draft-ietf-ancp-pon-04.txt   draft-ietf-ancp-pon-05.txt 
Network Working Group Nabil Bitar(ed.) Network Working Group Nabil Bitar(ed.)
Verizon Verizon
Internet Draft Internet Draft
Intended Status: Informational Sanjay Wadhwa (ed.) Intended Status: Informational Sanjay Wadhwa (ed.)
Alcatel-Lucent Alcatel-Lucent
Expires: June 02, 2013 Expires: August 25, 2013
Thomas Haag Thomas Haag
Deutsche Telekom Deutsche Telekom
Hongyu Li Hongyu Li
Huawei Technologies Huawei Technologies
December 02, 2012 February 25, 2013
Applicability of Access Node Control Mechanism to Applicability of Access Node Control Mechanism to
PON based Broadband Networks PON based Broadband Networks
draft-ietf-ancp-pon-04.txt draft-ietf-ancp-pon-05.txt
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 PON-based broadband access. The Access Node Control mechanism to Passive Optical Network (PON)-based
need for an Access Node Control mechanism between a Network broadband access. The need for an Access Node Control mechanism
Access Server (NAS) and an Access Node Complex (a combination of between a Network Access Server (NAS) and an Access Node Complex (a
Optical Line Termination (OLT) and Optical Network Termination combination of Optical Line Termination (OLT) and Optical Network
(ONT) elements) is described in a multi-service reference Termination (ONT) elements) is described in a multi-service reference
architecture in order to perform QoS-related, service-related and architecture in order to perform QoS-related, service-related and
Subscriber-related operations. The Access Node Control mechanism Subscriber-related operations. The Access Node Control mechanism is
is also extended for interaction between components of the Access also extended for interaction between components of the Access Node
Node Complex (OLT and ONT). The Access Node Control mechanism Complex (OLT and ONT). The Access Node Control mechanism will ensure
will ensure that the transmission of information between the NAS that the transmission of information between the NAS and Access Node
and Access Node Complex (ANX) and between the OLT and ONT within Complex (ANX) and between the OLT and ONT within an ANX does not need
an ANX does not need to go through distinct element managers but to go through distinct element managers but rather uses a direct
rather uses a direct device-to-device communication and stays on device-to-device communication and stays on net. This allows for
net. This allows for performing access link related operations performing access link related operations within those network
within those network elements to meet performance objectives. elements to meet performance objectives.
Status of this Memo Status of this Memo
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Table of Contents Table of Contents
1. Introduction............................................ 4 1. Introduction ..................................................... 3
2. Terminology............................................. 5 2. Terminology ...................................................... 5
3. Motivation for explicit extension of ANCP to FTTx PON.... 7 3. Motivation for explicit extension of ANCP to FTTx PON ............ 7
4. Reference Model for PON Based Broadband Access Network.. 8 4. Reference Model for PON Based Broadband Access Network ........... 8
4.1. Functional Blocks 11 4.1. Functional Blocks ............................................. 10
4.1.1. Home Gateway............................... 11 4.1.1. Home Gateway ............................................... 10
4.1.2. PON Access................................. 11 4.1.2. PON Access ................................................. 10
4.1.3. Access Node Complex........................ 11 4.1.3. Access Node Complex ........................................ 11
4.1.4. Access Node Complex Uplink to the NAS...... 12 4.1.4. Access Node Complex Uplink to the NAS ....................... 11
4.1.5. Aggregation Network........................ 12 4.1.5. Aggregation Network ......................................... 11
4.1.6. Network Access Server...................... 12 4.1.6. Network Access Server ....................................... 11
4.1.7. Regional Network........................... 12 4.1.7. Regional Network ............................................ 11
4.2. Access Node Complex Control Reference 4.2. Access Node Complex Control Reference Architecture Options .... 12
Architecture Options 13 4.2.1. ANCP+OMCI ANX Control ....................................... 12
4.2.1. ANCP+OMCI ANX Control...................... 13 4.2.2. All-ANCP ANX Control ........................................ 13
4.2.2. All-ANCP ANX Control....................... 14 5. Concept of Access Node Control Mechanism for PON Based Access ... 14
5. Concept of Access Node Control Mechanism for PON 6. Multicast ....................................................... 17
Based Access........................................... 15 6.1. Multicast Conditional Access .................................. 18
6. Multicast............................................. 18 6.2. Multicast Admission Control ................................... 20
6.1. Multicast Conditional Access 19 6.3. Multicast Accounting .......................................... 33
6.2. Multicast Admission Control 21 7. Remote Connectivity Check ....................................... 33
6.3. Multicast Accounting 33 8. Access Topology Discovery ....................................... 34
7. Remote Connectivity Check............................. 34 9. Access Loop Configuration ....................................... 36
8. Access Topology Discovery............................. 35 10. Security Considerations ........................................ 37
9. Access Loop Configuration............................. 37 11. Differences in ANCP applicability between DSL and PON .......... 38
10. Security Considerations.............................. 37 12. ANCP versus OMCI between the OLT and ONT/ONU ................... 39
11. Differences in ANCP applicability between DSL and PON. 38 13. IANA Considerations ............................................ 40
12. ANCP versus OMCI between the OLT and ONT/ONU......... 39 14. Acknowledgements ............................................... 40
13. IANA Consideration................................... 40 15. References ..................................................... 41
14. Acknowledgements..................................... 40 15.1. Normative References ........................................ 41
15. References.....................................,..... 40 15.2. Informative References ....................................... 41
15.1. Normative References 40
15.2. Informative References 41
1. Introduction 1. Introduction
Passive Optical Networks (PONs) based on BPON [G.983.1] and GPON Passive Optical Networks (PONs) based on BPON [G.983.1] and GPON
[G.984.1] are being deployed across carrier networks. There are [G.984.1] are being deployed across carrier networks. There are two
two models for PON deployment: Fiber to the building/curb models for PON deployment: Fiber to the building/curb (FTTB/FTTC),
(FTTB/FTTC), and Fiber to the Premises (FTTP). In the FTTB/C and Fiber to the Premises (FTTP). In the FTTB/C deployment, the last
deployment, the last mile connectivity to the subscriber premises mile connectivity to the subscriber premises is provided over the
is provided over the local Copper loop, often using Very High local Copper loop, often using Very High Speed Digital Subscriber
Speed Digital Subscriber line (VDSL). In the FTTP case, PON line (VDSL). In the FTTP case, PON extends to the premises of the
extends to the premises of the subscriber. In addition, there are subscriber. In addition, there are four main PON technologies: (1)
four main PON technologies: (1) Broadband PON (BPON), (2) Gigabit Broadband PON (BPON), (2) Gigabit PON (GPON), (3) 10-Gigabit PON (XG-
PON (GPON), (3) 10-Gigabit PON (XGPON), and (4) Ethernet PON PON), and (4) Ethernet PON (EPON). This document describes the
(EPON). This document describes the applicability of Access Node applicability of Access Node Control Protocol (ANCP) in the context
Control Protocol (ANCP) in the context of FTTB/C and FTTP of FTTB/C and FTTP deployments, focusing on BPON, GPON and XG-PON.
deployments, focusing on BPON, GPON and XPON. Architectural Architectural considerations lead to different ANCP compositions.
considerations lead to different ANCP compositions. Therefore, Therefore, the composition of ANCP communication between Access Nodes
the composition of ANCP communication between Access Nodes and and Network Access Server (NAS) is described using different models.
Network Access Server (NAS) is described using different models.
BPON, GPON and XPON in FTTP deployments provide large bandwidth BPON, GPON and XG-PON in FTTP deployments provide large bandwidth in
in the first mile, bandwidth that is an order of magnitude larger the first mile, bandwidth that is an order of magnitude larger than
than that provided by xDSL. In the downstream direction, BPON that provided by xDSL. In the downstream direction, BPON
provides 622 Mbps per PON while GPON provides 2.4 Gbps, and XPON provides 622 Mbps per PON while GPON provides 2.4 Gbps, and XG-PON
provides 10 Gbps. provides 10 Gbps.
In residential deployments, the number of homes sharing the same In residential deployments, the number of homes sharing the same PON
PON is limited by the technology and the network engineering is limited by the technology and the network engineering rules.
rules. Typical deployments have 32-64 homes per PON. Typical deployments have 32-64 homes per PON.
The motive behind BPON, GPON and XPON deployment is providing The motive behind BPON, GPON and XG-PON deployment is providing
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 low-delay, low-jitter, and low
packet-loss requirements. Data services (e.g., Internet services) packet-loss requirements. Data services (e.g., Internet services)
often require high throughput and can tolerate medium latency. often require high throughput and can tolerate medium latency. Data
Data services may include multimedia content download such as services may include multimedia content download such as video.
video. However, in that case, the video content is not required However, in that case, the video content is not required to be real-
to be real-time and/or it is low quality video. Video services, time and/or it is low quality video. Video services, on the other
on the other hand, are targeted to deliver Standard Definition or hand, are targeted to deliver Standard Definition or High Definition
High Definition video content in real-time or near-real time, video content in real-time or near-real time, depending on the
depending on the service model. Standard Definition content using service model. Standard Definition content using MPEG2 encoding
MPEG2 encoding requires on the order of 3.75 Mbps per stream requires on the order of 3.75 Mbps per stream while High definition
while High definition content using MPEG2 encoding requires on content using MPEG2 encoding requires on the order of 15-19 Mbps
the order of 15-19 Mbps depending on the level of compression depending on the level of compression used. Video services require
used. Video services require low-jitter and low-packet loss with low-jitter and low-packet loss with low start-time latency. There are
low start-time latency. There are two types of video services: on two types of video services: on demand and broadcast (known also as
demand and broadcast (known also as liner programming content). liner programming content). While linear programming content can be
While linear programming content can be provided over Layer1 on provided over Layer1 on the PON, the focus in this document is on
the PON, the focus in this document is on delivering linear delivering linear programming content over IP to the subscriber,
programming content over IP to the subscriber, using IP using IP multicast. Video on demand is also considered for delivery
multicast. Video on demand is also considered for delivery to the to the subscriber over IP using a unicast session model.
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. that preserves the quality of service of each service. Fundamental to
Fundamental to this architecture is ensuring that the video this architecture is ensuring that the video content (unicast and
content (unicast and multicast) delivered to the subscriber does multicast) delivered to the subscriber does not exceed the bandwidth
not exceed the bandwidth allocated to the subscriber for video allocated to the subscriber for video services. Architecture models
services. Architecture models often ensure that data is often ensure that data is guaranteed a minimum bandwidth and that
guaranteed a minimum bandwidth and that VoIP is guaranteed its VoIP is guaranteed its own bandwidth. In addition, QoS control across
own bandwidth. In addition, QoS control across services is often services is often performed at a Network Access Server (NAS), often
performed at a Network Access Server (NAS), often referred to as referred to as Broadband Network Gateway (BNG) for subscriber
Broadband Network Gateway (BNG) for subscriber management, per management, per subscriber and shared link resources. Efficient
subscriber and shared link resources. Efficient multicast video multicast video services require enabling multicast services in the
services require enabling multicast services in the access access network between the subscriber and the subscriber management
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 multicast on the Access Node (AN) complex composed of the Optical
IP multicast on the Access Node (AN) complex composed of the Network Terminal (ONT) or Unit (ONU) and Optical Line Terminal (OLT),
Optical Network Terminal (ONT) or Unit (ONU) and Optical Line as applicable. This is as opposed to Digital Subscriber Line (DSL)
Terminal (OLT), as applicable. This is as opposed to Digital deployments where multicast is enabled on the DSL Access Multiplexer
Subscriber Line (DSL) deployments where multicast is enabled on (DSLAM) only. The focus in this document will be on the ANCP
the DSL Access Multiplexer (DSLAM) only. The focus in this requirements needed for coordinated admission control of unicast and
document will be on the ANCP requirements needed for coordinated multicast video in FTTP/B/C PON environments between the AN complex
admission control of unicast and multicast video in FTTP/B/C PON (ANX) and the NAS, specifically focusing on bandwidth dedicated for
environments between the AN complex (ANX) and the NAS, multicast and shared bandwidth between multicast and unicast.
specifically focusing on bandwidth dedicated for multicast and
shared bandwidth between multicast and unicast.
[RFC5851] provides the framework and requirements for [RFC5851] provides the framework and requirements for coordinated
coordinated admission control between a NAS and an AN with admission control between a NAS and an AN with special focus on DSL
special focus on DSL deployments. This document extends that deployments. This document extends that framework and the related
framework and the related requirements to explicitly address requirements to explicitly address PON deployments.
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 fiber to the premises network architecture in which
unpowered splitters are used to enable the splitting of an unpowered splitters are used to enable the splitting of an optical
optical signal from a central office on a single optical fiber to signal from a central office on a single optical fiber to multiple
multiple premises. Up to 32-128 may be supported on the same PON. premises. Up to 32-128 may be supported on the same PON. A PON
A PON configuration consists of an Optical Line Terminal (OLT) at configuration consists of an Optical Line Terminal (OLT) at the
the Service Provider's Central Office (CO) and a number of Service Provider's Central Office (CO) and a number of Optical
Optical Network Units or Terminals (ONU/ONT) near end users, with Network Units or Terminals (ONU/ONT) near end users, with an optical
an optical distribution network (ODN) composed of fibers and distribution network (ODN) composed of fibers and splitters between
splitters between them. A PON configuration reduces the amount of them. A PON configuration reduces the amount of fiber and CO
fiber and CO equipment required compared with point-to-point equipment required compared with point-to-point architectures.
architectures.
- Access Node Complex (ANX): The Access Node Complex is composed - Access Node Complex (ANX): The Access Node Complex is composed of
of two geographically separated functional elements OLT and two geographically separated functional elements OLT and ONU/ONT. The
ONU/ONT. The general term Access Node Complex (ANX) will be used general term Access Node Complex (ANX) will be used when describing a
when describing a functionality which does not depend on the functionality which does not depend on the physical location but
physical location but rather on the "black box" behavior of OLT rather on the "black box" behavior of OLT and ONU/ONT.
and ONU/ONT.
-Optical Line Terminal (OLT): is located in the Service -Optical Line Terminal (OLT): is located in the Service provider's
provider's central office (CO). It terminates and aggregates central office (CO). It terminates and aggregates multiple PONs
multiple PONs (providing fiber access to multiple premises or (providing fiber access to multiple premises or neighborhoods) on the
neighborhoods) on the subscriber side, and interfaces with the subscriber side, and interfaces with the Network Access server (NAS)
Network Access server (NAS) that provides subscriber management. that provides subscriber management.
