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

Versions: 00 01 02 03 04 05 RFC 6934

  Network Working Group                          Nabil Bitar(ed.)
                                                 Verizon
  Internet Draft
  Intended Status: Informational                 Sanjay Wadhwa (ed.)
                                                 Alcatel-Lucent
  Expires: June 16, 2012
                                                 Thomas Haag
                                                 Deutsche Telekom
  
                                                 Hongyu Li
                                                 HuaweiTechnologies
  
                                                 January 16, 2012
  
              Applicability of Access Node Control Mechanism to
                         PON based Broadband Networks
  
                       draft-ietf-ancp-pon-02.txt
  
  Abstract
  
     The purpose of this document is to provide applicability of the
     Access Node Control Mechanism, as described in [RFC5851],
     to PON based broadband access. The need for an Access Node Control
     Mechanism between a Network Access Server (NAS) and an Access Node
     Complex (a combination of Optical Line Termination (OLT) and
     Optical Network Termination (ONT) elements) is described in a
     multi-service reference architecture in order to perform QoS-
     related, service-related and Subscriber-related operations. The
     Access Node Control Mechanism is also extended for interaction
     between components of the Access Node Complex (OLT and ONT). The
     Access Node Control mechanism will ensure that the transmission of
     information between the NAS and Access Node Complex (ANX) and
     between the OLT and ONT within an ANX does not need to go through
     distinct element managers but rather uses a direct device-to-
     device communication and stays on net. This allows for performing
     access link related operations within those network elements to
     meet performance objectives.
  
  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), its areas, and its working groups. Note that
     other groups may also distribute working documents as Internet-
     Drafts.
  
     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
  
  
  Bitar-Wadhwa          Expires June 16, 2012              [Page 1]


  Internet Draft     draft-ietf-ancp-pon-02              January 2012
  
  
     as reference material or to cite them other than as "work in
     progress."
  
     The list of current Internet-Drafts can be accessed at
     http://www.ietf.org/1id-abstracts.html.
  
     The list of Internet-Draft Shadow Directories can be accessed at
     http://www.ietf.org/shadow.html.
  
     This Internet-Draft will expire on June 16-02, 2012.
  
  
  Copyright Notice
  
     Copyright (c) 2012 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.
  
  Table of Contents
     1. Specification Requirements ................................. 3
     2. Introduction................................................ 3
     3. Terminology ................................................ 5
     4. Motivation for explicit extension of ANCP to FTTx PON ...... 6
     5. Reference Model for PON Based Broadband Access Network.......7
     5.1. Functional Blocks  ....................................... 9
     5.1.1. Home Gateway ........................................... 9
     5.1.2. PON Access   ........................................... 9
     5.1.3. Access Node Complex .................................... 9
     5.1.4. Access Node Complex Uplink to the NAS .................. 9
     5.1.5. Aggregation Network .................................... 9
     5.1.6. Network Access Server .................................. 10
     5.1.7. Regional Network ................................... ....10
     5.2. Access Node Complex Control Reference Architecture Options 10
     5.2.1. ANCP+OMCI ANX control   ................................ 10
     5.2.2. All-ANCP ANX Control.................................... 12
     6. Concept of Access Node Control Mechanism for PON based access12
     7. Multicast ...................................................14
     7.1. Multicast Conditional Access.............................. 15
     7.2. Multicast Admission Control .............................. 17
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 2]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
     7.3. Multicast Accounting .................................... 27
     8. Remote Connectivity Check .................................. 28
     9. Access Topology Discovery .................................. 29
     10. Access Loop Configuration ................................. 30
     11. ANCP versus OMCI between the OLT and ONT/ONU .............. 33
     12. IANA Considerations ....................................... 33
     13. Acknowledgements .......................................... 33
     14. References ................................................ 34
     14.1. Normative References .................................... 34
     14.2. Informative References .................................. 34
  
  
  
  
  
  1. Specification Requirements
  
     The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
     NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
     "OPTIONAL" in this document are to be interpreted as described in
     RFC 2119.
  
  2. Introduction
  
  Passive Optical Networks (PONs) based on BPON and GPON are being
  deployed across carrier networks. There are two models for PON
  deployment: Fiber to the building/curb (FTTB/FTTC), and Fiber to the
  Premises (FTTP). In the FTTB/C deployment, the last mile connectivity
  to the subscriber premises is provided over the local Copper loop,
  often using Very High Speed Digital Subscriber line (VDSL). In the
  FTTP case, PON extends to the premises of the subscriber. In
  addition, there are four main PON technologies: (1) Broadband PON
  (BPON), (2) Gigabit PON (GPON), (3) 10-Gigabit PON (XGPON), and (4)
  Ethernet PON (EPON). This document describes the applicability of
  Access Node Control Protocol (ANCP) in the context of FTTB/C and FTTP
  deployments, focusing on BPON, GPON and XPON. Architectural
  considerations lead to different ANCP compositions. Therefore, the
  composition of ANCP communication between Access Nodes and Network
  Access Server (NAS) is described using different models.
  
  BPON, GPON and XPON in FTTP deployments provide large bandwidth in
  the first mile, bandwidth that is an order of magnitude larger than
  that provided by xDSL. In the downstream direction, BPON provides 622
  Mbps per PON while GPON provides 2.4 Gbps, and XPON provides 10 Gbps.
  In residential deployments, the number of homes sharing the same PON
  is limited by the technology and the network engineering rules.
  Typical deployments have 32 homes per PON.
  
  The motive behind BPON, GPON and XPON deployment is providing triple-
  play services over IP: voice, video and data. Voice is generally low
  bandwidth but has low-delay, low-jitter, and low packet-loss
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 3]


  Internet Draft     draft-ietf-ancp-pon-02              January 2012
  
  
  requirements. Data services (e.g., Internet services) often require
  high throughput and can tolerate medium latency. Data services may
  include multimedia content download such as video. However, in that
  case, the video content is not required to be real-time and/or it is
  low quality video. Video services, on the other hand, are targeted to
  deliver Standard Definition or High Definition video content in real-
  time or near-real time, depending on the service model. Standard
  Definition content using MPEG2 encoding requires on the order of 3.75
  Mbps per stream while High definition content using MPEG2 encoding
  requires on the order of 15-19 Mbps depending on the level of
  compression used. Video services require low-jitter and low-packet
  loss with low start-time latency. There are two types of video
  services: on demand and broadcast (known also as liner programming
  content). While linear programming content can be provided over
  Layer1 on the PON, the focus in this document is on delivering linear
  programming content over IP to the subscriber, using IP multicast.
  Video on demand is also considered for delivery to the subscriber
  over IP using a unicast session model.
  
  
  Providing simultaneous triple-play services over IP with unicast
  video and multicast video, VoIP and data requires an architecture
  that preserves the quality of service of each service. Fundamental to
  this architecture is ensuring that the video content (unicast and
  multicast) delivered to the subscriber does not exceed the bandwidth
  Allocated to the subscriber for video services. Architecture models
  often ensure that data is guaranteed a minimum bandwidth and that
  VoIP is guaranteed its own bandwidth. In addition, QoS control across
  services is often performed at a Network Access Server (NAS), often
  referred to as Broadband Network Gateway (BNG) for subscriber
  management, per subscriber and shared link resources. Efficient
  multicast video services require enabling multicast services in the
  access network between the subscriber and the subscriber management
  platform. In the FTTP/B/C PON environment, this implies enabling IP
  multicast on the Access Node (AN) complex composed of the Optical
  Network Terminal (ONT) or Unit (ONU) and Optical Line Terminal (OLT),
  as applicable. This is as opposed to Digital Subscriber Line (DSL)
  deployments where multicast is enabled on the DSL Access Multiplexer
  (DSLAM) only. The focus in this document will be on the ANCP
  requirements needed for coordinated admission control of unicast and
  multicast video in FTTP/B/C PON environments between the AN complex
  (ANX) and the NAS, specifically focusing on bandwidth dedicated for
  multicast and shared bandwidth between multicast and unicast.
  
  [RFC5851] provides the framework and requirements for
  coordinated admission control between a NAS and an AN with special
  focus on DSL deployments. This document extends that framework and
  the related requirements to explicitly address PON deployments.
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 4]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  3. Terminology
  
  - PON (Passive Optical Network): a point-to-multipoint fiber to the
  premises network architecture in which unpowered splitters are used
  to enable the splitting of an optical signal from a central office on
  a single optical fiber to multiple premises. Up to 32-128 may be
  supported on the same PON. A PON configuration consists of an Optical
  Line Terminal (OLT) at the Service Provider's CO and a number of
  Optical Network Units or Terminals (ONU/ONT) near end users, with an
  optical distribution network (ODN) composed of fibers and splitters
  between them. A PON configuration reduces the amount of fiber and CO
  equipment required compared with point-to-point architectures.
  
  - Access Node Complex (ANX): The Access Node Complex is composed of
  two geographically separated functional elements OLT and ONU/ONT. The
  general term Access Node Complex (ANX) will be used when describing a
  functionality which does not depend on the physical location but
  rather on the "black box" behavior of OLT and ONU/ONT.
  
  -Optical Line Terminal (OLT): is located in the Service provider's
  central office (CO). It terminates and aggregates multiple PONs
  (providing fiber access to multiple premises or neighborhoods) on the
  subscriber side, and interfaces with the Network Access server (NAS)
  that provides subscriber management.
  
  - Optical Network Terminal (ONT): terminates PON on the network side
  and provides PON adaptation. The subscriber side interface and the
  location of the ONT are dictated by the type of network deployment.
  For a Fiber-to-the-Premise (FTTP) deployment (with Fiber all the way
  to the apartment or living unit), ONT has Ethernet (FE/GE/MoCA)
  connectivity with the Home Gateway (HGW)/Customer Premise Equipment
  (CPE). In certain cases, one ONT may provide connections to more than
  one Home Gateway at the same time.
  
