tech-invite   World Map     

IETF     RFCs     Groups     SIP     ABNFs    |    3GPP     Specs     Glossaries     Architecture     IMS     UICC    |    search     info

RFC 6320

Proposed STD
Pages: 82
Top     in Index     Prev     Next
in Group Index     Prev in Group     Next in Group     Group: ANCP

Protocol for Access Node Control Mechanism in Broadband Networks

Part 1 of 4, p. 1 to 10
None       Next RFC Part

Updated by:    7256


Top       ToC       Page 1 
Internet Engineering Task Force (IETF)                         S. Wadhwa
Request for Comments: 6320                                Alcatel-Lucent
Category: Standards Track                                     J. Moisand
ISSN: 2070-1721                                         Juniper Networks
                                                                 T. Haag
                                                        Deutsche Telekom
                                                                N. Voigt
                                                  Nokia Siemens Networks
                                                          T. Taylor, Ed.
                                                     Huawei Technologies
                                                            October 2011


    Protocol for Access Node Control Mechanism in Broadband Networks

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 operations
   related to Quality of Service, service, and subscribers.  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 the General Switch Management Protocol version 3
   (GSMPv3) described in RFC 3292, but with many modifications and
   extensions, to the point that the two protocols are not
   interoperable.  For this reason, ANCP was assigned a separate version
   number to distinguish it.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6320.

Page 2 
Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................5
      1.1. Historical Note ............................................6
      1.2. Requirements Language ......................................6
      1.3. Terminology ................................................6
   2. Broadband Access Aggregation ....................................8
      2.1. ATM-Based Broadband Aggregation ............................8
      2.2. Ethernet-Based Broadband Aggregation .......................9
   3. Access Node Control Protocol -- General Aspects ................10
      3.1. Protocol Version ..........................................10
      3.2. ANCP Transport ............................................10
      3.3. Encoding of Text Fields ...................................11
      3.4. Treatment of Reserved and Unused Fields ...................12
      3.5. The ANCP Adjacency Protocol ...............................12
           3.5.1. ANCP Adjacency Message Format ......................12
           3.5.2. ANCP Adjacency Procedures ..........................18
      3.6. ANCP General Message Formats ..............................29
           3.6.1. The ANCP Message Header ............................29
           3.6.2. The ANCP Message Body ..............................36
      3.7. General Principles for the Design of ANCP Messages ........37

Top      ToC       Page 3 
   4. Generally Useful ANCP Messages and TLVs ........................38
      4.1. Provisioning Message ......................................38
      4.2. Generic Response Message ..................................39
      4.3. Target TLV ................................................41
      4.4. Command TLV ...............................................41
      4.5. Status-Info TLV ...........................................42
   5. Introduction to ANCP Capabilities for Digital
      Subscriber Lines (DSLs) ........................................43
      5.1. DSL Access Line Identification ............................44
           5.1.1. Control Context (Informative) ......................44
           5.1.2. TLVs for DSL Access Line Identification ............45
   6. ANCP-Based DSL Topology Discovery ..............................48
      6.1. Control Context (Informative) .............................48
      6.2. Protocol Requirements .....................................50
           6.2.1. Protocol Requirements on the AN Side ...............50
           6.2.2. Protocol Requirements on the NAS Side ..............50
      6.3. ANCP Port Up and Port Down Event Message Descriptions .....51
      6.4. Procedures ................................................52
           6.4.1. Procedures on the AN Side ..........................52
           6.4.2. Procedures on the NAS Side .........................53
      6.5. TLVs for DSL Line Attributes ..............................53
           6.5.1. DSL-Line-Attributes TLV ............................53
           6.5.2. DSL-Type TLV .......................................54
           6.5.3. Actual-Net-Data-Rate-Upstream TLV ..................54
           6.5.4. Actual-Net-Data-Rate-Downstream TLV ................54
           6.5.5. Minimum-Net-Data-Rate-Upstream TLV .................55
           6.5.6. Minimum-Net-Data-Rate-Downstream TLV ...............55
           6.5.7. Attainable-Net-Data-Rate-Upstream TLV ..............55
           6.5.8. Attainable-Net-Data-Rate-Downstream TLV ............55
           6.5.9. Maximum-Net-Data-Rate-Upstream TLV .................56
           6.5.10. Maximum-Net-Data-Rate-Downstream TLV ..............56
           6.5.11. Minimum-Net-Low-Power-Data-Rate-Upstream TLV ......56
           6.5.12. Minimum-Net-Low-Power-Data-Rate-Downstream TLV ....56
           6.5.13. Maximum-Interleaving-Delay-Upstream TLV ...........57
           6.5.14. Actual-Interleaving-Delay-Upstream TLV ............57
           6.5.15. Maximum-Interleaving-Delay-Downstream TLV .........57
           6.5.16. Actual-Interleaving-Delay-Downstream ..............57
           6.5.17. DSL-Line-State TLV ................................58
           6.5.18. Access-Loop-Encapsulation TLV .....................58
   7. ANCP-Based DSL Line Configuration ..............................59
      7.1. Control Context (Informative) .............................59
      7.2. Protocol Requirements .....................................61
           7.2.1. Protocol Requirements on the NAS Side ..............61
           7.2.2. Protocol Requirements on the AN Side ...............61
      7.3. ANCP Port Management (Line Configuration) Message Format ..62
      7.4. Procedures ................................................64
           7.4.1. Procedures on the NAS Side .........................64
           7.4.2. Procedures on the AN Side ..........................64