- Optical Network Terminal (ONT): terminates PON on the network - Optical Network Terminal (ONT): terminates PON on the network side
side and provides PON adaptation. The subscriber side interface and provides PON adaptation. The subscriber side interface and the
and the location of the ONT are dictated by the type of network location of the ONT are dictated by the type of network deployment.
deployment. For a Fiber-to-the-Premise (FTTP) deployment (with For a Fiber-to-the-Premise (FTTP) deployment (with Fiber all the way
Fiber all the way to the apartment or living unit), ONT has to the apartment or living unit), ONT has Ethernet (FE/GE/MoCA)
Ethernet (FE/GE/MoCA) connectivity with the Home Gateway connectivity with the Home Gateway (HGW)/Customer Premise
(HGW)/Customer Premise Equipment(CPE). In certain cases, one ONT Equipment(CPE). In certain cases, one ONT may provide connections to
may provide connections to more than one Home Gateway at the same more than one Home Gateway at the same time.
time.
-Optical Network Unit (ONU): A generic term denoting a device -Optical Network Unit (ONU): A generic term denoting a device that
that terminates any one of the distributed (leaf) endpoints of an terminates any one of the distributed (leaf) endpoints of an Optical
Optical Distribution Node (ODN), implements a PON protocol, and Distribution Node (ODN), implements a PON protocol, and adapts PON
adapts PON PDUs to subscriber service interfaces. In case of an PDUs to subscriber service interfaces. In case of an MDU multi-
MDU multi-dwelling or multi-tenant unit, a multi-subscriber ONU dwelling or multi-tenant unit, a multi-subscriber ONU typically
typically resides in the basement or a wiring closet (FTTB case), resides in the basement or a wiring closet (FTTB case), and has
and has FE/GE/Ethernet over native Ethernet link or over xDSL FE/GE/Ethernet over native Ethernet link or over xDSL (typically
(typically VDSL) connectivity with each CPE at the subscriber VDSL) connectivity with each CPE at the subscriber premises. In the
premises. In the case where fiber is terminated outside the case where fiber is terminated outside the premises (neighborhood or
premises (neighborhood or curb side) on an ONT/ONU, the last-leg- curb side) on an ONT/ONU, the last-leg-premises connections could be
premises connections could be via existing or new Copper, with via existing or new Copper, with xDSL physical layer (typically
xDSL physical layer (typically VDSL). In this case, the ONU VDSL). In this case, the ONU effectively is a "PON fed DSLAM".
effectively is a "PON fed DSLAM".
-Network Access Server (NAS): Network element which aggregates -Network Access Server (NAS): Network element which aggregates
subscriber traffic from a number of ANs or ANXs. The NAS is often subscriber traffic from a number of ANs or ANXs. The NAS is often an
an injection point for policy management and IP QoS in the access injection point for policy management and IP QoS in the access
network. It is also referred to as Broadband Network Gateway network. It is also referred to as Broadband Network Gateway (BNG) or
(BNG) or Broadband Remote Access Server (BRAS). Broadband Remote Access Server (BRAS).
-Home Gateway (HGW): Network element that connects subscriber -Home Gateway (HGW): Network element that connects subscriber devices
devices to the AN or ANX and the access network. In case of xDSL, to the AN or ANX and the access network. In case of xDSL, the Home
the Home Gateway is an xDSL network termination that could either Gateway is an xDSL network termination that could either operate as a
operate as a Layer 2 bridge or as a Layer 3 router. In the latter Layer 2 bridge or as a Layer 3 router. In the latter case, such a
case, such a device is also referred to as a Routing Gateway device is also referred to as a Routing Gateway (RG). In the case of
(RG). In the case of PON, it is often a Layer3 routing device PON, it is often a Layer3 routing device with the ONT performing PON
with the ONT performing PON termination. termination.
-PON-Customer-ID: This is an identifier which uniquely identifies -PON-Customer-ID: This is an identifier which uniquely identifies the
the ANX and the access loop logical port on the ANX to the ANX and the access loop logical port on the ANX to the subscriber
subscriber (customer) premises, and is used in any interaction (customer) premises, and is used in any interaction between NAS and
between NAS and ANX that relates to access-loops. Logically it is ANX that relates to access-loops. Logically it is composed of
composed of information containing identification of the OLT (the information containing identification of the OLT (the OLT may be
OLT may be physically directly connected to the NAS), the PON physically directly connected to the NAS), the PON port on the OLT,
port on the OLT, the ONT/ONU, and the port on the ONT/ONU the ONT/ONU, and the port on the ONT/ONU connecting to the subscriber
connecting to the subscriber HGW. When acting as a DHCP relay HGW. When acting as a DHCP relay agent, the OLT can encode PON-
agent, the OLT can encode PON-Customer-ID in the "Agent-Circuit- Customer-ID in the "Agent-Circuit-Identifier" Sub-option in Option-82
Identifier" Sub-option in Option-82 of the DHCP messages [RFC3046]. 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 The fundamental difference between PON and DSL is that a PON is an
an optical broadcast network by definition. That is, at the PON optical broadcast network by definition. That is, at the PON level,
level, every ONT on the same PON sees the same signal. However, every ONT on the same PON sees the same signal. However, the ONT
the ONT filters only those PON frames addressed to it. Encryption filters only those PON frames addressed to it. Encryption is used on
is used on the PON to prevent eavesdropping. the PON to prevent eavesdropping.
The broadcast PON capability is very suitable to delivering
multicast content to connected premises, maximizing bandwidth
usage efficiency on the PON. Similar to DSL deployments, enabling
multicast on the Access Node Complex (ANX) provides for bandwidth
use efficiency on the path between the Access Node and the NAS as
well as improves the scalability of the NAS by reducing the
amount of multicast traffic being replicated at the NAS. However,
the broadcast capability on the PON enables the AN (OLT) to send
one copy on the PON as opposed to one copy to each receiver on
the PON. The PON multicast capability can be leveraged in the
case of GPON and BPON as discussed in this document.
Fundamental to leveraging the broadcast capability on the PON for
multicast delivery is the ability to assign a single encryption
key for all PON frames carrying all multicast channels or a key
per set of multicast channels that correspond to service
packages, or none. It should be noted that the ONT can be a
multi-Dwelling Unit (MDU) ONT with multiple Ethernet ports, each
connected to a living unit. Thus, the ONT must not only be able
to receive a multicast frame, but must also be able to forward
that frame only to the Ethernet port with receivers for the
corresponding channel.
In order to implement triple-play service delivery with necessary
"quality-of-experience", including end-to-end bandwidth optimized
multicast video delivery, there needs to be tight coordination
between the NAS and the ANX. This interaction needs to be near
real-time as services are requested via application or network
level signaling by broadband subscribers. ANCP as defined in
[RFC5851] for DSL based networks is very suitable to realize a
control protocol (with transactional exchange capabilities),
between PON enabled ANX and the NAS, and also between the
components comprising the ANX, i.e., between OLT and the ONT.
Typical use cases for ANCP in PON environment include the
following:
- Access topology discovery
- Access Loop Configuration
- Multicast
- Optimized multicast delivery The broadcast PON capability is very suitable to delivering multicast
content to connected premises, maximizing bandwidth usage efficiency
on the PON. Similar to DSL deployments, enabling multicast on the
Access Node Complex (ANX) provides for bandwidth use efficiency on
the path between the Access Node and the NAS as well as improves the
scalability of the NAS by reducing the amount of multicast traffic
being replicated at the NAS. However, the broadcast capability on the
PON enables the AN (OLT) to send one copy on the PON as opposed to
one copy to each receiver on the PON. The PON multicast capability
can be leveraged in the case of GPON and BPON as discussed in this
document.
- Unified video resource control Fundamental to leveraging the broadcast capability on the PON for
multicast delivery is the ability to assign a single encryption key
for all PON frames carrying all multicast channels or a key per set
of multicast channels that correspond to service packages, or none.
When supporting encryption for multicast channels, the encryption key
is generated by the OLT and sent by the OLT to each targeted ONT via
the ONT Management and Control Interface (OMCI) as described in
section 15.5.2 of ITU-T G.987.3 [G.987.3] for XG-PON. It should be
noted that the ONT can be a multi-Dwelling Unit (MDU) ONT with
multiple Ethernet ports, each connected to a living unit. Thus, the
ONT must not only be able to receive a multicast frame, but must also
be able to forward that frame only to the Ethernet port with
receivers for the corresponding channel.
- NAS based provisioning of ANX In order to implement triple-play service delivery with necessary
"quality-of-experience", including end-to-end bandwidth optimized
multicast video delivery, there needs to be tight coordination
between the NAS and the ANX. This interaction needs to be near real-
time as services are requested via application or network level
signaling by broadband subscribers. ANCP as defined in [RFC5851] for
DSL based networks is very suitable to realize a control protocol
(with transactional exchange capabilities), between PON enabled ANX
and the NAS, and also between the components comprising the ANX,
i.e., between OLT and the ONT. Typical use cases for ANCP in PON
environment include the following:
- Remote connectivity check - Access topology discovery
- Access Loop Configuration
- Multicast
- Optimized multicast delivery
- Unified video resource control
- NAS based provisioning of ANX
- 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 An overall end-to-end reference architecture of a PON access network
network is depicted in Figure 1 and Figure 2 with ONT serving a is depicted in Figure 1 and Figure 2 with ONT serving a single HGW,
single HGW, and ONT/ONU serving multiples HGWs, respectively. An and ONT/ONU serving multiples HGWs, respectively. An OLT may provide
OLT may provide FTTP and FTTB/C access at the same time but most FTTP and FTTB/C access at the same time but most likely not on the
likely not on the same PON port. Specifically, the following PON same PON port. Specifically, the following PON cases are addressed in
cases are addressed in the context of this reference the context of this reference architecture:
architecture:
- BPON with Ethernet uplink to the NAS and ATM on the PON
side.
- GPON/XPON with Ethernet uplink to the NAS and Ethernet - BPON with Ethernet uplink to the NAS and ATM on the PON
on the PON side side.
- GPON/XG-PON with Ethernet uplink to the NAS and Ethernet on
the PON side
In case of an Ethernet aggregation network that supports new QoS- In case of an Ethernet aggregation network that supports new QoS-
enabled IP services (including Ethernet multicast replication), enabled IP services (including Ethernet multicast replication), the
the architecture builds on the reference architecture specified architecture builds on the reference architecture specified in the
in the Broadband Forum (BBF) [TR-101]. The Ethernet aggregation Broadband Forum (BBF) [TR-101]. The Ethernet aggregation network
network between a NAS and an OLT may be degenerated to one or between a NAS and an OLT may be degenerated to one or more direct
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 aggregation technology for triple play services, the primary focus
focus throughout this document is on GPON/XPON and BPON with throughout this document is on GPON/XG-PON and BPON with Ethernet
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 FE/GE/VDSL
+---+ +---+ +---+ +---+
+----------------+ | |-|HGW| +----------------+ | |-|HGW|
+---------+ +-----+ | +-----+ +----+| | | +---+ +---------+ +-----+ | +-----+ +----+| | | +---+
| | +-|NAS |--| |Eth |--|OLT||-<PON>- | | | | +-|NAS |--| |Eth |--|OLT||-<PON>- | |
NSP---+Regional | | +-----+ | |Agg | | || | |ONT| +---+ NSP---+Regional | | +-----+ | |Agg | | || | |ONT| +---+
| | | | | | | || | | or|-|HGW| | | | | | | | || | | or|-|HGW|
|Broadband| | +-----+ | +-----+ +----+| | |ONU| +---+ |Broadband| | +-----+ | +-----+ +----+| | |ONU| +---+
|Network |-+-|NAS | +----------------+ | | | |Network |-+-|NAS | +----------------+ | | |
ASP---+ | | +-----+ | | | +---+ ASP---+ | | +-----+ | | | +---+
| | | +-----+ | | |-|HGW| | | | +-----+ | | |-|HGW|
+---------+ +-|NAS | | +---+ +---+ +---------+ +-|NAS | | +---+ +---+
+-----+ | +-----+ |
| +---+ +---+ | +---+ +---+
+-|ONT|-|HGW| +-|ONT|-|HGW|
+---+ +---+ +---+ +---+
Figure 2: FTTP/FTTB/C with multi-subscriber ONT/ONU serving
MTUs/MDUs.
The following sections describe the functional blocks and network Figure 2: FTTP/FTTB/C with multi-subscriber ONT/ONU serving MTUs/MDUs.
segments in the PON access reference architecture. The following sections describe the functional blocks and network
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 Customer Premises
Equipment (CPE) to the ANX and the access network. In case of Equipment (CPE) to the ANX and the access network. In case of PON,
PON, the HGW is a layer 3 router. In this case, the HGW performs the HGW is a layer 3 router. In this case, the HGW performs IP
IP configuration of devices within the home via DHCP, and configuration of devices within the home via DHCP, and performs
performs Network Address and Port Translation (NAPT) between the Network Address and Port Translation (NAPT) between the LAN and WAN
LAN and WAN side. In case of FTTP/B/C, the HGW connects to the side. In case of FTTP/B/C, the HGW connects to the ONT/ONU over an
ONT/ONU over an Ethernet interface. That Ethernet interface could Ethernet interface. That Ethernet interface could be over an Ethernet
be over an Ethernet physical port or over another medium. In case physical port or over another medium. In case of FTTP, it is possible
of FTTP, it is possible to have a single box GPON CPE solution, to have a single box GPON CPE solution, where the ONT encompasses the
where the ONT encompasses the HGW functionality as well as the HGW functionality as well as the GPON adaptation function.
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 connectivity between the ONT/ONU at the customer physical connectivity between the ONT/ONU at the customer
premises and the OLT. PON framing can be BPON (in case of BPON) premises and the OLT. PON framing can be BPON (in case of BPON)
or GPON (in case of GPON). The protocol encapsulation on BPON is or GPON (in case of GPON). The protocol encapsulation on BPON is
based on multi-protocol encapsulation over AAL5, defined in based on multi-protocol encapsulation over AAL5, defined in
[RFC2684]. This covers PPP over Ethernet (PPPoE, defined in [RFC2684]. This covers PPP over Ethernet (PPPoE, defined in
[RFC2516]), or bridged IP (IPoE). The protocol encapsulation on [RFC2516]), or bridged IP (IPoE). The protocol encapsulation on
GPON is always IPoE. In all cases, the connection between the AN GPON is always IPoE. In all cases, the connection between the AN
(OLT) and the NAS (or BNG) is assumed to be Ethernet in this (OLT) and the NAS (or BNG) is assumed to be 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. This 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 requirements for the ANX uplink are to provide traffic aggregation,
aggregation, Class of Service distinction and customer separation Class of Service distinction and customer separation and
and traceability. This can be achieved using an ATM or an traceability. This can be achieved using an ATM or an Ethernet based
Ethernet based technology. The focus in this document is on technology. The focus in this document is on Ethernet as stated
Ethernet as stated earlier. earlier.
4.1.5. Aggregation Network 4.1.5. Aggregation Network
The aggregation network provides traffic aggregation towards the The aggregation network provides traffic aggregation towards the NAS.
