Internet DRAFT - draft-zhao-opsawg-eoc-oam-model
draft-zhao-opsawg-eoc-oam-model
OPSAWG J. Zhao
Internet Draft Fudan University
Intended status: Informational X. Song
Expires: May 2015 Oriental Cable Network
J. Li
B-STAR
November 24, 2014
A Reference Model for OAM in Ethernet over Coaxial Access Network
draft-zhao-opsawg-eoc-oam-model-00.txt
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Abstract
This document describes an architectural and functional reference
model for the Operations, Administration and Maintenance (OAM) of
Ethernet over coaxial access network. This model applies to the
protocol between Coax Line Terminal and Coax Network Unit in the
access network.
Table of Contents
1. Introduction ................................................. 2
2. Terminology .................................................. 3
3. Network OAM Framework ........................................ 3
4. Reference Model for Interoperability ......................... 5
4.1. Basic Functionality Interoperability .................... 5
4.2. Service Interoperability ................................ 5
5. Protocol for Interoperability ................................ 5
6. Security Considerations ...................................... 7
7. IANA Considerations .......................................... 8
8. References ................................................... 8
8.1. Normative References .................................... 8
8.2. Informative References .................................. 8
1. Introduction
Ethernet over coaxial (EoC)provides a cost-effective way for
Internet service providers to ensure a high quality Internetaccess
for their subscribers with hybrid fiber coaxial network, while
accelerating the deployment of digital video service and the ability
to connect multiple devicesto the same coaxial cable.
For managing and controlling such an access network, a network
operator will prefer to have a unified scheduling, management, and
quality-of-service (QoS) environment that includes coaxial portions
of the hybrid fiber coaxial network. This can be achieved by
designing the Operations, Administration and Maintenance (OAM)[1]
functionalities, and by having a centralized OAM framework from the
cable head-end to the end-users' premises.
The document defines a reference model and associated protocol that
introduces requirements on an EoC system to support the
configuration and transport of a class of service between a coax
line terminal(CLT) and the coax network unit(CNU).
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The approach of the document is to outline the functionalities and
potential mechanisms for providing the OAM for EoC access network,
as well as illustrating interoperability protocol by example.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [2].
ACS Automatic Configuration Server
CLT CoaxialLine Terminal
CNU Coax Network Unit
EoC Ethernet over Coaxial
MAC Media Access Control
MDIO Management Data Input/Output
MME Management Message Entity
SNI Service Node Interface
OAM Operations, Administration and Maintenance
UNI User Network Interface
3. Network OAM Framework
The OAM reference architecture, as shown in figure 1,identifies the
elements that an EoC network minimally requires to perform and
communicate properly between the functional subsystems of the EoC
system.
According to the need for service and device management in EoC
system, the OAM framework includes:
o EoC functionality Management
Functionality management is a common tool for setting the
parameters of Ethernet signal over coaxial, e.g. radio frequency
and modulation.
o Service Management
Service management is responsible for setting Ethernet profiles,
e.g. VLAN, multicast, frame filtering, bandwidth, QoS, broadcast
flood, UNI port.
o Performance Management
Performance management is a key tool that allows users to
discover the performance of CLT port, CNU port and UNI by
measuring the metrics of Ethernet service and RF.
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o Failure Management
Failure management supports detecting and monitoring the state of
CLT and CNU continuously or at intervals. If failure occurs, it
will result in warning, or loopback detection, etc.
o Security Management
Security management defines the security measures for accessing
CNU, e.g. user and password authentication, privilege
authorization, and key management.
o System Management
System management describes the functionalities of software and
hardware maintenance, e.g. CNU remote boot, firmware update.
+------------------------------------------------------------+
| |
| +-----------+ +------------+ +------------+ |
| | Function- | | Service | | Performance| |
| | ality | | | | | |
| | Management| | Management | | Management | |
| +-----------+ +------------+ +------------+ |
| ^ ^ ^ |
| | | | |
| V V V |
|------------------------------------------------------------|
| |
| Network Operations, Administration and Maintenance |
| |
|------------------------------------------------------------|
| ^ ^ ^ |
| | | | |
| V V V |
| +-----------+ +------------+ +------------+ |
| | Failure | | Security | | System | |
| | | | | | | |
| | Management| | Management | | Management | |
| +-----------+ +------------+ +------------+ |
+------------------------------------------------------------+
Figure 1 OAM framework
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4. Reference Model for Interoperability
In the EoC system, the interoperability model includes basic
functionality interoperability and service interoperability.
4.1. Basic Functionality Interoperability
The basic functionality, which is specify by various EoC standards,
such as IEEE 1901-2010 [3], refers to the interoperability of
physical layer and the MAC layer implementation from different
manufacturers between CLT and CNU Ethernet services. The physical
layer interoperability includes the consistency of working frequency
and the modulation parameters of CLT and CNU. The MAC layer
interoperability includes the mechanism of CSMA / CA, TDMA, and
clock synchronization between CLT and CNU.
4.2. Service Interoperability
Service interoperability refers to the ability of proper service
operation and management between different CLT and CNU vendors. The
consistency includes user port related operation at terminals,
multicast operations, VLAN operations, QoS-related operations,
bandwidth-limiting operations. In addition, service interoperability
also includes all the management operations associated with the EoC
basic functionality (mainly the EoC system configuration and
management), as well as partially the service carrying operations
(mainly the configuration of service carrying).
