operations.  The requirements for ANCP and the context within which
   it operates are described in [RFC5851].

   The protocol specification takes GSMPv3 [RFC3292] as a starting
   point, and the implementor is directed to parts of [RFC3292] for the
   specification of some aspects of the protocol.  However, ANCP
   introduces so many extensions and modifications to GSMPv3 that the
   two protocols are not interoperable.

   ANCP provides its services to control applications operating in the
   AN and NAS respectively.  This relationship is shown in Figure 1.
   Specification of the control applications is beyond the scope of this
   document, but informative partial descriptions are provided as
   necessary to give a context for the operation of the protocol.

          Access Node                            Network Access Server
     +--------------------+                     +--------------------+
     | +----------------+ |                     | +----------------+ |
     | |   AN Control   | |                     | |  NAS Control   | |
     | |  Application   | |                     | |  Application   | |
     | +----------------+ |                     | +----------------+ |
     | +----------------+ |                     | +----------------+ |
     | |   ANCP Agent   | |    ANCP Messages    | |   ANCP Agent   | |
     | |   (AN side)    |<----------------------->|   (NAS side)   | |
     | +----------------+ |                     | +----------------+ |
     +--------------------+                     +--------------------+

   Figure 1:  Architectural Context For the Access Node Control Protocol

   At various points in this document, information flows between the
   control applications and ANCP are described.  The purpose of such
   descriptions is to clarify the boundary between this specification
   and, for example, [TR-147].  There is no intention to place limits on
   the degree to which the control application and the protocol
   implementation are integrated.

   This specification specifies ANCP transport over TCP/IP.  TCP
   encapsulation for ANCP is as defined for GSMPv3 in [RFC3293].  The
   alternative GSMPv3 encapsulation directly over Ethernet and ATM as
   defined in [RFC3293] is not considered for ANCP.




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   The organization of this document is as follows:

   o  The next two sub-sections introduce some terminology that will be
      useful in understanding the rest of the document.

   o  Section 2 provides a description of the access networks within
      which ANCP will typically be deployed.

   o  Section 3 specifies generally applicable aspects of the ANCP
      protocol.

   o  Section 4 specifies some messages and TLVs intended for use by
      multiple capabilities spanning multiple technologies.

   o  Section 5 and the three following sections describe and specify
      the ANCP implementation of three capabilities applicable to the
      control of DSL access technology: topology discovery, line
      configuration, and remote line connectivity testing.

   o  Section 9 is the IANA Considerations section.  Some codepoints are
      added to existing GSMPv3 registries set up by [RFC3292], but a
      number of new ANCP-specific registries are also defined.

   o  Section 10 addresses security considerations relating to ANCP,
      beginning with the requirements stated in [RFC5713].

   RFC EDITOR'S NOTE: the following paragraph should be deleted upon
   publication.

   At the time of writing of this specification some implementations of
   the ANCP protocol based on pre-standards drafts are already
   available.  These early-draft implementations use protocol version/
   sub-version 3.1.  The standard ANCP protocol will use version/
   sub-version 3.2 Adopting a new sub-version value provides a way to
   disambiguate the two protocols and provides support for running a
   pre-standard and a standards compliant ANCP implementation on any
   given ANCP node.  The mechanism used to identify the protocol
   version/sub-version is part of the adjacency negotiation process and
   it is described in detail in Section 3.5.  NOTE: this mechanism does
   not guarantee backwards compatibility of the published ANCP
   specification with those early-draft implementations.

1.1.  Requirements Language

   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 [RFC2119].




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   This specification uses requirements language in lower case and
   between quotation marks (e.g., "must") to denote requirements on the
   interface between ANCP and the control application.  Such
   requirements are inherently untestable but need to be taken into
   account by the implementor.

1.2.  Terminology

   This section repeats some definitions from [RFC5851], but also adds
   definitions for terms used only in this document.

   Access Node (AN):  [RFC5851] Network device, usually located at a
      service provider central office or street cabinet that terminates
      access (local) loop connections from subscribers.  In case the
      access loop is a Digital Subscriber Line (DSL), the Access Node
      provides DSL signal termination, and is referred to as a DSL
      Access Multiplexer (DSLAM).

   Network Access Server (NAS):  [RFC5851] Network element which
      aggregates subscriber traffic from a number of Access Nodes.  The
      NAS is an enforcement point for policy management and IP QoS in
      the access network.  It is also referred to as a Broadband Network
      Gateway (BNG) or Broadband Remote Access Server (BRAS).

   Home Gateway (HGW):  Network element that connects subscriber devices
      to the Access Node and the access network.  In the case of DSL,
      the Home Gateway is a DSL network termination that may operate
      either as a layer 2 bridge or as a layer 3 router.  In the latter
      case, such a device is also referred to as a Routing Gateway (RG).

   ANCP agent:  A logical entity that implements the ANCP protocol in
      the Access Node (AN-side) or NAS (NAS-side).

   Access Node control adjacency:  (modified from [RFC5851]) the
      relationship between the AN-side ANCP agent and the NAS-side ANCP
      agent for the purpose of exchanging Access Node Control Protocol
      messages.  The adjacency may either be up or down, depending on
      the result of the Access Node Control adjacency protocol
      operation.

   ANCP capability:  A specific set of ANCP messages, message content,
      and procedures required to implement a specific use case or set of
      use cases.  Some ANCP capabilities are applicable to just one
      access technology while others are technology independent.  The
      capabilities applicable to a given ANCP adjacency are negotiated
      during adjacency startup.





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   Type-Length-Value (TLV):  a data structure consisting of a sixteen-
      bit type field, a sixteen-bit length field, and a variable-length
      value field padded to the nearest 32-bit word boundary, as
      described in Section 3.6.2.  The value field of a TLV can contain
      other TLVs.  An IANA registry is maintained for values of the ANCP
      TLV Type field.

   Net data rate:  [RFC5851] defined by ITU-T G.993.2 [G.993.2], Section
      3.39, i.e., the portion of the total data rate that can be used to
      transmit user information (e.g., ATM cells or Ethernet frames).
      It excludes overhead that pertains to the physical transmission
      mechanism (e.g., trellis coding in the case of DSL).  It includes
      TPS-TC (Transport Protocol Specific - Transmission Convergence)
      encapsulation; this is zero for ATM encapsulation, and non-zero
      for 64/65 encapsulation.

   Line rate:  [RFC5851] defined by ITU-T G.993.2.  It contains the
      complete overhead including Reed-Solomon and trellis coding.

   DSL multi-pair bonding:  method for bonding (or aggregating) multiple
      xDSL lines into a single bi-directional logical link, henceforth
      referred to in this draft as "DSL bonded circuit".  DSL "multi-
      pair" bonding allows an operator to combine the data rates on two
      or more copper pairs, and deliver the aggregate data rate to a
      single customer.  ITU-T recommendations G.998.1 and G.998.2
      respectively describe ATM and Ethernet based multi-pair bonding.


2.   Broadband Access Aggregation

2.1.  ATM-based Broadband Aggregation

   The end to end DSL network consists of network service provider (NSP)
   and application service provider (ASP) networks, regional/access
   network, and customer premises network.  Figure 2 shows ATM broadband
   access network components.

   The regional/access network consists of the regional network, Network
   Access Server (NAS), and the access network as shown in Figure 2.
   Its primary function is to provide end-to-end transport between the
   customer premises and the NSP or ASP.

   The Access Node terminates the DSL signal.  It may be in the form of
   a DSLAM in the central office, or a remote DSLAM, or a Remote Access
   Multiplexer (RAM).  The Access Node is the first point in the network
   where traffic on multiple DSL lines will be aggregated onto a single
   network.




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   The NAS performs multiple functions in the network.  The NAS is the
   aggregation point for subscriber traffic.  It provides aggregation
   capabilities (e.g.  IP, PPP, ATM) between the Regional/Access Network
   and the NSP or ASP.  These include traditional ATM-based offerings
   and newer, more native IP-based services.  This includes support for
   Point-to-Point Protocol over ATM (PPPoA) and PPP over Ethernet
   (PPPoE), as well as direct IP services encapsulated over an
   appropriate layer 2 transport.

   Beyond aggregation, the NAS is also the enforcement point for policy
   management and IP QoS in the regional/access networks.  To allow IP
   QoS support over an existing non-IP-aware layer 2 access network
   without using multiple layer 2 QoS classes, a mechanism based on
   hierarchical scheduling is used.  This mechanism, defined in
   [TR-059], preserves IP QoS over the ATM network between the NAS and
   the routing gateway (RG) at the edge of the subscriber network, by
   carefully controlling downstream traffic in the NAS, so that
   significant queuing and congestion does not occur further down the
   ATM network.  This is achieved by using a diffserv-aware hierarchical
   scheduler in the NAS that will account for downstream trunk
   bandwidths and DSL synchronization rates.

   [RFC5851] provides detailed definitions of the functions of each
   network element in the broadband reference architecture.

                              Access                   Customer
                       <--- Aggregation -->  <------- Premises ------->
                              Network                   Network

                       +------------------+ +--------------------------+
   +---------+   +---+ | +-----+ +------+ | |+-----+ +---+ +---------+ |
NSP|         | +-|NAS|-| |ATM  |-|Access| --||DSL  |-|HGW|-|Subscriber||
---+ Regional| | +---+ | +-----+ | Node | | ||Modem| +---+ |Devices   ||
   |Broadband| | +---+ |         +------+ | |+-----+       +----------+|
ASP|Network  |-+-|NAS| +--------------|---+ +--------------------------+
---+         | | +---+                |     +--------------------------+
   |         | | +---+                |     |+-----+ +---+ +----------+|
   +---------+ +-|NAS|                +-----|| DSL |-|HGW|-|Subscriber||
                 +---+                      ||Modem| +---+ |Devices   ||
                                            |+-----+       +----------+|
                                            +--------------------------+
 HGW   : Home Gateway
 NAS   : Network Access Server

               Figure 2: ATM Broadband Aggregation Topology






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2.2.  Ethernet-Based Broadband Aggregation

   The Ethernet aggregation network architecture builds on the Ethernet
   bridging/switching concepts defined in IEEE 802.  The Ethernet
   aggregation network provides traffic aggregation, class of service
   distinction, and customer separation and traceability.  VLAN tagging
   defined in IEEE 802.1Q and being enhanced by IEEE 802.1ad is used as
   standard virtualization mechanism in the Ethernet aggregation
   network.  The aggregation devices are "provider edge bridges" defined
   in IEEE 802.ad.

   Stacked VLAN tags provide one possible way to create equivalent of
   "virtual paths" and "virtual circuits" in the aggregation network.
   The "outer" vlan can be used to create a form of "virtual path"
   between a given DSLAM and a given NAS.  "Inner" VLAN tags create a
   form of "virtual circuit" on a per DSL line basis.  This is the 1:1
   VLAN allocation model.  An alternative model is to bridge sessions
   from multiple subscribers behind a DSLAM into a single VLAN in the
   aggregation network.  This is the N:1 VLAN allocation model.  Section
   1.6 of [TR-101] provides brief definitions of these two models, while
   section 2.5.1 describes them in more detail.


3.  Access Node Control Protocol -- General Aspects

   This section specifies aspects of the Access Node Control Protocol
   (ANCP) that are generally applicable.  As indicated above, ANCP is
   derived from GSMPv3 [RFC3292].  Reference to [RFC3292] is made where
   this is applicable, but ANCP introduces numerous modifications and
   extensions to the basic GSMPv3 protocol.  Moreover, ANCP uses only a
   subset of the messages, message contents, and procedures defined for
   GSMPv3, and defines additional messages, message contents, and
   procedures that are specific to ANCP.

3.1.  Protocol Version

   GSMPv3 messages contain an 8-bit protocol version field.  As
   described below, ANCP subdivides this into two 4-bit sub-fields, for
   version and sub-version.  Implementations of this version of the ANCP
   specification MUST set the version sub-field to 3 and the sub-version
   sub-field to 1.  That is, the hexadecimal representation of the value
   of the complete protocol version field MUST be 0x31.

   RFC EDITOR'S NOTE: please change the value of sub-version in the
   above paragraph to 2 (respectively a version field value of 0x32) in
   the published specification.  For an explanation see the Introduction
   above.




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3.2.  ANCP Transport

   This document specifies the use of TCP/IP for transport of ANCP
   messages.  Other specifications may introduce additional transports
   in the future.

      In the case of ATM access, a separate PVC (control channel)
      capable of transporting IP MAY be configured between NAS and the
      AN for ANCP messages.

      In the case of an Ethernet access/aggregation network, a typical
      practice is to send the Access Node Control Protocol messages over
      a dedicated Ethernet virtual LAN (VLAN) using a separate VLAN
      identifier (VLAN ID).