NAS. The Aggregation network is assumed to be Ethernet in this The Aggregation network is assumed to be Ethernet in this document.
document.
4.1.6. Network Access Server 4.1.6. Network Access Server
The NAS is a network device which aggregates multiplexed The NAS is a network device which aggregates multiplexed Subscriber
Subscriber traffic from a number of ANXs. The NAS plays a central traffic from a number of ANXs. The NAS plays a central role in per-
role in per-subscriber policy enforcement and QoS. It is often subscriber policy enforcement and QoS. It is often referred to as a
referred to as a Broadband Network Gateway (BNG) or Broadband Broadband Network Gateway (BNG) or Broadband Remote Access Server
Remote Access Server (BRAS). A detailed definition of the NAS is (BRAS). A detailed definition of the NAS is given in [RFC2881]. The
given in [RFC2881]. The NAS interfaces to the aggregation network NAS interfaces to the aggregation network by means of 802.1Q or 802.1
by means of 802.1Q or 802.1 Q-in-Q Ethernet interfaces, and Q-in-Q Ethernet interfaces, and towards the Regional Network by means
towards the Regional Network by means of transport interfaces of transport interfaces (e.g., GigE, PPP over SONET). The NAS
(e.g., GigE, PPP over SONET). The NAS functionality corresponds functionality corresponds to the BNG functionality described in
to the BNG functionality described in BroadBand Forum (BBF) TR- BroadBand Forum (BBF) TR-101 [TR-101]. In addition, the NAS supports
101 [TR-101]. In addition, the NAS supports the Access Node the Access Node Control functionality defined for the respective use
Control functionality defined for the respective use cases in cases in this document.
this document.
4.1.7. Regional Network 4.1.7. Regional Network
The Regional Network connects one or more NAS and associated The Regional Network connects one or more NAS and associated Access
Access Networks to Network Service Providers (NSPs) and Networks to Network Service Providers (NSPs) and Application Service
Application Service Providers (ASPs). The NSP authenticates Providers (ASPs). The NSP authenticates access and provides and
access and provides and manages the IP address to Subscribers. It manages the IP address to Subscribers. It is responsible for overall
is responsible for overall service assurance and includes service assurance and includes Internet Service Providers (ISPs). The
Internet Service Providers (ISPs). The ASP provides application ASP provides application services to the application Subscriber
services to the application Subscriber (gaming, video, content on (gaming, video, content on demand, IP telephony, etc.). The NAS can
demand, IP telephony, etc.). The NAS can be part of the NSP be part of the NSP network. Similarly, the NSP can be the ASP.
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 Section 3 details the differences between xDSL access and PON access
access and the implication of these differences on DSLAM control and the implication of these differences on DSLAM control vs. OLT and
vs. OLT and ONT/ONU (access node complex (ANX)) control. The ONT/ONU (access node complex (ANX)) control. The following sections
following sections describe two reference models: (1) ANCP+OMCI describe two reference models: (1) ANCP+OMCI ANX control, and (2)
ANX control, and (2) all-ANCP ANX control. That is, the two all-ANCP ANX control. That is, the two models differ in the ONT/ONU
models differ in the ONT/ONU control within the ANX. control within the ANX. Implementations, out of the scope of this
Implementations, out of the scope of this document, may choose to document, may choose to implement one or the other based on the
implement one or the other based on the ONT/ONU type and the ONT/ONU type and the capabilities of the ONT/ONU and OLT. It is
capabilities of the ONT/ONU and OLT. It is possible for an OLT or possible for an OLT or an OLT PON port to connect to ONTs/ONUs with
an OLT PON port to connect to ONTs/ONUs with different different capabilities and for these two models to co-exist on the
capabilities and for these two models to co-exist on the same OLT same OLT and same PON. Section 12 describes the differences between
and same PON. Section 12 describes the differences between OMCI OMCI and ANCP in controlling the ONU/ONT.
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 XPON. 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. It enables the NAS to enforce
dynamic policies on the access node, and the access node to dynamic policies on the access node, and the access node to report
report events to the NAS among other functions. events to the NAS among other functions.
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. Figure 3 depicts the reference model for ANCP+OMCI ANX control. In
In this model, ANCP is enabled between the NAS and a connected this model, ANCP is enabled between the NAS and a connected OLT, and
OLT, and OMCI is enabled between the OLT and an attached ONT/ONU. OMCI is enabled between the OLT and an attached ONT/ONU. NAS
NAS communicates with the ANX via ANCP. The OLT acts as an communicates with the ANX via ANCP. The OLT acts as an ANCP/OMCI
ANCP/OMCI gateway for communicating necessary events and policies gateway for communicating necessary events and policies between the
between the OLT and ONT/ONU within the ANX and for communicating OLT and ONT/ONU within the ANX and for communicating relevant
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 ANCP/OMCI gateway will be
application dependent (e.g., multicast control, topology application dependent (e.g., multicast control, topology discovery)
discovery) and should be specified in a related specification. It and should be specified in a related specification. It should be
should be noted that some applications are expected to require noted that some applications are expected to require ANCP and/or OMCI
extensions. Such extensions are expected to be outside of ANCP extensions to map messages between OMCI and ANCP. OMCI extensions are
scope, and may need to be defined by the ITU-T. It should be likely to be defined by the ITU-T. It should also be noted that OMCI,
noted that OMCI, in addition to configuration and administration, in addition to configuration and administration, provides the
provides the capability to report status changes on an ONT/ONU capability to report status changes on an ONT/ONU with AVC (Attribute
with AVC (Attribute Value Change) notifications. When ONT/ONU's Value Change) notifications. When ONT/ONU's DSL or Ethernet UNI
DSL or Ethernet UNI attributes change, a related ME (management attributes change, a related ME (management Entity) will send a
Entity) will send a corresponding notification (AVC) to the OLT. corresponding notification (AVC) to the OLT. The OLT interworks such
The OLT interworks such notification into an ANCP report and notification into an ANCP report and sends it to the connected NAS
sends it to the connected NAS via the ANCP session between the via the ANCP session between the OLT and the NAS. As the ANCP report
OLT and the NAS. As the ANCP report contains information of contains information of ONT/ONU's UNI and OLT's PON port, NAS can
ONT/ONU's UNI and OLT's PON port, NAS can obtain accurate obtain accurate information of access topology.
information of access topology. +----------------------+
| ANX |
+----------------------+ +---------+ +---+ +---+ |+---+ +-------+ | +---+
| ANX | | | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT|-|-|HGW|
+---------+ +---+ +---+ |+---+ +-------+ | +---+ NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+
| | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT|-|-|HGW| |Broadband| | +---+ +---+ +----------------------+
NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+ |Network |-+-|NAS| |
|Broadband| | +---+ +---+ +----------------------+ ASP---+ | | +---+ |
|Network |-+-|NAS| | | | | +---+ |
ASP---+ | | +---+ | +---------+ +-|NAS| | +-------+ +---+
| | | +---+ | +---| +-<PON>-|ONU/ONT|-|HGW|
+---------+ +-|NAS| | +-------+ +---+ | +-------+ +---+
+---| +-<PON>-|ONU/ONT|-|HGW| | +---+ +---+
| +-------+ +---+ +--|ONT|-----|HGW|
| +---+ +---+ +---+ +---+
+--|ONT|-----|HGW| ANCP OMCI
+---+ +---+ +<--------------->+<----------->+
ANCP OMCI
+<--------------->+<----------->+
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
ONU: Optical Network Unit ONU: Optical Network Unit
Figure 3: Access Network with single ANCP+OMCI access control Figure 3: Access Network with single ANCP+OMCI access control
4.2.2. All-ANCP ANX Control 4.2.2. All-ANCP ANX Control
Figure 4 depicts the All-ANCP ANX control reference model. In Figure 4 depicts the All-ANCP ANX control reference model. In this
this model, an ANCP session is enabled between a NAS and a model, an ANCP session is enabled between a NAS and a connected OLT,
connected OLT, and another ANCP session is enabled between the and another ANCP session is enabled between the OLT and a connected
OLT and a connected ONT/ONU. ANCP enables communication of ONT/ONU. ANCP enables communication of policies and events between
policies and events between the OLT and the ANX. The OLT acts as the OLT and the ANX. The OLT acts as a gateway to relay policies and
a gateway to relay policies and events between the NAS and events between the NAS and ONT/ONU within the ANX in addition to
ONT/ONU within the ANX in addition to communicating policies and communicating policies and events between the OLT and ONT/ONU. It
events between the OLT and ONT/ONU. It should be noted that in should be noted that in this model, OMCI(not shown) is expected to be
this model, OMCI(not shown) is expected to be simultaneously simultaneously enabled between the ONT and OLT, supporting existing
enabled between the ONT and OLT, supporting existing OMCI OMCI capabilities and applications on the PON, independent of ANCP or
capabilities and applications on the PON, independent of ANCP or applications intended to be supported by ANCP.
applications intended to be supported by ANCP.
+----------------------+ +----------------------+
| Access Node Complex | | Access Node Complex |
| (ANX) | | (ANX) |
+---------+ +---+ +---+ |+---+ +-------+ | +---+ +---------+ +---+ +---+ |+---+ +-------+ | +---+
| | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT| |--|HGW| | | +-|NAS|--|Eth|--||OLT|-<PON>-|ONU/ONT| |--|HGW|
NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+ NSP---+Regional | | +---+ |Agg| |+---+ +-------+ | +---+
|Broadband| | +---+ +---+ +----------------------+ |Broadband| | +---+ +---+ +----------------------+
|Network |-+-|NAS| | |Network |-+-|NAS| |
ASP---+ | | +---+ | ASP---+ | | +---+ |
| | | +---+ | | | | +---+ |
+---------+ +-|NAS| | +-------+ +---+ +---------+ +-|NAS| | +-------+ +---+
+---| +-<PON>-|ONU/ONT|--|HGW| +---| +-<PON>-|ONU/ONT|--|HGW|
| +-------+ +---+ | +-------+ +---+
| |
| +-------+ +---+ | +-------+ +---+
+---|ONU/ONT|--|HGW| +---|ONU/ONT|--|HGW|
+-------+ +---+ +-------+ +---+
ANCP ANCP ANCP ANCP
+<----------------->+<---------->+ +<----------------->+<---------->+
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
ONU: Optical Network Unit ONU: Optical Network Unit
Figure 4: All-ANCP ANX Reference Model Figure 4: All-ANCP ANX Reference Model
5. Concept of Access Node Control Mechanism for PON Based 5. Concept of Access Node Control Mechanism for PON Based Access
Access
The high-level communication framework for an Access Node Control The high-level communication framework for an Access Node Control
mechanism is shown in Figure 5 for the ALL-ANCP ANX control mechanism is shown in Figure 5 for the ALL-ANCP ANX control model.
model. The Access Node Control mechanism defines a quasi real- The Access Node Control mechanism defines a quasi real-time, general-
time, general-purpose method for multiple network scenarios with purpose method for multiple network scenarios with an extensible
an extensible communication scheme, addressing the different use communication scheme, addressing the different use cases that are
cases that are described in the sections that follow. The access described in the sections that follow. The access node control
node control mechanism is also extended to run between OLT and mechanism is also extended to run between OLT and ONT/ONU. The
ONT/ONU. The mechanism consists of control function, and mechanism consists of control function, and reporting and/or
reporting and/or enforcement function. Controller function is enforcement function. Controller function is used to receive status
used to receive status information or admission requests from the information or admission requests from the reporting function. It is
reporting function. It is also used to trigger a certain behavior also used to trigger a certain behavior in the network element where
in the network element where the reporting and/or enforcement the reporting and/or enforcement function resides.
function resides.
The reporting function is used to convey status information to The reporting function is used to convey status information to the
the controller function that requires the information for controller function that requires the information for executing local
executing local functions. The enforcement function can be functions. The enforcement function can be contacted by the
contacted by the controller function to enforce a specific policy controller function to enforce a specific policy or trigger a local
or trigger a local action. The messages shown in Figure 5 show action. The messages shown in Figure 5 show the conceptual message
the conceptual message flow. The actual use of these flows, and flow. The actual use of these flows, and the times or frequencies
the times or frequencies when these messages are generated depend when these messages are generated depend on the actual use cases,
on the actual use cases, which are described in later sections. which are described in later sections.
+--------+ +--------+
| Policy | +----+ | Policy | +----+
| Server | +--<PON>---|ONT |------- HGW | Server | +--<PON>---|ONT |------- HGW
+--------+ + +----+ +---+ +--------+ + +----+ +---+
| + +----------|ONT|----HGW | + +----------|ONT|----HGW
| + | +---+ | + | +---+
| +----------------|-------------+ | +----------------|-------------+
+----+ | +----+ | +-----+ | +---+ +----+ | +----+ | +-----+ | +---+
|NAS |---------------| | | | |-|----|HGW| |NAS |---------------| | | | |-|----|HGW|
| |<------------->| | | | ONU | | +---+ | |<------------->| | | | ONU | | +---+
+----+ ANCP | |OLT |------<PON>----| | | +----+ ANCP | |OLT |------<PON>----| | |
| | | | | | | +---+ | | | | | | | +---+
| | | |<------------->| |------|HGW| | | | |<------------->| |------|HGW|
| | +----+ ANCP +-----+ | +---+ | | +----+ ANCP +-----+ | +---+
| +------------------------------+ | +------------------------------+
| | Access Node | | | Access Node |
| Control Request | | | Control Request | |
| ------------------>| Control Request | | ------------------>| Control Request |
| |-------------------->| | |-------------------->|
| | Control Response | | | Control Response |
| Control Response |<------------------- | | Control Response |<------------------- |
|<-------------------| | |<-------------------| |
| |Admission Request | | |Admission Request |
| Admission Request |<--------------------| | Admission Request |<--------------------|
|<-------------------| | |<-------------------| |
|Admission Response | | |Admission Response | |
|------------------->|Admission Response | |------------------->|Admission Response |
| |-------------------->| | |-------------------->|
|Information Report | | |Information Report | |
|<-------------------| | |<-------------------| |
Access Node Control Access Node Control Access Node Control Access Node Control
Mechanism Mechanism Mechanism Mechanism
<--------------------><--------------------> <--------------------><-------------------->
PPP, DHCP, IP
<------------------------------------------------------>
PPP, DHCP, IP Figure 5: Conceptual message flow for Access Node Control mechanism
<------------------------------------------------------> in all-ANCP ANX control model.
Figure 5: Conceptual message flow for Access Node Control As discussed previously, in different PON deployment scenarios, ANCP
mechanism in all-ANCP ANX control model. may be used in variant ways and may interwork with other protocols,
e.g., OMCI. In the ANCP+OMCI model described earlier, the NAS
maintains ANCP adjacency with the OLT while the OLT controls the
ONT/ONU via OMCI. The messages shown in Figure 6 show the conceptual
message flow for this model. The actual use of these flows, and the
times or frequencies when these messages are generated depend on the
actual use cases.
