draft-ietf-ancp-pon-05.txt   rfc6934.txt 
Network Working Group Nabil Bitar(ed.) Internet Engineering Task Force (IETF) N. Bitar, Ed.
Verizon Request for Comments: 6934 Verizon
Internet Draft Category: Informational S. Wadhwa, Ed.
Intended Status: Informational Sanjay Wadhwa (ed.) ISSN: 2070-1721 Alcatel-Lucent
Alcatel-Lucent T. Haag
Expires: August 25, 2013 Deutsche Telekom
Thomas Haag H. Li
Deutsche Telekom Huawei Technologies
June 2013
Hongyu Li
Huawei Technologies
February 25, 2013
Applicability of Access Node Control Mechanism to
PON based Broadband Networks
draft-ietf-ancp-pon-05.txt Applicability of the Access Node Control Mechanism to
Broadband Networks Based on Passive Optical Networks (PONs)
Abstract Abstract
The purpose of this document is to provide applicability of the The purpose of this document is to provide applicability of the
Access Node Control mechanism to Passive Optical Network (PON)-based Access Node Control Mechanism to broadband access based on Passive
broadband access. The need for an Access Node Control mechanism Optical Networks (PONs). The need for an Access Node Control
between a Network Access Server (NAS) and an Access Node Complex (a Mechanism between a Network Access Server (NAS) and an Access Node
combination of Optical Line Termination (OLT) and Optical Network Complex, composed of a combination of Optical Line Termination (OLT)
Termination (ONT) elements) is described in a multi-service reference and Optical Network Termination (ONT) elements, is described in a
architecture in order to perform QoS-related, service-related and multi-service reference architecture in order to perform QoS-related,
Subscriber-related operations. The Access Node Control mechanism is service-related, and subscriber-related operations. The Access Node
also extended for interaction between components of the Access Node Control Mechanism is also extended for interaction between components
Complex (OLT and ONT). The Access Node Control mechanism will ensure of the Access Node Complex (OLT and ONT). The Access Node Control
that the transmission of information between the NAS and Access Node Mechanism will ensure that the transmission of information between
Complex (ANX) and between the OLT and ONT within an ANX does not need the NAS and Access Node Complex (ANX) and between the OLT and ONT
to go through distinct element managers but rather uses a direct within an ANX does not need to go through distinct element managers
device-to-device communication and stays on net. This allows for but rather uses direct device-to-device communication and stays on
performing access link related operations within those network net. This allows for performing access-link-related operations
elements to meet performance objectives. within those network elements to meet performance objectives.
Status of this Memo
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Table of Contents Table of Contents
1. Introduction ..................................................... 3 1. Introduction ....................................................3
2. Terminology ...................................................... 5 2. Terminology .....................................................4
3. Motivation for explicit extension of ANCP to FTTx PON ............ 7 3. Motivation for Explicit Extension of ANCP to FTTx PON ...........6
4. Reference Model for PON Based Broadband Access Network ........... 8 4. Reference Model for PON-Based Broadband Access Network ..........7
4.1. Functional Blocks ............................................. 10 4.1. Functional Blocks ..........................................9
4.1.1. Home Gateway ............................................... 10 4.1.1. Home Gateway ........................................9
4.1.2. PON Access ................................................. 10 4.1.2. PON Access ..........................................9
4.1.3. Access Node Complex ........................................ 11 4.1.3. Access Node Complex ................................10
4.1.4. Access Node Complex Uplink to the NAS ....................... 11 4.1.4. Access Node Complex Uplink to the NAS ..............10
4.1.5. Aggregation Network ......................................... 11 4.1.5. Aggregation Network ................................10
4.1.6. Network Access Server ....................................... 11 4.1.6. Network Access Server ..............................10
4.1.7. Regional Network ............................................ 11 4.1.7. Regional Network ...................................10
4.2. Access Node Complex Control Reference Architecture Options .... 12 4.2. Access Node Complex Control Reference Architecture
4.2.1. ANCP+OMCI ANX Control ....................................... 12 Options ...................................................11
4.2.2. All-ANCP ANX Control ........................................ 13 4.2.1. ANCP+OMCI ANX Control ..............................11
5. Concept of Access Node Control Mechanism for PON Based Access ... 14 4.2.2. All-ANCP ANX Control ...............................12
6. Multicast ....................................................... 17 5. Concept of Access Node Control Mechanism for PON-Based Access ..13
6.1. Multicast Conditional Access .................................. 18 6. Multicast ......................................................16
6.2. Multicast Admission Control ................................... 20 6.1. Multicast Conditional Access ..............................16
6.3. Multicast Accounting .......................................... 33 6.2. Multicast Admission Control ...............................18
7. Remote Connectivity Check ....................................... 33 6.3. Multicast Accounting ......................................30
8. Access Topology Discovery ....................................... 34 7. Remote Connectivity Check ......................................31
9. Access Loop Configuration ....................................... 36 8. Access Topology Discovery ......................................32
10. Security Considerations ........................................ 37 9. Access Loop Configuration ......................................34
11. Differences in ANCP applicability between DSL and PON .......... 38 10. Security Considerations .......................................34
12. ANCP versus OMCI between the OLT and ONT/ONU ................... 39 11. Differences in ANCP Applicability between DSL and PON .........35
13. IANA Considerations ............................................ 40 12. ANCP versus OMCI between the OLT and ONT/ONU ..................36
14. Acknowledgements ............................................... 40 13. Acknowledgements ..............................................37
15. References ..................................................... 41 14. References ....................................................37
15.1. Normative References ........................................ 41 14.1. Normative References .....................................37
15.2. Informative References ....................................... 41 14.2. Informative References ...................................38
1. Introduction 1. Introduction
Passive Optical Networks (PONs) based on BPON [G.983.1] and GPON Passive Optical Networks (PONs) based on Broadband PON (BPON)
[G.984.1] are being deployed across carrier networks. There are two [G.983.1] and Gigabit PON (GPON) [G.984.1] are being deployed across
models for PON deployment: Fiber to the building/curb (FTTB/FTTC), carrier networks. There are two models for PON deployment: Fiber to
and Fiber to the Premises (FTTP). In the FTTB/C deployment, the last the Building/Curb (FTTB/FTTC) and Fiber to the Premises (FTTP). In
mile connectivity to the subscriber premises is provided over the the FTTB/C deployment, the last-mile connectivity to the subscriber
local Copper loop, often using Very High Speed Digital Subscriber premises is provided over the local copper loop, often using Very
line (VDSL). In the FTTP case, PON extends to the premises of the High Speed Digital Subscriber Line (VDSL). In the FTTP case, PON
subscriber. In addition, there are four main PON technologies: (1) extends to the premises of the subscriber. In addition, there are
Broadband PON (BPON), (2) Gigabit PON (GPON), (3) 10-Gigabit PON (XG- four main PON technologies: (1) BPON, (2) GPON, (3) 10-Gigabit PON
PON), and (4) Ethernet PON (EPON). This document describes the (XG-PON), and (4) Ethernet PON (EPON). This document describes the
applicability of Access Node Control Protocol (ANCP) in the context applicability of the Access Node Control Protocol (ANCP) in the
of FTTB/C and FTTP deployments, focusing on BPON, GPON and XG-PON. context of FTTB/C and FTTP deployments, focusing on BPON, GPON, and
Architectural considerations lead to different ANCP compositions. XG-PON. Architectural considerations lead to different ANCP
Therefore, the composition of ANCP communication between Access Nodes compositions. Therefore, the composition of ANCP communication
and Network Access Server (NAS) is described using different models. between Access Nodes (ANs) and Network Access Servers (NASs) is
described using different models.
BPON, GPON and XG-PON in FTTP deployments provide large bandwidth in BPON, GPON, and XG-PON in FTTP deployments provide large bandwidth in
the first mile, bandwidth that is an order of magnitude larger than the first mile, bandwidth that is an order of magnitude larger than
that provided by xDSL. In the downstream direction, BPON that provided by xDSL. In the downstream direction, BPON provides
provides 622 Mbps per PON while GPON provides 2.4 Gbps, and XG-PON 622 Mbit/s per PON, GPON provides 2.4 Gbit/s, and XG-PON provides 10
provides 10 Gbps. Gbit/s.
In residential deployments, the number of homes sharing the same PON In residential deployments, the number of homes sharing the same PON
is limited by the technology and the network engineering rules. is limited by the technology and the network engineering rules.
Typical deployments have 32-64 homes per PON. Typical deployments have 32-64 homes per PON.
The motive behind BPON, GPON and XG-PON deployment is providing The motive behind BPON, GPON, and XG-PON deployment is to provide
triple-play services over IP: voice, video and data. Voice is triple-play services over IP: voice, video, and data. Voice is
generally low bandwidth but has low-delay, low-jitter, and low generally low bandwidth but has requirements for low delay, low
packet-loss requirements. Data services (e.g., Internet services) jitter, and low packet loss. Data services (e.g., Internet services)
often require high throughput and can tolerate medium latency. Data often require high throughput and can tolerate medium latency. Data
services may include multimedia content download such as video. services may include multimedia content download such as video.
However, in that case, the video content is not required to be real- 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 time, and/or it is low-quality video. Video services, on the other
hand, are targeted to deliver Standard Definition or High Definition hand, are targeted to deliver Standard Definition or High Definition
video content in real-time or near-real time, depending on the video content in real time or near real time, depending on the
service model. Standard Definition content using MPEG2 encoding service model. Standard Definition content using MPEG2 encoding
requires on the order of 3.75 Mbps per stream while High definition requires on the order of 3.75 Mbit/s per stream while High Definition
content using MPEG2 encoding requires on the order of 15-19 Mbps content using MPEG2 encoding requires 15-19 Mbit/s depending on the
depending on the level of compression used. Video services require level of compression used. Video services require low jitter and low
low-jitter and low-packet loss with low start-time latency. There are packet loss with low start-time latency. There are two types of
two types of video services: on demand and broadcast (known also as video services: on demand and broadcast (known also as linear
liner programming content). While linear programming content can be programming content). While linear programming content can be
provided over Layer1 on the PON, the focus in this document is on provided over Layer 1 on the PON, the focus in this document is on
delivering linear programming content over IP to the subscriber, delivering linear programming content over IP to the subscriber using
using IP multicast. Video on demand is also considered for delivery IP multicast. Video on Demand (VoD) is also considered for delivery
to the subscriber over IP using a unicast session model. to the subscriber over IP using a unicast session model.
Providing simultaneous triple-play services over IP with unicast Providing simultaneous triple-play services over IP with unicast
video and multicast video, VoIP and data requires an architecture video and multicast video, VoIP, and data requires an architecture
that preserves the quality of service of each service. Fundamental to that preserves the quality of service of each service. Fundamental
this architecture is ensuring that the video content (unicast and to this architecture is ensuring that the video content (unicast and
multicast) delivered to the subscriber does not exceed the bandwidth multicast) delivered to the subscriber does not exceed the bandwidth
allocated to the subscriber for video services. Architecture models allocated to the subscriber for video services. Architecture models
often ensure that data is guaranteed a minimum bandwidth and that often ensure that data is guaranteed a minimum bandwidth and that
VoIP is guaranteed its own bandwidth. In addition, QoS control across VoIP is guaranteed its own bandwidth. In addition, QoS control
services is often performed at a Network Access Server (NAS), often across services is often performed at a Network Access Server (NAS),
referred to as Broadband Network Gateway (BNG) for subscriber often referred to as Broadband Network Gateway (BNG) for subscriber
management, per subscriber and shared link resources. Efficient management, per subscriber and shared link resources. Efficient
multicast video services require enabling multicast services in the multicast video services require enabling multicast services in the
access network between the subscriber and the subscriber management access network between the subscriber and the subscriber management
platform. In the FTTP/B/C PON environment, this implies enabling IP platform. In the FTTP/B/C PON environment, this implies enabling IP
multicast on the Access Node (AN) complex composed of the Optical multicast on the ANX composed of the Optical Network Terminal (ONT)
Network Terminal (ONT) or Unit (ONU) and Optical Line Terminal (OLT), or Unit (ONU) and Optical Line Terminal (OLT), as applicable. This
as applicable. This is as opposed to Digital Subscriber Line (DSL) is as opposed to Digital Subscriber Line (DSL) deployments where
deployments where multicast is enabled on the DSL Access Multiplexer multicast is enabled on the DSL Access Multiplexer (DSLAM) only. The
(DSLAM) only. The focus in this document will be on the ANCP focus in this document will be on the ANCP requirements needed for
requirements needed for coordinated admission control of unicast and coordinated admission control of unicast and multicast video in
multicast video in FTTP/B/C PON environments between the AN complex FTTP/B/C PON environments between the ANX and the NAS, specifically
(ANX) and the NAS, specifically focusing on bandwidth dedicated for focusing on bandwidth dedicated for multicast and shared bandwidth
multicast and shared bandwidth between multicast and unicast. between multicast and unicast.
[RFC5851] provides the framework and requirements for coordinated [RFC5851] provides the framework and requirements for coordinated
admission control between a NAS and an AN with special focus on DSL admission control between a NAS and an AN with special focus on DSL
deployments. This document extends that framework and the related deployments. This document extends that framework and the related
requirements to explicitly address PON deployments. requirements to explicitly address PON deployments.