   When transported over TCP, ANCP messages MUST use the encapsulation
   specified for GSMPv3 messages carried over TCP in [RFC3293].  This
   encapsulation consists of a four-byte header field prepended to the
   ANCP message as shown in Figure 3.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Identifier (0x880C)        |           Length              |
      |-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                         ANCP Message                          ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 3: Encapsulation of ANCP Messages Over TCP/IP

   The fields of the encapsulating header are as follows:

   Identifier:  This 2-byte field identifies a GSMP or ANCP message.
      The type code for GSMP and ANCP messages is 0x880C (i.e., the same
      as GSMP's Ethertype).

   Length:  This 2-byte unsigned integer indicates the total length of
      the ANCP message, not including the 4-byte encapsulating header.

   The Access Node MUST initiate the TCP session to the NAS.  This is a
   deviation from [RFC3293], which requires the controller to initiate
   the TCP connection to the switch.

      This is necessary to avoid static address provisioning on the NAS
      for all the ANs that are being served by the NAS.  It is easier to
      configure a given AN with the single IP address of the NAS that



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      serves the AN.

   The NAS MUST listen for incoming connections from the Access Nodes.
   Port 6068 is used for TCP connection.

   In the event of an ANCP transport protocol failure, all pending ANCP
   messages destined to the disconnected recipient SHOULD be discarded
   until the transport connection is re-established.

3.3.  Encoding of Text Fields

   In ANCP, all text fields use UTF-8 encoding [RFC3629].  Note that US
   ASCII characters have the same representation when coded as UTF-8 as
   they do when coded according to [US_ASCII].

   When extracting text fields from a message, the ANCP agent MUST NOT
   assume that the fields are zero-terminated.

3.4.  Treatment of Reserved and Unused Fields

   ANCP messages contain a number of fields that are unused or reserved.
   Some fields are always unused (typically because they were inherited
   from GSMPv3 but are not useful in the ANCP context).  Others are
   reserved in the current specification, but are provided for
   flexibility in future extensions to ANCP.  Both reserved and unused
   fields MUST be set to zeroes by the sender and MUST be ignored by the
   receiver.

   Unused bits in a flag field are shown in figures as 'x'.  The above
   requirement (sender set to zero, receiver ignore) applies to such
   unused bits.

3.5.  Use of the GSMPv3 Adjacency Protocol

   Section 11 of [RFC3292] defines the GSMPv3 adjacency protocol.  ANCP
   reuses the GSMPv3 adjacency protocol to synchronize the NAS and
   Access Nodes and maintain the ANCP session.  After the TCP connection
   is established, adjacency protocol messages MUST be exchanged as
   specified in Section 11 of [RFC3292], subject to the additional
   specifications of this section.  ANCP messages other than adjacency
   protocol messages MUST NOT be sent until the adjacency protocol has
   achieved synchronization.

3.5.1.  ANCP Adjacency Message Format

   The GSMPv3 adjacency message format defined in Section 11 of
   [RFC3292] is modified and extended for ANCP as shown in Figure 4
   below.  The 8-bit "version" field in the GSMPv3 adjacency protocol



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   messages is modified to carry the ANCP version (four bits) and sub-
   version (four bits).  See Section 3.1 for the values to set for
   version and sub-version for the present version of this
   specification.

   The semantics and suggested values for the Code, Sender Name,
   Receiver Name, Sender Instance, and Receiver Instance fields are as
   defined in Section 11 of [RFC3292].  The Sender Port, and Receiver
   Port SHOULD be set to 0 by both ends.  The pType field MAY be set to
   0 (No Partition) or another value depending on local configuration.
   The pFlag SHOULD be set to 1 (New Adjacency).

   In addition to the modification of the version field, ANCP adds
   several new fields.  These are described below the figure.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Ver |  Sub  | Message Type  |     Timer     |M|     Code    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Sender Name                          |
      +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                         Receiver Name                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Sender Port                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Receiver Port                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | PType | PFlag |               Sender Instance                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Partition ID  |              Receiver Instance                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Reserved      | # of Caps     | Total Length                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                   Capability Fields                           ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 4: ANCP Adjacency Message Format

   The fields added by ANCP are as follows:







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   Reserved (8 bits):  reserved for use by a future version of this
      specification.

   # of Caps:  indicates the number of capability fields that follow.

   Total Length:  indicates the total number of bytes occupied by the
      capability fields that follow.

   Capability Fields:  Each capability field indicates one ANCP
      capability supported by the sender of the adjacency message.
      Negotiation of a common set of capabilities to be supported within
      the ANCP session is described in Section 3.5.2.  The detailed
      format of a capability field is shown in Figure 5 and described
      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Capability Type           |   Capability Length           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                                                               ~
      ~                   Capability Data                             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 5: Capability Field

   The sub-fields of this structure are as follows:

   Capability Type:  indicates the specific capability supported.  An
      IANA registry exists for values of this sub-field.  The values
      specified by this document are listed below.

   Capability Length:  the number of bytes of data contained in the
      Capability Data sub-field, excluding padding.  If the definition
      of a particular capability includes no capability data, the value
      of the Capability Length sub-field is zero.

   Capability Data:  contains data associated with the capability as
      specified for that capability.  If the definition of a particular
      capability includes no capability data, the Capability Data sub-
      field is absent (has zero length).  Otherwise, the Capability Data
      sub-field MUST be padded with zeroes as required to terminate on a
      4-byte word boundary.  The possibility of specifying capability
      data provides the flexibility to advertise more than the mere
      presence or absence of a capability if needed.




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   The following capabilities are defined for ANCP as applied to DSL
   access:

   o  Capability Type : DSL Topology Discovery = 0x01

         Access technology: DSL

         Length (in bytes) : 0

         Capability Data : NULL

      For the detailed protocol specification of this capability see
      Section 6.

   o  Capability Type : DSL Line Configuration = 0x02

         Access technology: DSL

         Length (in bytes) : 0

         Capability Data : NULL

      For the detailed protocol specification of this capability see
      Section 7.

   o  Capability Type : DSL Remote Line Connectivity Testing = 0x04

         Access technology: DSL

         Length (in bytes) : 0

         Capability Data : NULL

      For the detailed protocol specification of this capability see
      Section 8.

3.5.2.  ANCP Adjacency Procedures

   Before beginning adjacency negotiation, the ANCP agent and the
   control application "must" agree on the set of capabilities that they
   support.  This agreement "must" include the transfer of any
   application-level information required to build the Capability Data
   fields within the Capability structures.  Note that none of the
   capabilities specified in this document require any such information.

   The NAS MUST set the M-flag in the SYN message (signifying it is the
   master).  Once the adjacency is established, periodic adjacency
   messages (type ACK) MUST be exchanged.  The default for the ACK



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   interval to be advertised in the adjacency messages is 25 seconds for
   ANCP.  The actual value SHOULD be configurable and is a deployment
   choice.  It is RECOMMENDED that both ends specify the same timer
   value; to achieve this, each end SHOULD compare the timer value in
   the first adjacency message it receives with its own preferred value
   and agree to use the higher of the two values.  That is, the node
   that receives a higher timer value than its own SHOULD reply in its
   subsequent adjacency messages (such as SYNACK, ACK) with the higher
   timer value.

   In the adjacency protocol the version and sub-version fields are used
   for version negotiation.  The version negotiation MUST be completed
   before synchronisation is achieved.  In a SYN message the version/
   sub-version fields always contain the highest version understood by
   the sender.  A receiver receiving a SYN message with a version/
   sub-version higher than it understands MUST silently discard that
   message.  A receiver receiving a SYN message with a version/
   sub-version within the range of versions that it understands MUST
   reply with a SYNACK with the version/sub-version from the received
   SYN in its ANCP version/sub-version fields.  This defines the
   version/sub-version of the ANCP protocol to be used while the
   adjacency remains synchronized.  All other ANCP messages within the
   session MUST use the agreed version in the version/sub-version
   fields.

   Both the NAS and the Access Node MUST advertise supported
   capabilities in the adjacency messages they send.  The same message
   MAY advertise capabilities for any mixture of access technologies.
   If a received adjacency message indicates no support for a capability
   that is supported by the receiving device, it MUST disable the
   capability locally and MUST send an updated adjacency message with
   the corresponding capability field omitted to match the received
   capability set.  This process will eventually result in both sides
   agreeing on the maximal common set of supported capabilities.  The
   adjacency MUST NOT come up if that common set is empty.

   Subsequent to adjacency startup, if the adjacency times out on either
   end, due to not receiving an adjacency message for a duration of (3 *
   Timer value), where the timer value is negotiated as described above,
   all the state received from the ANCP peer SHOULD be cleaned up, and
   the TCP connection SHOULD be closed.  The NAS MUST continue to listen
   for new connection requests.  The AN MUST try to re-establish the TCP
   connection and both sides MUST attempt to re-establish the adjacency.

   After initial synchronization, if at any time a capability mismatch
   is detected, the adjacency MUST be brought down (RSTACK MUST be
   generated by the device detecting the mismatch), and synchronization
   MUST be re-attempted.



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   The ANCP agent "must" notify the control application whenever an
   adjacency is either synchronized or lost.  When an adjacency is
   synchronized, the notification "must" include the set of capabilities
   negotiated with the peer along with any application-level information
   conveyed in Capability Data fields.

3.6.  ANCP General Message Formats

   This section describes the general format of ANCP messages other than
   the adjacency messages.

   The GSMPv3 general message format, used by all GSMP messages other
   than adjacency protocol messages, is defined in Section 3.1.1 of
   GSMPv3 [RFC3292].  ANCP modifies this base GSMPv3 message format as
   shown in Figure 6.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Vers  |  Sub  | Message Type  | Result|        Code           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Partition ID  |            Transaction Identifier             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |I|      SubMessage Number      |           Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                          Message Payload                      ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 6: ANCP General Message Format

3.6.1.  The ANCP Message Header

   The immediately visible differences from GSMPv3 are the subdivision
   of the Version field into version and sub-version, and the
   reallocation of space between Result and Code to enlarge the range
   for Code.  The 8-bit version field in the base GSMPv3 message header
   is split into two 4 bit fields for carrying the version and a sub-
   version of the ANCP protocol.  The Result field in the message header
   has been modified to be 4 bits long, and the Code field to be 12 bits
   long.

   A complete explanation of the header fields follows.







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3.6.1.1.  Version and Sub-Version Fields

   Together these fields reproduce the version of the ANCP protocol that
   was agreed for the session during adjacency negotiation.  See
   Section 3.1 for the values to set for version and sub-version for the
   present version of this specification.

3.6.1.2.  Message Type Field

   This field indicates the ANCP message type.  Message type values are
   registered in a common GSMPv3/ANCP IANA registry.

3.6.1.3.  Result Field

   The Result field is derived from GSMPv3 [RFC3292].  Ignore (0x0) is a
   new value added by ANCP.  The remaining Result values listed below
   are a subset of those defined for GSMPv3.  GSMPv3 expected the sender
   of a request to choose between NAck (0x1) and AckAll (0x2) according
   to its needs.  ANCP specifies what Result value each request should
   have.  Responses indicate either Success (0x3) or Failure (0x4) as
   the case may be.

   Ignore:  Res = 0x0 - Treat this field as a "no operation" and follow
      the response procedures specified for the received message type.

   Nack:  Res = 0x1 - Result value indicating that a response is
      expected to the request only in cases of failure caused during the
      processing of the message contents or of the contained
      directive(s).

   AckAll:  Res = 0x2 - Result value indicating that a response to the
      message is requested in all cases.

   Success:  Res = 0x3 - Result value indicating that this is a response
      and that the request was executed successfully.  The Code field
      for a successful result is typically 0, but MAY take on other
      values as specified for particular message types.

   Failure:  Res = 0x4 - Result value indicating that this is a response
      and that the request was not executed successfully.  The receiver
      of the response SHOULD take further action as indicated by the
      Code value and any diagnostic data contained in a Status-Info TLV
      included in the response.








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3.6.1.4.  Code Field

   This field gives further information concerning the result in a
   response message.  It is mostly used to pass an error code in a
   failure response but can also be used to give further information in
   a success response message or an event message.  In a request
   message, the Code field is not used and MUST be set to zero.

   A number of code values are specified below.  Specification of
   additional Code values in extensions or updates to this document MUST
   include the following information:

   o  Code value;

   o  One-line description;

   o  Where condition detected: (control application or ANCP agent);

   o  Further description (if any);

   o  Required additional information in the response message;

   o  Target (control application or ANCP agent at the peer that sent
      the original request);

   o  Action RECOMMENDED for the receiving ANCP agent

   In addition to any suggested action in the text which follows, the
   Code value SHOULD be logged in a MIB.  Where an action includes
   resending of a request, a given request SHOULD NOT be re-sent more
   than once.

   ANCP agents MAY use any of the Code values specified in the IANA
   registry "Global Switch Management Protocol version 3 (GSMPv3)
   Failure Response Message Name Space" if they appear applicable.  In
   particular, the values 2, 6, 7, and 19 appear to be reusable and are
   therefore documented below along with a few new ANCP-specific values.
   Values 30 and 31 are also reusable, but are more appropriately
   documented in a multicast extension document.