Top      ToC       Page 4 
      7.5. TLVs for DSL Line Configuration ...........................64
           7.5.1. Service-Profile-Name TLV ...........................65
   8. ANCP-Based DSL Remote Line Connectivity Testing ................65
      8.1. Control Context (Informative) .............................65
      8.2. Protocol Requirements .....................................66
           8.2.1. Protocol Requirements on the NAS Side ..............66
           8.2.2. Protocol Requirements on the AN Side ...............66
      8.3. Port Management (OAM) Message Format ......................67
      8.4. Procedures ................................................68
           8.4.1. NAS-Side Procedures ................................68
           8.4.2. AN-Side Procedures .................................69
      8.5. TLVs for the DSL Line Remote Connectivity Testing
           Capability ................................................70
           8.5.1. OAM-Loopback-Test-Parameters TLV ...................70
           8.5.2. Opaque-Data TLV ....................................71
           8.5.3. OAM-Loopback-Test-Response-String TLV ..............71
   9. IANA Considerations ............................................71
   10. IANA Actions ..................................................72
      10.1. ANCP Message Type Registry ...............................72
      10.2. ANCP Result Code Registry ................................73
      10.3. ANCP Port Management Function Registry ...................74
      10.4. ANCP Technology Type Registry ............................75
      10.5. ANCP Command Code Registry ...............................75
      10.6. ANCP TLV Type Registry ...................................75
      10.7. ANCP Capability Type Registry ............................77
      10.8. Joint GSMP / ANCP Version Registry .......................77
   11. Security Considerations .......................................77
   12. Contributors ..................................................79
   13. Acknowledgements ..............................................79
   14. References ....................................................79
      14.1. Normative References .....................................79
      14.2. Informative References ...................................80

Top      ToC       Page 5 
1.  Introduction

   This document 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
   Multiplexer, DSLAM) in order to perform operations related to quality
   of service (QoS), services, and subscriptions.  The requirements for
   ANCP and the context within which it operates are described in
   [RFC5851].

   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 in Section 3.2.

   The organization of this document is as follows:

   o  Sections 1.2 and 1.3 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.

Top      ToC       Page 6 
   o  Section 3 specifies generally applicable aspects of ANCP.

   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.  This section
      defines a number of new ANCP-specific registries as well as the
      joint GSMP/ANCP version registry mentioned below.

   o  Section 11 addresses security considerations relating to ANCP,
      beginning with the requirements stated in [RFC5713].

1.1.  Historical Note

   Initial implementations of the protocol that became ANCP were based
   on the General Switch Management Protocol version 3 (GSMPv3)
   [RFC3292].  The ANCP charter required the Working Group to develop
   its protocol based on these implementations.  In the end, ANCP
   introduced so many extensions and modifications to GSMPv3 that the
   two protocols are not interoperable.  Nevertheless, although this
   specification has no normative dependencies on [RFC3292], the mark of
   ANCP's origins can be seen in the various unused fields within the
   ANCP message header.

   Early in ANCP's development, the decision was made to use the same
   TCP port and encapsulation as GSMPv3, and by the time ANCP was
   finished, it was too late to reverse that decision because of
   existing implementations.  As a result, it is necessary to have a way
   for an ANCP peer to quickly distinguish ANCP from GSMP during initial
   adjacency negotiations.  This has been provided by a joint registry
   of GSMP and ANCP version numbers.  GSMP has version numbers 1 through
   3.  ANCP has the initial version number 50.

1.2.  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].

1.3.  Terminology

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

Top      ToC       Page 7 
   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 that
      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 ANCP 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 be either 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.

   Type-Length-Value (TLV):  A data structure consisting of a 16-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

Top      ToC       Page 8 
      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 access lines into a single bidirectional logical link,
      henceforth referred to in this document 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
      [G.998.1] and G.998.2 [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, a remote DSLAM, or a Remote Access
   Multiplexer (RAM).  The Access Node is the first point in the network
   where traffic on multiple DSL access lines will be aggregated onto a
   single network.

   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

Top      ToC       Page 9 
   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 do not occur farther 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

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 [IEEE802.1Q] and enhanced by [IEEE802.1ad], is used as the
   standard virtualization mechanism in the Ethernet aggregation
   network.  The aggregation devices are "provider edge bridges" defined
   in [IEEE802.1ad].

   Stacked VLAN tags provide one possible way to create an equivalent of
   "virtual paths" and "virtual circuits" in the aggregation network.
   The "outer" VLAN can be used to create a form of "virtual path"

Top      ToC       Page 10 
   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.



(page 10 continued on part 2)

Next RFC Part