  -Optical Network Unit (ONU): A generic term denoting a device that
  terminates any one of the distributed (leaf) endpoints of an Optical
  Distribution Node (ODN), implements a PON protocol, and adapts PON
  PDUs to subscriber service interfaces. In case of an MDU multi-
  dwelling or multi-tenant unit), a multi-subscriber ONU typically
  resides in the basement or a wiring closet (FTTB case), and has
  FE/GE/Ethernet over native Ethernet link or over xDSL (typically
  VDSL) connectivity with each CPE at the subscriber premises. In the
  case where fiber is terminated outside the premises (neighborhood or
  curb side) on an ONT/ONU, the last-leg-premises connections could be
  via existing or new Copper, with xDSL physical layer (typically
  VDSL). In this case, the ONU effectively is a "PON fed DSLAM".
  
  -Network Access Server (NAS): Network element which aggregates
  subscriber traffic from a number of ANs or ANXs. The NAS is often an
  injection point for policy management and IP QoS in the access
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 5]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  network. It is also referred to as Broadband Network Gateway (BNG) or
  Broadband Remote Access Server (BRAS).
  
  -Home Gateway (HGW): Network element that connects subscriber devices
  to the AN or ANX and the access network. In case of xDSL, the Home
  Gateway is an xDSL network termination that could either operate 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). In the case of
  PON, it is often a Layer3 routing device with the ONT performing PON
  termination.
  
  -PON-Customer-ID: This is an identifier which uniquely identifies the
  ANX and the access loop logical port on the ANX to the subscriber
  (customer) premises, and is used in any interaction between NAS and
  ANX that relates to access-loops. Logically it is composed of
  information containing identification of the OLT (the OLT may be
  physically directly connected to the NAS), the PON port on the OLT,
  the ONT/ONU, and the port on the ONT/ONU connecting to the subscriber
  HGW. When acting as a DHCP relay agent, the OLT can encode PON-
  Customer-ID in the "Agent-Circuit-Identifier" Sub-option in Option-82
  of the DHCP messages.
  
  4. Motivation for explicit extension of ANCP to FTTx PON
  
  The fundamental difference between PON and DSL is that a PON is an
  optical broadcast network by definition. That is, at the PON level,
  every ONT on the same PON sees the same signal. However, the ONT
  filters only those PON frames addressed to it. Encryption is used on
  the PON to prevent eavesdropping.
  
  The broadcast PON capability is very suitable to delivering multicast
  content to connected premises, maximizing bandwidth usage efficiency
  on the PON. Similar to DSL deployments, enabling multicast on the
  Access Node Complex (ANX) provides for bandwidth use efficiency on
  the path between the Access Node and the NAS as well as improves the
  scalability of the NAS by reducing the amount of multicast traffic
  being replicated at the NAS. However, the broadcast capability on the
  
  PON enables the AN (OLT) to send one copy on the PON as opposed to N
  copies of a multicast channel on the PON serving N premises being
  receivers. The PON multicast capability can be leveraged in the case
  of GPON and BPON as discussed in this document.
  
  Fundamental to leveraging the broadcast capability on the PON for
  multicast delivery is the ability to assign a single encryption key
  for all PON frames carrying all multicast channels or a key per set
  of multicast channels that correspond to service packages, or none.
  It should be noted that the ONT can be a multi-Dwelling Unit (MDU)
  ONT with multiple Ethernet ports, each connected to a living unit.
  Thus, the ONT must not only be able to receive a multicast frame, but
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 6]


  Internet Draft     draft-ietf-ancp-pon-02                 January 2012
  
  
  must also be able to forward that frame only to the Ethernet port
  with receivers for the corresponding channel.
  
  In order to implement triple-play service delivery with necessary
  "quality-of-experience", including end-to-end bandwidth optimized
  multicast video delivery, there needs to be tight coordination
  between the NAS and the ANX. This interaction needs to be near real-
  time as services are requested via application or network level
  signaling by broadband subscribers. ANCP as defined in [RFC5851]
  for DSL based networks is very suitable to realize a
  control protocol (with transactional exchange capabilities), between
  PON enabled ANX and the NAS, and also between the components
  comprising the ANX i.e. between OLT and the ONT. Typical use cases
  for ANCP in PON environment include the following:
  
       - Access topology discovery
  
       - Access Loop Configuration
  
       - Multicast
  
            - Optimized multicast delivery
  
            - Unified video resource control
  
            - NAS based provisioning of ANX
  
    - Remote connectivity check
  
  5. Reference Model for PON Based Broadband Access Network
  
  An overall end-to-end reference architecture of a PON access network
  is depicted in Figure 1 and Figure 2 with ONT serving a single HGW,
  and ONT/ONU serving multiples HGWs, respectively. An OLT may provide
  FTTP and FTTB/C access at the same time but most likely not on the
  same PON port. Specifically, the following PON cases are addressed in
  the context of this reference architecture:
  
       - BPON with Ethernet uplink to the NAS and ATM on the PON side.
  
       - GPON/XPON with Ethernet uplink to the NAS and Ethernet on the
  PON
          side
  
  In case of an Ethernet aggregation network that supports new QoS-
  enabled IP services (including Ethernet multicast replication), the
  architecture builds on the reference architecture specified in the
  Broadband Forum (BBF) [TR-101]. The Ethernet aggregation network
  between a NAS and an OLT may be degenerated to one or more direct
  physical Ethernet links.
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 7]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  Given the industry move towards Ethernet as the new access and
  aggregation technology for triple play services, the primary focus
  throughout this document is on GPON/XPON and BPON with Ethernet
  between the NAS and the OLT.
  
                                                 Access        Customer
                                <----------Aggregation-------><-Prem->
                                                 Network       Network
  
                                         +------------------+
                                         |  Access Node     |
                                         |  Complex (ANX)   |
           +---------+   +---+  +-----+  |+---+       +---+ |  +---+
           |         | +-|NAS|--|Eth  |--||OLT|-<PON>-|ONT|-|--|HGW|
     NSP---+Regional | | +---+  |Agg  |  |+---+       +---+ |  +---+
           |Broadband| | +---+  +-----+  +------------------+
           |Network  |-+-|NAS|                  |
     ASP---+         | | +---+                  |
           |         | | +---+                  |
           +---------+ +-|NAS|                  |       +---+  +---+
                         +---|                  +-<PON>-|ONT|--|HGW|
                                                    |   +---+  +---+
                                                    |
                                                    |   +---+  +---+
                                                    +---|ONT|--|HGW|
                                                        +---+  +---+
      HGW      : Home Gateway
      NAS      : Network Access Server
      PON      : Passive Optical Network
      OLT      : Optical Line Terminal
      ONT      : Optical Network Terminal
  
                          Figure 1.  Access Network with PON
  
  
                                                            FE/GE/VDSL
                                                            +---+ +---+
                                  +----------------+        |   |-|HGW|
           +---------+   +-----+  | +-----+  +----+|        |   | +---+
           |         | +-|NAS  |--| |Eth  |--|OLT||-<PON>-  |   |
     NSP---+Regional | | +-----+  | |Agg  |  |    ||    |   |ONT| +---+
           |         | |          | |     |  |    ||    |   | or|-|HGW|
           |Broadband| | +-----+  | +-----+  +----+|    |   |ONU| +---+
           |Network  |-+-|NAS  |  +----------------+    |   |   |
     ASP---+         | | +-----+                        |   |   | +---+
           |         | | +-----+                        |   |   |-|HGW|
           +---------+ +-|NAS  |                        |   +---+ +---+
                         +-----+                        |
                                                        |  +---+  +---+
                                                        +--|ONT|--|HGW|
                                                           +---+  +---+
      Figure 2. FTTP/FTTB/C with multi-subscriber ONT/ONU serving
  MTUs/MDUs
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 8]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  The following sections describe the functional blocks and network
  segments in the PON access reference architecture.
  
  5.1. Functional Blocks
  
  5.1.1. Home Gateway
  
  The Home Gateway (HGW) connects the different Customer Premises
  Equipment (CPE) to the ANX and the access network.  In case of PON,
  the HGW is a layer 3 router. In this case, the HGW performs IP
  configuration of devices within the home via DHCP, and performs
  Network Address and Port Translation (NAPT) between the LAN and WAN
  side. In case of FTTP/B/C, the HGW connects to the ONT/ONU over an
  Ethernet interface. That Ethernet interface could be over an Ethernet
  physical port or over another medium. In case of FTTP, it is possible
  to have a single box GPON CPE solution, where the ONT encompasses the
  HGW functionality as well as the GPON adaptation function.
  
  5.1.2. PON Access
  
  PON access is composed of the ONT/ONU and OLT. PON ensures physical
  connectivity between the ONT/ONU at the customer and the OLT. PON
  framing can be BPON (in case of BPON) or GPON (in case of GPON). The
  protocol encapsulation on BPON is based on multi-protocol
  encapsulation over AAL5, defined in [RFC2684].  This covers PPP over
  Ethernet (PPPoE, defined in [RFC2516]), or bridged IP (IPoE). The
  protocol encapsulation on GPON is always IPoE. In all cases, the
  connection between the AN
  (OLT) and the NAS (or BNG) is assumed to be Ethernet in this
  document.
  
  5.1.3. Access Node Complex
  
  This is composed of OLT and ONT/ONU and is defined in section 3.
  
  5.1.4. Access Node Complex Uplink to the NAS
  
  The ANX uplink connects the OLT to the NAS. The fundamental
  requirements for the ANX uplink are to provide traffic aggregation,
  Class of Service distinction and customer separation and
  traceability. This can be achieved using an ATM or an Ethernet based
  technology. The focus in this document is on Ethernet as stated
  earlier.
  