As discussed previously, in different PON deployment scenarios, +--------+
ANCP may be used in variant ways and may interwork with other | Policy |
protocols, e.g., OMCI. In the ANCP+OMCI model described earlier, | Server |
the NAS maintains ANCP adjacency with the OLT while the OLT +--------+ +---+ +---+
controls the ONT/ONU via OMCI. The messages shown in Figure 6 | +---- |ONT|--------|HGW|
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 | |
|<-------------------| |
ANCP Mechanoism OMCI
<--------------------><-------------------->
PPP, DHCP, IP
<------------------------------------------------------->
Figure 6: Conceptual Message Flow for ANCP+OMCI ANX control model. Figure 6: Conceptual Message Flow for ANCP+OMCI ANX control model.
6. Multicast 6. Multicast
With the rise of supporting IPTV services in a resource-efficient With the rise of supporting IPTV services in a resource-efficient
way, multicast services are becoming increasingly important. way, multicast services are becoming increasingly important.
In order to gain bandwidth optimization with multicast, the In order to gain bandwidth optimization with multicast, the
replication of multicast content per access-loop needs to be replication of multicast content per access-loop needs to be
distributed to the ANX. This can be done by ANX (OLT and ONT/ONU) distributed to the ANX. This can be done by ANX (OLT and ONT/ONU)
becoming multicast aware by implementing an IGMP snooping and/or becoming multicast aware by implementing an IGMP [RFC3376]
proxy function. The replication thus needs to be distributed snooping and/or proxy function [RFC4605]. The replication thus needs
between NAS, aggregation nodes, and ANX. In case of GPON, and in to be distributed between NAS, aggregation nodes, and ANX. In case of
case of BPON with Ethernet uplink, this is very viable. By GPON, and in case of BPON with Ethernet uplink, this is very viable.
introducing IGMP processing on the ANX and aggregation nodes, the By introducing IGMP processing on the ANX and aggregation nodes, the
multicast replication process is now divided between the NAS, the multicast replication process is now divided between the NAS, the
aggregation node(s) and ANX. This is in contrast to the ATM-based aggregation node(s) and ANX. This is in contrast to the ATM-based
model where NAS is the single element responsible for all model where NAS is the single element responsible for all multicast
multicast control and replication. In order to ensure backward control and replication. In order to ensure backward compatibility
compatibility with the ATM-based model, the NAS, aggregation node with the ATM-based model, the NAS, aggregation node and ANX need to
and ANX need to behave as a single logical device. This logical behave as a single logical device. This logical device must have
device must have exactly the same functionality as the NAS in the exactly the same functionality as the NAS in the ATM
ATM access/aggregation network. The Access Node Control Mechanism access/aggregation network. The Access Node Control Mechanism can be
can be used to make sure that this logical/functional equivalence used to make sure that this logical/functional equivalence is
is achieved by exchanging the necessary information between the achieved by exchanging the necessary information between the ANX and
ANX and the NAS. the NAS.
An alternative to multicast awareness in the ANX is for the An alternative to multicast awareness in the ANX is for the
subscriber to communicate the IGMP "join/leave" messages with the subscriber to communicate the IGMP "join/leave" messages with the
NAS, while the ANX is being transparent to these messages. In NAS, while the ANX is being transparent to these messages. In this
this scenario, the NAS can use ANCP to create replication state scenario, the NAS can use ANCP to create replication state in the ANX
in the ANX for efficient multicast replication. The NAS sends a for efficient multicast replication. The NAS sends a single copy of
single copy of the multicast stream towards the ANX. The NAS can the multicast stream towards the ANX. The NAS can perform network-
perform network-based conditional access and multicast admission based conditional access and multicast admission control on multicast
control on multicast joins, and create replication state in the joins, and create replication state in the ANX if the request is
ANX if the request is admitted by the NAS. admitted by the NAS.
The following sections describe various use cases related to The following sections describe various use cases related to
multicast. multicast.
6.1. Multicast Conditional Access 6.1. Multicast Conditional Access
In a Broadband FTTP/B/C access scenario, Service Providers may In a Broadband FTTP/B/C access scenario, Service Providers may want
want to dynamically control, at the network level, access to some to dynamically control, at the network level, access to some
multicast flows on a per user basis. This may be used in order to multicast flows on a per user basis. This may be used in order to
differentiate among multiple Service Offers or to differentiate among multiple Service Offers or to realize/reinforce
realize/reinforce conditional access based on customer conditional access based on customer subscription. Note that, in some
subscription. Note that, in some environments, application layer environments, application layer conditional access by means of
conditional access by means of Digital Rights Management (DRM) Digital Rights Management (DRM) for instance may provide sufficient
for instance may provide sufficient control so that network-based control so that network-based Multicast conditional access may not be
Multicast conditional access may not be needed. However, network needed. However, network level access control may add to the service
level access control may add to the service security by security by preventing the subscriber from receiving a non-subscribed
preventing the subscriber from receiving a non-subscribed channel. In addition, it enhances network security by preventing a
channel. In addition, it enhances network security by preventing multicast stream from being sent on a link or a PON based on a non-
a multicast stream from being sent on a link or a PON based on a subscriber request.
non-subscriber request.
Where network-based channel conditional access is desired, there Where network-based channel conditional access is desired, there are
are two approaches. It can be done on the NAS along with two approaches. It can be done on the NAS along with bandwidth-based
bandwidth-based admission control. The NAS can control the admission control. The NAS can control the replication state on the
replication state on the ANX based on the outcome of access and ANX based on the outcome of access and bandwidth based admission
bandwidth based admission control. This is covered in a later control. This is covered in a later section. The other approach is to
section. The other approach is to provision the necessary provision the necessary conditional access information on the ANX
conditional access information on the ANX (ONT/ONU and/or OLT) so (ONT/ONU and/or OLT) so the ANX can perform the conditional access
the ANX can perform the conditional access decisions decisions autonomously. For these cases, the NAS can use ANCP to
autonomously. For these cases, the NAS can use ANCP to provision provision black and white lists as defined in [RFC5851] on the ANX so
black and white lists as defined in [RFC5851] on the ANX so that that the ANX can decide locally to honor a join or not. It should be
the ANX can decide locally to honor a join or not. It should be noted that in the PON case, the ANX is composed of the ONT/ONU and
noted that in the PON case, the ANX is composed of the ONT/ONU OLT. Thus, this information can be programmed on the ONT/ONU and/or
and OLT. Thus, this information can be programmed on the ONT/ONU OLT. Programming this information on the ONT/ONU prevents
and/or OLT. Programming this information on the ONT/ONU prevents illegitimate joins from propagating further into the network. A third
illegitimate joins from propagating further into the network. A approach, outside of the scope, may be to program the HGW with the
third approach, outside of the scope, may be to program the HGW access list. A White list associated with an Access Port identifies
with the access list. A White list associated with an Access Port the multicast channels that are allowed to be replicated to that
identifies the multicast channels that are allowed to be port. A Black list associated with an Access Port identifies the
replicated to that port. A Black list associated with an Access multicast channels that are not allowed to be replicated to that
Port identifies the multicast channels that are not allowed to be port. It should be noted that the black list if not explicitly
replicated to that port. It should be noted that the black list programmed is the complement of the white list and vice versa.
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 If the ONT/ONU performs IGMP snooping and it is programmed with a
channel access list, the ONT/ONU will first check if the channel access list, the ONT/ONU will first check if the requested
requested multicast channel is part of a White list or a Black multicast channel is part of a White list or a Black list associated
list associated with the access port on which the IGMP join is with the access port on which the IGMP join is received. If the
received. If the channel is part of a White list, the ONT/ONU channel is part of a White list, the ONT/ONU will pass the join
will pass the join request upstream towards the NAS. The ONT/ONU request upstream towards the NAS. The ONT/ONU must not start
must not start replicating the associated multicast stream to the replicating the associated multicast stream to the access port if
access port if such a stream is received until it gets such a stream is received until it gets confirmation that it can do
confirmation that it can do so from the upstream node (NAS or so from the upstream node (NAS or OLT). Passing the channel access
OLT). Passing the channel access list is one of the admission list is one of the admission control criteria whereas bandwidth-based
control criteria whereas bandwidth-based admission control is admission control is another. If the channel is part of a Black list,
another. If the channel is part of a Black list, the ONT/ONU can the ONT/ONU can autonomously discard the message because the channel
autonomously discard the message because the channel is not is not authorized for that subscriber.
authorized for that subscriber.
The ONT/ONU, in addition to forwarding the IGMP join, sends an The ONT/ONU, in addition to forwarding the IGMP join, sends an ANCP
ANCP admission request to the OLT identifying the channel to be admission request to the OLT identifying the channel to be joined and
joined and the premises. Premises identification to the OLT can the premises. Premises identification to the OLT can be based on a
be based on a Customer-Port-ID that maps to the access port on Customer-Port-ID that maps to the access port on the ONT/ONU and
the ONT/ONU and known at the ONT/ONU and OLT. If the ONT/ONU has known at the ONT/ONU and OLT. If the ONT/ONU has a white list and/or
a white list and/or a black list per premises, the OLT need not a black list per premises, the OLT need not have such a list. If the
have such a list. If the ONT/ONU does not have such a list, the ONT/ONU does not have such a list, the OLT may be programmed with
OLT may be programmed with such a list for each premises. In this such a list for each premises. In this latter case, the OLT would
latter case, the OLT would perform the actions described earlier perform the actions described earlier on the ONT/ONU. Once the
on the ONT/ONU. Once the outcome of admission control outcome of admission control (conditional access and bandwidth based
(conditional access and bandwidth based admission control) is admission control) is determined by the OLT (either by interacting
determined by the OLT (either by interacting with the NAS or with the NAS or locally), it is informed to the ONT/ONU. OLT
locally), it is informed to the ONT/ONU. OLT Bandwidth based Bandwidth based admission control scenarios are defined in a later
admission control scenarios are defined in a later section. section.
The White List and Black List can contain entries allowing:
- An exact match for a (*,G) Any Source Multicast (ASM) The White List and Black List can contain entries allowing:
group (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
(SSM)channel (e.g., <S=s.t.u.v,G=g.h.i.l>); (e.g., <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
<G=g.h.i.l/Mask>); (SSM)channel (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 <S=s.t.u.v,G=g.h.i.l/Mask>);
by an Access Provider to broadband (e.g., FTTP) subscribers. For
this application, the IPTV subscription is typically bound to a
specific FTTP home, and the multicast channels that are part of
the subscription are well-known beforehand. Furthermore, changes
to the conditional access information are infrequent, since they
are bound to the subscription. Hence the ANX can be provisioned
with the conditional access information related to the IPTV
service.
Instead of including the channel list(s) at the ONT/ONU, the OLT The use of a White list and Black list may be applicable, for
or NAS can be programmed with these access lists. Having these instance, to regular IPTV services (i.e., Broadcast TV) offered by an
access lists on the ONT/ONU prevents forwarding of unauthorized Access Provider to broadband (e.g., FTTP) subscribers. For this
joins to the OLT or NAS, reducing unnecessary control load on application, the IPTV subscription is typically bound to a specific
these network elements. Similarly, performing the access control FTTP home, and the multicast channels that are part of the
at the OLT instead of the NAS, if not performed on the ONT/ONU, subscription are well-known beforehand. Furthermore, changes to the
will reduce unnecessary 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.
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.
6.2. Multicast Admission Control 6.2. Multicast Admission Control
The successful delivery of Triple Play Broadband services is The successful delivery of Triple Play Broadband services is quickly
quickly becoming a big capacity planning challenge for most of becoming a big capacity planning challenge for most of the Service
the Service Providers nowadays. Solely increasing available Providers nowadays. Solely increasing available bandwidth is not
bandwidth is not always practical, cost-economical and/or always practical, cost-economical and/or sufficient to satisfy end-
sufficient to satisfy end-user experience given not only the user experience given not only the strict QoS requirements of unicast
strict QoS requirements of unicast applications like VoIP and applications like VoIP and Video on Demand, but also the fast growth
Video on Demand, but also the fast growth of multicast of multicast interactive applications such as "video conferencing",
interactive applications such as "video conferencing", digital digital TV, and digital audio. These applications typically require
TV, and digital audio. These applications typically require low low delay, low jitter, low packet loss and high bandwidth. These
delay, low jitter, low packet loss and high bandwidth. These applications are also typically "non-elastic", which means that they
applications are also typically "non-elastic", which means that operate at a fixed bandwidth, which cannot be dynamically adjusted to
they operate at a fixed bandwidth, which cannot be dynamically the currently available bandwidth.
adjusted to the currently available bandwidth.
An Admission Control (AC) mechanism covering admission of An Admission Control (AC) mechanism covering admission of multicast
multicast traffic for the FTTP/B/C access is required in order to traffic for the FTTP/B/C access is required in order to avoid over-
avoid over-subscribing the available bandwidth and negatively subscribing the available bandwidth and negatively impacting the end-
impacting the end-user experience. Before honoring a user request user experience. Before honoring a user request to join a new
to join a new multicast flow, the combination of ANX and NAS must multicast flow, the combination of ANX and NAS must ensure admission
ensure admission control is performed to validate that there is control is performed to validate that there is enough video bandwidth
enough video bandwidth remaining on the PON, and on the uplink remaining on the PON, and on the uplink between the OLT and NAS to
between the OLT and NAS to carry the new flow (in addition to all carry the new flow (in addition to all other existing multicast and
other existing multicast and unicast video traffic) and that unicast video traffic) and that there is enough video bandwidth for
there is enough video bandwidth for the subscriber to carry that the subscriber to carry that flow. The solution needs to cope with
flow. The solution needs to cope with multiple flows per premises multiple flows per premises and needs to allow bandwidth to be
and needs to allow bandwidth to be dynamically shared across dynamically shared across multicast and unicast video traffic per
multicast and unicast video traffic per subscriber, PON, and subscriber, PON, and uplink (irrespective of whether unicast AC is
uplink (irrespective of whether unicast AC is performed by the performed by the NAS, or by some off-path Policy Server). It should
NAS, or by some off-path Policy Server). It should be noted that be noted that the shared bandwidth between multicast and unicast
the shared bandwidth between multicast and unicast video is under video is under operator control. That is, in addition to the shared
operator control. That is, in addition to the shared bandwidth, bandwidth, some video bandwidth could be dedicated to Video on
some video bandwidth could be dedicated to Video on Demand, while Demand, while other video bandwidth could be dedicated for multicast.
other video bandwidth could be dedicated for multicast.