2. Terminology 2. Terminology
- PON (Passive Optical Network) [G.983.1][G.984.1]: a point-to- - PON (Passive Optical Network) [G.983.1][G.984.1]: a point-to-
multipoint fiber to the premises network architecture in which multipoint FTTP network architecture in which unpowered splitters
unpowered splitters are used to enable the splitting of an optical are used to enable the splitting of an optical signal from a
signal from a central office on a single optical fiber to multiple central office on a single optical fiber to multiple premises. Up
premises. Up to 32-128 may be supported on the same PON. A PON to 32-128 may be supported on the same PON. A PON configuration
configuration consists of an Optical Line Terminal (OLT) at the consists of an Optical Line Terminal (OLT) at the service
Service Provider's Central Office (CO) and a number of Optical provider's central office (CO) and a number of Optical Network
Network Units or Terminals (ONU/ONT) near end users, with an optical Units or Terminals (ONUs/ONTs) near end users, with an Optical
distribution network (ODN) composed of fibers and splitters between Distribution Network (ODN) composed of fibers and splitters
them. A PON configuration reduces the amount of fiber and CO between them. A PON configuration reduces the amount of fiber and
equipment required compared with point-to-point architectures. CO equipment required compared with point-to-point architectures.
- Access Node Complex (ANX): The Access Node Complex is composed of - Access Node Complex (ANX): composed of two geographically
two geographically separated functional elements OLT and ONU/ONT. The separated functional elements -- OLT and ONU/ONT. The general
general term Access Node Complex (ANX) will be used when describing a term Access Node Complex (ANX) will be used when describing a
functionality which does not depend on the physical location but functionality that does not depend on the physical location but
rather on the "black box" behavior of OLT and ONU/ONT. rather on the "black box" behavior of OLT and ONU/ONT.
-Optical Line Terminal (OLT): is located in the Service provider's - Optical Line Terminal (OLT): is located in the service provider's
central office (CO). It terminates and aggregates multiple PONs central office (CO). It terminates and aggregates multiple PONs
(providing fiber access to multiple premises or neighborhoods) on the (providing fiber access to multiple premises or neighborhoods) on
subscriber side, and interfaces with the Network Access server (NAS) the subscriber side and interfaces with the Network Access Server
that provides subscriber management. (NAS) that provides subscriber management.
- Optical Network Terminal (ONT): terminates PON on the network side - Optical Network Terminal (ONT): terminates PON on the network side
and provides PON adaptation. The subscriber side interface and the and provides PON adaptation. The subscriber side interface and
location of the ONT are dictated by the type of network deployment. the location of the ONT are dictated by the type of network
For a Fiber-to-the-Premise (FTTP) deployment (with Fiber all the way deployment. For an FTTP deployment (with fiber all the way to the
to the apartment or living unit), ONT has Ethernet (FE/GE/MoCA) apartment or living unit), ONT has Ethernet (Fast Ethernet (FE) /
connectivity with the Home Gateway (HGW)/Customer Premise Gigabit Ethernet (GE) / Multimedia over Coax Alliance (MoCA))
Equipment(CPE). In certain cases, one ONT may provide connections to connectivity with the Home Gateway (HGW) / Customer Premises
more than one Home Gateway at the same time. 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 - Optical Network Unit (ONU): a generic term denoting a device that
terminates any one of the distributed (leaf) endpoints of an Optical terminates any one of the distributed (leaf) endpoints of an
Distribution Node (ODN), implements a PON protocol, and adapts PON Optical Distribution Network (ODN), implements a PON protocol, and
PDUs to subscriber service interfaces. In case of an MDU multi- adapts PON PDUs to subscriber service interfaces. In the case of
dwelling or multi-tenant unit, a multi-subscriber ONU typically a multi-dwelling unit (MDU) or multi-tenant unit (MTU), a multi-
resides in the basement or a wiring closet (FTTB case), and has subscriber ONU typically resides in the basement or a wiring
FE/GE/Ethernet over native Ethernet link or over xDSL (typically closet (FTTB case) and has FE/GE/Ethernet over native Ethernet
VDSL) connectivity with each CPE at the subscriber premises. In the link or over xDSL (typically VDSL) connectivity with each CPE at
case where fiber is terminated outside the premises (neighborhood or the subscriber premises. In the case where fiber is terminated
curb side) on an ONT/ONU, the last-leg-premises connections could be outside the premises (neighborhood or curb side) on an ONT/ONU,
via existing or new Copper, with xDSL physical layer (typically the last-leg-premises connections could be via existing or new
VDSL). In this case, the ONU effectively is a "PON fed DSLAM". 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 - Network Access Server (NAS): network element that aggregates
subscriber traffic from a number of ANs or ANXs. The NAS is often an subscriber traffic from a number of ANs or ANXs. The NAS is often
injection point for policy management and IP QoS in the access an injection point for policy management and IP QoS in the access
network. It is also referred to as Broadband Network Gateway (BNG) or network. It is also referred to as Broadband Network Gateway
Broadband Remote Access Server (BRAS). (BNG) or Broadband Remote Access Server (BRAS).
-Home Gateway (HGW): Network element that connects subscriber devices - Home Gateway (HGW): network element that connects subscriber
to the AN or ANX and the access network. In case of xDSL, the Home devices to the AN or ANX and the access network. In the case of
Gateway is an xDSL network termination that could either operate as a xDSL, the Home Gateway is an xDSL network termination that could
Layer 2 bridge or as a Layer 3 router. In the latter case, such a either operate as a Layer 2 bridge or as a Layer 3 router. In the
device is also referred to as a Routing Gateway (RG). In the case of latter case, such a device is also referred to as a Routing
PON, it is often a Layer3 routing device with the ONT performing PON Gateway (RG). In the case of PON, it is often a Layer 3 routing
termination. device with the ONT performing PON termination.
-PON-Customer-ID: This is an identifier which uniquely identifies the - PON-Customer-ID: identifier that uniquely identifies the ANX and
ANX and the access loop logical port on the ANX to the subscriber the access loop logical port on the ANX to the subscriber
(customer) premises, and is used in any interaction between NAS and (customer) premises and is used in any interaction between NAS and
ANX that relates to access-loops. Logically it is composed of ANX that relates to access loops. Logically, it is composed of
information containing identification of the OLT (the OLT may be information containing identification of the OLT (the OLT may be
physically directly connected to the NAS), the PON port on the OLT, physically and directly connected to the NAS), the PON port on the
the ONT/ONU, and the port on the ONT/ONU connecting to the subscriber OLT, the ONT/ONU, and the port on the ONT/ONU connecting to the
HGW. When acting as a DHCP relay agent, the OLT can encode PON- subscriber HGW. When acting as a DHCP relay agent, the OLT can
Customer-ID in the "Agent-Circuit-Identifier" Sub-option in Option-82 encode PON-Customer-ID in the "Agent Circuit ID" sub-option in
of the DHCP messages [RFC3046]. Option 82 of the DHCP messages [RFC3046].
3. Motivation for explicit extension of ANCP to FTTx PON 3. Motivation for Explicit Extension of ANCP to FTTx PON
The fundamental difference between PON and DSL is that a PON is an The fundamental difference between PON and DSL is that a PON is an
optical broadcast network by definition. That is, at the PON level, optical broadcast network by definition. That is, at the PON level,
every ONT on the same PON sees the same signal. However, the ONT 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 filters only those PON frames addressed to it. Encryption is used on
the PON to prevent eavesdropping. the PON to prevent eavesdropping.
The broadcast PON capability is very suitable to delivering multicast The broadcast PON capability is very suitable for delivering
content to connected premises, maximizing bandwidth usage efficiency multicast content to connected premises, maximizing bandwidth usage
on the PON. Similar to DSL deployments, enabling multicast on the efficiency on the PON. Similar to DSL deployments, enabling
Access Node Complex (ANX) provides for bandwidth use efficiency on multicast on the Access Node Complex (ANX) provides for bandwidth use
the path between the Access Node and the NAS as well as improves the efficiency on the path between the Access Node and the NAS as well as
scalability of the NAS by reducing the amount of multicast traffic improves the scalability of the NAS by reducing the amount of
being replicated at the NAS. However, the broadcast capability on the multicast traffic being replicated at the NAS. However, the
PON enables the AN (OLT) to send one copy on the PON as opposed to broadcast capability on the PON enables the AN (OLT) to send one copy
one copy to each receiver on the PON. The PON multicast capability on the PON as opposed to one copy to each receiver on the PON. The
can be leveraged in the case of GPON and BPON as discussed in this PON multicast capability can be leveraged in the case of GPON and
document. BPON as discussed in this document.
Fundamental to leveraging the broadcast capability on the PON for Fundamental to leveraging the broadcast capability on the PON for
multicast delivery is the ability to assign a single encryption key multicast delivery is the ability to assign no key, a single
for all PON frames carrying all multicast channels or a key per set encryption key for all PON frames carrying all multicast channels, or
of multicast channels that correspond to service packages, or none. a key per set of multicast channels that correspond to a service
When supporting encryption for multicast channels, the encryption key package. When supporting encryption for multicast channels, the
is generated by the OLT and sent by the OLT to each targeted ONT via encryption key is generated by the OLT and sent by the OLT to each
the ONT Management and Control Interface (OMCI) as described in targeted ONT via the ONT Management and Control Interface (OMCI) as
section 15.5.2 of ITU-T G.987.3 [G.987.3] for XG-PON. It should be described in Section 15.5.2 of ITU-T G.987.3 [G.987.3] for XG-PON.
noted that the ONT can be a multi-Dwelling Unit (MDU) ONT with It should be noted that the ONT can be a multi-dwelling unit (MDU)
multiple Ethernet ports, each connected to a living unit. Thus, the ONT with multiple Ethernet ports, each connected to a living unit.
ONT must not only be able to receive a multicast frame, but must also Thus, the ONT must not only be able to receive a multicast frame but
be able to forward that frame only to the Ethernet port with must also be able to forward that frame only to the Ethernet port
receivers for the corresponding channel. with receivers for the corresponding channel.
In order to implement triple-play service delivery with necessary In order to implement triple-play service delivery with necessary
"quality-of-experience", including end-to-end bandwidth optimized "quality-of-experience", including end-to-end bandwidth optimized
multicast video delivery, there needs to be tight coordination multicast video delivery, there needs to be tight coordination
between the NAS and the ANX. This interaction needs to be near real- between the NAS and the ANX. This interaction needs to be near real-
time as services are requested via application or network level time as services are requested via application- or network-level
signaling by broadband subscribers. ANCP as defined in [RFC5851] for signaling by broadband subscribers. ANCP, as defined in [RFC5851]
DSL based networks is very suitable to realize a control protocol for DSL based networks, is very suitable to realize a control
(with transactional exchange capabilities), between PON enabled ANX protocol (with transactional exchange capabilities) between the PON-
and the NAS, and also between the components comprising the ANX, enabled ANX and the NAS and also between the components comprising
i.e., between OLT and the ONT. Typical use cases for ANCP in PON the ANX, i.e., between the OLT and the ONT. Typical use cases for
environment include the following: ANCP in the PON environment include the following:
- Access topology discovery - Access topology discovery
- Access Loop Configuration - Access loop configuration
- Multicast - Multicast
- Optimized multicast delivery - Optimized multicast delivery
- Unified video resource control - Unified video resource control
- NAS based provisioning of ANX - NAS-based provisioning of ANX
- Remote connectivity check - Remote connectivity check
4. Reference Model for PON Based Broadband Access Network 4. Reference Model for PON-Based Broadband Access Network
An overall end-to-end reference architecture of a PON 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, is depicted in Figures 1 and 2 with ONT serving a single HGW, and
and ONT/ONU serving multiples HGWs, respectively. An OLT may provide 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 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 same PON port. Specifically, the following PON cases are addressed
the context of this reference architecture: in the context of this reference architecture:
- BPON with Ethernet uplink to the NAS and ATM on the PON - BPON with Ethernet uplink to the NAS and ATM on the PON side
side. - GPON/XG-PON with Ethernet uplink to the NAS and Ethernet on the
- GPON/XG-PON with Ethernet uplink to the NAS and Ethernet on PON side
the PON side
In case of an Ethernet aggregation network that supports new QoS- In the case of an Ethernet aggregation network that supports new QoS-
enabled IP services (including Ethernet multicast replication), the enabled IP services (including Ethernet multicast replication), the
architecture builds on the reference architecture specified in the architecture builds on the reference architecture specified in the
Broadband Forum (BBF) [TR-101]. The Ethernet aggregation network Broadband Forum (BBF) [TR-101]. The Ethernet aggregation network
between a NAS and an OLT may be degenerated to one or more direct between a NAS and an OLT may be degenerated to one or more direct
physical Ethernet links. physical Ethernet links.
Given the industry move towards Ethernet as the new access and Given the industry move towards Ethernet as the new access and
aggregation technology for triple play services, the primary focus aggregation technology for triple-play services, the primary focus
throughout this document is on GPON/XG-PON and BPON with Ethernet throughout this document is on GPON/XG-PON and BPON with Ethernet
between the NAS and the OLT. between the NAS and the OLT.