  5.1.5. Aggregation Network
  
  The aggregation network provides traffic aggregation towards the NAS.
  The Aggregation network is assumed to be Ethernet in this document.
  
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 9]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  5.1.6. Network Access Server
  
  The NAS is a network device which aggregates multiplexed Subscriber
  traffic from a number of ANXs. The NAS plays a central role in per-
  subscriber policy enforcement and QoS. It is often referred to as a
  Broadband Network Gateway (BNG) or Broadband Remote Access Server
  (BRAS). A detailed definition of the NAS is given in [RFC2881]. The
  NAS interfaces to the aggregation network by means of 802.1Q or 802.1
  Q-in-Q Ethernet interfaces, and towards the Regional Network by means
  of transport interfaces (e.g. GigE, PPP over SONET). The NAS
  functionality corresponds to the BNG functionality described in
  BroadBand Forum (BBF) TR-101 [TR-101]. In addition, the NAS supports
  the Access Node Control functionality defined for the respective use
  cases in this document.
  
  5.1.7. Regional Network
  
  The Regional Network connects one or more NAS and associated Access
  Networks to Network Service Providers (NSPs) and Application Service
  Providers (ASPs). The NSP authenticates access and provides and
  manages the IP address to Subscribers. It is responsible for overall
  service assurance and includes Internet Service Providers (ISPs). The
  ASP provides application services to the application Subscriber
  (gaming, video, content on demand, IP telephony etc.). The NAS can be
  part of the NSP network. Similarly, the NSP can be the ASP.
  
  5.2. Access Node Complex Control Reference Architecture Options
  
  Section 4 details the differences between xDSL access and PON access
  and the implication of these differences on DSLAM control vs. OLT and
  ONT/ONU (access node complex (ANX)) control. The following sections
  describe two reference models: (1) ANCP+OMCI ANX control, and (2)
  all-ANCP ANX control. That is, the two models differ in the ONT/ONU
  control within the ANX. Implementations, out of the scope of this
  document, may choose to implement one or the other based on the
  ONT/ONU type and the capabilities of the ONT/ONU and OLT. It is
  possible for an OLT or an OLT PON port to connect to ONTs/ONUs with
  different capabilities and for these two models to co-exist on the
  same OLT and same PON. Section 11 describes the differences between
  OMCI and ANCP in controlling the ONU/ONT.
  
  OMCI is designed as a protocol between the OLT and ONT/ONU. It
  enables the OLT to configure and administer capabilities on the
  ONT/ONU in BPON, GPON and XPON. ANCP is designed as a protocol
  between the NAS and access node. It enables the NAS to enforce
  dynamic policies on the access node, and the access node to report
  events to the NAS among other functions.
  
  5.2.1. ANCP+OMCI ANX control
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 10]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  Figure 3 depicts the reference model for ANCP+OMCI ANX control. In
  this model, ANCP is enabled between the NAS and a connected OLT, and
  OMCI is enabled between the OLT and an attached ONT/ONU. NAS
  communicates with the ANX via ANCP. The OLT acts as an ANCP/OMCI
  gateway for communicating necessary events and policies between the
  OLT and ONT/ONU within the ANX and for communicating relevant
  policies and events between the ONT/ONU and the NAS. The
  functionality performed by the OLT as ANCP/OMCI gateway will be
  application dependent (e.g., multicast control, topology discovery)
  and should be specified in a related specification. It should be
  noted that some applications are expected to require extensions. Such
  extensions are expected to outside of ANCP scope, and may need to be
  defined by the ITU-T. It should be noted that OMCI, in addition to
  configuration and administration, provides the capability to report
  status changes on an ONT/ONU with AVC (Attribute Value Change)
  notifications. When ONT/ONU's DSL or Ethernet UNI attributes change,
  a related ME (management Entity) will send a corresponding
  notification (AVC) to the OLT. The OLT interworks such notification
  into an ANCP report and sends it to the connected NAS via the ANCP
  session between the OLT and the NAS. As the ANCP report contains
  information of ONT/ONU's UNI and OLT's PON port, NAS can obtain
  accurate information of access topology.
  
                                         +----------------------+
                                         |         ANX          |
           +---------+   +---+  +-----+  |+---+       +-------+ | +---+
           |         | +-|NAS|--|Eth  |--||OLT|-<PON>-|ONU/ONT|-|-|HGW|
     NSP---+Regional | | +---+  |Agg  |  |+---+       +-------+ | +---+
           |Broadband| | +---+  +-----+  +----------------------+
           |Network  |-+-|NAS|                |
     ASP---+         | | +---+                |
           |         | | +---+                |
           +---------+ +-|NAS|                |       +-------+ +---+
                         +---|                +-<PON>-|ONU/ONT|-|HGW|
                                                   |  +-------+ +---+
                                                   .............
                                                   |     +---+ +---+
                                                   +-----|ONT|-|HGW|
                                                         +---+ +---+
                                ANCP                 OMCI
                       +<-------------->+<------------------->+
  
      HGW: Home Gateway
      NAS: Network Access Server
      PON: Passive Optical Network
      OLT: Optical Line Terminal
      ONT: Optical Network Terminal
      ONU: Optical Network Unit
         Figure 3: Access Network with single ANCP+OMCI access control
  
  
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 11]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  5.2.2. All-ANCP ANX Control
  
  Figure 4 depicts the All-ANCP ANX control reference model. In this
  model, an ANCP session is enabled between a NAS and a connected OLT,
  and another ANCP session is enabled between the OLT and a connected
  ONT/ONU. ANCP enables communication of policies and events between
  the OLT and the ANX. The OLT acts as a gateway to relay policies and
  events between the NAS and ONT/ONU within the ANX in addition to
  communicating policies and events between the OLT and ONT/ONU. It
  should be noted that in this model, OMCI (not shown) is expected to
  be simultaneously enabled between the ONT and OLT, supporting
  existing OMCI capabilities and applications on the PON, independent
  of ANCP or applications intended to be supported by ANCP.
  
                                         +----------------------+
                                         | Access Node Complex  |
                                         |      (ANX)           |
           +---------+   +---+  +-----+  |+---+       +-------+ |  +---+
           |         | +-|NAS|--|Eth  |--||OLT|-<PON>-|ONU/ONT| |--|HGW|
     NSP---+Regional | | +---+  |Agg  |  |+---+       +-------+ |  +---+
           |Broadband| | +---+  +-----+  +----------------------+
           |Network  |-+-|NAS|                  |
     ASP---+         | | +---+                  |
           |         | | +---+                  |
           +---------+ +-|NAS|                  |       +-------+  +---+
                         +---|                  +-<PON>-|ONU/ONT|--|HGW|
                                                    |   +-------+  +---+
                                                    .............
                                                    |   +-------+  +---+
                                                    +---|ONU/ONT|--|HGW|
                                                        +-------+  +---+
  
                                ANCP               ANCP
                       +<----------------->+<----------->+
  
      HGW: Home Gateway
      NAS: Network Access Server
      PON: Passive Optical Network
      OLT: Optical Line Terminal
      ONT: Optical Network Terminal
      ONU: Optical Network Unit
  
                        Figure 4:  All-ANCP ANX Reference Model
  
  
  
  6. Concept of Access Node Control Mechanism for PON based access
  
  The high-level communication framework for an Access Node Control
  Mechanism is shown in Figure 5 for the ALL-ANCP ANX control model.
  The Access Node Control Mechanism defines a quasi real-time, general-
  purpose method for multiple network scenarios with an extensible
  communication scheme, addressing the different use cases that are
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 12]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  described in the sections that follow. The access node control
  mechanism is also extended to run between OLT and ONT/ONU. The
  mechanism consists of control function, and reporting and/or
  enforcement function. Controller function is used to receive status
  information or admission requests from the reporting function. It is
  also used to trigger a certain behavior in the network element where
  the reporting and/or enforcement function resides.
  
  The reporting function is used to convey status information to the
  controller function that requires the information for executing local
  functions. The enforcement function can be contacted by the
  controller function to enforce a specific policy or trigger a local
  action. The messages shown in Figure 5 show the conceptual message
  flow. The actual use of these flows, and the times or frequencies
  when these messages are generated depend on the actual use cases,
  which are described in later sections.
  
  +--------+
  | Policy |                               +----+
  | Server |                    +--<PON>---|ONT |------- HGW
  +--------+                   +           +----+  +---+
       |                      +         +----------|ONT|------ HGW
       |                     +          |          +---+
       |               +----------------|-------------+
    +----+             | +----+         |     +-----+ |      +---+
    |NAS |---------------|    |         |     |     |-|------|HGW|
    |    |<------------->|    |         |     | ONU | |      +---+
    +----+     ANCP    | |OLT |------<PON>----|     | |
       |               | |    |               |     | |       +---+
       |               | |    |<------------->|     |-------- |HGW|
       |               | +----+    ANCP       +-----+ |       +---+
       |               +-----------------------------+
       |                    |    Access Node      |
       | Control Request    |                     |
       | ------------------>| Control Request     |
       |                    |-------------------->|
       |                    | Control Response    |
       | Control Response   |<------------------- |
       |<-------------------|                     |
       |                    |Admission Request    |
       | Admission Request  |<--------------------|
       |<-------------------|                     |
       |Admission Response  |                     |
       |------------------->|Admission Response   |
       |                    |-------------------->|
       |Information Report  |                     |
       |<-------------------|                     |
       Access Node Control     Access Node Control
           Mechanism                Mechanism
       <--------------------><-------------------->
  
                              PPP, DHCP, IP
       <----------------------------------------------------------->
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 13]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  
    Figure 5. Conceptual Message Flow for Access Node Control Mechanism
  in all-ANCP ANX control model
  
  As discussed previously, in different PON deployment scenarios, ANCP
  may be used in variant ways and may interwork with other protocols,
  e.g. OMCI. In the ANCP+OMCI model described earlier, the NAS
  maintains ANCP adjacency with the OLT while the OLT controls the
  ONT/ONU via OMCI. The messages shown in Figure 6 show the conceptual
  message flow for this model.  The actual use of these flows, and the
  times or frequencies when these messages are generated depend on the
  actual use cases.
  