The focus in this document will be on multicast-allocated The focus in this document will be on multicast-allocated bandwidth
bandwidth including the shared unicast and multicast bandwidth. including the shared unicast and multicast bandwidth. Thus,
Thus, supporting admission control requires some form of supporting admission control requires some form of synchronization
synchronization between the entities performing multicast AC between the entities performing multicast AC (e.g., the ANX and/or
(e.g., the ANX and/or NAS), the entity performing unicast AC NAS), the entity performing unicast AC (e.g., the NAS or a Policy
(e.g., the NAS or a Policy Server), and the entity actually Server), and the entity actually enforcing the multicast replication
enforcing the multicast replication (i.e., the NAS and the ANX). (i.e., the NAS and the ANX). This synchronization can be achieved in
This synchronization can be achieved in a number of ways: a number of ways:
- One approach is for the NAS to perform bandwidth based - One approach is for the NAS to perform bandwidth based
admission control on all multicast video traffic and admission control on all multicast video traffic and unicast
unicast video traffic that requires using the shared video traffic that requires using the shared bandwidth with
bandwidth with multicast. Based on the outcome of admission multicast. Based on the outcome of admission control, NAS then
control, NAS then controls the replication state on the controls the replication state on the ANX. The subscriber
ANX. The subscriber generates an IGMP join for the desired generates an IGMP join for the desired stream on its logical
stream on its logical connection to the NAS. The NAS connection to the NAS. The NAS terminates the IGMP message, and
terminates the IGMP message, and performs conditional performs conditional access and bandwidth based admission
access and bandwidth based admission control on the IGMP control on the IGMP request. The bandwidth admission control is
request. The bandwidth admission control is performed performed against the following:
against the following:
1. Available video bandwidth on the link to OLT 1. Available video bandwidth on the link to OLT
2. Available video bandwidth on the PON interface
3. Available video bandwidth on the last mile (access-port
on the ONT/ONU).
The NAS can locally maintain and track video bandwidth it manages 2. Available video bandwidth on the PON interface
for all the three levels mentioned above. The NAS can maintain
identifiers corresponding to the PON interface and the last mile
(customer interface). It also maintains a channel map,
associating every channel (or a group of channels sharing the
same bandwidth requirement) with a data rate. For instance, in
case of 1:1 VLAN representation of the premises, the outer tag
(S-VLAN) could be inserted by the ANX to correspond to the PON
interface on the OLT, and the inner-tag could be inserted by the
ANX to correspond to the access-line towards the customer.
Bandwidth tracking and maintenance for the PON interface and the
last-mile could be done on these VLAN identifiers. In case of N:1
representation, the single VLAN inserted by ANX could correspond
to the PON interface on the OLT. The access loop is represented
via Customer-Port-ID received in "Agent Circuit Identifier" sub-
option in DHCP messages.
The NAS can perform bandwidth accounting on received IGMP 3. Available video bandwidth on the last mile (access-port on
messages. The video bandwidth is also consumed by any unicast the ONT/ONU).
video being delivered to the CPE. NAS can perform video bandwidth
accounting and control on both IGMP messages and on requests for
unicast video streams when either all unicast admission control
is done by the NAS or an external policy server makes a request
to the NAS for using shared bandwidth with multicast as described
later in the document.
This particular scenario assumes the NAS is aware of the The NAS can locally maintain and track video bandwidth it manages for
bandwidth on the PON, and under all conditions can track the all the three levels mentioned above. The NAS can maintain
changes in available bandwidth on the PON. On receiving an IGMP identifiers corresponding to the PON interface and the last mile
Join message, NAS will perform bandwidth check on the subscriber (customer interface). It also maintains a channel map, associating
bandwidth. If this passes, and the stream is already being every channel (or a group of channels sharing the same bandwidth
forwarded on the PON by the OLT (which also means that it is requirement) with a data rate. For instance, in case of 1:1 VLAN
already forwarded by the NAS to the OLT), NAS will admit the representation of the premises, the outer tag (S-VLAN) could be
JOIN, update the available subscriber bandwidth, and transmit an inserted by the ANX to correspond to the PON interface on the OLT,
ANCP message to the OLT and in turn to the ONT/ONU to start and the inner-tag could be inserted by the ANX to correspond to the
replication on the customer port. If the stream is not already access-line towards the customer. Bandwidth tracking and maintenance
being replicated to the PON by the OLT, the NAS will also check for the PON interface and the last-mile could be done on these VLAN
the available bandwidth on the PON, and if it is not already identifiers. In case of N:1 representation, the single VLAN inserted
being replicated to the OLT it will check the bandwidth on the by ANX could correspond to the PON interface on the OLT. The access
link towards the OLT. If this passes, the available PON bandwidth loop is represented via Customer-Port-ID received in "Agent Circuit
and the bandwidth on the link towards the OLT are updated. The Identifier" sub-option in DHCP messages.
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.
+----+ The NAS can perform bandwidth accounting on received IGMP messages.
+---<PON>---------- |ONT |------ HGW The video bandwidth is also consumed by any unicast video being
+ +----+ delivered to the CPE. NAS can perform video bandwidth accounting and
+ +----+ control on both IGMP messages and on requests for unicast video
+ +--------- |ONT |------ HGW streams when either all unicast admission control is done by the NAS
+----+ +----+ + +----+ or an external policy server makes a request to the NAS for using
|NAS |---------------| |------<PON> shared bandwidth with multicast as described later in the document.
| |<------------->| | + +-----+
+----+ 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
orwarded on |
Customer-Port by|
|ONT/OLT. |
| |
Figure 7: Interactions for NAS based Multicast Admission Control This particular scenario assumes the NAS is aware of the bandwidth on
(no IGMP processing on ANX, and NAS maintains available video the PON, and under all conditions can track the changes in available
bandwidth for PON) upon channel join. bandwidth on the PON. On receiving an IGMP Join message, NAS will
perform bandwidth check on the subscriber bandwidth. If this passes,
and the stream is already being forwarded on the PON by the OLT
(which also means that it is already forwarded by the NAS to the
OLT), NAS will admit the JOIN, update the available subscriber
bandwidth, and transmit an ANCP message to the OLT and in turn to the
ONT/ONU to start replication on the customer port. If the stream is
not already being replicated to the PON by the OLT, the NAS will also
check the available bandwidth on the PON, and if it is not already
being replicated to the OLT it will check the bandwidth on the link
towards the OLT. If this passes, the available PON bandwidth and the
bandwidth on the link towards the OLT 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.
+----+ +----+
+---<PON>---------- |ONT |----- HGW +---<PON>---------- |ONT |------ HGW
+ +----+ + +----+
+ +----+ + +----+
+ +--------- |ONT |----- HGW + +--------- |ONT |------ HGW
+----+ +----+ + +----+ +----+ +----+ + +----+
|NAS |---------------| |------<PON> |NAS |---------------| |------<PON>
| |<------------->| | + +-----+ | |<------------->| | + +-----+
+----+ ANCP |OLT | +--------- | |---- HGW +----+ ANCP |OLT | +--------- | |----- HGW
| | | | | | | | | |
| | |<------------------>| ONU |-----HGW | | |<------------------>| ONU |------HGW
| +----+ ANCP | | +---+ | +----+ ANCP | | +---+
| | | |-----|HGW| | | | |-----|HGW|
| | +-----+ +---+ | | +-----+ +---+
| | | | | 1.IGMP JOIN(S/*,G) | |
| IGMP LEAVE(S/*,G) | | |<---------------------------------------------------------- |
|<-----------------------------------------------------------| 2.| | | |
| | | | +=======================+ | |
+====================+ | | | [Access Control & ] | |
[Admission Control ] | | | [Subscriber B/W ] | |
[<Resource Released> ] | | | [PON B/W & OLT link B/W ] | |
+====================+ | | | [based Admission Control] | |
| | | | +=======================+ | |
| | | | | | | |
| | | | |-------------------> | | |
|-------------------> | | | 3.ANCP Replication-Start| | |
ANCP Replication-Stop | | | (<S/*,G> or Multicast | | |
(<S/*,G> or Multicast MAC,Customer-Port-ID) | | |MAC,Customer-Port-ID>| --------------------> | |
| | | | | |4.ANCP Replication-Start |
| |---------------------> | | | (<S/*,G> or Multicast MAC,Customer-Port-ID)
| | ANCP Replication-Stop | | |-------------------> | | |
(<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
orwarded on |
Customer-Port by|
|ONT/OLT. |
| |
Figure 8: Interactions for NAS based Multicast Admission Control Figure 7: Interactions for NAS based Multicast Admission Control (no
(no IGMP processing on ANX, and NAS maintains available video IGMP processing on ANX, and NAS maintains available video bandwidth
bandwidth for PON) upon channel leave. for PON) upon channel join.
- An alternate approach is required if the NAS is not aware +----+
of the bandwidth on the PON. In this case the OLT does the PON +---<PON>---------- |ONT |----- HGW
bandwidth management, and requests NAS to perform bandwidth + +----+
admission control on subscriber bandwidth and the bandwidth on + +----+
the link to the OLT. Following are operations of various + +--------- |ONT |----- HGW
elements: +----+ +----+ + +----+
|NAS |---------------| |------<PON>
| |<------------->| | + +-----+
+----+ ANCP |OLT | +--------- | |---- HGW
| | | | |
| | |<------------------>| ONU |-----HGW
| +----+ ANCP | | +---+
| | | |-----|HGW|
| | +-----+ +---+
| | | |
| IGMP LEAVE(S/*,G) | |
|<-----------------------------------------------------------|
| | | |
+====================+ | | |
[Admission Control ] | | |
[<Resource Released> ] | | |
+====================+ | | |
| | | |
| | | |
| | | |
|-------------------> | | |
ANCP Replication-Stop | | |
(<S/*,G> or Multicast MAC,Customer-Port-ID) | |
| | | |
| |---------------------> | |
| | ANCP Replication-Stop | |
(<S/*,G> or Multicast MAC,Customer-Port-ID)
ANX operation: Figure 8: Interactions for NAS based Multicast Admission Control (no
- ONT/ONU can snoop IGMP messages. If conditional access IGMP processing on ANX, and NAS maintains available video bandwidth
is configured and the channel is in the Black list (or it is not for PON) upon channel leave.
on the White list), ONT will drop the IGMP Join. If the channel
passes the conditional access check, the ONT will forward the
IGMP Join, and will send a bandwidth admission control request to
the OLT. In case the multicast stream is already being received
on the PON, the ONT/ONU does not forward the stream to the access
port where IGMP is received till it has received a positive
admission control response from the OLT.
- OLT can snoop IGMP messages. It also receives a bandwidth - An alternate approach is required if the NAS is not aware of
admission control request from the ONT/ONU for the requested the bandwidth on the PON. In this case the OLT does the PON bandwidth
channel. It can be programmed with a channel bandwidth map. If management, and requests NAS to perform bandwidth admission control
the multicast channel is already being streamed on the PON, or on subscriber bandwidth and the bandwidth on the link to the OLT.
the channel bandwidth is less than the multicast available Following are operations of various elements:
bandwidth on the PON, the OLT forwards the IGMP request to the
NAS and keeps track of the subscriber (identified by customer-
Port-ID) as a receiver. If the channel is not already being
streamed on the PON, but the PON has sufficient bandwidth for
that channel, the OLT reduces the PON multicast video bandwidth
by the channel bandwidth and may optionally add the PON to the
multicast tree without activation for that channel. This is
biased towards a forward expectation that the request will be
accepted at the NAS. The OLT forwards the IGMP join to the NAS.
It also sends a bandwidth admission request to the NAS
identifying the channel, and the premises for which the request
is made. It sets a timer for the subscriber multicast entry
within which it expects to receive a request from the NAS that
relates to this request. If the PON available bandwidth is less
than the bandwidth of the requested channel, the OLT sends an
admission response (with a reject) to the ONT/ONU, and does not
forward the IGMP join to the NAS.
NAS operation: ANX operation:
The NAS receives the IGMP join from the subscriber on the - ONT/ONU can snoop IGMP messages. If conditional access is
subscriber connection. When NAS receives the admission control configured and the channel is in the Black list (or it is not on the
request from ANX (also signifying the bandwidth on the PON is White list), ONT will drop the IGMP Join. If the channel passes the
available), it performs admission control against the subscriber conditional access check, the ONT will forward the IGMP Join, and
available multicast bandwidth. If this check passes, and the NAS will send a bandwidth admission control request to the OLT. In case
is already transmitting that channel to the OLT, the request is the multicast stream is already being received on the PON, the
accepted. If the check passes and the NAS is not transmitting the ONT/ONU does not forward the stream to the access port where IGMP is
channel to the OLT yet, it performs admission control against the received till it has received a positive admission control response
multicast video available bandwidth (this includes the dedicated from the OLT.
multicast bandwidth and the shared bandwidth between multicast
and video on demand) on the link(s) to the OLT. If the check
passes, the request is accepted, the available video bandwidth
for the subscriber and downlink to the OLT are reduced by the
channel bandwidth, and the NAS sends an ANCP admission control
response (indicating accept) to the OLT, requesting the addition
of the subscriber to the multicast tree for that channel. The OLT
activates the corresponding multicast entry if not active and
maintains state of the subscriber in the list of receivers for
that channel. The OLT also sends an ANCP request to the ONT/ONU
to enable reception of the multicast channel and forwarding to
the subscriber access port. Otherwise, if the request is
rejected, the NAS will send an admission reject to the OLT, which
in turn removes the subscriber as a receiver for that channel (if
it were added), and credits back the channel bandwidth to the PON
video bandwidth if there is no other receiver on the PON for that
channel. The interactions between ANX and NAS are shown in
Figures 9 and 10.
If the OLT does not receive a response from the NAS within a set - OLT can snoop IGMP messages. It also receives a bandwidth
timer, the OLT removes the subscriber from the potential list of admission control request from the ONT/ONU for the requested channel.
receivers for the indicated channel. It also returns the It can be programmed with a channel bandwidth map. If the multicast
allocated bandwidth to the PON available bandwidth if there are channel is already being streamed on the PON, or the channel
no other receivers. In this case, the NAS may send a response to bandwidth is less than the multicast available bandwidth on the PON,
the OLT with no matching entry as the entry has been deleted. The the OLT forwards the IGMP request to the NAS and keeps track of the
OLT must perform admission control against the PON available subscriber (identified by customer-Port-ID) as a receiver. If the
bandwidth and may accept the request and send an ANCP request to channel is not already being streamed on the PON, but the PON has
the ONT/ONU to activate the corresponding multicast entry as sufficient bandwidth for that channel, the OLT reduces the PON
described earlier. If it does not accept the request, it will multicast video bandwidth by the channel bandwidth and may optionally
respond back to the NAS with a reject. The NAS shall credit back add the PON to the multicast tree without activation for that
the channel bandwidth to the subscriber. It shall also stop channel. This is biased towards a forward expectation that the
sending the channel to the OLT if that subscriber was the last request will be accepted at the NAS. The OLT forwards the IGMP join
leaf on the multicast tree towards the OLT. to the NAS. It also sends a bandwidth admission request to the NAS
identifying the channel, and the premises for which the request is
made. It sets a timer for the subscriber multicast entry within which
it expects to receive a request from the NAS that relates to this
request. If the PON available bandwidth is less than the bandwidth
of the requested channel, the OLT sends an admission response (with a
reject) to the ONT/ONU, and does not forward the IGMP join to the
NAS.