   Code value: 2

      *  One-line description: Invalid request message

      *  Where condition detected: ANCP agent

      *  Further description: The request was a properly formed message
         which violates the protocol through its timing or direction of



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         transmission.  The most likely reason for this outcome in the
         field will be a race condition.

      *  Required additional information in the response message: none,
         if the response message is of the same type as the request.  As
         specified in Section 4.2 if the response message is a Generic
         Response message.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: The original
         request MAY be re-sent once only after a short delay.  Inform
         the control application with appropriate identification of the
         failed transaction if the second attempt fails or no second
         attempt is made.

   Code value: 6

      *  One-line description: One or more of the specified ports are
         down

      *  Where condition detected: control application

      *  Further description (if any): This Code value indicates a state
         mismatch between the NAS and AN control applications, possibly
         due to a race condition.

      *  Required additional information in the response message: if the
         request identified multiple access lines or the response is a
         Generic Response message, then the response MUST contain a
         Status-Info TLV encapsulating TLV(s) containing the line
         identifier(s) of the access lines that are not operational.

      *  Target: control application at the peer that sent the original
         request

      *  Action RECOMMENDED for the receiving ANCP agent: indicate the
         error and forward the line identifier(s) to the control
         application.

   Code value: 7

      *  One-line description: Invalid Partition ID

      *  Where condition detected: ANCP agent

      *  Further description: This indicates that the request used a
         Partition ID value different from what was determined for this



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         partition during adjacency negotiation, implying a state
         mismatch between the ANCP agents.

      *  Required additional information in the response message: none,
         if the response message is of the same type as the request.  As
         specified in Section 4.2 if the response message is a Generic
         Response message.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: If multiple
         instances of this error occur, the requestor SHOULD cause the
         adjacency for the partition to be reset and renegotiated by
         sending an adjacency message with pType = 0 and Code = RSTACK
         as described in Section 11.3 of [RFC3292].

         NOTE: This specification provides no way for the NAS to do a
         complete audit of the current state stored on the AN.  Hence
         renegotiation of the adjacency with pFlag = 2 (connection state
         retained at the AN) MAY be attempted, but entails some risk of
         state mismatch.

   Code value: 19

      *  One-line description: Out of resources

      *  Where condition detected: ANCP protocol layer or control
         application

      *  Further description: (e.g., memory exhausted, etc.).  This Code
         value MUST be reported only by the AN, and indicates a
         condition that is probably unrelated to specific access lines
         (although it may be related to the specific request).

      *  Required additional information in the response message: none,
         if the response message is of the same type as the request.  As
         specified in Section 4.2 if the response message is a Generic
         Response message.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: If the NAS
         receives this Code value from multiple requests for the same AN
         in a short interval, it SHOULD reduce the rate at which it
         sends requests in proportion to the rate at which requests are
         failing with Code = 19.  It MAY retry individual requests.  If
         only a specific request is failing with Code = 19, the ANCP
         agent in the NAS MAY request the control application to



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         decompose the request into simpler components if this is
         possible.

   Code value: 81

      *  One-line description: Request message type not implemented

      *  Where condition detected: ANCP agent

      *  Further description: This could indicate a mismatch in protocol
         version or capability state.  It is also possible that support
         of a specific message is optional within some ANCP capability.

      *  Required additional information in the response message: none,
         if the response message is of the same type as the request.  As
         specified in Section 4.2 if the response message is a Generic
         Response message.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: If the
         receiver of this Code value expects that support of the message
         type concerned is mandatory according to the capabilities
         negotiated for the session, it SHOULD cause the adjacency for
         the partition to be reset and renegotiated by sending an
         adjacency message with pType = 0 and Code = RSTACK as described
         in Section 11.3 of [RFC3292].

   Code value: 83

      *  One-line description: Malformed message

      *  Where condition detected: ANCP agent

      *  Further description: This could be the result of corruption in
         transit, or an error in implementation at one end or the other.

      *  Required additional information in the response message: none,
         if the response message is of the same type as the request.  As
         specified in Section 4.2 if the response message is a Generic
         Response message.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: The request
         SHOULD be re-sent once to eliminate the possibility of in-
         transit corruption.




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   Code value: 84

      *  One-line description: Mandatory TLV missing

      *  Where condition detected: ANCP agent

      *  Further description: none.

      *  Required additional information in the response message: the
         response message MUST contain a Status-Info message that
         encapsulates an instance of each missing mandatory TLV, where
         the length is set to zero and the value field is empty (i.e.,
         only the four-byte TLV header is present).

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: resend the
         message with the missing TLV(s), if possible.  Otherwise,
         report the error to the control application with an indication
         of the missing information required to construct the missing
         TLV(s).

   Code value: 85

      *  One-line description: Invalid TLV contents

      *  Where condition detected: ANCP agent

      *  Further description: the contents of one or more TLVs in the
         request do not match the specifications provided for the those
         TLVs.

      *  Required additional information in the response message: the
         response MUST contain a Status-Info TLV encapsulating the
         erroneous TLVs copied from the original request.

      *  Target: ANCP agent at the peer that sent the original request

      *  Action RECOMMENDED for the receiving ANCP agent: correct the
         error and resend the request, if possible.  Otherwise, report
         the error to the control application with an indication of the
         erroneous information associated with the invalid TLV(s).

   Code value: 1280

      *  One-line description: One or more of the specified ports do not
         exist




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      *  Where condition detected: control application

      *  Further description (if any): this may indicate a configuration
         mismatch between the AN and the NAS or AAA.

      *  Required additional information in the response message: if the
         request identified multiple access lines or the response is a
         Generic Response message, then the response MUST contain a
         Status-Info TLV encapsulating TLV(s) containing the rejected
         line identifier(s).

      *  Target: control application at the peer that sent the original
         request

      *  Action RECOMMENDED for the receiving ANCP agent: indicate the
         error and forward the line identifiers to the control
         application.

   ANCP extensions defining new code values SHOULD use the range 256
   (0x100) through 511 (0x1FF) for this purpose.  The range of values
   from 256 to 4095 is reserved for allocation by IETF consensus.

3.6.1.5.  Partition ID

   The Partition ID field is a 8 bit number which signifies a partition
   on the AN.  The AN and NAS MAY agree on the partition ID using one of
   the following possible options:

   o  The partition ID MAY be configured on the AN and learned by the
      NAS in the adjacency message; or

   o  The partition ID MAY be statically configured on the NAS as part
      of configuring the neighbor information.

3.6.1.6.  Transaction ID

   The Transaction ID is a 24-bit field set by the sender of a request
   message to associate a response message with the original request
   message.  Unless otherwise specified for a given message type, the
   Transaction ID in request messages MUST be set to a value in the
   range (1, 2^24 - 1).  When used in this manner, the Transaction ID
   sequencing MUST be maintained independently for each message type
   within each ANCP adjacency.  Furthermore, it SHOULD be incremented
   linearly for each new message of the given type, cycling back to 1
   after running the full range.  For event messages, the Transaction ID
   SHOULD be set to zero.

   Unless otherwise specified, the default behaviour for all ANCP



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   responses is that the value of the Transaction ID MUST be copied from
   the corresponding request message.

3.6.1.7.  I flag and SubMessage Number

   In GSMPv3 these provide a mechanism for message fragmentation.
   Because ANCP uses TCP transport, this mechanism is unnecessary.  An
   ANCP agent SHOULD set the I Flag and subMessage Number fields to 1 to
   signify "no fragmentation".

3.6.1.8.  Length

   This field MUST be set to the length of the ANCP message in bytes,
   including its header fields and message body but excluding the four-
   byte encapsulating header defined in Section 3.2.

3.6.2.  The ANCP Message Body

   The detailed contents of the message payload portion of a given ANCP
   message can vary with the capability in the context of which it is
   being used.  However, the general format consists of zero or more
   fixed fields, followed by a variable amount of data in the form of
   Type-Length-Value (TLV) data structures.

   The general format of a TLV is shown in Figure 7:

    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 (IANA registered)    |          Length               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                            Value                              ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 7: General TLV Format

   The fields of a TLV are defined as follows:

   Type:  The TLV Type is a 16-bit unsigned value identifying the TLV
      type and nature of its contents.  An IANA registry has been
      established for ANCP TLV Type codes.

   Length:  The number of bytes of data in the Value field of the TLV,
      excluding any padding required to bring this TLV to a 4-byte word
      boundary (see "Value" below).  If a TLV contains other TLVs, any
      padding in the contained TLVs MUST be included in the value of



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      Length.  Depending on the specification of the TLV, the value of
      Length can be zero, a constant for all instances of the TLV, or a
      varying quantity.

   Value:  The actual data carried by the TLV, if any.  The value field
      in each TLV MUST be padded with zeroes as required to align with a
      4-byte word boundary.  The Value field of a TLV MAY include fixed
      fields and/or other TLVs.

   Unless otherwise specified, TLVs MAY be added to a message in any
   order.  If the recipient of a message does not understand a
   particular TLV, it MUST silently ignore it.

   A number of TLVs are specified in the remainder of this document.

3.7.  General Principles for the Design of ANCP Messages

   The GSMPv3 protocol [RFC3292] allows for two messaging constructs to
   support request/response interaction:

   a.  The same message type is used for both the request message and
       the response message.  The Result and Code field settings are
       used to differentiate between request and response messages.

   b.  The request and response messages use two different message
       types.

   The first approach is illustrated by the protocol specifications in
   Section 8.4, the second by specifications in Section 6.4.  The
   purpose of this section is to provide more details about the second
   approach in order to allow the use of this messaging construct for
   the development of additional ANCP extensions.

   As Section 3.6 indicated, all ANCP messages other than adjacency
   messages share a common header format.  When the response message
   type is different from that of the request, the specification of the
   request message will typically indicate that the Result field is set
   to Ignore (0x0) and provide procedures indicating explicitly when the
   receiver should generate a response and what message type it should
   use.

   The Transaction ID field is used to distinguish between multiple
   request messages of the same type and to associate a response message
   to a request.  Specifications of ANCP messages for applications not
   requiring response correlation SHOULD indicate that the Transaction
   ID MUST be set to zero in requests.  Applications that require
   response correlation SHOULD refer to the Transaction ID behaviour
   described in Section 3.6.1.



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   The specification for a response message SHOULD indicate in all cases
   that value of the Transaction Identifier MUST be set to that of the
   corresponding request message.  This allows the requester to
   establish whether or not correlation is needed (by setting a non-zero
   or zero value for the Transaction ID).


4.  Generally Useful ANCP Messages and TLVs

   This section defines two messages and a number of TLVs that could be
   useful in multiple capabilities.  In some cases the content is under-
   specified, with the intention that particular capabilities spell out
   the remaining details.

4.1.  Provisioning Message

   The Provisioning message is sent by the NAS to the AN to provision
   information of global scope (i.e., not associated with specific
   access lines) on the AN.  The Provisioning message has the format
   shown in Figure 8.  Support of the Provisioning message is OPTIONAL
   unless the ANCP agent claims support for a capability that requires
   its use.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           TCP/IP Encapsulating Header (Section 3.2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                ANCP General Message Header                    |
   +                      (Section 3.6.1)                          +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                             TLVs                              ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 8: Format of the Provisioning Message

   The message header field settings given below are REQUIRED in the
   Provisioning message.  The remaining message header fields MUST be
   set as specified in Section 3.6.1.  Which TLVs to carry in the
   Provisioning message is specified as part of the specification of the
   capabilities that use that message.  The Provisioning message MAY be
   used to carry data relating to more than one capability at once,
   assuming that the capabilities concerned can co-exist and have all
   been negotiated during adjacency establishment.




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   Message Type:  MUST be set to 93.

   Result:  MUST be set to 0x0 (Ignore).

   Code:  MUST be set to zero.

   Transaction ID:  MUST be populated with a non-zero value chosen in
      the manner described in Section 3.6.1.6.

   If the AN can process the message successfully and accept all the
   provisioning directives contained in it, the AN MUST NOT send any
   response.

   Unless otherwise specified for a particular capability, if the AN
   fails to process the message successfully it MUST send a Generic
   Response message (Section 4.2) indicating failure and providing
   appropriate diagnostic information.

4.2.  Generic Response Message

   This section defines the Generic Response message.  The Generic
   Response message MAY be specified as the appropriate response to a
   message defined in an extension to ANCP, instead of a more specific
   response message.  As a general guideline, specification of the
   Generic Response message as a response is appropriate where no data
   needs to be returned to the peer other than a result (success or
   failure), plus, in the case of a failure, a code indicating the
   reason for failure and a limited amount of diagnostic data.
   Depending on the particular use case, the Generic Response message
   MAY be sent by either the NAS or the AN.

   Support of the Generic Response message, both as sender and as
   receiver, is REQUIRED for all ANCP agents, regardless of what
   capabilities they support.

   The AN or NAS MAY send a Generic Response message indicating a
   failure condition independently of a specific request before closing
   the adjacency as a consequence of that failure condition.  In this
   case, the sender MUST set the Transaction ID field in the header and
   the Message Type field within the Status-Info TLV to zeroes.  The
   receiver MAY record the information contained in the Status-Info TLV
   for management use.