  +--------+
  | Policy |
  | Server |
  +--------+                                  +---+          +---+
       |                                +---- |ONT|----------|HGW|
       |                                |     +---+          +---+
       |               +--------------- |-------------+
    +----+             | +----+         |     +-----+ |      +---+
    |NAS |---------------|    |         |     |     |-|------|HGW|
    |    |<------------->|    |         |     | ONU | |      +---+
    +----+     ANCP    | |OLT |------<PON>----|     | |
       |               | |    |               |     | |      +---+
       |               | |    |<------------->|     |--------|HGW|
       |               | +----+    OMCI       +-----+ |      +---+
       |               +-----------------------------+
       |                    |    Access Node      |
       | Control Request    |                     |
       | ------------------>| Control Request     |
       |                    |-------------------->|
       |                    | Control Response    |
       | Control Response   |<------------------- |
       |<-------------------|                     |
       |                    |Admission Request    |
       | Admission Request  |<--------------------|
       |<-------------------|                     |
       |Admission Response  |                     |
       |------------------->|Admission Response   |
       |                    |-------------------->|
       |Information Report  |                     |
       |<-------------------|                     |
       Access Node Control     Operating Maintenance
           Mechanism          Control Interface (OMCI)
       <--------------------><-------------------->
  
                              PPP, DHCP, IP
       <--------------------------------------------------------->
  
    Figure 6: Conceptual Message Flow for ANCP+OMCI ANX control model
  
  7. Multicast
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 14]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  With the rise of supporting IPTV services in a resource-efficient
  way, multicast services are becoming increasingly important.
  
  In order to gain bandwidth optimization with multicast, the
  replication of multicast content per access-loop needs to be
  distributed to the ANX. This can be done by ANX (OLT and ONT/ONU)
  becoming multicast aware by implementing an IGMP snooping and/or
  proxy function. The replication thus needs to be distributed between
  NAS, aggregation nodes, and ANX. In case of GPON, and in case of BPON
  with Ethernet uplink, this is very viable. By introducing IGMP
  processing on the ANX and aggregation nodes, the multicast
  replication process is now divided between the NAS, the aggregation
  node(s) and ANX. This is in contrast to the ATM-based model, where
  NAS is the single element responsible for all multicast control and
  replication. In order to ensure backward compatibility with the ATM-
  based model, the NAS, aggregation node and ANX need to behave as a
  single logical device. This logical device must have exactly the same
  functionality as the NAS in the ATM access/aggregation network. The
  Access Node Control Mechanism can be used to make sure that this
  logical/functional equivalence is achieved by exchanging the
  necessary information between the ANX and the NAS.
  
  An alternative to multicast awareness in the ANX is for the
  subscriber to communicate the IGMP "join/leave" messages with the
  NAS, while the ANX is being transparent to these messages. In this
  scenario, the NAS can use ANCP to create replication state in the ANX
  for efficient multicast replication. The NAS sends a single copy of
  the multicast stream towards the ANX. The NAS can perform network-
  based conditional access and multicast admission control on multicast
  joins, and create replication state in the ANX if the request is
  admitted by the NAS.
  
  The following sections describe various use cases related to
  multicast.
  
  7.1. Multicast Conditional Access
  
  In a Broadband FTTP/B/C access scenario, Service Providers may want
  to dynamically control, at the network level, access to some
  multicast flows on a per user basis. This may be used in order to
  differentiate among multiple Service Offers or to realize/reinforce
  conditional access based on customer subscription. Note that, in some
  environments, application layer conditional access by means of
  Digital Rights Management (DRM) for instance may provide sufficient
  control, so that network-based Multicast conditional access may not
  be needed. However, network level access control may add to the
  service security by preventing the subscriber from receiving a non-
  subscribed channel. In addition, it enhances network security by
  preventing a multicast stream from being sent on a link or a PON
  based on a non-subscriber request.
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 15]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  
  Where network-based channel conditional access is desired, there are
  two approaches. It can be done on the NAS along with bandwidth based
  admission control. The NAS can control the replication state on the
  ANX based on the outcome of access and bandwidth based admission
  control. This is covered a later section. The other approach is to
  provision the necessary conditional access information on the ANX
  (ONT/ONU and/or OLT) so the ANX can perform the conditional access
  decisions autonomously.  For these cases, the NAS can use ANCP to
  provision black and white lists as defined in [RFC5851], on
  the ANX so that the ANX can decide locally to honor a join or not. It
  should be noted that in the PON case, the ANX is composed of the
  ONT/ONU and OLT. Thus, this information can be programmed on the
  ONT/ONU and/or OLT. Programming this information on the ONT/ONU
  prevents illegitimate joins from propagating further into the
  network. A third approach, outside of the scope, may be to program
  the HGW with the access list.
  A White list associated with an Access Port identifies the multicast
  channels that are allowed to be replicated to that port.  A Black
  list associated with an Access Port identifies the multicast channels
  that are not allowed to be replicated to that port. It should be
  noted that the black list if not explicitly programmed is the
  complement of the white list and vice versa.
  
  If the ONT/ONU performs IGMP snooping and it is programmed with a
  channel access list, the ONT/ONU will first check if the requested
  multicast channel is part of a White list or a Black list associated
  with the access port on which the IGMP join is received. If the
  channel is part of a White list, the ONT/ONU will pass the join
  request upstream towards the NAS. The ONT/ONU must not start
  replicating the associated multicast stream to the access port if
  such a stream is received until it gets confirmation that it can do
  so from the upstream node (NAS or OLT). Passing the channel access
  list is one of the admission control criteria whereas bandwidth-based
  admission control is another. If the channel is part of a Black list,
  the ONT/ONU can autonomously discard the message because the channel
  is not authorized for that subscriber.
  
  The ONT/ONU, in addition to forwarding the IGMP join, sends an ANCP
  admission request to the OLT identifying the channel to be joined and
  the premises. Premises identification to the OLT can be based on a
  Customer-Port-ID that maps to the access port on the ONT/ONU and
  known at the ONT/ONU and OLT. If the ONT/ONU has a white list and/or
  a black list per premises, the OLT need not have such a list. If the
  ONT/ONU does not have such a list, the OLT may be programmed with
  such a list for each premises. In this latter case, the OLT would
  perform the actions described earlier on the ONT/ONU. Once the
  outcome of admission control(conditional access and bandwidth based
  admission control) is determined by the OLT (either by interacting
  with the NAS or locally), it is informed to the ONT/ONU. OLT
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 16]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  Bandwidth based admission control scenarios are defined in a later
  section.
  
  The White List and Black List can contain entries allowing:
  
     -  An exact match for a (*,G) (Any Source Multicast (ASM) group
  (e.g. <G=g.h.i.l>);
  
     -  An exact match for a (S,G) Source Specific Multicast (SSM)
  channel (e.g.
        <S=s.t.u.v,G=g.h.i.l>);
  
     -  A mask-based range match for a (*,G) ASM group (e.g.
  <G=g.h.i.l/
        Mask>);
  
     - A mask-based range match for a (S,G) SSM channel (e.g.
       <S=s.t.u.v,G=g.h.i.l/Mask>);
  
  The use of a White list and Black list may be applicable, for
  instance, to regular IPTV services (i.e.  Broadcast TV) offered by an
  Access Provider to broadband (e.g., FTTP) subscribers.  For this
  application, the IPTV subscription is typically bound to a specific
  FTTP home, and the multicast channels that are part of the
  subscription are well-known beforehand.  Furthermore, changes to the
  conditional access information are infrequent, since they are bound
  to the subscription.  Hence the ANX can be provisioned with the
  conditional access information related to the IPTV service.
  
  Instead of including the channel list(s) at the ONT/ONU, the OLT or
  NAS can be programmed with these access lists. Having these access
  lists on the ONT/ONU prevents forwarding of unauthorized joins to the
  OLT or NAS, reducing unnecessary control load on these network
  elements. Similarly, performing the access control at the OLT instead
  of the NAS, if not performed on the ONT/ONU, will reduce unnecessary
  control load on the NAS.
  
  7.2. Multicast Admission Control
  
  The successful delivery of Triple Play Broadband services is quickly
  becoming a big capacity planning challenge for most of the Service
  Providers nowadays. Solely increasing available bandwidth is not
  always practical, cost-economical and/or sufficient to satisfy end-
  user experience given not only the strict QoS requirements of unicast
  applications like VoIP and Video on Demand, but also the fast growth
  of multicast interactive applications such as "video conferencing",
  digital TV, and digital audio.  These applications typically require
  low delay, low jitter, low packet loss and high bandwidth. These
  applications are also typically "non-elastic", which means that they
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 17]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  operate at a fixed bandwidth, which cannot be dynamically adjusted to
  the currently available bandwidth.
  