On processing an IGMP leave, the OLT will send an ANCP request to NAS operation:
NAS to release resources. NAS will release the subscriber
bandwidth. If this leave causes the stream to be no longer
required by the OLT, the NAS will update its replication state
and release the bandwidth on the NAS to OLT link.
If the subscriber makes a request for a unicast video stream The NAS receives the IGMP join from the subscriber on the subscriber
(i.e., Video on Demand), the request results in appropriate connection. When NAS receives the admission control request from ANX
application level signaling, which typically results in an (also signifying the bandwidth on the PON is available), it performs
application server requesting a policy server for bandwidth-based admission control against the subscriber available multicast
admission control for the VoD stream. The policy server after bandwidth. If this check passes, and the NAS is already transmitting
authorizing the request, can send a request to the NAS for the that channel to the OLT, the request is accepted. If the check passes
required bandwidth if it needs to use bandwidth that is shared and the NAS is not transmitting the channel to the OLT yet, it
with multicast. This request may be based on a protocol outside performs admission control against the multicast video available
of the scope of this document. The NAS checks if the available bandwidth (this includes the dedicated multicast bandwidth and the
video bandwidth (accounting for both multicast and unicast) per shared bandwidth between multicast and video on demand) on the
subscriber and for the link to the OLT is sufficient for the link(s) to the OLT. If the check passes, the request is accepted, the
request. If it is, it temporarily reserves the bandwidth and available video bandwidth for the subscriber and downlink to the OLT
sends an ANCP admission request to the OLT for the subscriber, are reduced by the channel bandwidth, and the NAS sends an ANCP
indicating the desired VoD bandwidth. If the OLT has sufficient admission control response (indicating accept) to the OLT, requesting
bandwidth on the corresponding PON, it reserves that bandwidth the addition of the subscriber to the multicast tree for that
and returns an accept response to the NAS. If not, it returns a channel. The OLT activates the corresponding multicast entry if not
reject to the NAS. If the NAS receives an accept, it returns an active and maintains state of the subscriber in the list of receivers
accept to the policy server which in turn returns an accept to for that channel. The OLT also sends an ANCP request to the ONT/ONU
the application server, and the video stream is streamed to the to enable reception of the multicast channel and forwarding to the
subscriber. This interaction is shown in Figure 11. If the NAS subscriber access port. Otherwise, if the request is rejected, the
does not accept the request from the policy server, it returns a NAS will send an admission reject to the OLT, which in turn removes
reject. If the NAS receives a reject from the OLT, it returns the the subscriber as a receiver for that channel (if it were added), and
allocated bandwidth to the subscriber and the downlink to the credits back the channel bandwidth to the PON video bandwidth if
OLT. there is no other receiver on the PON for that channel. The
interactions between ANX and NAS are shown in Figures 9 and 10.
+----+ If the OLT does not receive a response from the NAS within a set
+-------- |ONT |-------- HGW timer, the OLT removes the subscriber from the potential list of
+----+ +----+ + +----+ receivers for the indicated channel. It also returns the allocated
|NAS |---------------| |------<PON> bandwidth to the PON available bandwidth if there are no other
| |<------------->| | + +-----+ receivers. In this case, the NAS may send a response to the OLT with
+----+ ANCP |OLT | +--------- | |------ HGW no matching entry as the entry has been deleted. The OLT must perform
| | | ANCP | ONU | admission control against the PON available bandwidth and may accept
| +----+<------------------>+-----+-------HGW the request and send an ANCP request to the ONT/ONU to activate the
| | | | corresponding multicast entry as described earlier. If it does not
|1.IGMP Join(s/*,G) +=============+ +=============+ | accept the request, it will respond back to the NAS with a reject.
|<------------------[IGMP Snooping]---------[IGMP snooping]--| The NAS shall credit back the channel bandwidth to the subscriber. It
| +=============+ +=============+ | shall also stop sending the channel to the OLT if that subscriber was
| |2.Admission-Request | | the last leaf on the multicast tree towards the OLT.
| |(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.
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.
+----+ On processing an IGMP leave, the OLT will send an ANCP request to NAS
+--------- |ONT |------ HGW to release resources. NAS will release the subscriber bandwidth. If
+----+ +----+ + +----+ this leave causes the stream to be no longer required by the OLT, the
|NAS |---------------| |------<PON> NAS will update its replication state and release the bandwidth on
| |<------------->| | + +-----+ the NAS to OLT link.
+----+ ANCP |OLT | +--------- | |----- HGW
| | | ANCP |ONU |
| +----+<------------------>+-----+------HGW
| | | |
|1.IGMP Join(s/*,G) +=============+ +=============+ |
|<------------------[IGMP Snooping]--------[IGMP snooping]-- |
| +=============+ +=============+ |
| |2.Admission-Request | |
| |(Flow,Customer-Port-ID) | |
| |<---------------------- | |
| 2.+===============+ | |
| [ Access Ctrl ] | |
| [ & PON B/W ] | |
| [ Admission Ctrl] | |
| +===============+ PASS | |
|3.Admission-Request | | |
| <Flow,Customer-Port-ID> | |
|<--------------------| | |
4.+==================+ | | |
[Subscriber B/W ] | | |
[& OLT link B/W ] | | |
[Admission Ctrl ] | | |
+==================+FAIL | |
| | | |
|5.Admission-Reply-Fail | |
|<Flow,Cust-Port-ID> | | |
|-------------------->| | |
| 6.+==================+ | |
| [Release PON B/W ] | |
| [Remove Repl.State ] | |
| +==================+ | |
| | 7.Admission-Reply-Fail | |
| |<Flow,Cust-Port-ID> | |
| |----------------------> | |
| | 8.+============+ |
| | [Remove Repl.] |
| | [ State ] |
+============+
Figure 10: Interaction between NAS and ANX for Multicast Bandwidth
Admission Control in the All-ANCP ANX control model 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 If the subscriber makes a request for a unicast video stream (i.e.,
| App. Server|<----------------------------------------------- Video on Demand), the request results in appropriate application
| Server | level signaling, which typically results in an application server
+------------+ requesting a policy server for bandwidth-based admission control for
| 2. Admission-Request (VoD-Flow) the VoD stream. The policy server after authorizing the request, can
+-------+ send a request to the NAS for the required bandwidth if it needs to
|Policy | use bandwidth that is shared with multicast. This request may be
|Server | based on a protocol outside of the scope of this document. The NAS
+-------+ checks if the available video bandwidth (accounting for both
| + multicast and unicast) per subscriber and for the link to the OLT is
|<-|---3. Admission-Request sufficient for the request. If it is, it temporarily reserves the
| | bandwidth and sends an ANCP admission request to the OLT for the
+ | 8. Admission-Reply subscriber, indicating the desired VoD bandwidth. If the OLT has
+----+ + +----+ +-----+ sufficient bandwidth on the corresponding PON, it reserves that
|NAS |---------------|OLT |------<PON>-------|ONT |---HGW--CPE 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
+----+ ANCP +----+ | | returns an accept to the policy server which in turn returns an
4.| | | | accept to the application server, and the video stream is streamed to
+=================+ | | | the subscriber. This interaction is shown in Figure 11. If the NAS
[Subscriber B/W ] | | | does not accept the request from the policy server, it returns a
[& OLT link B/W ] | | | reject. If the NAS receives a reject from the OLT, it returns the
[Admission Ctrl ] | | | allocated bandwidth to the subscriber and the downlink to the OLT.
+=================+PASS | | |
| | | |
| 5.Admission-Request | | |
|(Bandwidth,PON-Port-ID) | |
|-------------------> | | |
| | | |
| 6.+===============+ | |
| [ PON B/W ] | |
| [ Admission Ctrl] | |
| +===============+ PASS | |
|7.Admission-Reply | | |
| <PON-Port-ID> | | |
|<------------------- | | |
Figure 11: Interactions for VoD Bandwidth Admission Control in +----+
the All-ANCP ANX control model. Similar functionality will be +-------- |ONT |-------- HGW
required when OMCI is enabled between the OLT and ONT in the +----+ +----+ + +----+
ANCP+OMCI ANX control model. In this latter case, the OLT will |NAS |---------------| |------<PON>
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 ] |
| | +============+ |
-A third possible approach is where the ANX is assumed to have a Figure 9: Interaction between NAS & ANX for Multicast Bandwidth
full knowledge to make an autonomous decision on admitting or Admission Control in the All-ANCP ANX control model upon success.
rejecting a multicast and a unicast join. With respect to the Similar functionality will be required when OMCI is enabled between the
interaction between ONT/ONU and OLT, the procedure is similar to OLT and ONT/ONU in the ANCP+OMCI ANX control model. In this latter case,
the first approach (i.e., NAS controlled replication). However, the OLT will act as ANCP-OMCI gateway.
when the OLT receives an IGMP request from a subscriber, it
performs admission control against that subscriber multicast
video bandwidth (dedicated and shared with Video on Demand), the
PON and uplink to the GWR. It should be noted in this case that
if there are multiple NAS-OLT links, either the link on which the
multicast stream must be sent is pre-determined, needs to be
selected by the OLT based on downstream bandwidth from NAS to OLT
and the selection is communicated to the NAS, or the OLT has to
be ready to receive the stream on any link. If the check passes,
the OLT updates the video available bandwidth per PON and
subscriber. The OLT adds the subscriber to the list of receivers
and the PON to the multicast tree, if it is not already on it. It
also sends an ANCP request to the ONT/ONU to add the subscriber
access port to that channel multicast tree, and sends an ANCP
message to the NAS informing it of the subscriber and link
available video bandwidth and the channel the subscriber joined.
The NAS upon receiving the ANCP information message, updates the
necessary information, including the OLT to the multicast tree if
it is not already on it. It should be noted in this case that the
ANCP message from the OLT to the NAS is being used to add the OLT
to a multicast tree as opposed to an IGMP message. The IGMP
message can also be sent by the OLT with the OLT acting as an
IGMP proxy at the expense of added messages. In this option, the
OLT acts as the network IGMP router for the subscriber.
For unicast video streams, the policy server receiving an +----+
admission request from an application server, as described +--------- |ONT |------ HGW
before, may query the OLT for admission control as it has all +----+ +----+ + +----+
information. If the OLT has sufficient bandwidth for the stream |NAS |---------------| |------<PON>
it reserves that bandwidth for the subscriber, PON and OLT uplink | |<------------->|OLT | + +-----+
to the NAS and returns an accept to the policy server. It also +----+ ANCP | | ANCP +----------| ONU |----- HGW
updates the NAS via an ANCP message of the subscriber available | +----+<----------------->+-----+------HGW
video bandwidth. If the OLT rejects the policy server request, it | | | |
will return a reject to the policy server. |1.IGMP Join(s/*,G) +=============+ +=============+ |
|<------------------[IGMP Snooping]--------[IGMP snooping]-- |
| +=============+ +=============+ |
| |2.Admission-Request | |
| |(Flow,Customer-Port-ID) | |
| |<---------------------- | |
| 2.+===============+ | |
| [ Access Ctrl ] | |
| [ & PON B/W ] | |
| [ Admission Ctrl] | |
| +===============+ PASS | |
|3.Admission-Request | | |
| <Flow,Customer-Port-ID> | |
|<--------------------| | |
4.| | | |
+==================+ | | |
[Subscriber B/W ] | | |
[& OLT link B/W ] | | |
[Admission Ctrl ] | | |
+==================+FAIL | |
| | | |
|5.Admission-Reply-Fail | |
|<Flow,Cust-Port-ID> | | |
|-------------------->| | |
| 6.+==================+ | |
| [Release PON B/W ] | |
| [Remove Repl.State ] | |
| +==================+ | |
| | 7.Admission-Reply-Fail | |
| |<Flow,Cust-Port-ID> | |
| |----------------------> | |
| | 8.+============+ |
| | [Remove Repl.] |
| | [ State ] |
| | +============+ |
Figure 10: Interaction between NAS and ANX for Multicast Bandwidth
Admission Control in the All-ANCP ANX control model 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.
It should be noted that if the policy server adjacency is with +------------+ 1. VoD Request
the NAS, the policy server may make the admission request to the | App. Server|<-----------------------------------------------
NAS. The NAS then sends an ANCP admission request to the OLT on | Server |
behalf of the policy server. The NAS returns an accept or reject to +------------+
the policy server if it gets a reject or accept, respectively, | 2. Admission-Request (VoD-Flow)
from the OLT. +-------+
|Policy |
|Server |
+-------+
| +
|<-|---3. Admission-Request
| |
+ | 8. Admission-Reply
+----+ + +----+ +-----+
|NAS |---------------|OLT |------<PON>-------|ONT |---HGW--CPE
| |<------------->| | +-----+ |
+----+ ANCP +----+ | |
| | | |
4.| | | |
+=================+ | | |
[Subscriber B/W ] | | |
[& OLT link B/W ] | | |
[Admission Ctrl ] | | |
+=================+PASS | | |
| | | |
| 5.Admission-Request | | |
|(Bandwidth,PON-Port-ID) | |
|-------------------> | | |
| | | |
| 6.+===============+ | |
| [ PON B/W ] | |
| [ Admission Ctrl] | |
| +===============+ PASS | |
|7.Admission-Reply | | |
| <PON-Port-ID> | | |
|<------------------- | | |
| | | |
Figure 11: Interactions for VoD Bandwidth Admission Control in the
All-ANCP ANX control model. Similar functionality will be required
when OMCI is enabled between the OLT and ONT in the ANCP+OMCI ANX
control model. In this latter case, the OLT will act as ANCP-OMCI
gateway.
-A third possible approach is where the ANX is assumed to have a full
knowledge to make an autonomous decision on admitting or rejecting a
multicast and a unicast join. With respect to the interaction between
ONT/ONU and OLT, the procedure is similar to the first approach
(i.e., NAS controlled replication). However, when the OLT receives an
IGMP request from a subscriber, it performs admission control against
that subscriber multicast video bandwidth (dedicated and shared with
Video on Demand), the PON and uplink to the NAS. It should be noted
in this case that if there are multiple NAS-OLT links, either the
link on which the multicast stream must be sent is pre-determined,
needs to be selected by the OLT based on downstream bandwidth from
NAS to OLT and the selection is communicated to the NAS, or the OLT
has to be ready to receive the stream on any link. If the check
passes, the OLT updates the video available bandwidth per PON and
subscriber. The OLT adds the subscriber to the list of receivers and
the PON to the multicast tree, if it is not already on it. It also
sends an ANCP request to the ONT/ONU to add the subscriber access
port to that channel multicast tree, and sends an ANCP message to the
NAS informing it of the subscriber and link available video bandwidth
and the channel the subscriber joined. The NAS upon receiving the
ANCP information message, updates the necessary information,
including the OLT to the multicast tree if it is not already on it.