Access Customer Access Customer
<---------Aggregation-------><-Prem-> <---------Aggregation-------><-Prem->
Network Network Network Network
+------------------+ +------------------+
| Access Node | | Access Node |
| Complex (ANX) | | Complex (ANX) |
+---------+ +---+ +-----+ |+---+ +---+ | +---+ +---------+ +---+ +-----+ |+---+ +---+ | +---+
| | +-|NAS|--|Eth |--||OLT|-<PON>-|ONT|-|--|HGW| | | +-|NAS|--|Eth |--||OLT|-<PON>-|ONT|-|--|HGW|
NSP---+Regional | | +---+ |Agg | |+---+ +---+ | +---+ NSP---+Regional | | +---+ |Agg | |+---+ +---+ | +---+
|Broadband| | +---+ +-----+ +------------------+ |Broadband| | +---+ +-----+ +------------------+
|Network |-+-|NAS| | |Network |-+-|NAS| |
ASP---+ | | +---+ | ASP---+ | | +---+ |
| | | +---+ | | | | +---+ |
+---------+ +-|NAS| | +---+ +---+ +---------+ +-|NAS| | +---+ +---+
+---| +-<PON>-|ONT|--|HGW| +---| +-<PON>-|ONT|--|HGW|
| +---+ +---+ | +---+ +---+
| |
| +---+ +---+ | +---+ +---+
+---|ONT|--|HGW| +---|ONT|--|HGW|
+---+ +---+ +---+ +---+
HGW : Home Gateway HGW : Home Gateway
NAS : Network Access Server NAS : Network Access Server
PON : Passive Optical Network PON : Passive Optical Network
OLT : Optical Line Terminal OLT : Optical Line Terminal
ONT : Optical Network Terminal ONT : Optical Network Terminal
Figure 1: Access Network with PON. Figure 1: Access Network with PON
FE/GE/VDSL
+---+ +---+
+----------------+ | |-|HGW|
+---------+ +-----+ | +-----+ +----+| | | +---+
| | +-|NAS |--| |Eth |--|OLT||-<PON>- | |
NSP---+Regional | | +-----+ | |Agg | | || | |ONT| +---+
|Broadband| | | | | | || | | or|-|HGW|
|Network | | +-----+ | +-----+ +----+| | |ONU| +---+
| |-+-|NAS | +----------------+ | | |
ASP---+ | | +-----+ | | | +---+
| | | +-----+ | | |-|HGW|
+---------+ +-|NAS | | +---+ +---+
+-----+ |
| +---+ +---+
+-|ONT|-|HGW|
+---+ +---+
FE/GE/VDSL Figure 2: FTTP/FTTB/C with Multi-Subscriber ONT/ONU Serving MTUs/MDUs
+---+ +---+
+----------------+ | |-|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. The following sections describe the functional blocks and network
The following sections describe the functional blocks and network segments in the PON access reference architecture.
segments in the PON access reference architecture.
4.1. Functional Blocks 4.1. Functional Blocks
4.1.1. Home Gateway 4.1.1. Home Gateway
The Home Gateway (HGW) connects the different Customer Premises The Home Gateway (HGW) connects the different CPEs to the ANX and the
Equipment (CPE) to the ANX and the access network. In case of PON, access network. In the case of PON, the HGW is a Layer 3 router. In
the HGW is a layer 3 router. In this case, the HGW performs IP this case, the HGW performs IP configuration of devices within the
configuration of devices within the home via DHCP, and performs home via DHCP and performs Network Address and Port Translation
Network Address and Port Translation (NAPT) between the LAN and WAN (NAPT) between the LAN and WAN side. In the case of FTTP/B/C, the
side. In case of FTTP/B/C, the HGW connects to the ONT/ONU over an HGW connects to the ONT/ONU over an Ethernet interface. That
Ethernet interface. That Ethernet interface could be over an Ethernet Ethernet interface could be over an Ethernet physical port or over
physical port or over another medium. In case of FTTP, it is possible another medium. In the case of FTTP, it is possible to have a single
to have a single box GPON CPE solution, where the ONT encompasses the box GPON CPE solution where the ONT encompasses the HGW functionality
HGW functionality as well as the GPON adaptation function. as well as the GPON adaptation function.
4.1.2. PON Access 4.1.2. PON Access
PON access is composed of the ONT/ONU and OLT. PON ensures PON access is composed of the ONT/ONU and OLT. PON ensures physical
physical connectivity between the ONT/ONU at the customer connectivity between the ONT/ONU at the customer premises and the
premises and the OLT. PON framing can be BPON (in case of BPON) OLT. PON framing can be BPON or GPON. The protocol encapsulation on
or GPON (in case of GPON). The protocol encapsulation on BPON is BPON is based on multi-protocol encapsulation over ATM Adaptation
based on multi-protocol encapsulation over AAL5, defined in Layer 5 (AAL5), defined in [RFC2684]. This covers PPP over Ethernet
[RFC2684]. This covers PPP over Ethernet (PPPoE, defined in (PPPoE, defined in [RFC2516]) or IP over Ethernet (IPoE). The
[RFC2516]), or bridged IP (IPoE). The protocol encapsulation on protocol encapsulation on GPON is always IPoE. In all cases, the
GPON is always IPoE. In all cases, the connection between the AN connection between the AN (OLT) and the NAS (or BNG) is assumed to be
(OLT) and the NAS (or BNG) is assumed to be Ethernet in this Ethernet in this document.
document.
4.1.3. Access Node Complex 4.1.3. Access Node Complex
This is composed of OLT and ONT/ONU and is defined in section 2. The Access Node Complex (ANX) is composed of OLT and ONT/ONU and is
defined in Section 2.
4.1.4. Access Node Complex Uplink to the NAS 4.1.4. Access Node Complex Uplink to the NAS
The ANX uplink connects the OLT to the NAS. The fundamental The ANX uplink connects the OLT to the NAS. The fundamental
requirements for the ANX uplink are to provide traffic aggregation, requirements for the ANX uplink are to provide traffic aggregation,
Class of Service distinction and customer separation and Class of Service distinction, customer separation, and traceability.
traceability. This can be achieved using an ATM or an Ethernet based This can be achieved using an ATM or an Ethernet-based technology.
technology. The focus in this document is on Ethernet as stated As stated earlier, the focus in this document is on Ethernet.
earlier.
4.1.5. Aggregation Network 4.1.5. Aggregation Network
The aggregation network provides traffic aggregation towards the NAS. The aggregation network provides traffic aggregation towards the NAS.
The Aggregation network is assumed to be Ethernet in this document. The aggregation network is assumed to be Ethernet in this document.
4.1.6. Network Access Server 4.1.6. Network Access Server
The NAS is a network device which aggregates multiplexed Subscriber The NAS is a network device that aggregates multiplexed subscriber
traffic from a number of ANXs. The NAS plays a central role in per- 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 subscriber policy enforcement and QoS. It is often referred to as a
Broadband Network Gateway (BNG) or Broadband Remote Access Server Broadband Network Gateway (BNG) or Broadband Remote Access Server
(BRAS). A detailed definition of the NAS is given in [RFC2881]. The (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 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 Q-in-Q Ethernet interfaces and towards the Regional Network by means
of transport interfaces (e.g., GigE, PPP over SONET). The NAS of transport interfaces (e.g., GigE, PPP over Synchronous Optical
functionality corresponds to the BNG functionality described in Network (SONET)). The NAS functionality corresponds to the BNG
BroadBand Forum (BBF) TR-101 [TR-101]. In addition, the NAS supports functionality described in BBF TR-101 [TR-101]. In addition, the NAS
the Access Node Control functionality defined for the respective use supports the Access Node Control functionality defined for the
cases in this document. respective use cases in this document.
4.1.7. Regional Network 4.1.7. Regional Network
The Regional Network connects one or more NAS and associated Access The Regional Network connects one or more NASs and associated access
Networks to Network Service Providers (NSPs) and Application Service networks to Network Service Providers (NSPs) and Application Service
Providers (ASPs). The NSP authenticates access and provides and Providers (ASPs). The NSP authenticates access and provides and
manages the IP address to Subscribers. It is responsible for overall manages the IP address to subscribers. It is responsible for overall
service assurance and includes Internet Service Providers (ISPs). The service assurance and includes Internet Service Providers (ISPs).
ASP provides application services to the application Subscriber The ASP provides application services to the application subscriber
(gaming, video, content on demand, IP telephony, etc.). The NAS can (gaming, video, content on demand, IP telephony, etc.). The NAS can
be part of the NSP network. Similarly, the NSP can be the ASP. be part of the NSP network. Similarly, the NSP can be the ASP.
4.2. Access Node Complex Control Reference Architecture Options 4.2. Access Node Complex Control Reference Architecture Options
Section 3 details the differences between xDSL access and PON access Section 3 details the differences between xDSL access and PON access
and the implication of these differences on DSLAM control vs. OLT and and the implication of these differences on DSLAM control versus OLT
ONT/ONU (access node complex (ANX)) control. The following sections and ONT/ONU (ANX) control. The following sections describe two
describe two reference models: (1) ANCP+OMCI ANX control, and (2) reference models: (1) ANCP+OMCI ANX control and (2) All-ANCP ANX
all-ANCP ANX control. That is, the two models differ in the ONT/ONU control. That is, the two models differ in the ONT/ONU control
control within the ANX. Implementations, out of the scope of this within the ANX. Choosing which model to implement may be based on
document, may choose to implement one or the other based on the the ONT/ONU type and the capabilities of the ONT/ONU and OLT; this is
ONT/ONU type and the capabilities of the ONT/ONU and OLT. It is an implementation-specific decision that is outside the scope of this
possible for an OLT or an OLT PON port to connect to ONTs/ONUs with document. It is possible for an OLT or an OLT PON port to connect to
different capabilities and for these two models to co-exist on the ONTs/ONUs with different capabilities and for these two models to co-
same OLT and same PON. Section 12 describes the differences between exist on the same OLT and same PON. Section 12 describes the
OMCI and ANCP in controlling the ONU/ONT. differences between OMCI and ANCP in controlling the ONU/ONT.
OMCI is designed as a protocol between the OLT and ONT/ONU. It OMCI is designed as a protocol between the OLT and ONT/ONU. It
enables the OLT to configure and administer capabilities on the enables the OLT to configure and administer capabilities on the
ONT/ONU in BPON, GPON and XG-PON. ANCP is designed as a protocol ONT/ONU in BPON, GPON, and XG-PON. ANCP is designed as a protocol
between the NAS and access node. It enables the NAS to enforce between the NAS and Access Node. Among other functions, it enables
dynamic policies on the access node, and the access node to report the NAS to enforce dynamic policies on the Access Node and the Access
events to the NAS among other functions. Node to report events to the NAS.
4.2.1. ANCP+OMCI ANX Control 4.2.1. ANCP+OMCI ANX Control
Figure 3 depicts the reference model for ANCP+OMCI ANX control. In 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 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 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 communicates with the ANX via ANCP. The OLT acts as an ANCP/OMCI
gateway for communicating necessary events and policies between the gateway for communicating necessary events and policies between the
OLT and ONT/ONU within the ANX and for communicating relevant OLT and ONT/ONU within the ANX and for communicating relevant
policies and events between the ONT/ONU and the NAS. The policies and events between the ONT/ONU and the NAS. The
functionality performed by the OLT as ANCP/OMCI gateway will be functionality performed by the OLT as an ANCP/OMCI gateway will be
application dependent (e.g., multicast control, topology discovery) application dependent (e.g., multicast control, topology discovery)
and should be specified in a related specification. It should be and should be specified in a related specification. It should be
noted that some applications are expected to require ANCP and/or OMCI noted that some applications are expected to require ANCP and/or OMCI
extensions to map messages between OMCI and ANCP. OMCI extensions are extensions to map messages between OMCI and ANCP. OMCI extensions
likely to be defined by the ITU-T. It should also be noted that OMCI, are likely to be defined by the ITU-T. It should also be noted that
in addition to configuration and administration, provides the in addition to configuration and administration, OMCI provides the
capability to report status changes on an ONT/ONU with AVC (Attribute capability to report status changes on an ONT/ONU with AVC (Attribute
Value Change) notifications. When ONT/ONU's DSL or Ethernet UNI Value Change) notifications. When the ONT/ONU's DSL or Ethernet
attributes change, a related ME (management Entity) will send a User-Network Interface (UNI) attributes change, a related Management
corresponding notification (AVC) to the OLT. The OLT interworks such Entity will send a corresponding notification (AVC) to the OLT. The
notification into an ANCP report and sends it to the connected NAS OLT interworks such a notification into an ANCP report and sends it
via the ANCP session between the OLT and the NAS. As the ANCP report to the connected NAS via the ANCP session between the OLT and the
contains information of ONT/ONU's UNI and OLT's PON port, NAS can NAS. As the ANCP report contains information of ONT/ONU's UNI and
obtain accurate information of access topology. 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 | ANX |
PON: Passive Optical Network +---------+ +---+ +---+ |+---+ +-------+ | +---+
OLT: Optical Line Terminal | | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT|-|-|HGW|
ONT: Optical Network Terminal NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+
ONU: Optical Network Unit |Broadband| | +---+ +---+ +----------------------+
|Network |-+-|NAS| |
ASP---+ | | +---+ |
| | | +---+ |
+---------+ +-|NAS| | +-------+ +---+
+---| +-<PON>-|ONU/ONT|-|HGW|
| +-------+ +---+
| +---+ +---+
+--|ONT|-----|HGW|
+---+ +---+
ANCP OMCI
+<--------------->+<----------->+
Figure 3: Access Network with single ANCP+OMCI access control HGW: Home Gateway
NAS: Network Access Server
PON: Passive Optical Network
OLT: Optical Line Terminal
ONT: Optical Network Terminal
ONU: Optical Network Unit
4.2.2. All-ANCP ANX Control Figure 3: Access Network with Single ANCP+OMCI Control
Figure 4 depicts the All-ANCP ANX control reference model. In this 4.2.2. All-ANCP ANX Control
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.