  An Admission Control (AC) mechanism covering admission of multicast
  traffic for the FTTP/B/C access is required, in order to avoid over-
  subscribing the available bandwidth and negatively impacting the end-
  user experience. Before honoring a user request to join a new
  multicast flow, the combination of ANX and NAS MUST ensure admission
  control is performed to validate that there is enough video bandwidth
  remaining on the PON, and on the uplink between the OLT and NAS to
  carry the new flow (in addition to all other existing multicast and
  unicast video traffic) and that there is enough video bandwidth for
  the subscriber to carry that flow. The solution needs to cope with
  multiple flows per premises and needs to allow bandwidth to be
  dynamically shared across multicast and unicast video traffic per
  subscriber, PON, and uplink (irrespective of whether unicast AC is
  performed by the NAS, or by some off-path Policy Server). It should
  be noted that the shared bandwidth between multicast and unicast
  video is under operator control. That is, in addition to the shared
  bandwidth, some video bandwidth could be dedicated to Video on
  Demand, while other video bandwidth could be dedicated for multicast.
  The focus in this document will be on multicast-allocated bandwidth
  including the shared unicast and multicast bandwidth. Thus,
  supporting admission control requires some form of synchronization
  between the entities performing multicast AC (e.g., the ANX and/or
  NAS), the entity performing unicast AC (e.g. the NAS or a Policy
  Server), and the entity actually enforcing the multicast replication
  (i.e., the NAS and the ANX).  This synchronization can be achieved in
  a number of ways:
  
     - One approach is for the NAS to perform bandwidth based
       admission control
     on all multicast video traffic and unicast video traffic that
     requires using the shared bandwidth with multicast. Based on the
     outcome of admission control, NAS then controls the replication
     state on the ANX.  The subscriber generates an IGMP join for the
     desired stream on its logical connection to the NAS. The NAS
     terminates the IGMP message, performs conditional access, and
     bandwidth based admission control on the IGMP request. The
     bandwidth admission control is performed against the following:
  
       1. Available video bandwidth on the link to OLT
  
       2. Available video bandwidth on the PON interface
  
       3. Available video bandwidth on the last mile (access-port on
  the
          ONT/ONU).
  
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 18]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
     The NAS can locally maintain and track video bandwidth it manages
  for all the three levels mentioned above. The NAS can maintain
  identifiers corresponding to the PON interface and the last mile
  (customer interface). It also maintains a channel map, associating
  every channel (or a group of channels sharing the same bandwidth
  requirement) with a data rate. For instance, in case of 1:1 VLAN
  representation of the premises, the outer tag (S-VLAN) could be
  inserted by the ANX to correspond to the PON interface on the OLT,
  and the inner-tag could be inserted by the ANX to correspond to the
  access-line towards the customer. Bandwidth tracking and maintenance
  for the PON interface and the last-mile could be done on these VLAN
  identifiers. In case of N:1 representation, the single VLAN inserted
  by ANX could correspond to the PON interface on the OLT. The access
  loop is represented via Customer-Port-ID received in "Agent Circuit
  Identifier" sub-option in DHCP messages.
  
     The NAS can perform bandwidth accounting on received IGMP
  messages. The video bandwidth is also consumed by any unicast video
  being delivered to the CPE. NAS can perform video bandwidth
  accounting and control on both IGMP messages and on requests for
  unicast video streams when either all unicast admission control is
  done by the NAS or an external policy server makes a request to the
  NAS for using shared bandwidth with multicast as described later in
  the document.
  
     This particular scenario assumes the NAS is aware of the bandwidth
  on the PON, and under all conditions can track the changes in
  available bandwidth on the PON. On receiving an IGMP Join message,
  NAS will perform bandwidth check on the subscriber bandwidth. If this
  passes, and the stream is already being forwarded on the PON by the
  OLT (which also means that it is already forwarded by the NAS to the
  OLT), NAS will admit the JOIN, update the available subscriber
  bandwidth, and transmit an ANCP message to the OLT and in turn to the
  ONT/ONU to start replication on the customer port. If the stream is
  not already being replicated to the PON by the OLT, the NAS will also
  check the available bandwidth on the PON, and if it is not already
  being replicated to the OLT it will check the bandwidth on the link
  towards the OLT. If this passes, the available PON bandwidth and the
  bandwidth on the link towards the OLT is updated. The NAS adds the
  OLT as a leaf to the multicast tree for that stream.
  
     On receiving the message to start replication, the OLT will add
  the PON interface to its replication state if the stream is not
  already being forwarded on that PON. Also, the OLT will send an ANCP
  message to direct the ONT/ONU to add or update its replication state
  with the customer port for that channel. The interaction between ANX
  and NAS is shown in Figures 7 and 8. For unicast video streams,
  application level signaling from the CPE typically triggers an
  application server to request bandwidth based admission control from
  a policy server. The policy server can in turn interact with the NAS
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 19]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  to request the bandwidth for the unicast video flow if it needs to
  use shared bandwidth with multicast. If the bandwidth is available,
  NAS will reserve the bandwidth, update the bandwidth pools for
  subscriber bandwidth, the PON bandwidth, and the bandwidth on the
  link towards the OLT, and send a response to the policy server, which
  is propagated back to the application server to start streaming.
  Otherwise, the request is rejected.
  
                                                 +----+
                             +---<PON>---------- |ONT |-------- HGW
                            +                    +----+
                           +                     +----+
                          +           +--------- |ONT |-------- HGW
  +----+               +----+        +           +----+
  |NAS |---------------|    |------<PON>
  |    |<------------->|    |        +           +-----+
  +----+     ANCP      |OLT |         +--------- |     |------- HGW
    |                  |    |                    |     |
    |                  |    |<------------------>| ONU |--------HGW
    |                  +----+    ANCP            |     |       +---+
    |                     |                      |     |-------|HGW|
    |                     |                      +-----+       +---+
    |           1.IGMP JOIN(S/*,G)                |                |
    |<------------------------------------------------------------ |
  2.|                     |                       |                |
  +=======================+                       |                |
  [Access Control &       ]                       |                |
  [Subscriber B/W         ]                       |                |
  [PON B/W & OLT link B/W ]                       |                |
  [based Admission Control]                       |                |
  +=======================+                       |                |
    |                     |                       |                |
    |-------------------> |                       |                |
  3.ANCP Replication-Start|                       |                |
    (<S/*,G> or Multicast |                       |                |
    |MAC,Customer-Port-ID>| --------------------> |                |
    |                     |4.ANCP Replication-Start                |
    |                     |(<S/*,G> or Multicast MAC,Customer-Port-ID)
    |-------------------> |                       |                |
    |5.Multicast Flow(S,G)|                       |                |
    |On Multicast VLAN    |---------------------> |                |
    |                     |6.Multicast Flow (S,G) |                |
    |                     |forwarded on           |                |
    |                     |Unidirectional         |                |
    |                     |<Multicast GEM-PORT>   |                |
    |                     |on the PON by OLT      |--------------> |
                                                  |7. Multicast Flow
                                                  |forwarded on    |
                                                  |Customer-Port by|
                                                  |ONT/OLT.        |
                                                  |                |
  Figure 7. Interactions for NAS based Multicast Admission Control (no
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 20]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  IGMP processing on ANX, and NAS maintains available video bandwidth
  for PON).
  
                                                 +----+
                             +---<PON>---------- |ONT |-------- HGW
                            +                    +----+
                           +                     +----+
                          +           +--------- |ONT |-------- HGW
  +----+               +----+        +           +----+
  |NAS |---------------|    |------<PON>
  |    |<------------->|    |        +           +-----+
  +----+     ANCP      |OLT |         +--------- |     |------- HGW
    |                  |    |                    |     |
    |                  |    |<------------------>| ONU |--------HGW
    |                  +----+    ANCP            |     |        +---+
    |                     |                      |     |--------|HGW|
    |                     |                      +-----+        +---+
    |                     |                       |                |
    |            IGMP LEAVE(S/*,G)                |                |
    |<------------------------------------------------------------ |
    |                     |                       |                |
  +====================+  |                       |                |
  [Admission Control   ]  |                       |                |
  [<Resource Released> ]  |                       |                |
  +====================+  |                       |                |
    |                     |                       |                |
    |                     |                       |                |
    |                     |                       |                |
    |-------------------> |                       |                |
   ANCP Replication-Stop  |                       |                |
    (<S/*,G> or Multicast MAC,Customer-Port-ID)   |                |
    |                     |                       |                |
    |                     |---------------------> |                |
    |                     | ANCP Replication-Stop |                |
                         (<S/*,G> or Multicast MAC,Customer-Port-ID)
  
  Figure 8. Interactions for NAS based Multicast Admission Control (no
  IGMP processing on ANX, and NAS maintains available video bandwidth
  for PON).
  
  
  
    - An alternate approach is required if the NAS is not aware of the
  bandwidth on the PON. In this case the OLT does the PON bandwidth
  management, and requests NAS to perform bandwidth admission control
  on subscriber bandwidth and the bandwidth on the link to the OLT.
  
       ANX operation:
  
       - ONT/ONU can snoop IGMP messages. If conditional access is
  configured and the channel is in the Black list (or it is not on the
  White list), ONT will drop the IGMP Join. If the channel passes the
  conditional access check, the ONT will forward the IGMP Join,and will
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 21]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  send a bandwidth admission control request to the OLT. In case the
  multicast stream is already being received on the PON, the ONT/ONU
  does not forward the stream to the access port where IGMP is received
  till it has received a positive admission control response from the
  OLT.
  
       - OLT can snoop IGMP messages.  It also receives a bandwidth
  admission control request from the ONT/ONU for the requested
  channel. It can be programmed with a channel bandwidth map. If
  the multicast channel is already being streamed on the PON, or
  the channel bandwidth is less than the multicast available
  bandwidth on the PON, the OLT forwards the IGMP request to the
  NAS and keeps track of the subscriber (identified by customer-
  Port-ID) as a receiver. If the channel is not already being
  streamed on the PON, but the PON has sufficient bandwidth for
  that channel, the OLT reduces the PON multicast video bandwidth
  by the channel bandwidth and may optionally add the PON to the
  multicast tree without activation for that channel. This is
  biased towards a forward expectation that the request will be
  accepted at the NAS. The OLT forwards the IGMP join to the NAS.
  It also sends a bandwidth admission request to the NAS
  identifying the channel, and the premises for which the request
  is made. It sets a timer for the subscriber multicast entry
  within which it expects to receive a request from the NAS that
  relates to this request.  If the PON available bandwidth is
  less than the bandwidth of the requested channel, the OLT sends
  an admission response (with a reject) to the ONT/ONU, and does not
  forward the IGMP join to the NAS.
  