   The format of the Generic Response message is shown in Figure 9







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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           TCP/IP Encapsulating Header (Section 3.2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                ANCP General Message Header                    |
   +                      (Section 3.6.1)                          +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Access line identifying TLV(s)                 |
   +                (copied from original request)                 +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Status-Info TLV                            |
   ~                     (Section 4.5)                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   NOTE: TLVs MAY be in a different order from what is shown in this
   figure.

            Figure 9: Structure of the Generic Response Message

   This document specifies the following header fields.  The remaining
   fields in the ANCP general message header MUST be set as specified in
   Section 3.6.1.

   Message Type:  MUST be set to 91.

   Result:  MUST be set to 0x3 (Success) or 0x4 (Failure).

   Code:  MUST be set to zero for success or an appropriate non-zero
      value for failure.

   Transaction ID:  MUST be copied from the message to which this
      message is a response.

   If the original request applied to a specific access line or set of
   lines, the TLVs identifying the line(s) and possibly the user MUST be
   copied into the Generic Response message at the top level.

   The Status-Info TLV MAY be present in a success response, to provide
   a warning as defined for a specific request message type.  It MUST be
   present in a failure response.  See Section 4.5 for a detailed
   description of the Status-Info TLV.  The actual contents will depend
   on the request message type this message is responding to and the
   value of the Code field.




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   To prevent an infinite loop of error responses, if the Generic
   Response message is itself in error, the receiver MUST NOT generate
   an error response in return.

4.3.  Target TLV

   Type:  0x1000 to 0x1020 depending on the specific content.  Only
      0x1000 has been assigned in this specification (see below).
      Support of any specific variant of the Target TLV is OPTIONAL
      unless the ANCP agent claims support for a capability that
      requires its use.

   Description:  The Target TLV (0x1000 - 0x1020) is intended to be a
      general means to represent different types of objects.

   Length:  Variable, depending on the specific object type.

   Value:  Target information as defined for each object type.  The
      Value field MAY consist of sub-TLVs.

   TLV Type 0x1000 is assigned to a variant of the Target TLV
   representing a single access line and encapsulating one or more sub-
   TLVs identifying the target.  Figure 10 is an example illustrating
   the TLV format for a single port identified by an Access-Loop-
   Circuit-ID TLV (0x0001) (Section 5.1.2.1).

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    TLV Type = 0x1000          |Length = Circuit-ID Length + 4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Access-Loop-Circuit-ID=0x0001 |       Circuit-ID Length       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                    Access Loop Circuit ID                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 10: Example of Target TLV For Single Access Line

4.4.   Command TLV

   Type:  0x0011

   Description:  The Command TLV (0x0011) is intended to be a general
      means of encapsulating one or more command directives in a TLV
      oriented message.  The semantics of the command can be specified
      for each message type using it.  I.e., the specification of each



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      message type that can carry the Command TLV is expected to define
      the meaning of the content of the payload, although re-use of
      specifications is, of course, permissible when appropriate.
      Support of any specific variant of the Command TLV is OPTIONAL
      unless the ANCP agent claims support for a capability that
      requires its use.

   Length:  Variable, depending on the specific contents.

   Value:  Command information as defined for each message type.  The
      field MAY include sub-TLVs.  The contents of this TLV MUST be
      specified as one "command" or alternatively a sequence of one or
      more "commands", each beginning with a one-byte Command Code and
      possibly including other data following the Command Code.  An IANA
      registry has been established for Command Code values.  This
      document reserves the Command Code value 0 as an initial entry in
      the registry.

4.5.  Status-Info TLV

   Name:  Status-Info

   Type:  0x0106

   Description:  The Status-Info-TLV is intended to be a general
      container for warning or error diagnostics relating to commands
      and/or requests.  It is a supplement to the Code field in the ANCP
      general header.  The specifications for individual message types
      MAY indicate the use of this TLV as part of responses,
      particularly for failures.  As mentioned above, the Generic
      Response message will usually include an instance of the Status-
      Info TLV.  Support of the Status-Info TLV, both as sender and as
      receiver, is REQUIRED for all ANCP agents, regardless of what
      capabilities they support.

   Length:  Variable, depending on the specific contents.

   Value:  The following fixed fields.  In addition, sub-TLVs MAY be
      appended to provide further diagnostic information.

      Reserved (one byte):  see Section 3.4 for handling of reserved
         fields.

      Msg Type:  Message Type of the request for which this TLV is
         providing diagnostics.






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      Error Message Length:  Number of bytes in the error message,
         excluding padding.  This MAY be zero if no error message is
         provided.

      Error Message:  Human-readable string providing information about
         the warning or error condition.  Padded with zeroes as
         necessary to extend to a four-byte word boundary.

      Section 3.6.1.4 provides recommendations for what TLVs to add in
      the Status-Info TLV for particular values of the message header
      Code field.

   Figure 11 illustrates the Status-Info TLV.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    TLV Type = 0x0106          |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Reserved   |  Msg Type     |      Error Message Length     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Error Message (padded to 4 byte boundary)              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           optional sub-TLVs...                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 11: The Status-Info TLV


5.  Introduction To ANCP Capabilities For Digital Subscriber Lines (DSL)

   DSL is a widely deployed access technology for Broadband Access for
   Next Generation Networks.  Specifications such as [TR-059], [TR-058],
   and [TR-092] describe possible architectures for these access
   networks.  The scope of these specifications includes the delivery of
   voice, video, and data services.

   The next three sections of this document specify basic ANCP
   capabilities for use specifically in controlling Access Nodes serving
   DSL access (Tech Type = 0x05).  The same ANs could be serving other
   access technologies (e.g.  Metro-Ethernet, Passive Optical
   Networking, WiMax), in which case the AN will also have to support
   the corresponding other-technology-specific capabilities.  Those
   additional capabilities are outside the scope of the present
   document.






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5.1.  DSL Access Line Identification

   Most ANCP messages involve actions relating to a specific access
   line.  Thus it is necessary to describe how access lines are
   identified within those messages.  This section defines four TLVs for
   that purpose and provides an informative description of how they are
   used.

5.1.1.  Control Context (Informative)

   Three types of identification are described in [TR-101] and provided
   for in the TLVs defined in this section:

   o  identification of an access line by its logical appearance on the
      user side of the Access Node;

   o  identification of an access line by its logical appearance on the
      NAS side of the Access Node; and

   o  identification down to the user or host level as a supplement to
      access line identification in one of the other two forms.

   All of these identifiers originate with the AN control application,
   during the process of DSL topology discovery.  The control
   application chooses which identifiers to use and the values to place
   into them on a line-by-line basis, based on AN configuration and
   deployment considerations.

   Aside from its use in ANCP signalling, access line identification is
   also used in DHCP transactions involving hosts served by DSL.  Either
   the AN or the NAS can serve as a DHCP relay node.  [TR-101] requires
   the AN or NAS in this role to add access line identification in
   Option 82 (Information) to each DHCP request it forwards to the DHCP
   server.  It is desirable for efficiency that the identification used
   in this signalling should be the same as the identification used in
   ANCP messages.

   From the point of view of ANCP itself, the identifiers are opaque.
   From the point of view of the AN control application, the syntax for
   the user-side access line identifier is the same as specified in
   Section 3.9.3 of [TR-101] for DHCP Option 82.  The syntax for the
   ASCII form of the NAS-side access line identifier will be similar.

   Access line identification by logical appearance on the user side of
   the Access Node will always identify a DSL loop uniquely.
   Identification by the logical appearance on the NAS side of the
   Access Node is unique only if there is a one-to-one mapping between
   the appearances on the two sides and no identity-modifying



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   aggregation between the AN and the NAS.  In other cases, and in
   particular in the case of Ethernet aggregation using the N:1 VLAN
   model, the user-side access line identification is necessary, but the
   NAS-side identification is potentially useful information allowing
   the NAS to build up a picture of the aggregation network topology.

   Additional identification down to the user or host level is intended
   to supplement rather than replace either of the other two forms of
   identification.

      Sections 3.8 and 3.9 of [TR-101] are contradictory on this point.
      It is assumed here that Section 3.9 is meant to be authoritative.

   The user-level identification takes the form of an administered
   string which again is opaque at the ANCP level.

   The NAS control application will use the identifying information it
   receives from the AN directly for some purposes.  For examples, see
   the introductory part of Section 3.9 of [TR-101].  For other
   purposes, the NAS will build a mapping between the unique access line
   identification provided by the AN, the additional identification of
   the user or host (where provided), and the IP interface on a
   particular host.  For access lines with static IP address assignment
   that mapping could be configured instead.

5.1.2.  TLVs For DSL Access Line Identification

   This section provides a normative specification of the TLVs that ANCP
   provides to carry the types of identification just described.  The
   Access-Loop-Circuit-ID TLV identifies an access line by its logical
   appearance on the user side of the Access Node.  Two alternatives,
   the Access-Aggregation-Circuit-ID-ASCII TLV and the Access-
   Aggregation-Circuit-ID-Binary TLV, identify an access line by its
   logical appearance on the NAS side of the Access Node.  It is
   unlikely that a given AN uses both of these TLVs, either for the same
   line or for different lines, since they carry equivalent information.
   Finally, the Access-Loop-Remote-Id TLV contains an operator-
   configured string that uniquely identifies the user on the associated
   access line, as described in Sections 3.9.1 and 3.9.2 of [TR-101].

   As normative requirements on ANCP agents conforming to this section:

   o  ANCP agents MUST be able to build and send the Access-Loop-
      Circuit-ID TLV, the Access-Loop-Remote-Id TLV, and either the
      Access-Aggregation-Circuit-ID-ASCII TLV or the Access-Aggregation-
      Circuit-ID-Binary TLV (implementation choice), when passed the
      associated information from the AN control application.




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   o  ANCP agents MUST be able to receive all four TLV types, extract
      the relevant information, and pass it to the control application.

   o  If the Access-Loop-Remote-Id TLV is present in a message, it MUST
      be accompanied by an Access-Loop-Circuit-ID TLV and/or an Access-
      Aggregation-Circuit-ID-xxx TLV with two VLAN identifiers.

         The Access-Loop-Remote-Id TLV is not enough to identify an
         access line uniquely on its own.  As indicated above, an
         Access-Aggregation-Circuit-ID-xxx TLV with two VLAN identifiers
         may or may not identify an access line uniquely, but this is up
         to the control application to decide.

   o  If the Access-Aggregation-Circuit-ID-xxx TLV is present in a
      message with just one VLAN identifier, it MUST be accompanied by
      an Access-Loop-Circuit-ID TLV.

5.1.2.1.  Access-Loop-Circuit-ID TLV

   Type:  0x0001

   Description:  a locally administered human-readable string generated
      by or configured on the Access Node, identifying the corresponding
      access loop logical port on the user side of the Access Node.

   Length:  up to 63 bytes

   Value:  ASCII string

5.1.2.2.  Access-Loop-Remote-Id TLV

   Type:  0x0002

   Description:  an operator-configured string that uniquely identifies
      the user on the associated access line, as described in Sections
      3.9.1 and 3.9.2 of [TR-101].

   Length:  up to 63 bytes

   Value:  ASCII string

5.1.2.3.  Access-Aggregation-Circuit-ID-Binary TLV

   Type:  0x0006







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   Description:  This TLV identifies or partially identifies a specific
      access line by means of its logical circuit identifier on the NAS
      side of the Access Node.

      For Ethernet access aggregation, where a per-subscriber (stacked)
      VLAN can be applied (1:1 model as defined in [TR-101]), the TLV
      contains two value fields.  Each field carries a 12-bit VLAN
      identifier (which is part of the VLAN tag defined by IEEE 802.1Q).
      The first field MUST carry the inner VLAN identifier, while the
      second field MUST carry the outer VLAN identifier.

      When the N:1 VLAN model is used, only one VLAN tag is available.
      For the N:1 model, the Access-Aggregation-Circuit-ID-Binary TLV
      contains a single value field, which MUST carry the 12-bit VLAN
      identifier derived from the single available VLAN tag.

      In the case of an ATM aggregation network, where the DSLAM is
      directly connected to the NAS (without an intermediate ATM
      switch), the VPI and VCI on the DSLAM uplink correspond uniquely
      to the DSL line on the DSLAM.  The Access-Aggregation-Circuit-ID-
      Binary TLV MAY be used to carry the VPI and VCI.  The first value
      field of the TLV MUST carry the VCI, while the second value field
      MUST carry the VPI.

      Each identifier MUST be placed in the low-order bits of its
      respective 32-bit field, with the higher-order bits set to zero.
      The ordering of the bits of the identifer MUST be the same as when
      the identifier is transmitted on the wire to identify an Ethernet
      frame or ATM cell.

      The Access-Aggregation-Circuit-ID-Binary is illustrated in
      Figure 12.

   Length:  4 or 8 bytes

   Value:  one or two 32-bit binary fields.