+----------------------+ Figure 4 depicts the All-ANCP ANX control reference model. In this
| Access Node Complex | model, an ANCP session is enabled between a NAS and a connected OLT,
| (ANX) | and another ANCP session is enabled between the OLT and a connected
+---------+ +---+ +---+ |+---+ +-------+ | +---+ ONT/ONU. ANCP enables communication of policies and events between
| | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT| |--|HGW| the OLT and the ANX. The OLT acts as a gateway to relay policies and
NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+ events between the NAS and ONT/ONU within the ANX in addition to
|Broadband| | +---+ +---+ +----------------------+ communicating policies and events between the OLT and ONT/ONU. It
|Network |-+-|NAS| | should be noted that in this model, OMCI (not shown) is expected to
ASP---+ | | +---+ | be simultaneously enabled between the ONT and OLT, supporting
| | | +---+ | existing OMCI capabilities and applications on the PON, independent
+---------+ +-|NAS| | +-------+ +---+ of ANCP or applications intended to be supported by ANCP.
+---| +-<PON>-|ONU/ONT|--|HGW|
| +-------+ +---+
|
| +-------+ +---+
+---|ONU/ONT|--|HGW|
+-------+ +---+
ANCP 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|
+-------+ +---+
HGW: Home Gateway ANCP ANCP
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 HGW: Home Gateway
NAS: Network Access Server
PON: Passive Optical Network
OLT: Optical Line Terminal
ONT: Optical Network Terminal
ONU: Optical Network Unit
5. Concept of Access Node Control Mechanism for PON Based Access Figure 4: All-ANCP ANX Control Reference Model
The high-level communication framework for an Access Node Control 5. Concept of Access Node Control Mechanism for PON-Based Access
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
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 The high-level communication framework for an Access Node Control
controller function that requires the information for executing local Mechanism is shown in Figure 5 for the All-ANCP ANX control model.
functions. The enforcement function can be contacted by the The Access Node Control Mechanism defines a quasi-real-time, general-
controller function to enforce a specific policy or trigger a local purpose method for multiple network scenarios with an extensible
action. The messages shown in Figure 5 show the conceptual message communication scheme, addressing the different use cases that are
flow. The actual use of these flows, and the times or frequencies described in the sections that follow. The Access Node Control
when these messages are generated depend on the actual use cases, Mechanism is also extended to run between OLT and ONT/ONU. The
which are described in later sections. mechanism consists of a controller function and a reporting and/or
enforcement function. The 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
| Policy | +----+ controller function that requires the information for executing local
| Server | +--<PON>---|ONT |------- HGW functions. The enforcement function can be contacted by the
+--------+ + +----+ +---+ controller function to enforce a specific policy or trigger a local
| + +----------|ONT|----HGW 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.
|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
<------------------------------------------------------>
Figure 5: Conceptual message flow for Access Node Control mechanism +--------+
in all-ANCP ANX control model. | 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
<------------------------------------------------------>
As discussed previously, in different PON deployment scenarios, ANCP Figure 5: Conceptual Message Flow for Access Node Control Mechanism
may be used in variant ways and may interwork with other protocols, in All-ANCP ANX Control Model
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.
+--------+ As discussed previously, in different PON deployment scenarios, ANCP
| Policy | may be used in variant ways and may interwork with other protocols,
| Server | e.g., OMCI. In the ANCP+OMCI control model described earlier, the
+--------+ +---+ +---+ NAS maintains ANCP adjacency with the OLT while the OLT controls the
| +---- |ONT|--------|HGW| 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.
|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 +--------+
<-------------------------------------------------------> | 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)
<--------------------><-------------------->
Figure 6: Conceptual Message Flow for ANCP+OMCI ANX control model. PPP, DHCP, IP
<------------------------------------------------------->
6. Multicast Figure 6: Conceptual Message Flow for ANCP+OMCI ANX Control Model
With the rise of supporting IPTV services in a resource-efficient 6. Multicast
way, multicast services are becoming increasingly important.
In order to gain bandwidth optimization with multicast, the With the rise of supporting IPTV services in a resource-efficient
replication of multicast content per access-loop needs to be way, multicast services are becoming increasingly important.
distributed to the ANX. This can be done by ANX (OLT and ONT/ONU)
becoming multicast aware by implementing an IGMP [RFC3376]
snooping and/or proxy function [RFC4605]. 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 In order to gain bandwidth optimization with multicast, the
subscriber to communicate the IGMP "join/leave" messages with the replication of multicast content per access loop needs to be
NAS, while the ANX is being transparent to these messages. In this distributed to the ANX. This can be done by ANX (OLT and ONT/ONU)
scenario, the NAS can use ANCP to create replication state in the ANX becoming multicast aware by implementing an IGMP [RFC3376] snooping
for efficient multicast replication. The NAS sends a single copy of and/or proxy function [RFC4605]. The replication thus needs to be
the multicast stream towards the ANX. The NAS can perform network- distributed between NAS, aggregation nodes, and ANX. In the case of
based conditional access and multicast admission control on multicast GPON and in the case of BPON with Ethernet uplink, this is very
joins, and create replication state in the ANX if the request is viable. By introducing IGMP processing on the ANX and aggregation
admitted by the NAS. 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.
The following sections describe various use cases related to An alternative to multicast awareness in the ANX is for the
multicast. 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.
6.1. Multicast Conditional Access The following sections describe various use cases related to
multicast.
In a Broadband FTTP/B/C access scenario, Service Providers may want 6.1. Multicast Conditional Access
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.
Where network-based channel conditional access is desired, there are In a broadband FTTP/B/C access scenario, service providers may want
two approaches. It can be done on the NAS along with bandwidth-based to dynamically control, at the network level, access to some
admission control. The NAS can control the replication state on the multicast flows on a per user basis. This may be used in order to
ANX based on the outcome of access and bandwidth based admission differentiate among multiple Service Offers or to realize/reinforce
control. This is covered in a later section. The other approach is to conditional access based on customer subscription. Note that, in
provision the necessary conditional access information on the ANX some environments, application-layer conditional access by means of
(ONT/ONU and/or OLT) so the ANX can perform the conditional access Digital Rights Management (DRM), for instance, may provide sufficient
decisions autonomously. For these cases, the NAS can use ANCP to control so that network-based multicast conditional access may not be
provision black and white lists as defined in [RFC5851] on the ANX so needed. However, network-level access control may add to the service
that the ANX can decide locally to honor a join or not. It should be security by preventing the subscriber from receiving a non-subscribed
noted that in the PON case, the ANX is composed of the ONT/ONU and channel. In addition, it enhances network security by preventing a
OLT. Thus, this information can be programmed on the ONT/ONU and/or multicast stream from being sent on a link or a PON based on a non-
OLT. Programming this information on the ONT/ONU prevents subscriber request.
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 Where network-based channel conditional access is desired, there are
channel access list, the ONT/ONU will first check if the requested two approaches. First, it can be done on the NAS along with
multicast channel is part of a White list or a Black list associated bandwidth-based admission control. The NAS can control the
with the access port on which the IGMP join is received. If the replication state on the ANX based on the outcome of access and
channel is part of a White list, the ONT/ONU will pass the join bandwidth-based admission control. This is covered in a later
request upstream towards the NAS. The ONT/ONU must not start section. A second approach is to provision the necessary conditional
replicating the associated multicast stream to the access port if access information on the ANX (ONT/ONU and/or OLT) so the ANX can
such a stream is received until it gets confirmation that it can do perform the conditional access decisions autonomously. For these
so from the upstream node (NAS or OLT). Passing the channel access cases, the NAS can use ANCP to provision black and white lists as
list is one of the admission control criteria whereas bandwidth-based defined in [RFC5851] on the ANX so that the ANX can decide locally to
admission control is another. If the channel is part of a Black list, honor a join or not. It should be noted that in the PON case, the
the ONT/ONU can autonomously discard the message because the channel ANX is composed of the ONT/ONU and OLT. Thus, this information can
is not authorized for that subscriber. 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 of this document, 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.
The ONT/ONU, in addition to forwarding the IGMP join, sends an ANCP If the ONT/ONU performs IGMP snooping and is programmed with a
admission request to the OLT identifying the channel to be joined and channel access list, the ONT/ONU will first check if the requested
the premises. Premises identification to the OLT can be based on a multicast channel is part of a white list or a black list associated
Customer-Port-ID that maps to the access port on the ONT/ONU and with the Access Port on which the IGMP join is received. If the
known at the ONT/ONU and OLT. If the ONT/ONU has a white list and/or channel is part of a white list, the ONT/ONU will pass the join
a black list per premises, the OLT need not have such a list. If the request upstream towards the NAS. The ONT/ONU must not start
ONT/ONU does not have such a list, the OLT may be programmed with replicating the associated multicast stream to the Access Port if
such a list for each premises. In this latter case, the OLT would such a stream is received until it gets confirmation that it can do
perform the actions described earlier on the ONT/ONU. Once the so from the upstream node (NAS or OLT). Passing the channel access
outcome of admission control (conditional access and bandwidth based list is one of the admission control criteria whereas bandwidth-based
admission control) is determined by the OLT (either by interacting admission control is another. If the channel is part of a black
with the NAS or locally), it is informed to the ONT/ONU. OLT list, the ONT/ONU can autonomously discard the message because the
Bandwidth based admission control scenarios are defined in a later channel is not authorized for that subscriber.
section.
The White List and Black List can contain entries allowing: 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 is
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 the 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
bandwidth-based admission control scenarios are defined in a later
section.
- An exact match for a (*,G) Any Source Multicast (ASM) group The white list and black list can contain entries allowing:
(e.g., <G=g.h.i.l>);
- An exact match for a (S,G) Source Specific Multicast - An exact match for a (*,G) Any-Source Multicast (ASM) group (e.g.,
(SSM)channel (e.g., <S=s.t.u.v,G=g.h.i.l>); <G=g.h.i.l>)
- A mask-based range match for a (*,G) ASM group (e.g., - An exact match for a (S,G) Source-Specific Multicast (SSM) channel
<G=g.h.i.l/Mask>); (e.g., <S=s.t.u.v,G=g.h.i.l>)
- A mask-based range match for a (S,G) SSM channel (e.g., - A mask-based range match for a (*,G) ASM group (e.g.,
<S=s.t.u.v,G=g.h.i.l/Mask>); <G=g.h.i.l/Mask>)
The use of a White list and Black list may be applicable, for - A mask-based range match for a (S,G) SSM channel (e.g.,
instance, to regular IPTV services (i.e., Broadcast TV) offered by an <S=s.t.u.v,G=g.h.i.l/Mask>)
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 The use of a white list and black list may be applicable, for
NAS can be programmed with these access lists. Having these access instance, to regular IPTV services (i.e., Broadcast TV) offered by an
lists on the ONT/ONU prevents forwarding of unauthorized joins to the Access Provider to broadband (e.g., FTTP) subscribers. For this
OLT or NAS, reducing unnecessary control load on these network application, the IPTV subscription is typically bound to a specific
elements. Similarly, performing the access control at the OLT instead FTTP home, and the multicast channels that are part of the
of the NAS, if not performed on the ONT/ONU, will reduce unnecessary subscription are well-known beforehand. Furthermore, changes to the
control load on the NAS. 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.
6.2. Multicast Admission Control 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.
The successful delivery of Triple Play Broadband services is quickly 6.2. Multicast Admission Control
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
operate at a fixed bandwidth, which cannot be dynamically adjusted to
the currently available bandwidth.
An Admission Control (AC) mechanism covering admission of multicast The successful delivery of triple-play broadband services is quickly
traffic for the FTTP/B/C access is required in order to avoid over- becoming a big capacity-planning challenge for most of the service
subscribing the available bandwidth and negatively impacting the end- providers nowadays. Solely increasing available bandwidth is not
user experience. Before honoring a user request to join a new always practical, cost-economical, and/or sufficient to satisfy end-
multicast flow, the combination of ANX and NAS must ensure admission user experience given not only the strict QoS requirements of unicast
control is performed to validate that there is enough video bandwidth applications like VoIP and Video on Demand but also the fast growth
remaining on the PON, and on the uplink between the OLT and NAS to of multicast interactive applications such as "video conferencing",
carry the new flow (in addition to all other existing multicast and digital TV, and digital audio. These applications typically require
unicast video traffic) and that there is enough video bandwidth for low delay, low jitter, low packet loss, and high bandwidth. These
the subscriber to carry that flow. The solution needs to cope with applications are also typically "non-elastic", which means that they
multiple flows per premises and needs to allow bandwidth to be operate at a fixed bandwidth that cannot be dynamically adjusted to
dynamically shared across multicast and unicast video traffic per the currently available bandwidth.
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 An Admission Control (AC) Mechanism covering admission of multicast
including the shared unicast and multicast bandwidth. Thus, traffic for the FTTP/B/C access is required in order to avoid over-
supporting admission control requires some form of synchronization subscribing the available bandwidth and negatively impacting the end-
between the entities performing multicast AC (e.g., the ANX and/or user experience. Before honoring a user request to join a new
NAS), the entity performing unicast AC (e.g., the NAS or a Policy multicast flow, the combination of ANX and NAS must ensure admission
Server), and the entity actually enforcing the multicast replication control is performed to validate that there is enough video bandwidth
(i.e., the NAS and the ANX). This synchronization can be achieved in remaining on the PON and on the uplink between the OLT and NAS to
a number of ways: 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.