  NAS operation:
  
  The NAS receives the IGMP join from the subscriber on the
  subscriber connection.  When NAS receives the admission control
  request from ANX (also signifying the bandwidth on the PON is
  available), it performs admission control against the subscriber
  available multicast bandwidth. If this check passes, and the NAS is
  already transmitting that channel to the OLT, the request is
  accepted. If the check passes and the NAS is not transmitting the
  channel to the OLT yet, it performs admission control against the
  multicast video available bandwidth (this includes the dedicated
  multicast bandwidth and the shared bandwidth between multicast and
  video on demand) on the link(s) to the OLT. If the check passes,
  the request is accepted, the available video bandwidth for the
  subscriber and downlink to the OLT are reduced by the channel
  bandwidth, and the NAS sends an ANCP admission control response
  (indicating accept) to the OLT, requesting the addition of the
  subscriber to the multicast tree for that channel. The OLT
  activates the corresponding multicast entry if not active and
  maintains state of the subscriber in the list of receivers for that
  channel. The OLT also sends an ANCP request to the ONT/ONU to enable
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 22]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  reception of the multicast channel and forwarding to the subscriber
  access port. Otherwise, if the request is rejected, the NAS will
  send an admission reject to the OLT, which in turns removes the
  subscriber as a receiver for that channel (if it were added), and
  credits back the channel bandwidth to the PON video bandwidth if
  there is no other receiver on the PON for that channel. The
  interactions between ANX and NAS are shown in Figures 9 and 10.
  
  If the OLT does not receive a response from the NAS within a set
  timer, the OLT removes the subscriber from the potential list of
  receivers for the indicated channel. It also returns the allocated
  bandwidth to the PON available bandwidth if there are no other
  receivers. In this case, the NAS may send a response to the OLT
  with no matching entry as the entry has been deleted. The OLT must
  perform admission control against the PON available bandwidth and
  may accept the request and send an ANCP request to the ONT/ONU to
  activate the corresponding multicast entry as described earlier. If
  it does not accept the request, it will respond back to the NAS
  with a reject. The NAS shall credit back the channel bandwidth to
  the subscriber. It shall also stop sending the channel to the OLT
  if that subscriber was the last leaf on the multicast tree towards
  the OLT.
  
  On processing an IGMP leave, the OLT will send an ANCP request to
  NAS to release resources. NAS will release the subscriber
  bandwidth. If this leave causes the stream to be no longer required
  by the OLT, the NAS will update its replication state and release
  the bandwidth on the NAS to OLT link.
  
  If the subscriber makes a request for a unicast video stream (i.e.,
  Video on Demand), the request results in appropriate application
  level signaling, which typically results in an application server
  requesting a policy server for bandwidth-based admission control
  for the VoD stream. The policy server after authorizing the
  request, can send a request to the NAS for the required bandwidth
  if it needs to use bandwidth that is shared with multicast. This
  request may be based on a protocol outside of the scope of this
  document. The NAS checks if the available video bandwidth
  (accounting for both multicast and unicast) per subscriber and for
  the link to the OLT is sufficient for the request. If it is, it
  temporarily reserves the bandwidth and sends an ANCP admission
  request to the OLT for the subscriber, indicating the desired VoD
  bandwidth. If the OLT has sufficient bandwidth on the corresponding
  PON, it reserves that bandwidth and returns an accept response
  to the NAS. If not, it returns a reject to the NAS. If the NAS
  receives an accept, it returns an accept to the policy server which
  in turn returns an accept to the application server, and the video
  stream is streamed to the subscriber. This interaction is shown in
  Figure 11. If the NAS does not accept the request from the policy
  server, it returns a reject. If the NAS receives a reject from the
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 23]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  OLT, it returns the allocated bandwidth to the subscriber and
  the downlink to the OLT.
                                                +----+
                                      +-------- |ONT |-------- HGW
  +----+               +----+        +          +----+
  |NAS |---------------|    |------<PON>
  |    |<------------->|    |        +           +-----+
  +----+     ANCP      |OLT |         +--------- |     |--------- HGW
    |                  |    |    ANCP            |     |
    |                  |    |<-----------------> | ONU |----------HGW
    |                  +----+                    +-----+
    |                     |                        |               |
    |1.IGMP Join(s/*,G) +=============+         +=============+    |
    |<------------------[IGMP Snooping]---------[IGMP snooping]--- |
    |                   +=============+         +=============+    |
    |                     |2.Admission-Request     |               |
    |                     |(Flow,Customer-Port-ID) |               |
    |                     |<---------------------- |               |
    |                3.+===============+           |               |
    |                  [ Access Ctrl   ]           |               |
    |                  [ & PON B/W     ]           |               |
    |                  [ Admission Ctrl]           |               |
    |                  +===============+ PASS      |               |
    |4.Admission-Request  |                        |               |
    | <Flow,              |                        |               |
    |  Customer-Port-ID>  |                        |               |
    |<--------------------|                        |               |
  5.|                     |                        |               |
  +=================+     |                        |               |
  [Subscriber B/W   ]     |                        |               |
  [& OLT link B/W   ]     |                        |               |
  [Admission Ctrl   ]     |                        |               |
  +=================+PASS |                        |               |
    |                     |                        |               |
    |6.Admission-Reply-Pass                        |               |
    |<Flow,Customer-Port-ID>                       |               |
    |-------------------->|                        |               |
    |            7.+========================+      |               |
    |              [Update Replication State]      |               |
    |              +========================+      |               |
    |                     | 8.Admission-Reply-Pass |               |
    |                     |(<Flow,Cust-Port-ID>    |               |
    |                     |----------------------> |               |
    |                     |                 9.+============+       |
    |                     |                   [Update Repl.]       |
    |                     |                   [   State    ]       |
    |                     |                   +============+       |
  
  Figure 9. Interaction between NAS & ANX for Multicast Bandwidth
  Admission Control in the All-ANCP ANX control model. Similar
  functionality will be required when OMCI is enabled between the OLT
  and ONT/ONU in the ANCP+OMCI ANX control model. In this latter case,
  the OLT will act as ANCP-OMCI gateway.
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 24]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  
                                                 +----+
                                      +--------- |ONT |-------- HGW
  +----+               +----+        +           +----+
  |NAS |---------------|    |------<PON>
  |    |<------------->|    |        +           +-----+
  +----+     ANCP      |OLT |         +--------- |     |--------- HGW
    |                  |    |    ANCP            |     |
    |                  |    |<------------------>| ONU |----------HGW
    |                  +----+                    +-----+
    |                     |                        |               |
    |1.IGMP Join(s/*,G) +=============+        +=============+     |
    |<------------------[IGMP Snooping]--------[IGMP snooping]---- |
    |                   +=============+        +=============+     |
    |                     |2.Admission-Request     |               |
    |                     |(Flow,Customer-Port-ID) |               |
    |                     |<---------------------- |               |
    |                2.+===============+           |               |
    |                  [ Access Ctrl   ]           |               |
    |                  [ & PON B/W     ]           |               |
    |                  [ Admission Ctrl]           |               |
    |                  +===============+ PASS      |               |
    |3.Admission-Request  |                        |               |
    | <Flow,Customer-Port-ID>                      |               |
    |<--------------------|                        |               |
  4.|                     |                        |               |
  +==================+    |                        |               |
  [Subscriber B/W    ]    |                        |               |
  [& OLT link B/W    ]    |                        |               |
  [Admission Ctrl    ]    |                        |               |
  +==================+FAIL                         |               |
    |                     |                        |               |
    |5.Admission-Reply-Fail                        |               |
    |<Flow,Cust-Port-ID>  |                        |               |
    |-------------------->|                        |               |
    |            6.+==================+            |               |
    |              [Release PON B/W   ]            |               |
    |              [Remove Repl.State ]            |               |
    |              +==================+            |               |
    |                     | 7.Admission-Reply-Fail |               |
    |                     |<Flow,Cust-Port-ID>     |               |
    |                     |----------------------> |               |
    |                     |                 8.+============+       |
    |                     |                   [Remove Repl.]       |
    |                     |                   [   State    ]       |
    |                     |                   +============+       |
  
  Figure 10. Interaction between NAS and ANX for Multicast Bandwidth
  Admission Control in the All-ANCP ANX control model. Similar
  functionality will be required when OMCI is enabled between the OLT
  and ONT/ONU in the ANCP+OMCI ANX control model. In this latter case,
  the OLT will act as ANCP-OMCI gateway.
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 25]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  +------------+              1. VoD Request
  | App. Server|<----------------------------------------------------
  | Server     |
  +------------+
    | 2. Admission-Request (VoD-Flow)
  +-------+
  |Policy |
  |Server |
  +-------+
   |  +
   |<-|---3. Admission-Request
   |  |
   +  | 8. Admission-Reply
  +----+        +      +----+                  +-----+
  |NAS |---------------|OLT |------<PON>-------|ONT  |------HGW----CPE
  |    |<------------->|    |                  +-----+       |
  +----+     ANCP      +----+                      |         |
    |                     |                        |         |
  4.|                     |                        |         |
  +=================+     |                        |         |
  [Subscriber B/W   ]     |                        |         |
  [& OLT link B/W   ]     |                        |         |
  [Admission Ctrl   ]     |                        |         |
  +=================+PASS |                        |         |
    |                     |                        |         |
    | 5.Admission-Request |                        |         |
    |(Bandwidth,PON-Port-ID)                       |         |
    |-------------------> |                        |         |
    |                     |                        |         |
    |                6.+===============+           |         |
    |                  [   PON B/W     ]           |         |
    |                  [ Admission Ctrl]           |         |
    |                  +===============+ PASS      |         |
    |7.Admission-Reply    |                        |         |
    | <PON-Port-ID>       |                        |         |
    |<------------------- |                        |         |
    |                     |                        |         |
    |                     |                        |         |
  
  
  Figure 11. Interactions for VoD Bandwidth Admission Control in the
  All-ANCP ANX control model. Similar functionality will be required
  when OMCI is enabled between the OLT and ONT in the ANCP+OMCI ANX
  control model. In this latter case, the OLT will act as ANCP-OMCI
  gateway.
  