It should be noted in this case that the ANCP message from the OLT to
the NAS is being used to add the OLT to a multicast tree as opposed
to an IGMP message. The IGMP message can also be sent by the OLT with
the OLT acting as an IGMP proxy at the expense of added messages. In
this option, the OLT acts as the network IGMP router for the
subscriber.
For unicast video streams, the policy server receiving an admission
request from an application server, as described before, may query
the OLT for admission control as it has all information. If the OLT
has sufficient bandwidth for the stream it reserves that bandwidth
for the subscriber, PON and OLT uplink to the NAS and returns an
accept to the policy server. It also updates the NAS via an ANCP
message of the subscriber available video bandwidth. If the OLT
rejects the policy server request, it will return a reject to the
policy server.
It should be noted that if the policy server adjacency is with the
NAS, the policy server may make the admission request to the NAS. The
NAS then sends an ANCP admission request to the OLT on behalf of the
policy server. The NAS returns an accept or reject to the policy server
if it gets a reject or accept, respectively, from the OLT.
6.3. Multicast Accounting 6.3. Multicast Accounting
It may be desirable to perform accurate per-user or per Access
Loop time or volume based accounting. In case the ANX is
performing the traffic replication process, it knows when
replication of a multicast flow to a particular Access Port or
user starts and stops. Multicast accounting can be addressed in
two ways:
- ANX keeps track of when replication starts or stops, and It may be desirable to perform accurate per-user or per Access Loop
reports this information to the NAS for further processing. In time or volume based accounting. In case the ANX is performing the
this case, ANCP can be used to send the information from the ANX traffic replication process, it knows when replication of a multicast
to the NAS. This can be done with the Information Report message. flow to a particular Access Port or user starts and stops. Multicast
The NAS can then generate the appropriate time and/or volume accounting can be addressed in two ways:
accounting information per Access Loop and per multicast flow, to
be sent to the accounting system. The ANCP requirements to
support this approach are specified in [RFC5851]. If the
replication function is distributed between the OLT and ONT/ONU,
a query from the NAS will result in OLT generating a query to the
ONT/ONU.
- ANX keeps track of when replication starts or stops, and - ANX keeps track of when replication starts or stops, and reports
generates the time and/or volume based accounting information per this information to the NAS for further processing. In this case,
Access Loop and per multicast flow, before sending it to a ANCP can be used to send the information from the ANX to the NAS.
central accounting system for logging. Since ANX communicates This can be done with the Information Report message. The NAS can
with this accounting system directly, the approach does not then generate the appropriate time and/or volume accounting
require the use of ANCP. It is therefore beyond the scope of this information per Access Loop and per multicast flow, to be sent to the
document; It may also be desirable for the NAS to have the accounting system. The ANCP requirements to support this approach are
capability to asynchronously query the ANX to obtain an specified in [RFC5851]. If the replication function is distributed
instantaneous status report related to multicast flows currently between the OLT and ONT/ONU, a query from the NAS will result in OLT
replicated by the ANX. Such a reporting functionality could be generating a query to the ONT/ONU.
useful for troubleshooting and monitoring purposes. If the
replication function in the ANX is distributed between the OLT - ANX keeps track of when replication starts or stops, and generates
and the ONT/ONU, then for some of the information required by the the time and/or volume based accounting information per Access Loop
NAS (such as the list of access-ports on which a flow is being and per multicast flow, before sending it to a central accounting
forwarded or list of flows being forwarded on an access-port), a system for logging. Since ANX communicates with this accounting
query to the OLT from the NAS will result in a query from OLT to system directly, the approach does not require the use of ANCP. It is
ONT/ONU. The OLT responds back to the NAS when it receives the therefore beyond the scope of this document. It may also be desirable
response from the ONT/ONU. Also, if the list of PONs on which for the NAS to have the capability to asynchronously query the ANX to
replication is happening for a multicast channel or the list of obtain an instantaneous status report related to multicast flows
channels being replicated on a PON is what is desired, the OLT currently replicated by the ANX. Such a reporting functionality could
can return this information. be useful for troubleshooting and monitoring purposes. If the
replication function in the ANX is distributed between the OLT and
the ONT/ONU, then for some of the information required by the NAS
(such as the list of access-ports on which a flow is being forwarded
or list of flows being forwarded on an access-port), a query to the
OLT from the NAS will result in a query from OLT to ONT/ONU. The OLT
responds back to the NAS when it receives the response from the
ONT/ONU. Also, if the list of PONs on which replication is happening
for a multicast channel or the list of channels being replicated on a
PON is what is desired, the OLT can return this information.
7. Remote Connectivity Check 7. Remote Connectivity Check
In an end-to-end Ethernet aggregation network, end-to-end In an end-to-end Ethernet aggregation network, end-to-end Ethernet
Ethernet OAM as specified in IEEE 802.1ag and ITU-T OAM as specified in IEEE 802.1ag and ITU-T Recommendation Y.1730/1731
Recommendation Y.1730/1731 can provide Access Loop connectivity can provide Access Loop connectivity testing and fault isolation.
testing and fault isolation. However, most HGWs do not yet
support these standard Ethernet OAM procedures. Also, in a mixed
Ethernet and ATM access network (e.g., Ethernet based aggregation
upstream from the OLT, and BPON downstream), interworking
functions for end-to-end OAM are not yet standardized or widely
available. Until such mechanisms become standardized and widely
available, Access Node Control mechanism between NAS and ANX can
be used to provide a simple mechanism to test connectivity of an
access-loop from the NAS.
Triggered by a local management interface, the NAS can use the However, most HGWs do not yet support these standard Ethernet OAM
Access Node Control Mechanism (Control Request Message) to procedures. Also, in a mixed Ethernet and ATM access network (e.g.,
initiate an Access Loop test between Access Node and HGW or Ethernet based aggregation upstream from the OLT, and BPON
ONT/ONU. On reception of the ANCP message, the OLT can trigger downstream), interworking functions for end-to-end OAM are not yet
native OAM procedures defined for BPON in [G.983.1] and for GPON standardized or widely available. Until such mechanisms become
in [G.984.1]. The Access Node can send the result of the test to standardized and widely available, Access Node Control mechanism
the NAS via a Control Response message. between NAS and ANX can be used to provide a simple mechanism to test
connectivity of an access-loop from the NAS.
Triggered by a local management interface, the NAS can use the Access
Node Control Mechanism (Control Request Message) to initiate an
Access Loop test between Access Node and HGW or ONT/ONU. On reception
of the ANCP message, the OLT can trigger native OAM procedures
defined for BPON in [G.983.1] and for GPON in [G.984.1]. The Access
Node can send the result of the test to the NAS via a Control
Response message.
8. Access Topology Discovery 8. Access Topology Discovery
In order to avoid congestion in the network, manage and utilize In order to avoid congestion in the network, manage and utilize the
the network resources better, and ensure subscriber fairness, NAS network resources better, and ensure subscriber fairness, NAS
performs hierarchical shaping and scheduling of the traffic by performs hierarchical shaping and scheduling of the traffic by
modeling different congestion points in the network (such as the modeling different congestion points in the network (such as the
last-mile, access Node uplink, and the access facing port). last-mile, access Node uplink, and the access facing port).
Such mechanisms require that the NAS gains knowledge about the Such mechanisms require that the NAS gains knowledge about the
topology of the access network, the various links being used and topology of the access network, the various links being used and
their respective rates. Some of the information required is their respective rates. Some of the information required is somewhat
somewhat dynamic in nature (e.g., DSL line rate in case the last dynamic in nature (e.g., DSL line rate in case the last mile is xDSL
mile is xDSL based, e.g., in case of "PON fed DSLAMs" for based, e.g., in case of "PON fed DSLAMs" for FTTC/FTTB scenarios),
FTTC/FTTB scenarios), hence cannot come from a provisioning hence cannot come from a provisioning and/or inventory management
and/or inventory management OSS system. Some of the information Operations Support System (OSS). Some of the information varies less
varies less frequently (e.g., capacity of the OLT uplink), but frequently (e.g., capacity of the OLT uplink), but nevertheless needs
nevertheless needs to be kept strictly in sync between the actual to be kept strictly in sync between the actual capacity of the uplink
capacity of the uplink and the image the NAS has of it. and the image the NAS has of it.
OSS systems are rarely able to enforce in a reliable and scalable OSS systems are rarely able to enforce in a reliable and scalable
manner the consistency of such data, notably across manner the consistency of such data, notably across organizational
organizational boundaries under certain deployment scenarios. boundaries under certain deployment scenarios. The Access Topology
The Access Topology Discovery function allows the NAS to perform Discovery function allows the NAS to perform these advanced functions
these advanced functions without having to depend on an error- without having to depend on an error-prone and possibly complex
prone and possibly complex integration with an OSS system. integration with an OSS system.
The rate of the access-loop can be communicated via ANCP The rate of the access-loop can be communicated via ANCP (Information
(Information Report Message) from the ONT/ONU to the OLT in the Report Message) from the ONT/ONU to the OLT in the All-ANCP ANX
All-ANCP ANX control model or via OMCI in the ANCP+OMCI ANX control model or via OMCI in the ANCP+OMCI ANX control model, and
control model, and then from OLT to the NAS via ANCP. then from OLT to the NAS via ANCP. Additionally, during the time the
Additionally, during the time the DSL NT is active, data rate DSL NT is active, data rate changes can occur due to environmental
changes can occur due to environmental conditions (the DSL Access conditions (the DSL Access Loop can get "out of sync" and can retrain
Loop can get "out of sync" and can retrain to a lower value, or to a lower value, or the DSL Access Loop could use Seamless Rate
the DSL Access Loop could use Seamless Rate Adaptation making the Adaptation making the actual data rate fluctuate while the line is
actual data rate fluctuate while the line is active). In this active). In this case, ANX sends an additional Information Report to
case, ANX sends an additional Information Report to the NAS each the NAS each time the Access Loop attributes change above a threshold
time the Access Loop attributes change above a threshold value. value. Existing DSL procedures are not applicable in this case
Existing DSL procedures are not applicable in this case because because an adapted message flow and additional TLVs are needed.
an adapted message flow and additional TLVs are needed.
+--------+
| Policy |
| Server | +---+ +---+
+--------+ +-----------|ONT|---|HGW|
| | +---+ +---+
| +--------------- |-----------------+
+----+ | +----+ | +-----+ | +---+
|NAS |------------ | | | | | |-|-|HGW|
| |<----------> | | | | |ONT/ | | +---+
+----+ ANCP | |OLT |------<PON>--------|ONU | |
| | | | | | | +---+
| | | |<----------------->| |---|HGW|
| | +----+ OMCI +-----+ | +---+
| +----------------------------------+
| | Access Node |
| | |
| |------GPON Ranging------|
| Port Status Message| ONT Port UP |
|<------------------ |<-----------------------|
|Port Configuration GPON Line/Service Profile|
|------------------> |<---------------------->|
| ONT/ONI Port UP| |
|<------------------ | |
| ANCP | OMCI |
<-------------------><----------------------->|
PPP, DHCP, IP
<------------------------------------------------------>
Figure 12: Message Flow for the use case of Topology Discovery
for the ANCP+OMCI access control model.
Figure 12 depicts a message flow for topology discovery when +--------+
using the ANCP+OMCI access control model. Basically, when an | Policy |
ONT/ONU gets connected to a PON, the OLT detects a new device and | Server |
a GPON Ranging process starts. During this process the ONT/ONU +--------+ +---+ +---+
becomes authorized by the OLT and identified by ONT/ONU ID, PON | +-----------|ONT|---|HGW|
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 |NAS |------------ | | | | | |-|-|HGW|
OLT reports the final status to NAS with information about | |<----------> | | | | |ONT/ | | +---+
service profile and other information such as the ONT/ONU port +----+ ANCP | |OLT |------<PON>--------|ONU | |
rate to the subscriber for instance. | | | | | | | +---+
| | | |<----------------->| |---|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
<------------------------------------------------------>
9. Access Loop Configuration Figure 12: Message Flow for the use case of Topology Discovery for
the ANCP+OMCI access control model.
Topology Discovery reports access port identification to NAS when Figure 12 depicts a message flow for topology discovery when using
sending an Access Port Discovery message. This informs NAS the ANCP+OMCI access control model. Basically, when an ONT/ONU gets
identification of PON port on an Access Node. Based on Access connected to a PON, the OLT detects a new device and a GPON Ranging
Port Identification and on customer identification, service process starts. During this process the ONT/ONU becomes authorized by
related parameters could be configured on an OLT and an ONU/ONT. 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.
Service related parameters could be sent to OLT via ANCP before 9. Access Loop Configuration
or after an ONU/ONT is up. Sending of ANCP loop Configuration Topology Discovery reports access port identification to NAS when
messages from NAS can be triggered by a management system or by sending an Access Port Discovery message. This informs NAS
customer identification and authentication after Topology identification of PON port on an Access Node. Based on Access Port
Discovery. It may be used for first time configuration (zero Identification and on customer identification, service related
touch) or for updating/upgrading customer's profile like C-VLAN parameters could be configured on an OLT and an ONU/ONT.
ID, S-VLAN ID, and service bandwidth.
Parameters of UNI (subscriber interface to HGW/CPE) of ONU/ONT Service related parameters could be sent to OLT via ANCP before or
can also be configured via ANCP. When the ONU/ONT supports ANCP, after an ONU/ONT is up. Sending of ANCP loop Configuration messages
parameters of the UNI on ONU/ONT are sent to the ONU/ONT via from NAS can be triggered by a management system or by customer
ANCP. If the ONU/ONT does not support ANCP, but only OMCI, identification and authentication after Topology Discovery. It may be
parameters have to be sent from the NAS to the OLT via ANCP used for first time configuration (zero touch) or for
first. Then, the OLT translates such configuration into OMCI and updating/upgrading customer's profile like C-VLAN ID, S-VLAN ID, and
sends it to the ONU/ONT. service bandwidth.
Parameters of the User to Network Interface (UNI), which is the
subscriber interface to HGW/CPE of ONU/ONT, can also be configured
via ANCP. When the ONU/ONT supports ANCP, parameters of the UNI on
ONU/ONT are sent to the ONU/ONT via ANCP. If the ONU/ONT does not
support ANCP, but only OMCI, parameters have to be sent from the NAS
to the OLT via ANCP first. Then, the OLT translates such
configuration into OMCI and sends it to the ONU/ONT.