Other management operations other than the specifiedabove,can be
defined as well, but it's not in the scope of this document.
5. Protocol for Interoperability
The service interoperability of EoC system includes two aspects: 1)
protocol for interaction between CLT and CNU, which is implemented
via the management message exchange; 2) an Interoperability
Management Module(IMM) at CNU, which handles management message and
transforms the message into specific format. For conventional CNU,
the IMM need transform Management Message Entity(MME)into MDIO
signals for layer 2 switching. For CNU with home gateway functions,
IMM just forwards the MME to gateway transparently.
The protocol for service interoperability defines the procedure for
setting / reading the profile attributes, handling OAM requests and
responses, and performing version management.
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The CNU which works as a home gateway, implements the management
functionalities by forwarding messages via Interoperability
Management Module. For the extended MME destined for home gateway,
Interoperability Management Module change the destination MAC
address as the MAC address of the home gateway, and forwards it to
home gateway. For the extended MME destined for CLT,
Interoperability Management Module change the destination MAC
address as the MAC address of EoC module, and forwarded it to CLT.
+-------------CNU----------------+
+----+ | +----+ +-----+ +-----+ |
|CLT | | | | | | | | |
| |<----------->| | | MME | | MME | HG | |
| | MME | |EoC |<--->|IMM |<--->| | |
| | | | | | |MDIO | SW | |
| | | | | | | | | |
+----+ | +----+ +-----+ +-----+ |
+--------------------------------+
HG: Home Gateway, SW: Switch, MME: Management Message Entity
IMM: Interoperability Management Module
Figure 2 Interoperability between CLT and CNU
The typical interaction between the CLT and CNU can be illustrated
using an example. After CNU gets online, the configuration
management is performed by BOSS and NMS automatically through the
management channel. The procedure works as follows.
1. After CNU start, Interoperability Management Module reads the
functional attributes of CNU;
2. CNU Interoperability Management Module registers extended MME at
EoC module. After the registration, all registered extended MME
will be forwarded to Interoperability Management Module for
processing.
3. After receiving online message from CNU, CLT sends the extended
MME to query the attribute the CNU.
1. Interoperability Management Module reply the attributes,
including the MAC address of the home gateway using extended MME.
2. CLT sends the CNU's online authentication information to NMS. The
authentication information includes the MAC addresses of EoC
module and the home gateway.
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3. NMS and BOSS handle CNU authentication. If authenticated, the
VLAN and IP information (Note: Including the subnet mask, IP
gateway, ACS URL, DNS IP) will be sent to CLT using configuration
profile.
4. After the receipt of the configuration profile, CLT first parses
the configuration parameters and encapsulates the parameters of
home gateway with extend MME, and then send it to CNU. If CLT
does not receive any profile, it will send CNU online
authentication information to the NMS periodically.
5. After Interoperability Management Module received extended MME,
it will set the destination as the MAC address of home gateway,
and the source as the MAC address of EoC module. Then it sends
the modified MME to the home gateway.
6. Upon receiving the extended MME, the home gateway will configure
its VLAN IP information (Note: Including the subnet mask, IP
gateways, ACS URL, DNS IP) and sends the results back to CLT.
7. After received the MME from home gateway, Interoperability
Management Module will set the source of the extended MME as the
EoC MAC address.
8. After CLT received home gateway's MME on its successful
configuration, it will establish the relationship between the
home gateway and CNU locally. The configuration information of
home gateway will be stored as well.
9. Home gateway will establish TR069 connection with ACS after it
received the configuration management profile of VLAN and IP(note:
including the subnet mask, IP gateway, ACS URL).
Other OAM operations can be illustrated in a similar way. The
interaction between CLT and CNU extended MME message.
6. Security Considerations
This document discusses a reference model for implementing OAM in
Ethernet over Coaxial access network. The solution to some of the
problems discussed can have security implications, such as when a
malicious client's attack on a protocol can create a false illusion
of failures, or prevent the detection of actual ones.
Malicious client should not be able to use non-EoC interfaces to
insert EoC-specific OAM transactions. Providing a secure mechanism
for EoC OAM is required if EoC-specific protocols are to be used
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successfully. Therefore, authentication and authorization for OAM
MUST be considered when designing OAM-related mechanisms, which
satisfy the reference model presented in this document.
7. IANA Considerations
This memo does not have any IANA considerations.
8. References
8.1. Normative References
[1] Andersson, L., Van Helvoort, H., Bonica, R., Romascanu, D.,
Mansfield, S., "Guidelines for the use the OAM acronym in the
IETF ", RFC 6291, June 2011.
[2] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[3] IEEE 1901-2010, "IEEE Standard for Broadband over Power Line
Networks: Medium Access Control and Physical Layer
Specifications" December 2010.
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Authors' Addresses
Jin Zhao
Fudan University
825 Zhangheng Rd., Shanghai 201203, China
Email: jzhao@fudan.edu.cn
Xuhong Song
Oriental Cable Network
2860 Jinke Rd., Shanghai 201203, China
Email: songxh@scn.com.cn
Jin Li
B-STAR
1158 Xiehe Rd., Shanghai 200335, China
Email: jli@b-star.cn
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