     -A third possible approach is where the ANX is assumed to have a
  full knowledge to make an autonomous decision on admitting or
  rejecting a multicast and a unicast join. With respect to the
  interaction between ONT/ONU and OLT, the procedure is similar to the
  first approach (i.e. NAS controlled replication). However, when the
  OLT receives an IGMP request from a subscriber, it performs
  admission control against that subscriber multicast video bandwidth
  (dedicated and shared with Video on Demand), the PON and uplink to
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 26]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  the GWR. It should be noted in this case that if there are multiple
  NAS-OLT links, either the link on which the multicast stream must
  be sent is pre-determined, needs to be selected by the OLT based on
  downstream bandwidth from NAS to OLT and the selection is
  communicated to the NAS, or the OLT has to be ready to receive the
  stream on any link. If the check passes, the OLT updates the video
  available bandwidth per PON and subscriber. The OLT adds the
  subscriber to the list of receivers and the PON to the multicast
  tree, if it is not already on it. It also sends an ANCP request to
  the ONT/ONU to add the subscriber access port to that channel
  multicast tree, and sends an ANCP message to the NAS informing it of
  the subscriber and link available video bandwidth and the channel the
  subscriber joined. The NAS upon receiving the ANCP information
  message, updates the necessary information, including the OLT to the
  multicast tree if it is not already on it. It should be noted
  in this case that the ANCP message from the OLT to the NAS is being
  used to add the OLT to a multicast tree as opposed to an IGMP
  message. The IGMP message can also be sent by the OLT with the OLT
  acting as an IGMP proxy at the expense of added messages. In this
  option, the OLT acts as the network IGMP router for the subscriber.
  
  For unicast video streams, the policy server receiving an admission
  request from an application server, as described before, may query
  the OLT for admission control as it has all information. If the OLT
  has sufficient bandwidth for the stream it reserves that bandwidth
  for the subscriber, PON and OLT uplink to the NAS and returns an
  accept to the policy server. It also updates the NAS via an ANCP
  message of the subscriber available video bandwidth. If the OLT
  rejects the policy server request, it will return a reject to the
  policy server.
  
  It should be noted that if the policy server adjacency is with the
  NAS, the policy server may make the admission request to the NAS.
  The NAS then sends an ANCP admission request to the OLT on behalf of
  the policy server. The NAS returns an accept or reject to the policy
  server if it gets a reject or accept, respectively, from the OLT.
  
  7.3. Multicast Accounting
  
  It may be desirable to perform accurate per-user or per Access Loop
  time or volume based accounting.  In case the ANX is performing the
  traffic replication process, it knows when replication of a multicast
  flow to a particular Access Port or user starts and stops. Multicast
  accounting can be addressed in two ways:
  
    - ANX keeps track of when replication starts or stops, and reports
  this information to the NAS for further processing. In this case,
  ANCP can be used to send the information from the ANX to the NAS.
  This can be done with the Information Report message. The NAS can
  then generate the appropriate time and/or volume accounting
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 27]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  information per Access Loop and per multicast flow, to be sent to the
  accounting system. The ANCP requirements to support this approach are
  specified in [RFC5851]. If the replication function is
  distributed between the OLT and ONT/ONU, a query from the NAS will
  result in OLT generating a query to the ONT/ONU.
  
    - ANX keeps track of when replication starts or stops, and
  generates the time and/or volume based accounting information per
  Access Loop and per multicast flow, before sending it to a central
  accounting system for logging. Since ANX communicates with this
  accounting system directly, the approach does not require the use of
  ANCP. It is therefore beyond the scope of this document;
  
  It may also be desirable for the NAS to have the capability to
  asynchronously query the ANX to obtain an instantaneous status report
  related to multicast flows currently replicated by the ANX. Such a
  reporting functionality could be useful for troubleshooting and
  monitoring purposes. If the replication function in the ANX is
  distributed between the OLT and the ONT/ONU, then for some of the
  information required by the NAS (such as the list of access-ports on
  which a flow is being forwarded or list of flows being forwarded on
  an access-port), a query to the OLT from the NAS will result in a
  query from OLT to ONT/ONU. The OLT responds back to the NAS when it
  receives the response from the ONT/ONU. Also, if the list of PONs on
  which replication is happening for a multicast channel or the list of
  channels being replicated on a PON is what is desired, the OLT can
  return this information.
  
  8. Remote Connectivity Check
  
  In an end-to-end Ethernet aggregation network, end-to-end Ethernet
  OAM as specified in IEEE 802.1ag and ITU-T Recommendation Y.1730/1731
  can provide Access Loop connectivity testing and fault isolation.
  However, most HGWs do not yet support these standard Ethernet OAM
  procedures. Also, in a mixed Ethernet and ATM access network (e.g.,
  Ethernet based aggregation upstream from the OLT, and BPON
  downstream), interworking functions for end-to-end OAM are not yet
  standardized or widely available. Until such mechanisms become
  standardized and widely available, Access Node Control mechanism
  between NAS and ANX can be used to provide a simple mechanism to test
  connectivity of an access-loop from the NAS.
  
  Triggered by a local management interface, the NAS can use the Access
  Node Control Mechanism (Control Request Message) to initiate an
  Access Loop test between Access Node and HGW or ONT/ONU. On reception
  of the ANCP message, the OLT can trigger native OAM procedures
  defined for BPON in [G.983.1] and for GPON in [G.984.1]. The Access
  Node can send the result of the test to the NAS via a Control
  Response message.
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 28]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  9. Access Topology Discovery
  
  In order to avoid congestion in the network, manage and utilize the
  network resources better, and ensure subscriber fairness, NAS
  performs hierarchical shaping and scheduling of the traffic by
  modeling different congestion points in the network (such as the
  last-mile, Access Node uplink, and the access facing port).
  
  Such mechanisms require that the NAS gains knowledge about the
  topology of the access network, the various links being used and
  their respective rates. Some of the information required is somewhat
  dynamic in nature (e.g.  DSL line rate in case the last mile is xDSL
  based, e.g., in case of "PON fed DSLAMs" for FTTC/FTTB scenarios),
  hence cannot come from a provisioning and/or inventory management OSS
  system. Some of the information varies less frequently (e.g.,
  capacity of the OLT uplink), but nevertheless needs to be kept
  strictly in sync between the actual capacity of the uplink and the
  image the NAS has of it.
  
  OSS systems are rarely able to enforce in a reliable and scalable
  manner the consistency of such data, notably across organizational
  boundaries under certain deployment scenarios.  The Access Topology
  Discovery function allows the NAS to perform these advanced functions
  without having to depend on an error-prone and possibly complex
  integration with an OSS system.
  
  The rate of the access-loop can be communicated via ANCP (Information
  Report Message) from the ONT/ONU to the OLT in the All-ANCP ANX
  control model or via OMCI in the ANCP+OMCI ANX control model, and
  then from OLT to the NAS via ANCP. Additionally, during the time the
  DSL NT is active, data rate changes can occur due to environmental
  conditions (the DSL Access Loop can get "out of sync" and can retrain
  to a lower value, or the DSL Access Loop could use Seamless Rate
  Adaptation making the actual data rate fluctuate while the line is
  active). In this case, ANX sends an additional Information Report to
  the NAS each time the Access Loop attributes change above a threshold
  value. Existing DSL procedures are not applicable in this case
  because an adapted message flow and additional TLVs are needed.
  
  
  
  
  
  
  
  
  
  
  
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 29]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  +--------+
  | Policy |
  | Server |
  +--------+                   +                    +---+     +---+
       |                      +         +-----------|ONT|---- |HGW|
       |                     +          |           +---+     +---+
       |               +--------------- |-------------------+
    +----+             | +----+         |           +-----+ | +---+
    |NAS |------------ | |    |         |           |     |-|-|HGW|
    |    |<----------> | |    |         |           |ONT/ | | +---+
    +----+     ANCP    | |OLT |------<PON>--------- |ONU  | |
       |               | |    |                     |     | | +---+
       |               | |    |<------------------> |     |---|HGW|
       |               | +----+       OMCI          +-----+ | +---+
       |               +------------------------------------+
       |                    |      Access Node        |
       |                    |                         |
       |                    |------GPON Ranging------ |
       | Port Status Message|      ONT Port UP        |
       |<------------------ |<----------------------- |
       |Port Configuration  |GPON Line/Service Profile|
       |------------------> |<----------------------> |
       |     ONT/ONI Port UP|                         |
       |<------------------ |                         |
       |                    |                         |
       |      ANCP          |         OMCI            |
       <-------------------><-----------------------> |
                              PPP, DHCP, IP
       <----------------------------------------------------------->
  
    Figure 12: Message Flow for the use case of Topology Discovery for
  the ANCP+OMCI access control model.
  
  Figure 12 depicts a message flow for topology discovery when using
  the ANCP+OMCI access control model. Basically, when an ONT/ONU gets
  connected to a PON, the OLT detects a new device and a GPON Ranging
  process starts. During this process the ONT/ONU becomes authorized by
  the OLT and identified by ONT/ONU ID, PON Port ID and max Bandwidth.
  This port status is reported via ANCP to the NAS and then potentially
  the policy server via another mechanism that is out of scope of this
  document. In a second step after GPON Service profile is assigned
  from OLT to ONT/ONU, the OLT reports the final status to NAS with
  information about service profile and other information such as the
  ONT/ONU port rate to the subscriber for instance.
  