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    TLV Type = 0x0006          |        Length = 4 or 8        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Single VLAN Identifier, inner VLAN identifier, or VCI        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                Outer VLAN identifier or VPI                   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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          Figure 12: The Access-Aggregation-Circuit-ID-Binary TLV

5.1.2.4.  Access-Aggregation-Circuit-ID-ASCII TLV

   Type:  0x0003

   Description:  This TLV transmits the ASCII equivalent of the Access-
      Aggregation-Circuit-ID-Binary TLV.  As mentioned in the previous
      section, the AN control application will use a format similar to
      that specified in Section 3.9.3 of [TR-101] for the format of the
      "circuit-id".

      As an extension to the present document, the Access Node could
      convey to the NAS the characteristics (e.g., bandwidth) of the
      uplink on the Access Node.  This TLV or the binary equivalent
      defined above then serves the purpose of uniquely identifying the
      uplink whose characteristics are being defined.  The present
      document does not specify the TLVs needed to convey the uplink
      characteristics.

   Length:  up to 63 bytes

   Value:  ASCII string


6.  ANCP Based DSL Topology Discovery

   Section 3.1 of [RFC5851] describes the requirements for the DSL
   Topology Discovery capability.

6.1.  Control Context (Informative)

   The AN control application in the DSLAM requests ANCP to send a DSL-
   specific Port Up message to the NAS under the following
   circumstances:

   o  when a new adjacency with the NAS is established, for each DSL
      loop that is synchronized at that time;

   o  subsequent to that, whenever a DSL loop resynchronizes; and

   o  whenever the AN control application wishes to signal that a line
      attribute has changed.

   The AN control application in the DSLAM requests ANCP to send a DSL-
   specific Port Down message to the NAS under the following
   circumstances:




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   o  when a new adjacency with the NAS is established, for each DSL
      loop that is provisioned but not synchronized at that time;

   o  whenever a DSL loop that is equipped in an AN but administratively
      disabled is signalled as "IDLE"; and

   o  subsequent to that, whenever a DSL loop loses synchronization.

   The AN control application passes information to identify the DSL
   loop to ANCP to include in the Port Up or Port Down message, along
   with information relating to DSL loop attributes.

   In the case of bonded copper loops to the customer premise (as per
   DSL multi-pair bonding described by [G.988.1] and [G.988.2]), the AN
   control application requests that ANCP send DSL-specific Port Up and
   Port Down messages for the aggregate "DSL bonded circuit"
   (represented as a single logical port) as well as the individual DSL
   loops of which it is comprised.  The information relating to DSL line
   attributes that is passed by the AN control application is aggregate
   information.

   ANCP generates the DSL-specific Port Up or Port Down message and
   transfers it to the NAS.  ANCP on the NAS side passes an indication
   to the NAS control application that a DSL Port Up or Port Down
   message has been received along with the information contained in the
   message.

   The NAS control application updates its view of the DSL loop state,
   performs any required accounting operations, and uses any included
   line attributes to adjust the operation of its queueing/scheduling
   mechanisms as they apply to data passing to and from that DSL loop.

   Figure 13 summarizes the interaction.


















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   1.   Home            Access                          NAS
       Gateway           Node

             ----------->     -------------------------->
                  DSL          Port Up (Event message)
                 Signal        (default line parameters)

   2.   Home            Access                          NAS
       Gateway           Node

             ----------->     -------------------------->
                  DSL           Port Up (Event message)
                Resynch        (updated line parameters)

   3.   Home            Access                          NAS
       Gateway           Node

             ----------->     -------------------------->
             Loss of          Port Down (Event message)
             DSL Signal       (selected line parameters)

          Figure 13: ANCP Message Flow For DSL Topology Discovery

6.2.  Protocol Requirements

   The DSL topology discovery capability is assigned capability type
   0x0001.  No capability data is associated with this capability.

6.2.1.  Protocol Requirements On the AN Side

   The AN-side ANCP agent MUST be able to create DSL-specific Port Up
   and Port Down messages according to the format specified in
   Section 6.3.

   The AN-side ANCP agent MUST conform to the normative requirements of
   Section 5.1.2.

   The AN-side ANCP agent "must" be able to accept any information
   passed to it by the AN control application that can validly be
   included in any of the line attribute TLVs specified in Section 6.5,
   MUST package that information as TLVs, and MUST include these TLVs,
   encapsulated in the DSL-Line-Attributes TLV, within the Port Up or
   Port Down message.

   The AN-side ANCP agent MUST follow the AN-side procedures associated
   with DSL-specific Port Up and Port Down messages as they are
   specified in Section 6.4.




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6.2.2.  Protocol Requirements On the NAS Side

   The NAS-side ANCP agent MUST be able to receive and validate DSL-
   specific Port Up and Port Down messages according to the format
   specified in Section 6.3.

   The NAS-side ANCP agent MUST conform to the normative requirements of
   Section 5.1.2.

   The NAS-side ANCP agent MUST follow the NAS-side procedures
   associated with DSL-specific Port Up and Port Down messages as they
   are specified in Section 6.4.

   The NAS-side ANCP agent MUST be able to extract the information
   contained in any of the TLVs specified in Section 6.5 and "must" be
   able to make that information available to the NAS control
   application.

6.3.  ANCP Port UP and Port DOWN Event Message Descriptions

   The ANCP Port UP and Port DOWN Event messages are derived from the
   GSMPv3 Event message shown in Section 9 of [RFC3292].  The modified
   format used for DSL topology discovery is shown in Figure 14.




























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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           TCP/IP Encapsulating Header (Section 3.2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                ANCP General Message Header                    |
   +                      (Section 3.6.1)                          +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Port (unused)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Port Session Number (unused)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Event Sequence Number (unused)                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +---                 Label (8 bytes, unused)                 ---+
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|x|x|x|x| Message Type  |   Tech Type   |  Reserved     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     # of TLVs                 | Extension Block length (bytes)|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                 Access line identifying TLV(s)                ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                DSL-Line-Attributes TLV                        |
   ~        (MANDATORY in Port Up, OPTIONAL in Port Down)          ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   NOTE: TLVs MAY be in a different order from what is shown in this
   figure.

    Figure 14: Format Of the ANCP Port Up and Port Down Event Messages
                        For DSL Topology Discovery

   See Section 3.6.1 for a description of the ANCP general message
   header.  The Message Type field MUST be set to 80 for Port Up, 81 for
   Port Down.  The 12 bit Code field MUST be set to 0.  The 4 bit Result
   field MUST be set to 0 (signifying Ignore).  The 24-bit Transaction
   Identifier field MUST be set to 0.  Other fields in the general
   header MUST be set as described in Section 3.6.

   The Port, Port Session Number, and Event Sequence Number fields are
   not used by the DSL Topology Discovery capability.  The Label field
   (including the Stacked Label Indicator and the unused flags at the



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   start of the Label field), is also unused, and MUST be treated as an
   unused fixed 8-byte field.  The handling of unused/reserved fields is
   described in Section 3.4.

   The remaining message fields belong to the "extension block" added to
   the original GSMPv3 message by ANCP, and are described as follows:

   Extension Flags:  The flag bits denoted by 'x' are currently
      unspecified and reserved.

   Message Type:  Message Type has the same value as in the general
      header (i.e., 80 or 81).

   Tech Type:  MUST be set to 0x05 (DSL).

   # of TLVs:  the number of TLVs that follow, not counting TLVs
      encapsulated within other TLVs.

   Extension Block Length:  the total length of the TLVs carried in the
      extension block in bytes, including any padding within individual
      TLVs.

   TLVs:  one or more TLVs to identify a DSL line and zero or more TLVs
      to define its characteristics.

6.4.  Procedures

6.4.1.  Procedures On the AN Side

   The AN-side ANCP agent MUST create and transmit a DSL-specific Port
   Up or Port Down message when requested by the AN control application
   and presented with the information needed to build a valid message,
   except if transmission is inhibited by a rate-dampening mechanism.
   It is RECOMMENDED that the Access Node use a dampening mechanism per
   DSL loop to control the rate at which state changes are communicated
   to the NAS.

   At the top level, the extension block within a DSL-specific Port Up
   or Port Down message MUST include TLVs from Section 5.1.2 to identify
   the DSL loop.

   TLVs presenting DSL line attributes (i.e., the TLVs specified in
   Section 6.5) MUST be encapsulated within the DSL-Line-Attributes TLV.
   When the DSL-Line-Attributes TLV is present in a message, it MUST
   contain at least one such TLV and will generally contain more than
   one.  In the Port Up message, the DSL-Line-Attributes TLV MUST be
   present.  In the Port Down message, the DSL-Line-Attributes TLV MAY
   be present.



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   If the AN-side ANCP agent is unable to satisfy a request from the AN
   control application because it detects an error in the request or
   because it receives a Generic Response message indicating an error in
   a Port Up or Port Down message that it has sent and is unable to
   recover from that error at the protocol level, it "must" inform the
   application, including any available diagnostic information.

6.4.2.  Procedures On the NAS Side

   The NAS-side ANCP agent MUST be prepared to receive Port Up and Port
   Down messages for a given DSL loop or logical port at any time after
   negotiation of an adjacency has been completed.  It is possible for
   two Port Up messages in succession to be received for the same DSL
   loop without an intervening Port Down message, and vice versa.

   The NAS-side ANCP agent SHOULD validate each message against the
   specifications given in Section 6.3 and the TLV specifications given
   in Section 5.1.2 and Section 6.5.  If it finds an error it MAY
   generate a Generic Response message containing an appropriate Result
   Code value.  If it does so, the message MUST contain copies of all of
   the identifier TLVs from Section 5.1.2 that were present in the Port
   Up or Port Down message.  The message SHOULD also contain a Status-
   Info TLV which in turn contains other information appropriate to the
   message header Code value as described in Section 3.6.1.4.

   If the received message passes validation, the NAS-side ANCP agent
   "must" extract the information from the TLVs contained in the message
   and present that information along with an indication of reported
   event type to the NAS control application.  If validation of
   individual TLVs fails but the message as a whole can be processed,
   the NAS-side ANCP agent "may" pass the valid message contents to the
   NAS control application.

6.5.  TLVs For DSL Line Attributes

   As specified above, the DSL-Line-Attributes TLV is inserted into the
   Port Up or Port Down message at the top level.  The remaining TLVs
   defined below are encapsulated within the DSL-Line-Attributes TLV.

6.5.1.  DSL-Line-Attributes TLV

   Type:  0x0004

   Description:  This TLV encapsulates attribute values for a DSL line
      serving a subscriber.






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   Length:  variable (up to 1024 bytes)

   Value:  one or more encapsulated TLVs corresponding to DSL line
      attributes.  The DSL-Line-Attributes TLV MUST contain at least one
      TLV when it is present in a Port Up or Port Down message.  The
      actual contents are determined by the AN control application.

6.5.2.  DSL-Type TLV

   Type:  0x0091

   Description:  Indicates the type of transmission system in use.

   Length:  4 bytes

   Value:  32 bit unsigned integer

         ADSL1 = 1

         ADSL2 = 2

         ADSL2+ = 3

         VDSL1 = 4

         VDSL2 = 5

         SDSL = 6

         OTHER = 0

6.5.3.  Actual-Net-Data-Rate-Upstream TLV

   Type:  0x0081

   Description:  Actual upstream net data rate on a DSL line.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.4.  Actual-Net-Data-Rate-Downstream TLV

   Type:  0x0082







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   Description:  Actual downstream net data rate on a DSL line.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.5.  Minimum-Net-Data-Rate-Upstream TLV

   Type:  0x0083

   Description:  Minimum upstream net data rate desired by the operator.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.6.  Minimum-Net-Data-Rate-Downstream TLV

   Type:  0x0084

   Description:  Minimum downstream net data rate desired by the
      operator.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.7.  Attainable-Net-Data-Rate-Upstream TLV

   Type:  0x0085

   Description:  Maximum net upstream rate that can be attained on the
      DSL line.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.8.  Attainable-Net-Data-Rate-Downstream TLV

   Type:  0x0086

   Description:  Maximum net downstream rate that can be attained on the
      DSL line.







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   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.9.  Maximum-Net-Data-Rate-Upstream TLV

   Type:  0x0087

   Description:  Maximum net upstream data rate desired by the operator.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.10.  Maximum-Net-Data-Rate-Downstream TLV

   Type:  0x0088

   Description:  Maximum net downstream data rate desired by the
      operator.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.11.  Minimum-Net-Low-Power-Data-Rate-Upstream TLV

   Type:  0x0089

   Description:  Minimum net upstream data rate desired by the operator
      in low power state.

   Length:  4 bytes

   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.12.  Minimum-Net-Low-Power-Data-Rate-Downstream TLV

   Type:  0x008A

   Description:  Minimum net downstream data rate desired by the
      operator in low power state.

   Length:  4 bytes







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   Value:  Rate in Kbits/s as a 32 bit unsigned integer

6.5.13.  Maximum-Interleaving-Delay-Upstream TLV

   Type:  0x008B

   Description:  maximum one way interleaving delay.