- One approach is for the NAS to perform bandwidth based The focus in this document is on multicast-allocated bandwidth
admission control on all multicast video traffic and unicast including the shared unicast and multicast bandwidth. Thus,
video traffic that requires using the shared bandwidth with supporting admission control requires some form of synchronization
multicast. Based on the outcome of admission control, NAS then between the entities performing multicast AC (e.g., the ANX and/or
controls the replication state on the ANX. The subscriber NAS), the entity performing unicast AC (e.g., the NAS or a policy
generates an IGMP join for the desired stream on its logical server), and the entity actually enforcing the multicast replication
connection to the NAS. The NAS terminates the IGMP message, and (i.e., the NAS and the ANX). This synchronization can be achieved in
performs conditional access and bandwidth based admission a number of ways.
control on the IGMP request. The bandwidth admission control is
performed against the following:
1. Available video bandwidth on the link to OLT 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 and performs conditional access and bandwidth-based
admission control on the IGMP request. The bandwidth admission
control is performed against the following:
2. Available video bandwidth on the PON interface 1. Available video bandwidth on the link to OLT
3. Available video bandwidth on the last mile (access-port on 2. Available video bandwidth on the PON interface
the ONT/ONU).
The NAS can locally maintain and track video bandwidth it manages for 3. Available video bandwidth on the last mile (Access Port on the
all the three levels mentioned above. The NAS can maintain ONT/ONU)
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 NAS can locally maintain and track video bandwidth it manages for
The video bandwidth is also consumed by any unicast video being all the three levels mentioned above. The NAS can maintain
delivered to the CPE. NAS can perform video bandwidth accounting and identifiers corresponding to the PON interface and the last mile
control on both IGMP messages and on requests for unicast video (customer interface). It also maintains a channel map, associating
streams when either all unicast admission control is done by the NAS every channel (or a group of channels sharing the same bandwidth
or an external policy server makes a request to the NAS for using requirement) with a data rate. For instance, in the case of 1:1 VLAN
shared bandwidth with multicast as described later in the document. 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 the 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 the
"Agent Circuit ID" sub-option in DHCP messages.
This particular scenario assumes the NAS is aware of the bandwidth on The NAS can perform bandwidth accounting on received IGMP messages.
the PON, and under all conditions can track the changes in available The video bandwidth is also consumed by any unicast video being
bandwidth on the PON. On receiving an IGMP Join message, NAS will delivered to the CPE. NAS can perform video bandwidth accounting and
perform bandwidth check on the subscriber bandwidth. If this passes, control on both IGMP messages and on requests for unicast video
and the stream is already being forwarded on the PON by the OLT streams when either all unicast admission control is done by the NAS
(which also means that it is already forwarded by the NAS to the or an external policy server makes a request to the NAS for using
OLT), NAS will admit the JOIN, update the available subscriber shared bandwidth with multicast as described later in the document.
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 are 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 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.
+----+ This particular scenario assumes the NAS is aware of the bandwidth on
+---<PON>---------- |ONT |------ HGW the PON and can track the changes in available bandwidth on the PON
+ +----+ under all conditions. On receiving an IGMP join message, NAS will
+ +----+ perform bandwidth check on the subscriber bandwidth. If this passes
+ +--------- |ONT |------ HGW 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
|NAS |---------------| |------<PON> OLT), NAS will admit the join, update the available subscriber
| |<------------->| | + +-----+ bandwidth, and transmit an ANCP message to the OLT and in turn to the
+----+ ANCP |OLT | +--------- | |----- HGW 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
| | |<------------------>| ONU |------HGW check the available bandwidth on the PON, and if it is not already
| +----+ ANCP | | +---+ being replicated to the OLT, it will check the bandwidth on the link
| | | |-----|HGW| towards the OLT. If this passes, the available PON bandwidth and the
| | +-----+ +---+ bandwidth on the link towards the OLT are updated. The NAS adds the
| 1.IGMP JOIN(S/*,G) | | 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
2.| | | | 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
[Access Control & ] | | ONT/ONU to add or update its replication state with the customer port
[Subscriber B/W ] | | for that channel. The interaction between ANX and NAS is shown in
[PON B/W & OLT link B/W ] | | Figures 7 and 8. For unicast video streams, application-level
[based Admission Control] | | 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 to request the
|-------------------> | | | bandwidth for the unicast video flow if it needs to use shared
3.ANCP Replication-Start| | | bandwidth with multicast. If the bandwidth is available, NAS will
(<S/*,G> or Multicast | | | reserve the bandwidth; update the bandwidth pools for subscriber
|MAC,Customer-Port-ID>| --------------------> | | bandwidth, the PON bandwidth, and the bandwidth on the link towards
| |4.ANCP Replication-Start | the OLT; and send a response to the policy server, which is
| (<S/*,G> or Multicast MAC,Customer-Port-ID) propagated back to the application server to start streaming.
|-------------------> | | | Otherwise, the request is rejected.
|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
orwarded on |
Customer-Port by|
|ONT/OLT. |
| |
Figure 7: Interactions for NAS based Multicast Admission Control (no +----+
IGMP processing on ANX, and NAS maintains available video bandwidth +---<PON>---------- |ONT |------ HGW
for PON) upon channel join. + +----+
+ +----+
+ +--------- |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
+---<PON>---------- |ONT |----- HGW (No IGMP Processing on ANX and NAS Maintains Available Video
+ +----+ Bandwidth for PON) upon Channel Join
+ +----+ +----+
+ +--------- |ONT |----- HGW +---<PON>---------- |ONT |----- HGW
+----+ +----+ + +----+ + +----+
|NAS |---------------| |------<PON> + +----+
| |<------------->| | + +-----+ + +--------- |ONT |----- HGW
+----+ ANCP |OLT | +--------- | |---- HGW +----+ +----+ + +----+
| | | | | |NAS |---------------| |------<PON>
| | |<------------------>| ONU |-----HGW | |<------------->| | + +-----+
| +----+ ANCP | | +---+ +----+ ANCP |OLT | +--------- | |---- HGW
| | | |-----|HGW| | | | | |
| | +-----+ +---+ | | |<------------------>| ONU |-----HGW
| | | | | +----+ ANCP | | +---+
| IGMP LEAVE(S/*,G) | | | | | |-----|HGW|
|<-----------------------------------------------------------| | | +-----+ +---+
| | | | | | | |
+====================+ | | | | IGMP leave (S/*,G) | |
[Admission Control ] | | | |<-----------------------------------------------------------|
[<Resource Released> ] | | | | | | |
+====================+ | | | +====================+ | | |
| | | | [Admission Control ] | | |
| | | | [<Resource Released> ] | | |
| | | | +====================+ | | |
|-------------------> | | | | | | |
ANCP Replication-Stop | | | | | | |
(<S/*,G> or Multicast MAC,Customer-Port-ID) | | | | | |
| | | | |-------------------> | | |
| |---------------------> | | ANCP Replication-Stop | | |
| | ANCP Replication-Stop | | (<S/*,G> or Multicast MAC,Customer-Port-ID) | |
(<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 Figure 8: Interactions for NAS-Based Multicast Admission Control
IGMP processing on ANX, and NAS maintains available video bandwidth (No IGMP Processing on ANX and NAS Maintains Available Video
for PON) upon channel leave. Bandwidth for PON) upon Channel Leave
- An alternate approach is required if the NAS is not aware of An alternate approach is required if the NAS is not aware of the
the bandwidth on the PON. In this case the OLT does the PON bandwidth bandwidth on the PON. In this case, the OLT does the PON bandwidth
management, and requests NAS to perform bandwidth admission control management and requests NAS to perform bandwidth admission control on
on subscriber bandwidth and the bandwidth on the link to the OLT. subscriber bandwidth and the bandwidth on the link to the OLT.
Following are operations of various elements: Following are operations of various elements:
ANX operation: ANX operation:
- ONT/ONU can snoop IGMP messages. If conditional access is - 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 configured and the channel is in the black list (or it is not on
White list), ONT will drop the IGMP Join. If the channel passes the the white list), ONT will drop the IGMP join. If the channel
conditional access check, the ONT will forward the IGMP Join, and passes the conditional access check, the ONT will forward the IGMP
will send a bandwidth admission control request to the OLT. In case join and will send a bandwidth admission control request to the
the multicast stream is already being received on the PON, the OLT. If the multicast stream is already being received on the
ONT/ONU does not forward the stream to the access port where IGMP is PON, the ONT/ONU does not forward the stream to the Access Port
received till it has received a positive admission control response where IGMP is received until it has received a positive admission
from the OLT. control response from the OLT.
- OLT can snoop IGMP messages. It also receives a bandwidth - OLT can snoop IGMP messages. It also receives a bandwidth
admission control request from the ONT/ONU for the requested channel. admission control request from the ONT/ONU for the requested
It can be programmed with a channel bandwidth map. If the multicast channel. It can be programmed with a channel bandwidth map. If
channel is already being streamed on the PON, or the channel the multicast channel is already being streamed on the PON or the
bandwidth is less than the multicast available bandwidth on the PON, channel bandwidth is less than the available multicast bandwidth
the OLT forwards the IGMP request to the NAS and keeps track of the on the PON, the OLT forwards the IGMP request to the NAS and keeps
subscriber (identified by customer-Port-ID) as a receiver. If the track of the subscriber (identified by Customer-Port-ID) as a
channel is not already being streamed on the PON, but the PON has receiver. If the channel is not already being streamed on the PON
sufficient bandwidth for that channel, the OLT reduces the PON but the PON has sufficient bandwidth for that channel, the OLT
multicast video bandwidth by the channel bandwidth and may optionally reduces the PON multicast video bandwidth by the channel bandwidth
add the PON to the multicast tree without activation for that and may optionally add the PON to the multicast tree without
channel. This is biased towards a forward expectation that the activation for that channel. This is biased towards a forward
request will be accepted at the NAS. The OLT forwards the IGMP join expectation that the request will be accepted at the NAS. The OLT
to the NAS. It also sends a bandwidth admission request to the NAS forwards the IGMP join to the NAS. It also sends a bandwidth
identifying the channel, and the premises for which the request is admission request to the NAS identifying the channel and the
made. It sets a timer for the subscriber multicast entry within which premises for which the request is made. It sets a timer for the
it expects to receive a request from the NAS that relates to this subscriber multicast entry within which it expects to receive a
request. If the PON available bandwidth is less than the bandwidth request from the NAS that relates to this request. If the
of the requested channel, the OLT sends an admission response (with a available PON bandwidth is less than the bandwidth of the
reject) to the ONT/ONU, and does not forward the IGMP join to the requested channel, the OLT sends an admission response (with a
NAS. reject) to the ONT/ONU and does not forward the IGMP join to the
NAS.
NAS operation: NAS operation:
The NAS receives the IGMP join from the subscriber on the subscriber The NAS receives the IGMP join from the subscriber on the subscriber
connection. When NAS receives the admission control request from ANX connection. When NAS receives the admission control request from ANX
(also signifying the bandwidth on the PON is available), it performs (also signifying the bandwidth on the PON is available), it performs
admission control against the subscriber available multicast admission control against the subscriber's available multicast
bandwidth. If this check passes, and the NAS is already transmitting bandwidth. If this check passes, and the NAS is already transmitting
that channel to the OLT, the request is accepted. If the check passes that channel to the OLT, the request is accepted. If the check
and the NAS is not transmitting the channel to the OLT yet, it passes and the NAS is not transmitting the channel to the OLT yet, it
performs admission control against the multicast video available performs admission control against the available multicast video
bandwidth (this includes the dedicated multicast bandwidth and the bandwidth (this includes the dedicated multicast bandwidth and the
shared bandwidth between multicast and video on demand) on 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 link(s) to the OLT. If the check passes, the request is accepted,
available video bandwidth for the subscriber and downlink to the OLT the available video bandwidth for the subscriber and downlink to the
are reduced by the channel bandwidth, and the NAS sends an ANCP OLT are reduced by the channel bandwidth, and the NAS sends an ANCP
admission control response (indicating accept) to the OLT, requesting admission control response (indicating accept) to the OLT, requesting
the addition of the subscriber to the multicast tree for that the addition of the subscriber to the multicast tree for that
channel. The OLT activates the corresponding multicast entry if not channel. The OLT activates the corresponding multicast entry if not
active and maintains state of the subscriber in the list of receivers 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 for that channel. The OLT also sends an ANCP request to the ONT/ONU
to enable reception of the multicast channel and forwarding to the to enable reception of the multicast channel and forwarding to the
subscriber access port. Otherwise, if the request is rejected, the subscriber Access Port. Otherwise, if the request is rejected, the
NAS will send an admission reject to the OLT, which in turn removes NAS will send an admission reject to the OLT, which, in turn, removes
the subscriber as a receiver for that channel (if it were added), and the subscriber as a receiver for that channel (if it was added) and
credits back the channel bandwidth to the PON video bandwidth if credits back the channel bandwidth to the PON video bandwidth if
there is no other receiver on the PON for that channel. The there is no other receiver on the PON for that channel. The
interactions between ANX and NAS are shown in Figures 9 and 10. 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 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 timer, the OLT removes the subscriber from the potential list of
receivers for the indicated channel. It also returns the allocated receivers for the indicated channel. It also returns the allocated
bandwidth to the PON available bandwidth if there are no other bandwidth to the available PON bandwidth if there are no other
receivers. In this case, the NAS may send a response to the OLT with 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 no matching entry as the entry has been deleted. The OLT must
admission control against the PON available bandwidth and may accept perform admission control against the available PON bandwidth and may
the request and send an ANCP request to the ONT/ONU to activate the accept the request and send an ANCP request to the ONT/ONU to
corresponding multicast entry as described earlier. If it does not activate the corresponding multicast entry as described earlier. If
accept the request, it will respond back to the NAS with a reject. it does not accept the request, it will respond back to the NAS with
The NAS shall credit back the channel bandwidth to the subscriber. It a reject. The NAS shall credit back the channel bandwidth to the
shall also stop sending the channel to the OLT if that subscriber was subscriber. It shall also stop sending the channel to the OLT if
the last leaf on the multicast tree towards the OLT. 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 On processing an IGMP leave, the OLT will send an ANCP request to NAS
to release resources. NAS will release the subscriber bandwidth. If to release resources. NAS will release the subscriber bandwidth. If
this leave causes the stream to be no longer required by the OLT, the 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 NAS will update its replication state and release the bandwidth on
the NAS to OLT link. the NAS to OLT link.