  10.Access Loop Configuration
  
  Topology Discovery reports access port identification to NAS when
  sending an Access Port Discovery message. This informs NAS
  identification of PON port on an Access Node. Based on Access Port
  Identification and on customer identification, service related
  parameters could be configured on an OLT and an ONU/ONT.
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 30]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  Service related parameters could be sent to OLT via ANCP before or
  after an ONU/ONT is up. Sending of ANCP loop Configuration messages
  from NAS can be triggered by a management system or by customer
  identification and authentication after Topology Discovery. It may be
  used for first time configuration (zero touch) or for
  updating/upgrading customer's profile like C-VLAN ID, S-VLAN ID, and
  service bandwidth.
  
  Parameters of UNI (subscriber interface to HGW/CPE) of ONU/ONT can
  also be configured via ANCP. When the ONU/ONT supports ANCP,
  parameters of the UNI on ONU/ONT are sent to the ONU/ONT via ANCP. If
  the ONU/ONT does not support ANCP, but only OMCI, parameters have to
  be sent from the NAS to the OLT via ANCP first. Then, the OLT
  translates such configuration into OMCI and sends it to the ONU/ONT.
  
  9  Security Considerations
  
  [RFC5713] lists the ANCP related security threats that could be
  encountered on the Access Node and the NAS. It develops a threat
  model for ANCP security, and lists the security functions that are
  required at the ANCP level.
  
  With Multicast handling as described in this document, ANCP protocol
  activity between the ANX and the NAS is triggered by join/leave
  requests coming from the end-user equipment.  This could potentially
  be used for denial of service attack against the ANX and/or the NAS.
  
  To mitigate this risk, the NAS and ANX MAY implement control plane
  protection mechanisms such as limiting the number of multicast flows
  a given user can simultaneously join, or limiting the maximum rate of
  join/leave from a given user.
  
  Protection against invalid or unsubscribed flows can be deployed via
  provisioning black lists as close to the subscriber as possible (e.g.
  in the ONT).
  
  
  
  10 Differences in ANCP applicability between DSL and PON
  
  As it currently stands, both ANCP framework [RFC5851] and
  protocol [RFC6320] are defined in context of DSL access. Due to
  inherent differences between PON and DSL access technologies, ANCP
  needs a few extensions for supporting the use-cases outlined in this
  document for PON based access. These specific differences and
  extensions are outlined below.
  
  - In PON, the access-node functionality is split between OLT and ONT.
  Therefore, ANCP interaction between NAS and AN translates to
  transactions between NAS and OLT and between OLT and ONT. The
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 31]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  processing of ANCP messages (e.g. for multicast replication control)
  on the OLT can trigger generation of ANCP messages from OLT to ONT.
  Similarly, ANCP messages from ONT to the OLT can trigger ANCP
  exchange between the ONT and the NAS (e.g. admission-request
  messages). This is illustrated in the generic message flows in
  Figures 5
  and 6 of section 6. In case of DSL, the ANCP exchange is contained
  between
  two network elements (NAS and the DSLAM).
  
  - The PON connection to the ONT is a shared medium between multiple
  ONTs on the same PON. The local-loop in case of DSL is point-to-
  point. In case of DSL access network, the access facing port on the
  NAS (i.e. port to the network between NAS and the DSLAM), and the
  access-facing ports on the DSLAM (i.e. customer's local-loop) are the
  two bandwidth constraint points that need to be considered for
  performing bandwidth based admission control for multicast video and
  VOD delivered to the customer. In case of PON access, in addition to
  the bandwidth constraint on the NAS to OLT facing ports, and the
  subscriber allocated bandwidth for video services, the bandwidth
  available on the PON for video is an additional constraint that needs
  to be considered for bandwidth based admission control. If the
  bandwidth control is centralized in NAS (as described in option 1 of
  section 7.2), then the NAS needs to support additional logic to
  consider available PON bandwidth before admitting a multicast request
  or a VOD request by the user. Accordingly, ANCP needs to identify the
  customer access port and the PON on which the customer ONT is. If the
  PON bandwidth control is performed on the OLT (as defined in second
  option in section 7.2), then additional ANCP request and response
  messages are required for NAS to query the OLT to determine available
  PON bandwidth when a request to admit a VOD flow is received on the
  NAS (as shown in Figure 9 in section 7.2) or for the OLT to inform
  the NAS what stream bandwidth is sent to the subscriber for the NAS
  to take appropriate action (e.g., bandwidth adjustment for various
  types of traffic).
  
  - In PON, the multicast replication can potentially be performed on
  three different network elements: (1) on the NAS (2) on the OLT for
  replication to multiple PON ports and (3) on the ONT/ONU for
  replication to multiple customer ports. In case of DSL, the
  replication can potentially be performed on NAS and/or the DSLAM.
  Section 7.2 defines options for multicast replication in case of PON.
  In the first option, the multicast replication is done on the AN, but
  is controlled from NAS via ANCP (based on the reception of per-
  customer IGMP messages on the NAS). In this option, the NAS needs to
  supply to the OLT the set of PON-customer-IDs (as defined in section
  3) to which the multicast stream needs to be replicated. The PON-
  customer-ID identifies the OLT and the PON ports on the OLT as well
  as the ONT and the access-ports on the ONT where the multicast stream
  needs to be replicated. Upon receiving the request to update its
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 32]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  multicast replication state, the OLT MUST update its replication
  state with the indicated PON ports, but MAY also need to interact
  with the ONT via ANCP to update the multicast replication state on
  the ONT with the set of access-ports (as indicated by the NAS).In
  case of DSL, the DSLAM only needs to update its own replication state
  based on the set of access-ports indicated by the NAS.
  
  - For reporting purposes, ANCP must enable the NAS to query the OLT
  for channels replicated on a PON or a list of PONs and to specific
  access ports. The latter should trigger the OLT to query the ONT for
  a list of channels being replicated on all access ports or on
  specific access ports to the premise. In DSL case, it is sufficient
  to query the DSLAM for a list of channels being replicated on an
  access port or a list of access ports.
  
  11.ANCP versus OMCI between the OLT and ONT/ONU
  
  ONT Management and Control Interface (OMCI) [OMCI] is specified for
  in-band ONT management via the OLT. This includes configuring
  parameters on the ONT/ONU. Such configuration can include adding an
  access port on the ONT to a multicast tree and the ONT to a multicast
  tree. Thus, OMCI can be a potential replacement for ANCP between the
  OLT and ONT/ONU, albeit it may not be suitable protocol for dynamic
  transactions as required for the multicast application.
  
  If OMCI is selected to be enabled between the OLT and ONT/ONU to
  carry the same information elements that would be carried over ANCP,
  the OLT must perform the necessary translation between ANCP and OMCI
  for replication control messages received via ANCP. OMCI is an
  already available control channel, while ANCP requires a TCP/IP stack
  on the ONT/ONU that can be used by an ANCP client and accordingly it
  requires that the ONT/ONU be IP addressable for ANCP. Most ONTs/ONUs
  today have a TCP/IP stack used by certain applications (e.g., VoIP,
  IGMP snooping). ANCP may use the same IP address that is often
  assigned to SIP or depending on the implementation may require a
  different address. Sharing the same IP address between SIP and ANCP
  may have other network implications on traffic routing. Using a
  separate IP address for the purpose of ONT/ONU management or ANCP
  specifically may often be required when supporting ANCP. These
  considerations may favor OMCI in certain environments. However, OMCI
  will not allow some of the transactions required in approach 2, where
  the ONT/ONU sends unsolicited requests to the OLT rather than being
  queried or configured by OLT requests.
  
  12. IANA Considerations
  
   This document does not require actions by IANA.
  
  13. Acknowledgements
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 33]


  Internet Draft     draft-ietf-ancp-pon-02                January 2012
  
  
  14. References
  
  14.1. Normative References
  
  [RFC2516]  Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D.,
  and R. Wheeler, "A Method for Transmitting PPP Over
  Ethernet (PPPoE)", RFC 2516, February 1999.
  
  [RFC2684]  Grossman, D. and J. Heinanen, "Multiprotocol Encapsulation
  over ATM Adaptation Layer 5", RFC 2684, September 1999.
  
  14.2. Informative References
  
  [RFC2881] Mitton, D. and M. Beadles, "Network Access Server
  Requirements Next Generation (NASREQNG) NAS Model", RFC 2881, Jul
  2000.
  
  [RFC5851] Ooghe, S., et al., "Framework and Requirements
  for Access Node Control Mechanism in Broadband Networks", RFC 5851,
  May 2010.
  
  [G.983.1] ITU-T recommendation G.983.1, Broadband optical access
  systems based on Passive Optical Networks (PON).
  
  [G.984.1] ITU-T recommendation G.984.1 Gigabit-capable Passive
  Optical Networks (G-PON): General characteristics
  
  [TR-101] Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL
  Aggregation", DSL Forum TR-101, May 2006.
  
  [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.
  
  [OMCI] ITU-T recommendation G.984.4 GPON ONT Management and Control
  Interface (OMCI) Specifications.
  
  [RFC6320] Taylor, T., et al, "Protocol for Access Node Control
  Mechanism in Broadband Networks", RFC 6320,  October 2011.
  
  
  Authors' Addresses
  
     Nabil Bitar
     Verizon
     60 Sylvan Road
     Waltham, MA 02451
     Email: nabil.n.bitar@verizon.com
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 34]


  Internet Draft     draft-ietf-ancp-pon-02                 January 2012
  
  
     Sanjay Wadhwa
     Alcatel-Lucent
     701 East Middlefield Road
     Mountain View, CA, 94043
     Email: sanjay.wadhwa@alcatel-lucent.com
  
     Hongyu Li
     Email: hongyu.lihongyu@huawei.com
  
     Thomas Haag
     Email: HaagT@telekom.de
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  Bitar-Wadhwa       Expires June 16, 2012                 [Page 35]
  

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