   Length:  4 bytes

   Value:  Time in ms as a 32 bit unsigned integer

6.5.14.  Actual-Interleaving-Delay-Upstream TLV

   Type:  0x008C

   Description:  Value corresponding to the interleaver setting.

   Length:  4 bytes

   Value:  Time in ms as a 32 bit unsigned integer

6.5.15.  Maximum-Interleaving-Delay-Downstream TLV

   Type:  0x008D

   Description:  maximum one way interleaving delay.

   Length:  4 bytes

   Value:  Time in ms as a 32 bit unsigned integer

6.5.16.  Actual-Interleaving-Delay-Downstream

   Type:  0x008E

   Description:  Value corresponding to the interleaver setting.

   Length:  4 bytes

   Value:  Time in ms as a 32 bit unsigned integer

6.5.17.  DSL-Line-State TLV








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   Type:  0x008F

   Description:  The state of the DSL line.

   Length:  4 bytes

   Value:  32 bit unsigned integer

         SHOWTIME = 1

         IDLE = 2

         SILENT = 3

6.5.18.  Access-Loop-Encapsulation TLV

   Type:  0x0090

   Description:  The data link protocol and, optionally, the
      encapsulation overhead on the access loop.  When this TLV is
      present, at least the data link protocol MUST be indicated.  The
      encapsulation overhead MAY be indicated.  The Access Node MAY
      choose to not convey the encapsulation on the access loop by
      specifying values of 0 (NA) for the two encapsulation fields.

   Length:  3 bytes

   Value:  The three bytes (most to least significant) and valid set of
      values for each byte are defined as follows:

         Byte 1: Data Link

            ATM AAL5 = 0

            ETHERNET = 1

         Byte 2: Encapsulation 1

            NA = 0

            Untagged Ethernet = 1

            Single-tagged Ethernet = 2

            Double-tagged Ethernet = 3






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         Byte 3: Encapsulation 2

            NA = 0

            PPPoA LLC = 1

            PPPoA NULL = 2

            IPoA LLC = 3

            IPoA NuLL = 4

            Ethernet over AAL5 LLC with FCS = 5

            Ethernet over AAL5 LLC without FCS = 6

            Ethernet over AAL5 NULL with FCS = 7

            Ethernet over AAL5 NULL without FCS = 8

   The Access-Loop-Encapsulation TLV is illustrated in Figure 15.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    TLV Type = 0x0090          |        Length = 3             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Data link     |    Encaps 1   |    Encaps 2   | Padding (=0)  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 15: The Access-Loop-Encapsulation TLV


7.  ANCP based DSL Line Configuration

   The use case for ANCP-based DSL Line Configuration is described in
   Section 3.2 of [RFC5851].

7.1.  Control Context (Informative)

   Triggered by topology information reporting a new DSL line or
   triggered by a subsequent user session establishment (PPP or DHCP),
   RADIUS/AAA sends service parameters to the NAS control application
   for configuration on the access line.  The NAS control application
   passes the request on to the NAS-side agent, which sends the
   information to the AN by means of a Port Management (line
   configuration) message.  The AN-side agent passes this information up
   to the AN control application, which applies it to the line.



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   Figure 16 summarizes the interaction.

     Home            Access               NAS             RADIUS/AAA
    Gateway           Node                             Policy Server

          ----------->     --------------->
              DSL          Port Up message)
             Signal       (line parameters)

          -------------------------------->   -------------->
                  PPP/DHCP Session            Authentication &
                                              authorization

                          <----------------
                            Port Management message
                            (line configuration)

   Figure 16: Message Flow - ANCP Mapping For Initial Line Configuration

   The NAS could update the line configuration as a result of a
   subscriber service change (e.g. triggered by the policy server).
   Figure 17 summarizes the interaction.

User     Home            Access         NAS
        Gateway           Node

             -------------------------->
               PPP/DHCP Session

   -------------------------------------------------------> Web portal,
               Service on demand                              OSS, etc.
                                                                 |
                                           <--------------  RADIUS/AAA
                                             Change of     Policy Server
                                           authorization

                             <------------
                              Port Management
                                  message
                              (new profile)

   Figure 17: Message flow - ANCP Mapping For Updated Line Configuration

7.2.  Protocol Requirements

   The DSL line configuration capability is assigned capability type
   0x0002.  No capability data is associated with this capability.




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7.2.1.  Protocol Requirements On the NAS Side

   The NAS-side ANCP agent MUST be able to create DSL-specific Port
   Management (line configuration) messages according to the format
   specified in Section 7.3.

   The NAS-side ANCP agent MUST conform to the normative requirements of
   Section 5.1.2.

   The NAS-side ANCP agent "must" be able to accept any information
   passed to it by the NAS control application that may validly be
   included in any of the TLVs specified in Section 7.5.

      In the current version of this specification only one such TLV is
      defined.

   The NAS-side ANCP agent MUST package that information as TLVs, and
   MUST include these TLVs within the Port Management (line
   configuration) message.

   The NAS-side ANCP agent MUST follow the NAS-side procedures
   associated with DSL-specific Port Management (line configuration)
   messages as they are specified in Section 7.4.

7.2.2.  Protocol Requirements On the AN Side

   The AN-side ANCP agent MUST conform to the normative requirements of
   Section 5.1.2.

   The AN-side ANCP agent MUST be able to receive and validate DSL-
   specific Port Management (line configuration) messages according to
   the format specified in Section 7.3.

   The AN-side ANCP agent MUST follow the AN-side procedures associated
   with DSL-specific Port Management (line configuration) messages as
   specified in Section 7.4.

   The NAS-side ANCP agent MUST be able to extract the information
   contained in any of the TLVs listed in Section 7.2.1 and "must" make
   that information available to the NAS control application.

7.3.  ANCP Port Management (Line Configuration) Message Format

   The ANCP Port Management message for DSL line configuration has the
   format shown in Figure 18.






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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           TCP/IP Encapsulating Header (Section 3.2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                ANCP General Message Header                    |
   +                      (Section 3.6.1)                          +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Port (unused)                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Port Session Number (unused)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Event Sequence Number  (unused)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|x|x|x|x|x|x|x| Dur. (unused) |  Function=8   | X-Function=0  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Event Flags  (unused)       | Flow Control Flags  (unused)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|x|x|x|x| Message Type  |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     # of TLVs               | Extension Block length (bytes)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                 Access line identifying TLV(s)                ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                Line configuration TLV(s)                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   NOTE: TLVs MAY be in a different order from what is shown in this
   figure.

       Figure 18: Port Management Message For DSL Line Configuration

   See Section 3.6 for a description of the ANCP general message header.
   The Message Type field MUST be set to 32.  The 12 bit Code field MUST
   be set to 0.  The 4 bit Result field MUST be set to either 1 (NAck)
   or 2 (AckAll), as determined by policy on the NAS.  The 24-bit
   Transaction Identifier field MUST be set to a positive value.  Other
   fields in the general header MUST be set as described in Section 3.6.

   As with the Port Up and Port Down messages described above, the Port
   Management message format defined in [RFC3292] has been modified to
   contain additional data in an "extension block" at the end of the
   message.  Also, the original two byte Function field has been



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   modified to contain one byte for the Function field indicating a
   specific action to be taken by the recipient of the message, and one
   byte for X-Function field, which further qualifies the action
   specified in the Function field.  Any Function specific data MUST be
   carried in TLVs in the extension block.

   The Port, Port Session Number, and Event Sequence Number fields are
   not used by the DSL Line Configuration capability.  The handling of
   unused/reserved fields is described in Section 3.4.

   The remaining message fields are described as follows:

   R Flag:  not used by ANCP.

   Additional Port Management flags:  the flag bits marked 'x' following
      the R flag are not used by ANCP.

   Duration:  not used for DSL line configuration.

   Function:  action to be performed.  For line configuration, Function
      MUST be set to 8 (Configure Connection Service Data).  This action
      type requests the Access Node (i.e., DSLAM) to apply service
      configuration data contained in the line configuration TLVs to the
      DSL line designated by the access line identifying TLVs.

   X-Function:  qualifies the action set by Function.  For DSL line
      configuration, this field MUST be set to 0.

   Event Flags:  not used by ANCP.

   Flow Control Flags:  not used by ANCP.

   Extension Flags:  the flag bits denoted by 'x' before the Message
      Type field are reserved for future use.

   Message Type:  Message Type has the same value as in the general
      header (i.e., 32).

   Reserved (16 bits):  reserved for future use.

   # of TLVs:  the number of TLVs that follow, not counting TLVs
      encapsulated within other TLVs.

   Extension Block Length:  the total length of the TLVs carried in the
      extension block in bytes, including any padding within individual
      TLVs.





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   TLVs:  two or more TLVs to identify a DSL line and configure its
      service data.

   Other ANCP capabilities, either specific to DSL or technology-
   independent, MAY reuse the Port Management message for service
   configuration.  If the settings of the fixed fields are compatible
   with the settings just described, the same Port Management message
   that is used for DSL line configuration MAY be used to carry TLVs
   relating to the other capabilities that apply to the same DSL loop.

   Use of the Port Management message for configuration MAY also be
   generalized to other access technologies, if the respective
   capabilities specify use of access line identifiers appropriate to
   those technologies in place of the identifiers defined in
   Section 5.1.2.

7.4.  Procedures

   Service configuration MAY be performed on an access line regardless
   of its current state.

7.4.1.  Procedures On the NAS Side

   When requested by the NAS control application and presented with the
   necessary information to do so, the NAS-side agent MUST create and
   send a Port Management message with the fixed fields set as described
   in the previous section.  The message MUST contain one or more TLVs
   to identify an access line according the requirements of
   Section 5.1.2.  The NAS MUST include one or more TLVs to configure
   line service parameters for that line.  Section 7.5 currently
   identifies only one such TLV, Service-Profile-Name, but other TLVs
   MAY be added by extensions to ANCP.

7.4.2.  Procedures On the AN Side

   The AN-side ANCP agent MUST be prepared to receive Port Management
   (line configuration) messages for a given DSL loop or logical port at
   any time after negotiation of an adjacency has been completed.

   The AN-side ANCP agent SHOULD validate each message against the
   specifications given in Section 7.3 and the TLV specifications given
   in Section 5.1.2 and Section 7.5.  If it finds an error it MUST
   return a Port Management response message which copies the Port
   Management request as it was received, but has the Result header
   field set to 0x04 (Failure) and the Code field set to the appropriate
   value.  The AN-side agent MAY add a Status-Info TLV (Section 4.5) to
   provide further information on the error, particularly if this is
   recommended in Section 3.6.1.4 for the given Code value.  If it does



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   so, the various length fields and the # of TLVs field within the
   message MUST be adjusted accordingly.

   If the received message passes validation, the AN-side ANCP agent
   "must" extract the information from the TLVs contained in the message
   and present that information to the AN control application.  In
   addition, if the Result header field was set to 0x2 (AckAll) in the
   original request, the AN-side agent "must" indicate to the AN control
   application that a response is required.  When the AN control
   application indicates that it has processed the request successfully,
   the AN-side agent MUST return a Port Management response message
   which duplicates the request except that the Result header field is
   set to 0x3 (Success).  (The Code field, as in the original request,
   has value 0.)

7.5.  TLVs For DSL Line Configuration

   Currently only the following TLV is specified for DSL line
   configuration.  More TLVs may be defined in a future version of this
   specification or in ANCP extensions for individual service attributes
   of a DSL line (e.g. rates, interleaving delay, multicast channel
   entitlement access-list).

7.5.1.  Service-Profile-Name TLV

   Type:  0x0005

   Description:  Reference to a pre-configured profile on the DSLAM that
      contains service specific data for the subscriber.

   Length:  up to 64 bytes

   Value:  ASCII string containing the profile name (which the NAS
      learns from a policy server after a subscriber is authorized).


8.  ANCP-Based DSL Remote Line Connectivity Testing

   The use case and requirements for ANCP-Based DSL remote line
   connectivity testing are specified in Section 3.3 of [RFC5851]

8.1.  Control Context (Informative)

   The NAS control application initiatea a request for remote
   connectivity testing for a given access loop.  The NAS control
   application can provide loop count and timeout test parameters and
   opaque data for its own use with the request.  The loop count
   parameter indicates the number of test messages or cells to be used.



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   The timeout parameter indicates the longest that the NAS control
   application will wait for a result.

   The request is passed in a Port Management (OAM) message.  If the NAS
   control application has supplied test parameters, they are used,
   otherwise the AN control application uses default test parameters.
   If a loop count parameter provided by the NAS is outside the valid
   range, the AN does not execute the test, but returns a result
   indicating that the test has failed due to an invalid parameter.  If
   the test takes longer than the timeout value (default or provided by
   the NAS) the AN control application can return a failure result
   indicating timeout or else can send no response.  The AN control
   application can provide a human-readable string describing the test
   results,for both failures and successes.  If provided, this string is
   included in the response.  Responses always include the opaque data,
   if any, provided by the NAS control application.