If the subscriber makes a request for a unicast video stream (i.e., If the subscriber makes a request for a unicast video stream (i.e.,
Video on Demand), the request results in appropriate application Video on Demand), the request results in appropriate application-
level signaling, which typically results in an application server level signaling, which typically results in an application server
requesting a policy server for bandwidth-based admission control for requesting a policy server for bandwidth-based admission control for
the VoD stream. The policy server after authorizing the request, can the VoD stream. After authorizing the request, the policy server can
send a request to the NAS for the required bandwidth if it needs to 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 use bandwidth that is shared with multicast. This request may be
based on a protocol outside of the scope of this document. The NAS based on a protocol outside of the scope of this document. The NAS
checks if the available video bandwidth (accounting for both checks if the available video bandwidth (accounting for both
multicast and unicast) per subscriber and for the link to the OLT is multicast and unicast) per subscriber and for the link to the OLT is
sufficient for the request. If it is, it temporarily reserves the sufficient for the request. If it is, it temporarily reserves the
bandwidth and sends an ANCP admission request to the OLT for the bandwidth and sends an ANCP admission request to the OLT for the
subscriber, indicating the desired VoD bandwidth. If the OLT has subscriber, indicating the desired VoD bandwidth. If the OLT has
sufficient bandwidth on the corresponding PON, it reserves that sufficient bandwidth on the corresponding PON, it reserves that
bandwidth and returns an accept response to the NAS. If not, it 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 a reject to the NAS. If the NAS receives an accept, it
returns an accept to the policy server which in turn returns an returns an accept to the policy server, which, in turn, returns an
accept to the application server, and the video stream is streamed to accept to the application server, and the video stream is streamed to
the subscriber. This interaction is shown in Figure 11. If the NAS the subscriber. This interaction is shown in Figure 11. If the NAS
does not accept the request from the policy server, it returns a does not accept the request from the policy server, it returns a
reject. If the NAS receives a reject from the OLT, it returns the reject. If the NAS receives a reject from the OLT, it returns the
allocated bandwidth to the subscriber and the downlink to the OLT. allocated bandwidth to the subscriber and the downlink to the OLT.
+----+ It should be noted that similar functionality to that described in
+-------- |ONT |-------- HGW this section and depicted in Figures 9, 10, and 11 will be required
+----+ +----+ + +----+ when OMCI is enabled between the OLT and ONT/ONU in the ANCP+OMCI ANX
|NAS |---------------| |------<PON> control model. In the latter case, the OLT will act as an ANCP-OMCI
| |<------------->|OLT | + +-----+ gateway.
+----+ ANCP | | ANCP +--------- | ONU |------ HGW
| +----+<------------------>+-----+-------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 upon success. +-------- |ONT |-------- HGW
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, |NAS |---------------| |------<PON>
the OLT will act as ANCP-OMCI gateway. | |<------------->|OLT | + +-----+
+----+ ANCP | | ANCP +--------- | ONU |------ HGW
| +----+<------------------>+-----+-------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
+--------- |ONT |------ HGW Admission Control in the All-ANCP ANX Control Model upon Success
+----+ +----+ + +----+ +----+
|NAS |---------------| |------<PON> +--------- |ONT |------ HGW
| |<------------->|OLT | + +-----+ +----+ +----+ + +----+
+----+ ANCP | | ANCP +----------| ONU |----- HGW |NAS |---------------| |------<PON>
| +----+<----------------->+-----+------HGW | |<------------->|OLT | + +-----+
| | | | +----+ ANCP | | ANCP +----------| ONU |----- HGW
|1.IGMP Join(s/*,G) +=============+ +=============+ | | +----+<----------------->+-----+------HGW
|<------------------[IGMP Snooping]--------[IGMP snooping]-- | | | | |
| +=============+ +=============+ | |1.IGMP join(S/*,G) +=============+ +=============+ |
| |2.Admission-Request | | |<------------------[IGMP Snooping]--------[IGMP snooping]-- |
| |(Flow,Customer-Port-ID) | | | +=============+ +=============+ |
| |<---------------------- | | | |2.Admission-Request | |
| 2.+===============+ | | | |(Flow,Customer-Port-ID) | |
| [ Access Ctrl ] | | | |<---------------------- | |
| [ & PON B/W ] | | | 2.+===============+ | |
| [ Admission Ctrl] | | | [ Access Ctrl ] | |
| +===============+ PASS | | | [ & PON B/W ] | |
|3.Admission-Request | | | | [ Admission Ctrl] | |
| <Flow,Customer-Port-ID> | | | +===============+ PASS | |
|<--------------------| | | |3.Admission-Request | | |
4.| | | | | <Flow,Customer-Port-ID> | |
+==================+ | | | |<--------------------| | |
[Subscriber B/W ] | | | 4.| | | |
[& OLT link B/W ] | | | +==================+ | | |
[Admission Ctrl ] | | | [Subscriber B/W ] | | |
+==================+FAIL | | [& OLT link B/W ] | | |
| | | | [Admission Ctrl ] | | |
|5.Admission-Reply-Fail | | +==================+FAIL | |
|<Flow,Cust-Port-ID> | | | | | | |
|-------------------->| | | |5.Admission-Reply-Fail | |
| 6.+==================+ | | |<Flow,Cust-Port-ID> | | |
| [Release PON B/W ] | | |-------------------->| | |
| [Remove Repl.State ] | | | 6.+==================+ | |
| +==================+ | | | [Release PON B/W ] | |
| | 7.Admission-Reply-Fail | | | [Remove Repl.State ] | |
| |<Flow,Cust-Port-ID> | | | +==================+ | |
| |----------------------> | | | | 7.Admission-Reply-Fail | |
| | 8.+============+ | | |<Flow,Cust-Port-ID> | |
| | [Remove Repl.] | | |----------------------> | |
| | [ State ] | | | 8.+============+ |
| | +============+ | | | [Remove Repl.] |
Figure 10: Interaction between NAS and ANX for Multicast Bandwidth | | [ State ] |
Admission Control in the All-ANCP ANX control model upon failure. | | +============+ |
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.
+------------+ 1. VoD Request Figure 10: Interaction between NAS and ANX for Multicast Bandwidth
| App. Server|<----------------------------------------------- Admission Control in the All-ANCP ANX Control Model upon Failure
| Server | +------------+ 1. VoD Request
+------------+ | App. Server|<-----------------------------------------------
| 2. Admission-Request (VoD-Flow) | Server |
+-------+ +------------+
|Policy | | 2. Admission-Request (VoD-Flow)
|Server | +-------+
+-------+ |Policy |
| + |Server |
|<-|---3. Admission-Request +-------+
| | | +
+ | 8. Admission-Reply |<-|---3. Admission-Request
+----+ + +----+ +-----+ | |
|NAS |---------------|OLT |------<PON>-------|ONT |---HGW--CPE + | 8. Admission-Reply
| |<------------->| | +-----+ | +----+ + +----+ +-----+
+----+ ANCP +----+ | | |NAS |---------------|OLT |------<PON>-------|ONT |---HGW--CPE
| | | | | |<------------->| | +-----+ |
4.| | | | +----+ ANCP +----+ | |
+=================+ | | | | | | |
[Subscriber B/W ] | | | 4.| | | |
[& OLT link B/W ] | | | +=================+ | | |
[Admission Ctrl ] | | | [Subscriber B/W ] | | |
+=================+PASS | | | [& OLT link B/W ] | | |
| | | | [Admission Ctrl ] | | |
| 5.Admission-Request | | | +=================+PASS | | |
|(Bandwidth,PON-Port-ID) | | | | | |
|-------------------> | | | | 5.Admission-Request | | |
| | | | |(Bandwidth,PON-Port-ID) | |
| 6.+===============+ | | |-------------------> | | |
| [ PON B/W ] | | | | | |
| [ Admission Ctrl] | | | 6.+===============+ | |
| +===============+ PASS | | | [ PON B/W ] | |
|7.Admission-Reply | | | | [ Admission Ctrl] | |
| <PON-Port-ID> | | | | +===============+ PASS | |
|<------------------- | | | |7.Admission-Reply | | |
| | | | | <PON-Port-ID> | | |
|<------------------- | | |
| | | |
Figure 11: Interactions for VoD Bandwidth Admission Control in the Figure 11: Interactions for VoD Bandwidth Admission Control
All-ANCP ANX control model. Similar functionality will be required in the All-ANCP ANX Control Model
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 A third possible approach is where the ANX is assumed to have full
knowledge to make an autonomous decision on admitting or rejecting a knowledge to make an autonomous decision on admitting or rejecting a
multicast and a unicast join. With respect to the interaction between multicast and a unicast join. With respect to the interaction
ONT/ONU and OLT, the procedure is similar to the first approach between ONT/ONU and OLT, the procedure is similar to the first
(i.e., NAS controlled replication). However, when the OLT receives an approach (i.e., NAS-controlled replication). However, when the OLT
IGMP request from a subscriber, it performs admission control against receives an IGMP request from a subscriber, it performs admission
that subscriber multicast video bandwidth (dedicated and shared with control against that subscriber multicast video bandwidth (dedicated
Video on Demand), the PON and uplink to the NAS. It should be noted and shared with Video on Demand), the PON, and uplink to the NAS. It
in this case that if there are multiple NAS-OLT links, either the should be noted in this case that if there are multiple NAS-OLT
link on which the multicast stream must be sent is pre-determined, links, either the link on which the multicast stream must be sent is
needs to be selected by the OLT based on downstream bandwidth from pre-determined, needs to be selected by the OLT based on downstream
NAS to OLT and the selection is communicated to the NAS, or the OLT bandwidth from NAS to OLT and the selection is communicated to the
has to be ready to receive the stream on any link. If the check NAS, or the OLT has to be ready to receive the stream on any link.
passes, the OLT updates the video available bandwidth per PON and If the check passes, the OLT updates the available video bandwidth
subscriber. The OLT adds the subscriber to the list of receivers and per PON and subscriber. The OLT adds the subscriber to the list of
the PON to the multicast tree, if it is not already on it. It also receivers and the PON to the multicast tree if it is not already on
sends an ANCP request to the ONT/ONU to add the subscriber access it. It also sends an ANCP request to the ONT/ONU to add the
port to that channel multicast tree, and sends an ANCP message to the subscriber Access Port to that channel multicast tree and sends an
NAS informing it of the subscriber and link available video bandwidth ANCP message to the NAS informing it of the subscriber and link
and the channel the subscriber joined. The NAS upon receiving the available video bandwidth and the channel the subscriber joined. The
ANCP information message, updates the necessary information, NAS, upon receiving the ANCP information message, updates the
including the OLT to the multicast tree if it is not already on it. necessary information, including the OLT to the multicast tree if it
It should be noted in this case that the ANCP message from the OLT to is not already on it. It should be noted in this case that the ANCP
the NAS is being used to add the OLT to a multicast tree as opposed message from the OLT to the NAS is being used to add the OLT to a
to an IGMP message. The IGMP message can also be sent by the OLT with multicast tree as opposed to an IGMP message. The IGMP message can
the OLT acting as an IGMP proxy at the expense of added messages. In also be sent by the OLT with the OLT acting as an IGMP proxy at the
this option, the OLT acts as the network IGMP router for the expense of added messages. In this option, the OLT acts as the
subscriber. network IGMP router for the subscriber.
For unicast video streams, the policy server receiving an admission For unicast video streams, the policy server receiving an admission
request from an application server, as described before, may query request from an application server, as described before, may query
the OLT for admission control as it has all information. If the OLT the OLT for admission control as it has all information. If the OLT
has sufficient bandwidth for the stream it reserves that bandwidth has sufficient bandwidth for the stream, it reserves that bandwidth
for the subscriber, PON and OLT uplink to the NAS and returns an for the subscriber, the PON, and OLT uplink to the NAS and returns an
accept to the policy server. It also updates the NAS via an ANCP accept to the policy server. It also updates the NAS (via an ANCP
message of the subscriber available video bandwidth. If the OLT message) of the subscriber's available video bandwidth. If the OLT
rejects the policy server request, it will return a reject to the rejects the policy server request, it will return a reject to the
policy server. policy server.