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 model for ANCP security, and lists the security functions that are
are required at the ANCP level. required at the ANCP level.
With Multicast handling as described in this document, ANCP With Multicast handling as described in this document, ANCP protocol
protocol activity between the ANX and the NAS is triggered by activity between the ANX and the NAS is triggered by join/leave
join/leave requests coming from the end-user equipment. This requests coming from the end-user equipment. This could potentially
could potentially be used for denial of service attack against be used for denial of service attack against the ANX and/or the NAS.
the ANX and/or the NAS.
To mitigate this risk, the NAS and ANX may implement control To mitigate this risk, the NAS and ANX may implement control plane
plane protection mechanisms such as limiting the number of protection mechanisms such as limiting the number of multicast flows
multicast flows a given user can simultaneously join, or limiting a given user can simultaneously join, or limiting the maximum rate of
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 Protection against invalid or unsubscribed flows can be deployed via
via provisioning black lists as close to the subscriber as provisioning black lists as close to the subscriber as possible
possible (e.g., in the ONT). (e.g., in the ONT).
User activity logging for accounting or tracking purposes could raise
privacy concerns if not appropriately protected. To protect such
information, logging/accounting information can be exchanged with the
corresponding server over a secure channel, and the information can
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 As it currently stands, both ANCP framework [RFC5851] and protocol
protocol [RFC6320] are defined in context of DSL access. Due to [RFC6320] are defined in context of DSL access. Due to inherent
inherent differences between PON and DSL access technologies, differences between PON and DSL access technologies, ANCP needs a few
ANCP needs a few extensions for supporting the use-cases outlined extensions for supporting the use-cases outlined in this document for
in this document for PON based access. These specific differences PON based access. These specific differences and extensions are
and extensions are outlined below. outlined below.
- In PON, the access-node functionality is split between OLT and - In PON, the access-node functionality is split between OLT and ONT.
ONT. Therefore, ANCP interaction between NAS and AN translates to 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 processing of ANCP messages (e.g., for multicast replication control)
control) on the OLT can trigger generation of ANCP messages from on the OLT can trigger generation of ANCP messages from OLT to ONT.
OLT to ONT. Similarly, ANCP messages from ONT to the OLT can Similarly, ANCP messages from ONT to the OLT can trigger ANCP
trigger ANCP exchange between the OLT and the NAS (e.g., exchange between the OLT and the NAS (e.g., admission-request
admission-request messages). This is illustrated in the generic messages). This is illustrated in the generic message flows in
message flows in Figures 5 and 6 of section 5. In case of DSL, Figures 5 and 6 of section 5. In case of DSL, the ANCP exchange is
the ANCP exchange is contained between two network elements (NAS contained between two network elements (NAS and the DSLAM).
and the DSLAM).
- The PON connection to the ONT is a shared medium between - The PON connection to the ONT is a shared medium between multiple
multiple ONTs on the same PON. The local-loop in case of DSL is ONTs on the same PON. The local-loop in case of DSL is point-to-
point-to-point. In case of DSL access network, the access facing point. In case of DSL access network, the access facing port on the
port on the NAS (i.e., port to the network between NAS and the NAS (i.e., port to the network between NAS and the DSLAM), and the
DSLAM), and the access-facing ports on the DSLAM (i.e., access-facing ports on the DSLAM (i.e., customer's local-loop) are
customer's local-loop) are the two bandwidth constraint points the two bandwidth constraint points that need to be considered for
that need to be considered for performing bandwidth based performing bandwidth based admission control for multicast video and
admission control for multicast video and VoD delivered to the VoD delivered to the customer. In case of PON access, in addition to
customer. In case of PON access, in addition to the bandwidth the bandwidth constraint on the NAS to OLT facing ports, and the
constraint on the NAS to OLT facing ports, and the subscriber subscriber allocated bandwidth for video services, the bandwidth
allocated bandwidth for video services, the bandwidth available available on the PON for video is an additional constraint that needs
on the PON for video is an additional constraint that needs to be to be considered for bandwidth based admission control. If the
considered for bandwidth based admission control. If the bandwidth control is centralized in NAS (as described in option 1 of
bandwidth control is centralized in NAS (as described in option 1 section 6.2), then the NAS needs to support additional logic to
of section 6.2), then the NAS needs to support additional logic consider available PON bandwidth before admitting a multicast request
to consider available PON bandwidth before admitting a multicast or a VoD request by the user. Accordingly, ANCP needs to identify the
request or a VoD request by the user. Accordingly, ANCP needs to customer access port and the PON on which the customer ONT is. If the
identify the customer access port and the PON on which the PON bandwidth control is performed on the OLT (as defined in second
customer ONT is. If the PON bandwidth control is performed on the option in section 6.2), then additional ANCP request and response
OLT (as defined in second option in section 6.2), then additional messages are required for NAS to query the OLT to determine available
ANCP request and response messages are required for NAS to query PON bandwidth when a request to admit a VOD flow is received on the
the OLT to determine available PON bandwidth when a request to NAS (as shown in Figure 9 in section 6.2) or for the OLT to inform
admit a VOD flow is received on the NAS (as shown in Figure 9 in the NAS what stream bandwidth is sent to the subscriber for the NAS
section 6.2) or for the OLT to inform the NAS what stream to take appropriate action (e.g., bandwidth adjustment for various
bandwidth is sent to the subscriber for the NAS to take types of traffic).
appropriate action (e.g., bandwidth adjustment for various types
of traffic).
- In PON, the multicast replication can potentially be performed - In PON, the multicast replication can potentially be performed on
on three different network elements: (1) on the NAS (2) on the three different network elements: (1) on the NAS (2) on the OLT for
OLT for replication to multiple PON ports, and (3) on the ONT/ONU replication to multiple PON ports, and (3) on the ONT/ONU for
for replication to multiple customer ports. In case of DSL, the replication to multiple customer ports. In 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 Section 6.2 defines options for multicast replication in case of PON.
PON. In the first option, the multicast replication is done on In the first option, the multicast replication is done on the AN, but
the AN, but is controlled from NAS via ANCP (based on the is controlled from NAS via ANCP (based on the reception of per-
reception of per-customer IGMP messages on the NAS). In this customer IGMP messages on the NAS). In this option, the NAS needs to
option, the NAS needs to supply to the OLT the set of PON- supply to the OLT the set of PON-customer-IDs (as defined in section
customer-IDs (as defined in section 2) to which the multicast 2) to which the multicast stream needs to be replicated. The PON-
stream needs to be replicated. The PON-customer-ID identifies the customer-ID identifies the OLT and the PON ports on the OLT as well
OLT and the PON ports on the OLT as well as the ONT and the as the ONT and the access-ports on the ONT where the multicast stream
access-ports on the ONT where the multicast stream needs to be needs to be replicated. Upon receiving the request to update its
replicated. Upon receiving the request to update its multicast multicast replication state, the OLT must update its replication
replication state, the OLT must update its replication state with state with the indicated PON ports, but may also need to interact
the indicated PON ports, but may also need to interact with the with the ONT via ANCP to update the multicast replication state on
ONT via ANCP to update the multicast replication state on the ONT the ONT with the set of access-ports (as indicated by the NAS). In
with the set of access-ports (as indicated by the NAS). In case case of DSL, the DSLAM only needs to update its own replication state
of DSL, the DSLAM only needs to update its own replication state based on the set of access-ports indicated by the NAS.
based on the set of access-ports indicated by the NAS.
- For reporting purposes, ANCP must enable the NAS to query the - For reporting purposes, ANCP must enable the NAS to query the OLT
OLT for channels replicated on a PON or a list of PONs and to for channels replicated on a PON or a list of PONs and to specific
specific access ports. The latter should trigger the OLT to query access ports. The latter should trigger the OLT to query the ONT for
the ONT for a list of channels being replicated on all access a list of channels being replicated on all access ports or on
ports or on specific access ports to the premises. In DSL case, specific access ports to the premises. In DSL case, it is sufficient
it is sufficient to query the DSLAM for a list of channels being to query the DSLAM for a list of channels being replicated on an
replicated on an access port or a list of access ports. 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 ONT Management and Control Interface (OMCI) [OMCI] is specified for
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 parameters on the ONT/ONU. Such configuration can include adding an
an access port on the ONT to a multicast tree and the ONT to a access port on the ONT to a multicast tree and the ONT to a multicast
multicast tree. Thus, OMCI can be a potential replacement for tree. Thus, OMCI can be a potential replacement for ANCP between the
ANCP between the OLT and ONT/ONU, albeit it may not a be suitable OLT and ONT/ONU, albeit it may not a be suitable protocol for dynamic
protocol for dynamic transactions as required for the multicast transactions as required for the multicast application.
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 carry the same information elements that would be carried over ANCP,
ANCP, the OLT must perform the necessary translation between ANCP the OLT must perform the necessary translation between ANCP and OMCI
and OMCI for replication control messages received via ANCP. OMCI for replication control messages received via ANCP. OMCI is an
is an already available control channel, while ANCP requires a already available control channel, while ANCP requires a TCP/IP stack
TCP/IP stack on the ONT/ONU that can be used by an ANCP client on the ONT/ONU that can be used by an ANCP client and accordingly it
and accordingly it requires that the ONT/ONU be IP addressable requires that the ONT/ONU be IP addressable for ANCP. Most ONTs/ONUs
for ANCP. Most ONTs/ONUs today have a TCP/IP stack used by today have a TCP/IP stack used by certain applications (e.g., VoIP,
certain applications (e.g., VoIP, IGMP snooping). ANCP may use IGMP snooping). ANCP may use the same IP address that is often
the same IP address that is often assigned for VoIP or depending assigned for VoIP or depending on the implementation may require a
on the implementation may require a different address. Sharing different address. Sharing the same IP address between VoIP and ANCP
the same IP address between VoIP and ANCP may have other network may have other network implications on how the VoIP agent is
implications on traffic routing. Using a separate IP address for addressed and on traffic routing. For instance, the VoIP traffic
the purpose of ONT/ONU management or ANCP specifically may often to/from the ONT is often encapsulated in a VLAN-tagged Ethernet frame
be required when supporting ANCP. These considerations may favor and switched at layer2 through the OLT to the NAS where it is routed.
OMCI in certain environments. However, OMCI will not allow some The VoIP agent in this case looks like another subscriber to the NAS.
of the transactions required in approach 2, where the ONT/ONU On the other hand, the ANCP session between the ONT and OLT is
sends unsolicited requests to the OLT rather than being queried or terminated at the OLT. Thus, the OLT must be able to receive/send IP
configured by OLT requests. traffic to/from the OLT, which will not work using this setting.
Using a separate IP address for the purpose of ONT/ONU management or
ANCP specifically may often be required when supporting ANCP. These
considerations may favor OMCI in certain environments. However, OMCI
will not allow some of the transactions required in approach 2, where
the ONT/ONU sends unsolicited requests to the OLT rather than being
queried or configured by OLT requests.
13. IANA Consideration 13. IANA Considerations
This document does not require actions by IANA. This document does not require actions by IANA.
14. Acknowledgements 14. Acknowledgements
The authors are thanksful to Rajesh Yadav and Francois Le The authors are thanksful to Rajesh Yadav and Francois Le Faucheur
Faucheur for valuable comments and discussions. for valuable comments and discussions.
15. References 15. References
15.1. Normative References 15.1. Normative References
[RFC2516] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, [RFC2516] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D.,
D., and R. Wheeler, "A Method for Transmitting PPP Over and R. Wheeler, "A Method for Transmitting PPP Over
Ethernet (PPPoE)", RFC 2516, February 1999. Ethernet (PPPoE)", RFC 2516, February 1999.
[RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol [RFC2684] Grossman, D. and J. Heinanen, "Multiprotocol Encapsulation
Encapsulation over ATM Adaptation Layer 5", RFC 2684, September over ATM Adaptation Layer 5", RFC 2684, September 1999.
1999.
[RFC3376] Cain, B., et al, "Internet Group Management Interface,
Version 3", RFC 3376, October 2002.
[RFC4605] Fenner, W., et al, "Internet Group Management Protocol
(IGMP)/Multicast Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, August 2006.
15.2. Informative References 15.2. Informative References
[RFC2881] Mitton, D. and M. Beadles, "Network Access Server [RFC2881] Mitton, D. and M. Beadles, "Network Access Server
Requirements Next Generation (NASREQNG) NAS Model", RFC 2881, Jul Requirements Next Generation (NASREQNG) NAS Model", RFC 2881, July
2000. 2000.
[RFC5851] Ooghe, S., et al., "Framework and Requirements [RFC5851] Ooghe, S., et al., "Framework and Requirements for Access
for Access Node Control Mechanism in Broadband Networks", RFC Node Control Mechanism in Broadband Networks", RFC 5851, May 2010.
5851, May 2010.
[G.983.1] ITU-T recommendation G.983.1, Broadband optical access [G.983.1] ITU-T G.983.1, "Broadband optical access systems based on
systems based on Passive Optical Networks (PON). Passive Optical Networks (PON)".
[G.984.1] ITU-T recommendation G.984.1 Gigabit-capable Passive [G.984.1] ITU-T G.984.1, "Gigabit-capable Passive Optical Networks
Optical Networks (G-PON): General characteristics. (G-PON): General characteristics".
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", [RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC3046, January 2011. RFC3046, January 2011.
[TR-101] Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL [TR-101] Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL
Aggregation", DSL Forum TR-101, May 2006. Aggregation", DSL Forum TR-101, May 2006.
[RFC5713] Moustafa, H., Tschofenig, H., and S. De Cnodder, [RFC5713] Moustafa, H., Tschofenig, H., and S. De Cnodder,
"Security Threats and Security Requirements for the Access Node "Security Threats and Security Requirements for the Access Node
Control Protocol (ANCP)", RFC 5713, January 2010. Control Protocol (ANCP)", RFC 5713, January 2010.
[OMCI] ITU-T recommendation G.984.4 GPON ONT Management and [OMCI] ITU-T G.984.4, "GPON ONT Management and Control Interface
Control Interface (OMCI) Specifications. (OMCI) Specifications".
[RFC6320] Taylor, T., et al, "Protocol for Access Node Control [RFC6320] Taylor, T., et al, "Protocol for Access Node Control
Mechanism in Broadband Networks", RFC 6320, October 2011. Mechanism in Broadband Networks", RFC 6320, October 2011.
[G.987.3] ITU-T G.987.3, "10-Gigabit-capable passive optical
networks(XG-PON): Transmission convergence (TC) layer specification".
Authors' Addresses Authors' Addresses
Nabil Bitar Nabil Bitar
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
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
Hongyu Li Thomas Haag
Email: hongyu.lihongyu@huawei.com Deutsche Telekom
Email: HaagT@telekom.de
Thomas Haag Hongyu Li
Email: HaagT@telekom.de Huawei Technologies
Email: hongyu.lihongyu@huawei.com
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