   Figure 19 summarizes the interaction.

 +-------------+    +-----+       +-------+           +----------------+
 |Radius/AAA   |----|NAS  |-------| DSLAM |-----------|    CPE         |
 |Policy Server|    +-----+       +-------+           | (DSL Modem +   |
 +-------------+                                      |Routing Gateway)|
                                                      +----------------+
                  Port Management Message
                  (Remote Loopback          ATM loopback
                   Trigger Request)         OR EFM Loopback
                1.  ---------------->     2. --------->
                                             <--------+
                     3. <---------------
                     Port Management Message
                (Remote Loopback Test Response)

                Figure 19: Message Flow For ANCP based OAM

8.2.  Protocol Requirements

   The DSL remote line connectivity testing capability is assigned
   capability type 0x0004.  No capability data is associated with this
   capability.

8.2.1.  Protocol Requirements On the NAS Side

   The NAS-side ANCP agent MUST be able to create DSL-specific Port
   Management (OAM) messages according to the format specified in
   Section 8.3.

   The NAS-side ANCP agent MUST conform to the normative requirements of



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   Section 5.1.2.

   The NAS-side ANCP agent "must" be able to accept any information
   passed to it by the NAS control application that may validly be
   included in any of the TLVs specified in Section 8.5.

   The NAS-side ANCP agent MUST package that information as TLVs, and
   MUST include these TLVs within the Port Management (OAM) message.

   The NAS-side ANCP agent MUST follow the NAS-side procedures
   associated with DSL-specific Port Management (OAM) messages as they
   are specified in Section 8.4.

8.2.2.  Protocol Requirements On the AN Side

   The AN-side ANCP agent MUST conform to the normative requirements of
   Section 5.1.2.

   The AN-side ANCP agent MUST be able to receive and validate DSL-
   specific Port Management (OAM) messages according to the format
   specified in Section 8.3.

   The AN-side ANCP agent MUST follow the AN-side procedures associated
   with DSL-specific Port Management (OAM) messages as specified in
   Section 8.4.

   The NAS-side ANCP agent MUST be able to extract the information
   contained in any of the TLVs listed in Section 8.2.1 and "must" make
   that information available to the NAS control application.

8.3.  Port Management (OAM) Message Format

   The Port Management message for DSL line testing has the same format
   as for DSL line configuration (see Section 7.3), with the following
   differences:

   o  The Result field in the request SHOULD be set to AckAll (0x1), to
      allow the NAS to receive the information contained in a successful
      test response.

   o  The Function field MUST be set to 9 (Remote Loopback).  (The
      X-Function field continues to be 0.)

   o  The appended TLVs in the extension value field include testing-
      related TLVs rather than subcriber service information.

   The Port Management (OAM) message is illustrated in Figure 20.




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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           TCP/IP Encapsulating Header (Section 3.2)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                ANCP General Message Header                    |
   +                      (Section 3.6.1)                          +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Port (unused)                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Port Session Number (unused)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Event Sequence Number  (unused)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|x|x|x|x|x|x|x| Dur. (unused) |  Function=9   | X-Function=0  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Event Flags  (unused)       | Flow Control Flags  (unused)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x|x|x|x|x|x|x|x| Message Type  |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     # of TLVs               | Extension Block length (bytes)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                 Access line identifying TLV(s)                ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                   Testing-related TLVs                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   NOTE: TLVs MAY be in a different order from what is shown in this
   figure.

    Figure 20: Port Management Message For DSL Line Remote Connectivity
                                  Testing

8.4.  Procedures

   From the point of view of ANCP, it is permissible to attempt line
   connectivity testing regardless of the state of the line.  However,
   testing could fail in some states due to technology limitations.

8.4.1.  NAS-Side Procedures

   When requested by the NAS control application and presented with the
   necessary information to do so, the NAS-side agent MUST create and



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   send a Port Management (OAM) request with the fixed fields set as
   described in the previous section.  The message MUST contain one or
   more TLVs to identify an access line according the requirements of
   Section 5.1.2.  The NAS MAY include the Opaque-Data TLV and/or the
   OAM-Loopback-Test-Parameters TLV (defined in Section 8.5) to
   configure the loopback test for that line.

8.4.2.  AN-Side Procedures

   The AN-side ANCP agent SHOULD validate each message against the
   specifications given in Section 8.3 and the TLV specifications given
   in Section 5.1.2 and Section 8.5.  If it finds an error it MUST
   return a Port Management response message which copies the Port
   Management request as it was received, but has the Result header
   field set to 0x04 (Failure) and the Code field set to the appropriate
   value.  Code value 1289 as described below MAY apply, as well as the
   other Code values documented in Section 3.6.1.4.  Code value 1289
   SHOULD be used if the OAM-Loopback-Test-Parameters TLV is present
   with an invalid value of the Count field.  The AN-side agent MAY add
   a Status-Info TLV (Section 4.5) to provide further information on the
   error, particularly if this is recommended in Section 3.6.1.4 for the
   given Code value.  If it does so, the various length fields and the #
   of TLVs field within the message MUST be adjusted accordingly.

   If the received message passes validation, the AN-side ANCP agent
   "must" extract the information from the TLVs contained in the message
   and present that information to the AN control application.  It MUST
   NOT generate an immediate response to the request, but MUST instead
   wait for the AN control application to indicate that the response
   should be sent.

   When requested by the AN control application and presented with the
   necessary information to do so, the AN-side agent MUST create and
   send a Port Management (OAM) response to the original request.  The
   Result field MUST be set to Success (0x3) or Failure (0x4), and the
   Code field SHOULD be set to one of the following values, as indicated
   by the AN control application.

   1280 (0x500):  Specified access line does not exist.  See the
      documentation of Code 3/1280 in Section 3.6.1.4 for more
      information.  The Result header field MUST be set to Failure
      (0x4).

   1281 (0x501):  Loopback test timed out.  The Result header field MUST
      be set to Failure (0x4).






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   1283 (0x503):  DSL line status showtime

   1284 (0x504):  DSL line status idle

   1285 (0x505):  DSL line status silent

   1286 (0x506):  DSL line status training

   1287 (0x507):  DSL line integrity error

   1288 (0x508):  DSLAM resource not available.  The Result header field
      MUST be set to Failure (0x04).

   1289 (0x509):  Invalid test parameter.  The Result header field MUST
      be set to Failure (0x4).

   All other fields of the request including the TLVs MUST be copied
   into the response unchanged, except that in a successful response the
   OAM-Loopback-Test-Parameters TLV MUST NOT appear.  If the AN control
   application has provided the necessary information, the AN-side agent
   MUST also include an instance of the OAM-Loopback-Test-Response-
   String TLV in the response.

8.5.  TLVs For the DSL Line Remote Connectivity Testing Capability

   The following TLVs have been defined for use with the DSL line
   testing capability.

8.5.1.  OAM-Loopback-Test-Parameters TLV

   Type:  0x0007

   Description:  Parameters intended to override the default values for
      this loopback test.

   Length:  2 bytes

   Value:  two unsigned 1 byte fields described below (listed in order
      of most to least significant).

         Byte 1: Count.  Number of loopback cells/messages that should
         be generated on the local loop as part of the loopback test.
         The Count value SHOULD be greater than 0 and less than or equal
         to 32.

         Byte 2: Timeout.  Upper bound on the time in seconds that the
         NAS will wait for a response from the DSLAM.  The value 0 MAY
         be used, but has a special meaning.



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   The OAM-Loopback-Test-Parameters TLV is illustrated in Figure 21

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    TLV Type = 0x0007          |        Length = 2             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Count       |  Timeout      |         Padding (=0)          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 21: The OAM-Loopback-Test-Parameters TLV

8.5.2.  Opaque-Data TLV

   Type:  0x0008

   Description:  An 8 byte opaque field used by the NAS control
      application for its own purposes (e.g., response correlation.)
      The procedures in Section 8.4.2 ensure that if it is present in
      the request it is copied unchanged to the response.

   Length:  8 bytes

   Value:  Two 32 bit unsigned integers.

8.5.3.  OAM-Loopback-Test-Response-String TLV

   Type:  0x0009

   Description:  Suitably formatted string containing useful details
      about the test that the NAS will display for the operator, exactly
      as received from the DSLAM (no manipulation or interpretation by
      the NAS).

   Length:  up to 128 bytes

   Value:  UTF-8 encoded string of text.


9.  IANA Considerations

   RFC EDITOR'S NOTE: please replace "RFCXXXX" with the number of this
   specification.

9.1.  Summary

   This section requests the following IANA actions:




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   o  addition of message types to the GSMPv3 Message Type Name Space
      registry;

   o  addition of a result type to the GSMPv3 Result Type Name Space
      registry;

   o  extension of limits and addition of failure codes to the GSMPv3
      Failure Response Message Name Space registry;

   o  establishment of the following new ANCP registries:

         ANCP Function Codes;

         ANCP Technology Types;

         ANCP Command Codes;

         ANCP TLV Types;

         ANCP Capabilities.

9.2.  IANA Actions

   IANA is requested to add a new message category to the GSMPv3 Message
   Type Name Space registry: "Access Network Control Protocol (ANCP)
   Messages".  IANA is requested to add the following entries under that
   category:

        +------------------+----------------+--------+-----------+
        | Message Name     | Message Number | Status | Reference |
        +------------------+----------------+--------+-----------+
        | Generic Response | 91             |        | RFCXXXX   |
        | Provisioning     | 93             |        | RFCXXXX   |
        +------------------+----------------+--------+-----------+

   IANA is requested to implement the following modification to the
   General Switch Management Protocol version 3 (GSMPv3) Result Type
   Name Space registry:

           +--------------+-----------------------+-----------+
           | Result Value | Result Type Name      | Reference |
           +--------------+-----------------------+-----------+
           | 0            | Ignore (was Reserved) | RFCXXXX   |
           +--------------+-----------------------+-----------+

   IANA is requested to implement the following modifications to the
   GSMPv3 Failure Response Message Name Space:




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   o  Add the following note to the registry:

         This registry is shared with the Access Node Control Protocol
         (ANCP) [RFCXXXX].  GSMPv3 [RFC3292] allows values up to a
         maximum of 255.  ANCP extends this maximum to 4095.  Hence
         values above 255 are applicable to ANCP only.

   o  Extend the table of registration procedures as indicated.

   o  Add entries to the failure response message name table as
      indicated.

   o  Replace the ranges of unassigned codes at the end of the failure
      response message name table as indicated.

           +----------+------------------------+---------------+
           | Range    | Registration Procedure | Notes         |
           +----------+------------------------+---------------+
           | 256-4095 | IETF Consensus         | ANCP use only |
           +----------+------------------------+---------------+

   +-------+----------------------------------------------+-----------+
   | Value | Failure Response Message Name                | Reference |
   +-------+----------------------------------------------+-----------+
   | 81    | Request message type not implemented (0x51)  | RFCXXXX   |
   | 83    | Malformed message (0x53)                     | RFCXXXX   |
   | 84    | Mandatory TLV missing (0x54)                 | RFCXXXX   |
   | 85    | Invalid value in TLV (0x55)                  | RFCXXXX   |
   | 1280  | Specified access line does not exist (0x500) | RFCXXXX   |
   | 1281  | Loopback test timed out (0x501)              | RFCXXXX   |
   | 1282  | Reserved (0x502)                             | RFCXXXX   |
   | 1283  | DSL line status showtime (0x503)             | RFCXXXX   |
   | 1284  | DSL line status idle (0x504)                 | RFCXXXX   |
   | 1285  | DSL line status silent (0x505)               | RFCXXXX   |
   | 1286  | DSL line status training (0x506)             | RFCXXXX   |
   | 1287  | DSL line integrity error (0x507)             | RFCXXXX   |
   | 1288  | DSLAM resource not available (0x508)         | RFCXXXX   |
   | 1289  | Invalid test parameter (0x509)               | RFCXXXX   |
   +-------+----------------------------------------------+-----------+












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         +-----------+-------------------------------+-----------+
         | Value     | Failure Response Message Name | Reference |
         +-----------+-------------------------------+-----------+
         | 8-9       | Unassigned                    |           |
         | 47-59     | Unassigned                    |           |
         | 86-127    | Unassigned                    |           |
         | 160-255   | Unassigned                    |           |
         | 256-1279  | Unassigned (ANCP use only)    |           |
         | 1290-4095 | Unassigned (ANCP use only)    |           |
         +-----------+-------------------------------+-----------+

   IANA is requested to create a new ANCP Port Management Function Name
   registry, with the following initial entries.  Additions to this
   registry will be by IETF Consensus.  Values may range from 0 to 255.

      NOTE: future extensions of ANCP may need to establish sub-
      registries of permitted X-Function values for specific values of
      Function.