It should be noted that if the policy server adjacency is with the 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, the policy server may make the admission request to the NAS.
NAS then sends an ANCP admission request to the OLT on behalf of the The NAS then sends an ANCP admission request to the OLT on behalf of
policy server. The NAS returns an accept or reject to the policy server the policy server. The NAS returns an accept or reject to the policy
if it gets a reject or accept, respectively, from the OLT. server if it gets a reject or accept, respectively, from the OLT.
6.3. Multicast Accounting 6.3. Multicast Accounting
It may be desirable to perform accurate per-user or per Access Loop It may be desirable to perform accurate time- or volume-based
time or volume based accounting. In case the ANX is performing the accounting per user or per access loop. If the ANX is performing the
traffic replication process, it knows when replication of a multicast traffic replication process, it knows when replication of a multicast
flow to a particular Access Port or user starts and stops. Multicast flow to a particular Access Port or user starts and stops. Multicast
accounting can be addressed in two ways: accounting can be addressed in two ways:
- ANX keeps track of when replication starts or stops, and reports - ANX keeps track of when replication starts or stops and reports
this information to the NAS for further processing. In this case, 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. 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 This can be done with the Information Report message. The NAS can
then generate the appropriate time and/or volume accounting then generate the appropriate time and/or volume accounting
information per Access Loop and per multicast flow, to be sent to the information per access loop and per multicast flow to be sent to
accounting system. The ANCP requirements to support this approach are the accounting system. The ANCP requirements to support this
specified in [RFC5851]. If the replication function is distributed approach are specified in [RFC5851]. If the replication function
between the OLT and ONT/ONU, a query from the NAS will result in OLT is distributed between the OLT and ONT/ONU, a query from the NAS
generating a query to the ONT/ONU. will result in OLT generating a query to the ONT/ONU.
- ANX keeps track of when replication starts or stops, and generates - ANX keeps track of when replication starts or stops and generates
the time and/or volume based accounting information per Access Loop the time- and/or volume-based accounting information per access
and per multicast flow, before sending it to a central accounting loop and per multicast flow, before sending it to a central
system for logging. Since ANX communicates with this accounting accounting system for logging. Since ANX communicates with this
system directly, the approach does not require the use of ANCP. It is accounting system directly, the approach does not require the use
therefore beyond the scope of this document. It may also be desirable of ANCP. It is therefore beyond the scope of this document. It
for the NAS to have the capability to asynchronously query the ANX to may also be desirable for the NAS to have the capability to
obtain an instantaneous status report related to multicast flows asynchronously query the ANX to obtain an instantaneous status
currently replicated by the ANX. Such a reporting functionality could report related to multicast flows currently replicated by the ANX.
be useful for troubleshooting and monitoring purposes. If the Such a reporting functionality could be useful for troubleshooting
replication function in the ANX is distributed between the OLT and and monitoring purposes. If the replication function in the ANX
the ONT/ONU, then for some of the information required by the NAS is distributed between the OLT and the ONT/ONU, then for some of
(such as the list of access-ports on which a flow is being forwarded the information required by the NAS (such as the list of Access
or list of flows being forwarded on an access-port), a query to the Ports on which a flow is being forwarded or list of flows being
OLT from the NAS will result in a query from OLT to ONT/ONU. The OLT forwarded on an Access Port), a query to the OLT from the NAS will
responds back to the NAS when it receives the response from the result in a query from the OLT to the ONT/ONU. The OLT responds
ONT/ONU. Also, if the list of PONs on which replication is happening back to the NAS when it receives the response from the ONT/ONU.
for a multicast channel or the list of channels being replicated on a Also, if the list of PONs on which replication is happening for a
PON is what is desired, the OLT can return this information. multicast channel or the list of channels being replicated on a
PON is what is desired, the OLT can return this information.
7. Remote Connectivity Check 7. Remote Connectivity Check
In an end-to-end Ethernet aggregation network, end-to-end Ethernet 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 Operations, Administration, and Maintenance (OAM), as specified in
can provide Access Loop connectivity testing and fault isolation. IEEE 802.1ag [802.1ag] and ITU-T Recommendation Y.1730/1731 [Y.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, the 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.
However, most HGWs do not yet support these standard Ethernet OAM Triggered by a local management interface, the NAS can use the Access
procedures. Also, in a mixed Ethernet and ATM access network (e.g., Node Control Mechanism (Control Request message) to initiate an
Ethernet based aggregation upstream from the OLT, and BPON access loop test between an Access Node and a HGW or ONT/ONU. On
downstream), interworking functions for end-to-end OAM are not yet reception of the ANCP message, the OLT can trigger native OAM
standardized or widely available. Until such mechanisms become procedures defined for BPON in [G.983.1] and for GPON in [G.984.1].
standardized and widely available, Access Node Control mechanism The Access Node can send the result of the test to the NAS via a
between NAS and ANX can be used to provide a simple mechanism to test Control Response message.
connectivity of an access-loop from the NAS.
Triggered by a local management interface, the NAS can use the Access 8. Access Topology Discovery
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.
8. 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).
In order to avoid congestion in the network, manage and utilize the Such mechanisms require that the NAS gains knowledge about the
network resources better, and ensure subscriber fairness, NAS topology of the access network, the various links being used, and
performs hierarchical shaping and scheduling of the traffic by their respective rates. Some of the information required is somewhat
modeling different congestion points in the network (such as the dynamic in nature (e.g., DSL line rate if the last mile is xDSL
last-mile, access Node uplink, and the access facing port). based, such as in the case of "PON-fed DSLAMs" for FTTC/FTTB
scenarios) and hence cannot come from a provisioning and/or inventory
management Operations Support System (OSS). 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.
Such mechanisms require that the NAS gains knowledge about the OSSs are rarely able to enforce the consistency of such data in a
topology of the access network, the various links being used and reliable and scalable manner, notably across organizational
their respective rates. Some of the information required is somewhat boundaries under certain deployment scenarios. The Access Topology
dynamic in nature (e.g., DSL line rate in case the last mile is xDSL Discovery function allows the NAS to perform these advanced functions
based, e.g., in case of "PON fed DSLAMs" for FTTC/FTTB scenarios), without having to depend on an error-prone and possibly complex
hence cannot come from a provisioning and/or inventory management integration with an OSS.
Operations Support System (OSS). 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 The rate of the access loop can be communicated via ANCP (Information
manner the consistency of such data, notably across organizational Report message) from the ONT/ONU to the OLT in the All-ANCP ANX
boundaries under certain deployment scenarios. The Access Topology control model or via OMCI in the ANCP+OMCI ANX control model, and
Discovery function allows the NAS to perform these advanced functions then from OLT to the NAS via ANCP. Additionally, during the time the
without having to depend on an error-prone and possibly complex DSL NT is active, data rate changes can occur due to environmental
integration with an OSS system. 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 to make 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.
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 | Policy |
control model or via OMCI in the ANCP+OMCI ANX control model, and | Server |
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 | +-----------|ONT|---|HGW|
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 |NAS |------------ | | | | | |-|-|HGW|
the NAS each time the Access Loop attributes change above a threshold | |<----------> | | | | |ONT/ | | +---+
value. Existing DSL procedures are not applicable in this case +----+ ANCP | |OLT |------<PON>--------|ONU | |
because an adapted message flow and additional TLVs are needed. | | | | | | | +---+
| | | |<----------------->| |---|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
| Policy | the ANCP+OMCI Control Model
| 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 Figure 12 depicts a message flow for topology discovery when using
the ANCP+OMCI access control model. the ANCP+OMCI 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 the GPON service
profile is assigned from OLT to ONT/ONU, the OLT reports the final
status to NAS with information about the service profile and other
information such as the ONT/ONU port rate to the subscriber, for
instance.
Figure 12 depicts a message flow for topology discovery when using 9. Access Loop Configuration
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.
9. Access Loop Configuration Topology Discovery provides Access Port Identification to the NAS
Topology Discovery reports access port identification to NAS when when sending an Access Port Discovery message. This informs NAS
sending an Access Port Discovery message. This informs NAS identification of a PON port on an Access Node. Based on Access Port
identification of PON port on an Access Node. Based on Access Port Identification and on customer identification, service-related
Identification and on customer identification, service related parameters could be configured on an OLT and an ONU/ONT.
parameters could be configured on an OLT and an ONU/ONT.
Service related parameters could be sent to OLT via ANCP before or Service-related parameters could be sent to OLT via ANCP before or
after an ONU/ONT is up. Sending of ANCP loop Configuration messages after an ONU/ONT is up. Sending of ANCP loop configuration messages
from NAS can be triggered by a management system or by customer from NAS can be triggered by a management system or by customer
identification and authentication after Topology Discovery. It may be identification and authentication after Topology Discovery. It may
used for first time configuration (zero touch) or for be used for first-time configuration (zero touch) or for
updating/upgrading customer's profile like C-VLAN ID, S-VLAN ID, and updating/upgrading customer's profile like C-VLAN ID, S-VLAN ID, and
service bandwidth. service bandwidth.
Parameters of the User to Network Interface (UNI), which is the Parameters of the User-Network Interface (UNI), which is the
subscriber interface to HGW/CPE of ONU/ONT, can also be configured 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 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 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 support ANCP but only OMCI, parameters have to be sent from the NAS
to the OLT via ANCP first. Then, the OLT translates such to the OLT via ANCP first. Then, the OLT translates such
configuration into OMCI and sends it to the ONU/ONT. configuration into OMCI and sends it to the ONU/ONT.
10. Security Considerations 10. Security Considerations
[RFC5713] lists the ANCP related security threats that could be [RFC5713] lists the ANCP-related security threats that could be
encountered on the Access Node and the NAS. It develops a threat encountered on the Access Node and the NAS. It develops a threat
model for ANCP security, and lists the security functions that are model for ANCP security and lists the security functions that are
required at the ANCP level. required at the ANCP level.
With Multicast handling as described in this document, ANCP protocol With multicast handling as described in this document, ANCP protocol
activity between the ANX and the NAS is triggered by join/leave activity between the ANX and the NAS is triggered by join/leave
requests coming from the end-user equipment. This could potentially requests coming from the end-user equipment. This could potentially
be used for denial of service attack against the ANX and/or the NAS. be used for a denial-of-service attack against the ANX and/or the
NAS.
To mitigate this risk, the NAS and ANX may implement control plane To mitigate this risk, the NAS and ANX may implement control plane
protection mechanisms such as limiting the number of multicast flows protection mechanisms such as limiting the number of multicast flows
a given user can simultaneously join, or limiting the maximum rate of a given user can simultaneously join or limiting the maximum rate of
join/leave from a given user. join/leave from a given user.
Protection against invalid or unsubscribed flows can be deployed via Protection against invalid or unsubscribed flows can be deployed via
provisioning black lists as close to the subscriber as possible provisioning black lists as close to the subscriber as possible
(e.g., in the ONT). (e.g., in the ONT).
User activity logging for accounting or tracking purposes could raise User activity logging for accounting or tracking purposes could raise
privacy concerns if not appropriately protected. To protect such privacy concerns if not appropriately protected. To protect such
information, logging/accounting information can be exchanged with the information, logging/accounting information can be exchanged with the
corresponding server over a secure channel, and the information can corresponding server over a secure channel, and the information can
be stored securely with policy-driven controlled access. be stored securely with policy-driven controlled access.
11. Differences in ANCP applicability between DSL and PON 11. Differences in ANCP Applicability between DSL and PON
As it currently stands, both ANCP framework [RFC5851] and protocol As it currently stands, both ANCP framework [RFC5851] and protocol
[RFC6320] are defined in context of DSL access. Due to inherent [RFC6320] are defined in the context of DSL access. Due to inherent
differences between PON and DSL access technologies, ANCP needs a few differences between PON and DSL access technologies, ANCP needs a few
extensions for supporting the use-cases outlined in this document for extensions for supporting the use cases outlined in this document for
PON based access. These specific differences and extensions are PON-based access. These specific differences and extensions are
outlined below. outlined below.
- In PON, the access-node functionality is split between OLT and ONT. - In PON, the access-node functionality is split between OLT and
Therefore, ANCP interaction between NAS and AN translates to ONT. Therefore, ANCP interaction between NAS and AN translates to
transactions between NAS and OLT and between OLT and ONT. The transactions between NAS and OLT and between OLT and ONT. The
processing of ANCP messages (e.g., for multicast replication control) processing of ANCP messages (e.g., for multicast replication
on the OLT can trigger generation of ANCP messages from OLT to ONT. control) on the OLT can trigger generation of ANCP messages from
Similarly, ANCP messages from ONT to the OLT can trigger ANCP OLT to ONT. Similarly, ANCP messages from ONT to the OLT can
exchange between the OLT and the NAS (e.g., admission-request trigger ANCP exchange between the OLT and the NAS (e.g., admission
messages). This is illustrated in the generic message flows in request messages). This is illustrated in the generic message
Figures 5 and 6 of section 5. In case of DSL, the ANCP exchange is flows in Figures 5 and 6 of Section 5. In the case of DSL, the
contained between two network elements (NAS and the DSLAM). ANCP exchange is contained between two network elements (NAS and
the DSLAM).
- The PON connection to the ONT is a shared medium between multiple - 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- ONTs on the same PON. In the case of DSL, the local loop is
point. In case of DSL access network, the access facing port on the point-to-point. In the case of a DSL access network, the access-
NAS (i.e., port to the network between NAS and the DSLAM), and the facing port on the NAS (i.e., port to the network between NAS and
access-facing ports on the DSLAM (i.e., customer's local-loop) are the DSLAM) and the access-facing ports on the DSLAM (i.e.,
the two bandwidth constraint points that need to be considered for customer's local loop) are the two bandwidth constraint points
performing bandwidth based admission control for multicast video and that need to be considered for performing bandwidth-based
VoD delivered to the customer. In case of PON access, in addition to admission control for multicast video and VoD delivered to the
the bandwidth constraint on the NAS to OLT facing ports, and the customer. In the case of PON access, in addition to the bandwidth
subscriber allocated bandwidth for video services, the bandwidth constraint on the NAS to OLT facing ports and the subscriber-
available on the PON for video is an additional constraint that needs allocated bandwidth for video services, the bandwidth available on
to be considered for bandwidth based admission control. If the the PON for video is an additional constraint that needs to be
bandwidth control is centralized in NAS (as described in option 1 of considered for bandwidth-based admission control. If the
section 6.2), then the NAS needs to support additional logic to bandwidth control is centralized in the NAS (as described in the
consider available PON bandwidth before admitting a multicast request first approach in Section 6.2), then the NAS needs to support
or a VoD request by the user. Accordingly, ANCP needs to identify the additional logic to consider available PON bandwidth before
customer access port and the PON on which the customer ONT is. If the admitting a multicast request or a VoD request by the user.
PON bandwidth control is performed on the OLT (as defined in second Accordingly, ANCP needs to identify the customer Access Port and
option in section 6.2), then additional ANCP request and response the PON on which the customer ONT is. If the PON bandwidth
messages are required for NAS to query the OLT to determine available control is performed on the OLT (as defined in the second approach
PON bandwidth when a request to admit a VOD flow is received on the in Section 6.2), then additional ANCP request and response
NAS (as shown in Figure 9 in section 6.2) or for the OLT to inform messages are required for NAS to query the OLT to determine
the NAS what stream bandwidth is sent to the subscriber for the NAS available PON bandwidth when a request to admit a VoD flow is
to take appropriate action (e.g., bandwidth adjustment for various received on the NAS (as shown in Figure 9 in Section 6.2) or for
types of traffic). 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 - In PON, the multicast replication can potentially be performed on
three different network elements: (1) on the NAS (2) on the OLT for three different network elements: (1) on the NAS, (2) on the OLT
replication to multiple PON ports, and (3) on the ONT/ONU for for replication to multiple PON ports, and (3) on the ONT/ONU for
replication to multiple customer ports. In case of DSL, the replication to multiple customer ports. In the case of DSL, the
replication can potentially be performed on NAS and/or the DSLAM. replication can potentially be performed on NAS and/or the DSLAM.
Section 6.2 defines options for multicast replication in case of PON. Section 6.2 defines options for multicast replication in the case
In the first option, the multicast replication is done on the AN, but of PON. In the first option, the multicast replication is done on
is controlled from NAS via ANCP (based on the reception of per- the AN but is controlled from NAS via ANCP (based on the reception
customer IGMP messages on the NAS). In this option, the NAS needs to of per-customer IGMP messages on the NAS). In this option, the
supply to the OLT the set of PON-customer-IDs (as defined in section NAS needs to supply the OLT the set of PON-customer-IDs (as
2) to which the multicast stream needs to be replicated. The PON- defined in Section 2) to which the multicast stream needs to be
customer-ID identifies the OLT and the PON ports on the OLT as well replicated. The PON-customer-ID identifies the OLT and the PON
as the ONT and the access-ports on the ONT where the multicast stream ports on the OLT as well as the ONT and the Access Ports on the
needs to be replicated. Upon receiving the request to update its ONT where the multicast stream needs to be replicated. Upon
multicast replication state, the OLT must update its replication receiving the request to update its multicast replication state,
state with the indicated PON ports, but may also need to interact the OLT must update its replication state with the indicated PON
with the ONT via ANCP to update the multicast replication state on ports but may also need to interact with the ONT via ANCP to
the ONT with the set of access-ports (as indicated by the NAS). In update the multicast replication state on the ONT with the set of
case of DSL, the DSLAM only needs to update its own replication state Access Ports (as indicated by the NAS). In the case of DSL, the
based on the set of access-ports indicated by the NAS. 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 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 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 Access Ports. The latter should trigger the OLT to query the ONT
a list of channels being replicated on all access ports or on for a list of channels being replicated on all Access Ports or on
specific access ports to the premises. In DSL case, it is sufficient specific Access Ports to the premises. In a DSL case, it is
to query the DSLAM for a list of channels being replicated on an sufficient to query the DSLAM for a list of channels being
access port or a list of access ports. replicated on an Access Port or a list of Access Ports.
12. ANCP versus OMCI between the OLT and ONT/ONU 12. ANCP versus OMCI between the OLT and ONT/ONU
ONT Management and Control Interface (OMCI) [OMCI] is specified for ONT Management and Control Interface (OMCI) [OMCI] is specified for
in-band ONT management via the OLT. This includes configuring in-band ONT management via the OLT. This includes configuring
parameters on the ONT/ONU. Such configuration can include adding an 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 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 tree. Thus, OMCI can be a potential replacement for ANCP between the
OLT and ONT/ONU, albeit it may not a be suitable protocol for dynamic OLT and ONT/ONU, albeit it may not be a suitable protocol for dynamic
transactions as required for the multicast application. transactions as required for the multicast application.
If OMCI is selected to be enabled between the OLT and ONT/ONU to 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, carry the same information elements that would be carried over ANCP,
the OLT must perform the necessary translation between ANCP and OMCI the OLT must perform the necessary translation between ANCP and OMCI
for replication control messages received via ANCP. OMCI is an for replication control messages received via ANCP. OMCI is an
already available control channel, while ANCP requires a TCP/IP stack 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 on the ONT/ONU that can be used by an ANCP client, and accordingly,
requires that the ONT/ONU be IP addressable for ANCP. Most ONTs/ONUs it requires that the ONT/ONU be IP addressable for ANCP. Most
today have a TCP/IP stack used by certain applications (e.g., VoIP, ONTs/ONUs today have a TCP/IP stack used by certain applications
IGMP snooping). ANCP may use the same IP address that is often (e.g., VoIP and IGMP snooping). ANCP may use the same IP address
assigned for VoIP or depending on the implementation may require a that is often assigned for VoIP or, depending on the implementation,
different address. Sharing the same IP address between VoIP and ANCP may require a different address. Sharing the same IP address between
may have other network implications on how the VoIP agent is VoIP and ANCP may have other network implications on how the VoIP
addressed and on traffic routing. For instance, the VoIP traffic agent is addressed and on traffic routing. For instance, the VoIP
to/from the ONT is often encapsulated in a VLAN-tagged Ethernet frame traffic to/from the ONT is often encapsulated in a VLAN-tagged
and switched at layer2 through the OLT to the NAS where it is routed. Ethernet frame and switched at Layer 2 through the OLT to the NAS
The VoIP agent in this case looks like another subscriber to the NAS. where it is routed. The VoIP agent in this case looks like another
On the other hand, the ANCP session between the ONT and OLT is subscriber to the NAS. On the other hand, the ANCP session between
terminated at the OLT. Thus, the OLT must be able to receive/send IP the ONT and OLT is terminated at the OLT. Thus, the OLT must be able
traffic to/from the OLT, which will not work using this setting. to receive/send IP traffic to/from the OLT, which will not work using
Using a separate IP address for the purpose of ONT/ONU management or this setting. Using a separate IP address for the purpose of ONT/ONU
ANCP specifically may often be required when supporting ANCP. These management or ANCP specifically may often be required when supporting
considerations may favor OMCI in certain environments. However, OMCI ANCP. These considerations may favor OMCI in certain environments.
will not allow some of the transactions required in approach 2, where However, OMCI will not allow some of the transactions required in
the ONT/ONU sends unsolicited requests to the OLT rather than being approach 2, where the ONT/ONU sends unsolicited requests to the OLT
queried or configured by OLT requests. rather than being queried or configured by OLT requests.
13. IANA Considerations 13. Acknowledgements
This document does not require actions by IANA. The authors thank Rajesh Yadav and Francois Le Faucheur for their
valuable comments and discussions.
14. Acknowledgements 14. References
The authors are thanksful to Rajesh Yadav and Francois Le Faucheur 14.1. Normative References
for valuable comments and discussions.
15. 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.
15.1. Normative References [RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol Encapsulation
over ATM Adaptation Layer 5", RFC 2684, September 1999.
[RFC2516] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D., [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
and R. Wheeler, "A Method for Transmitting PPP Over Thyagarajan, "Internet Group Management Protocol, Version
Ethernet (PPPoE)", RFC 2516, February 1999. 3", RFC 3376, October 2002.
[RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol Encapsulation [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick,
over ATM Adaptation Layer 5", RFC 2684, September 1999. "Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, August 2006.
[RFC3376] Cain, B., et al, "Internet Group Management Interface, 14.2. Informative References
Version 3", RFC 3376, October 2002.
[RFC4605] Fenner, W., et al, "Internet Group Management Protocol [802.1ag] IEEE 802.1ag, "Connectivity Fault Management", December
(IGMP)/Multicast Listener Discovery (MLD)-Based Multicast Forwarding 2007.
("IGMP/MLD Proxying")", RFC 4605, August 2006.
15.2. Informative References [RFC2881] Mitton, D. and M. Beadles, "Network Access Server
Requirements Next Generation (NASREQNG) NAS Model", RFC
2881, July 2000.
[RFC2881] Mitton, D. and M. Beadles, "Network Access Server [RFC5851] Ooghe, S., Voigt, N., Platnic, M., Haag, T., and S.
Requirements Next Generation (NASREQNG) NAS Model", RFC 2881, July Wadhwa, "Framework and Requirements for an Access Node
2000. Control Mechanism in Broadband Multi-Service Networks",
RFC 5851, May 2010.
[RFC5851] Ooghe, S., et al., "Framework and Requirements for Access [G.983.1] ITU-T G.983.1, "Broadband optical access systems based on
Node Control Mechanism in Broadband Networks", RFC 5851, May 2010. Passive Optical Networks (PON)", January 2005.
[G.983.1] ITU-T G.983.1, "Broadband optical access systems based on [G.984.1] ITU-T G.984.1, "Gigabit-capable Passive Optical Networks
Passive Optical Networks (PON)". (GPON): General characteristics", March 2008.
[G.984.1] ITU-T G.984.1, "Gigabit-capable Passive Optical Networks [RFC3046] Patrick, M., "DHCP Relay Agent Information Option", RFC
(G-PON): General characteristics". 3046, January 2001.
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", [TR-101] Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL
RFC3046, January 2011. Aggregation", DSL Forum TR-101, May 2006.
[TR-101] Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL [RFC5713] Moustafa, H., Tschofenig, H., and S. De Cnodder, "Security
Aggregation", DSL Forum TR-101, May 2006. Threats and Security Requirements for the Access Node
Control Protocol (ANCP)", RFC 5713, January 2010.
[RFC5713] Moustafa, H., Tschofenig, H., and S. De Cnodder, [OMCI] ITU-T G.984.4, "Gigabit-capable passive optical networks
"Security Threats and Security Requirements for the Access Node (G-PON): ONT management and control interface
Control Protocol (ANCP)", RFC 5713, January 2010. specification", February 2008.
[OMCI] ITU-T G.984.4, "GPON ONT Management and Control Interface [RFC6320] Wadhwa, S., Moisand, J., Haag, T., Voigt, N., and T.
(OMCI) Specifications". Taylor, Ed., "Protocol for Access Node Control Mechanism
in Broadband Networks", RFC 6320, October 2011.
[RFC6320] Taylor, T., et al, "Protocol for Access Node Control [G.987.3] ITU-T G.987.3, "10-Gigabit-capable passive optical
Mechanism in Broadband Networks", RFC 6320, October 2011. networks(XG-PON): Transmission convergence (TC) layer
specification", October 2010.
[G.987.3] ITU-T G.987.3, "10-Gigabit-capable passive optical [Y.1731] ITU-T Y.1731, "OAM functions and mechanisms for Ethernet
networks(XG-PON): Transmission convergence (TC) layer specification". based networks", May 2006.
Authors' Addresses Authors' Addresses
Nabil Bitar Nabil Bitar (editor)
Verizon Verizon
60 Sylvan Road 60 Sylvan Road
Waltham, MA 02451 Waltham, MA 02451
Email: nabil.n.bitar@verizon.com EMail: nabil.n.bitar@verizon.com
Sanjay Wadhwa Sanjay Wadhwa (editor)
Alcatel-Lucent Alcatel-Lucent
701 East Middlefield Road 701 East Middlefield Road
Mountain View, CA, 94043 Mountain View, CA, 94043
Email: sanjay.wadhwa@alcatel-lucent.com EMail: sanjay.wadhwa@alcatel-lucent.com
Thomas Haag Thomas Haag
Deutsche Telekom Deutsche Telekom
Email: HaagT@telekom.de EMail: HaagT@telekom.de
Hongyu Li Hongyu Li
Huawei Technologies Huawei Technologies
Email: hongyu.lihongyu@huawei.com EMail: hongyu.lihongyu@huawei.com
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