    +----------------+-----------------------------------+-----------+
    | Function Value | Function Name                     | Reference |
    +----------------+-----------------------------------+-----------+
    | 0              | Reserved                          | RFCXXXX   |
    | 1-7            | Unassigned                        |           |
    | 8              | Configure Connection Service Data | RFCXXXX   |
    | 9              | Remote Loopback                   | RFCXXXX   |
    | 10-255         | Unassigned                        |           |
    +----------------+-----------------------------------+-----------+

   IANA is requested to create a new ANCP Version registry, with
   additions by IETF consensus.  The initial entries are as follows:

           +---------+-------------+--------------+-----------+
           | Version | Sub-Version | Name         | Reference |
           +---------+-------------+--------------+-----------+
           | 3       | 1           | Pre-standard |           |
           | 3       | 2           | ANCPv1       | RFCXXXX   |
           +---------+-------------+--------------+-----------+

   IANA is requested to create a new ANCP Technology Type registry, with
   additions by IETF Consensus.  Values may range from 0 to 255.  The
   initial entries are as follows:









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             +-----------------+----------------+-----------+
             | Tech Type Value | Tech Type Name | Reference |
             +-----------------+----------------+-----------+
             | 0               | Any technology | RFCXXXX   |
             | 1               | PON            | RFCXXXX   |
             | 2-4             | Unassigned     |           |
             | 5               | DSL            | RFCXXXX   |
             | 6-254           | Unassigned     |           |
             | 255             | Reserved       | RFCXXXX   |
             +-----------------+----------------+-----------+

   IANA is requested to create a new ANCP Command Code registry, with
   additions by IETF Consensus.  The initial entry is as follows:

     +--------------------+-----------------------------+-----------+
     | Command Code Value | Command Code Directive Name | Reference |
     +--------------------+-----------------------------+-----------+
     | 0                  | Reserved                    | RFCXXXX   |
     +--------------------+-----------------------------+-----------+

   IANA is requested to create a new ANCP TLV Type registry, with
   additions by IETF Consensus.  Values may range from 0x0000 to 0xFFFF.
   New assignments should be in the range of values from 0x0100 upwards.
   The initial entries are as follows:



























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   +--------------+----------------------------------------+-----------+
   | Type Code    | TLV Name                               | Reference |
   +--------------+----------------------------------------+-----------+
   | 0x0000       | Reserved                               | RFCXXXX   |
   | 0x0001       | Access-Loop-Circuit-ID                 | RFCXXXX   |
   | 0x0002       | Access-Loop-Remote-Id                  | RFCXXXX   |
   | 0x0003       | Access-Aggregation-Circuit-ID-ASCII    | RFCXXXX   |
   | 0x0004       | DSL-Line-Attributes                    | RFCXXXX   |
   | 0x0005       | Service-Profile-Name                   | RFCXXXX   |
   | 0x0006       | Access-Aggregation-Circuit-ID-Binary   | RFCXXXX   |
   | 0x0007       | OAM-Loopback-Test-Parameters           | RFCXXXX   |
   | 0x0008       | Opaque-Data                            | RFCXXXX   |
   | 0x0009       | OAM-Loopback-Test-Response-String      | RFCXXXX   |
   | 0x000a-0x001 | Unassigned                             |           |
   | 0            |                                        |           |
   | 0x0011       | Command                                | RFCXXXX   |
   | 0x0012-0x008 | Unassigned                             |           |
   | 0            |                                        |           |
   | 0x0081       | Actual-Net-Data-Upstream               | RFCXXXX   |
   | 0x0082       | Actual-Net-Data-Rate-Downstream        | RFCXXXX   |
   | 0x0083       | Minimum-Net-Data-Rate-Upstream         | RFCXXXX   |
   | 0x0084       | Minimum-Net-Data-Rate-Downstream       | RFCXXXX   |
   | 0x0085       | Attainable-Net-Data-Rate-Upstream      | RFCXXXX   |
   | 0x0086       | Attainable-Net-Data-Rate-Downstream    | RFCXXXX   |
   | 0x0087       | Maximum-Net-Data-Rate-Upstream         | RFCXXXX   |
   | 0x0088       | Maximum-Net-Data-Rate-Downstream       | RFCXXXX   |
   | 0x0089       | Minimum-Net-Low-Power-Data-Rate-Upstre | RFCXXXX   |
   |              | am                                     |           |
   | 0x008A       | Minimum-Net-Low-Power-Data-Rate-Downst | RFCXXXX   |
   |              | ream                                   |           |
   | 0x008B       | Maximum-Interleaving-Delay-Upstream    | RFCXXXX   |
   | 0x008C       | Actual-Interleaving-Delay-Upstream     | RFCXXXX   |
   | 0x008D       | Maximum-Interleaving-Delay-Downstream  | RFCXXXX   |
   | 0x008E       | Actual-Interleaving-Delay-Downstream   | RFCXXXX   |
   | 0x008F       | DSL-Line-State                         | RFCXXXX   |
   | 0x0090       | Access-Loop-Encapsulation              | RFCXXXX   |
   | 0x0091       | DSL-Type                               | RFCXXXX   |
   | 0x092-0x0105 | Unassigned                             |           |
   | 0x0106       | Status-Info                            | RFCXXXX   |
   | 0x0107-0x0FF | Unassigned                             |           |
   | F            |                                        |           |
   | 0x1000       | Target (single access line variant)    | RFCXXXX   |
   | 0x1001 -     | Reserved for Target variants           | RFCXXXX   |
   | 0x1020       |                                        |           |
   | 0x1021-0xFFF | Unassigned                             |           |
   | F            |                                        |           |
   +--------------+----------------------------------------+-----------+




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   IANA is requested to create a new ANCP Capability registry, with
   additions by IETF Consensus.  Values may range from 0 to 255.  The
   specification for a given capability MUST indicate whether it applies
   to a specific access technology or applies to all access
   technologies.  The specification MUST further indicate whether the
   capability is associated with any capability data.  The initial
   entries in the ANCP capability registry are as follows:

   +-------+-------------------+------------+--------------+-----------+
   | Value | Capability Type   | Technology | Capability   | Reference |
   |       | Name              |            | Data         |           |
   +-------+-------------------+------------+--------------+-----------+
   | 0     | Reserved          |            |              | RFCXXXX   |
   | 1     | DSL Topology      | DSL        | None         | RFCXXXX   |
   |       | Discovery         |            |              |           |
   | 2     | DSL Line          | DSL        | None         | RFCXXXX   |
   |       | Configuration     |            |              |           |
   | 3     | Reserved          |            |              | RFCXXXX   |
   | 4     | DSL Line Testing  | DSL        | None         | RFCXXXX   |
   | 5-255 | Unassigned        |            |              |           |
   +-------+-------------------+------------+--------------+-----------+


10.  Security Considerations

   Security of the ANCP protocol is discussed in [RFC5713].  A number of
   security requirements on ANCP are stated in Section 8 of that
   document.  Those applicable to ANCP itself are listed here:

   o  The protocol solution MUST offer authentication of the AN to the
      NAS.

   o  The protocol solution MUST offer authentication of the NAS to the
      AN.

   o  The protocol solution MUST allow authorization to take place at
      the NAS and the AN.

   o  The protocol solution MUST offer replay protection.

   o  The protocol solution MUST provide data-origin authentication.

   o  The protocol solution MUST be robust against denial-of-service
      (DoS) attacks.  In this context, the protocol solution MUST
      consider a specific mechanism for the DoS that the user might
      create by sending many IGMP messages.





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   o  The protocol solution SHOULD offer confidentiality protection.

   o  The protocol solution SHOULD ensure that operations in default
      configuration guarantees a low number of AN/NAS protocol
      interactions.

   Most of these requirements relate to secure transport of ANCP.
   Robustness against denial-of-service attacks partly depends on
   transport and partly on protocol design.  Ensuring a low number of
   AN/NAS protocol interactions in default mode is purely a matter of
   protocol design.

   For secure transport, either the combination of IPsec with IKEv2
   (references below) or the use of TLS [RFC5246] will meet the
   requirements listed above.  The deciding point is a detail of
   protocol design that was unavailable when [RFC5713] was written.  The
   ANCP adjacency is a major point of vulnerability for denial-of-
   service attacks.  If the adjacency can be shut down, either the AN
   clears its state pending reestablishment of the adjacency, or the
   possibility of mismatches between the AN's and NAS's view of state on
   the AN is opened up.  Two ways to cause an adjacency to be taken down
   are to modify messages so that the ANCP agents conclude that they are
   no longer synchronized, or to attack the underlying TCP session.  TLS
   will protect message contents, but not the TCP connection.  One has
   to use either IPsec or the TCP authentication option [RFC5925] for
   that.  Hence the conclusion that ANCP MUST run over IPsec with IKEv2
   for authentication and key management.

   In greater detail: the ANCP stack MUST include IPsec [RFC4301]
   running in transport mode, since the AN and NAS are the endpoints of
   the path.  The Encapsulating Security Payload (ESP) [RFC4303] MUST be
   used, in order to satisfy the requirement for data confidentiality.
   ESP MUST be configured for the combination of confidentiality,
   integrity, anti-replay capability.  The traffic flow confidentiality
   service of ESP is unnecessary and, in fact, unworkable in the case of
   ANCP.

   IKEv2 [RFC5996] is also REQUIRED, to meet the requirements for mutual
   authentication and authorization.  Since the NAS and AN MAY be in
   different trust domains, the use of certificates for mutual
   authentication could be the most practical approach.  However, this
   is up to the operator(s) concerned.

   The AN MUST play the role of initiator of the IKEv2 conversation.







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11.  Acknowledgements

   The authors would like to thank everyone who provided comments or
   inputs to this document.  Swami Subramanian was an early member of
   the authors' team.  The ANCP Working Group is grateful to Roberta
   Maglione, who served as design team member and primary editor of this
   document for two years before stepping down.  The authors acknowledge
   the inputs provided by Wojciech Dec, Peter Arberg, Josef Froehler,
   Derek Harkness, Kim Hyldgaard, Sandy Ng, Robert Peschi, and Michel
   Platnic.


12.  References

12.1.  Normative References

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

   [RFC3292]  Doria, A., Hellstrand, F., Sundell, K., and T. Worster,
              "General Switch Management Protocol (GSMP) V3", RFC 3292,
              June 2002.

   [RFC3293]  Worster, T., Doria, A., and J. Buerkle, "General Switch
              Management Protocol (GSMP) Packet Encapsulations for
              Asynchronous Transfer Mode (ATM), Ethernet and
              Transmission Control Protocol (TCP)", RFC 3293, June 2002.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)",
              RFC 5996, September 2010.

12.2.  Informative References

   [G.988.1]  "ITU-T recommendation G.998.1, ATM-based multi-pair
              bonding", 2005.

   [G.988.2]  "ITU-T recommendation G.998.2, Ethernet-based multi-pair
              bonding,", 2005.



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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5713]  Moustafa, H., Tschofenig, H., and S. De Cnodder, "Security
              Threats and Security Requirements for the Access Node
              Control Protocol (ANCP)", RFC 5713, January 2010.

   [RFC5851]  Ooghe, S., Voigt, N., Platnic, M., Haag, T., and S.
              Wadhwa, "Framework and Requirements for an Access Node
              Control Mechanism in Broadband Multi-Service Networks",
              RFC 5851, May 2010.

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, June 2010.

   [TR-058]   Elias, M. and S. Ooghe, "DSL Forum TR-058, Multi-Service
              Architecture & Framework Requirements", September 2003.

   [TR-059]   Anschutz, T., "DSL Forum TR-059, DSL Evolution -
              Architecture Requirements for the Support of QoS-Enabled
              IP Services", September 2003.

   [TR-092]   DSL Forum (now the Broadband Forum), "DSL Forum TR-092,
              Broadband Remote access server requirements document",
              2005.

   [TR-101]   Cohen et al, "Architecture & Transport: "Migration to
              Ethernet Based DSL Aggregation", DSL Forum TR-101", 2005.

   [TR-147]   Voight et al, "Layer 2 Control Mechanism For Broadband
              Multi-Service Architectures", 2008.

   [US_ASCII]
              American National Standards Institute, "Coded Character
              Set - 7-bit American Standard Code for Information
              Interchange", ANSI X.34, 1986.


Authors' Addresses

   Sanjay Wadhwa
   Alcatel-Lucent


   Phone:
   Fax:
   Email: sanjay.wadhwa@alcatel-lucent.com




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   Jerome Moisand
   Juniper Networks
   10 Technology Park Drive
   Westford, MA  01886
   USA

   Phone:
   Fax:
   Email: jmoisand@juniper.net


   Thomas Haag
   Deutsche Telekom
   Heinrich-Hertz-Strasse 3-7
   Darmstadt,   64295
   Germany

   Phone: +49 6151 628 2088
   Fax:
   Email: haagt@telekom.de


   Norbert Voigt
   Nokia Siemens Networks
   Siemensallee 1
   Greifswald  17489
   Germany

   Email: norbert.voigt@nsn.com


   Tom Taylor (editor)
   Huawei Technologies
   Ottawa
   Canada

   Email: tom111.taylor@bell.net














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