TELECOMMUNICATION STUDY PERIOD 2001-2004 |
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Question(s): |
5 - |
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(Ref. :
COM 4 每 D 109 每 E) |
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Title: |
Framework for the Integrated Management of Hybrid Circuit/Packet Networks |
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Summary
This recommendation describes the environment in which integrated management of Hybrid Circuit/Packet Networks (including ATM and IP based networks) must operate.
This contribution proposes text for a draft new
recommendation: M.3017, which is composed of the TD-PLEN-0085 of the 2002-04-08
TABLE
OF CONTENTS
3.1 Definitions Imported from ITU-T G.805
3.2 Other Definitions in This Recommendation
3.2.2 Hybrid
Circuit/Packet IP Network
3.2.4 Technology-Specific
Network
3.2.5 Multi-Technology Networks
3.2.6 Integrated
Network Management System
3.2.7 Technology-Specific Network Management System
6.2.3 Topology
versus Architecture
6.3.1.1 SDH/SONET
Ring-Based Physical Architecture
6.3.1.2 Optical ADM
Ring-Based Physical Architecture
6.3.1.3 Optical Mesh-Based
Physical Architecture
6.3.2 Key
for Reference Architecture Figures
6.3.3 Reference
Architecture 1A
6.3.4 Reference
Architecture 1B
6.3.5 Reference
Architecture 2C
6.3.6 Reference
Architecture 3C
7.1 The
relationship between technology-specific
networks in HCPN environment
8 Management
Environment in hybrid circuit/packet networks
8.1 TMN
Management Architectures for HCPN
8.1.1.1 Descriptions for Logical Architecture Option 1
8.1.1.2 Descriptions for Logical Architecture Option 2
8.1.1.3 Descriptions for Logical Architecture Option 3
8.1.1.4 Descriptions for Logical Architecture Option 4
8.1.2 IP-Based
Management Architectures
8.1.3 SNMP-based
Architectures
8.2 Protocol
Architectures and Interworking
8.2.1 General
Purpose Paradigms
8.2.2 Special
Purpose Paradigms
Figure 1/M.3017 每 Point-to-Point Topology
Figure 2/M.3017 每 Linear Chain Topology
Figure 3/M.3017 每 Star Topology
Figure 4/M.3017 每 Tree Topology
Figure 5/M.3017 每 Ring Topology
Figure 6/M.3017 每 Mesh Topology
Figure 7/M.3017 每 Fully Connected Mesh Topology
Figure 8/M.3017 每 Highly Connected Mesh Topology
Figure 9/M.3017 每 Topologies at Physical and Logical Layers
Figure 10/M.3017 每 Example Physical Configuration of SDH/SONET Ring-based Physical
Architecture
Figure 11/M.3017 每 Example Physical Configuration of Optical ADM Ring-based Physical
Architecture
Figure 12/M.3017 每 Example Physical Configuration of Optical Mesh -based Physical
Architecture
Figure 13/M.3017 每 Legend for Reference Architecture Figures
Figure 14/M.3017 每 Reference Architecture 1A
Figure 15/M.3017 每 Reference Architecture 1B
Figure 16/M.3017 每 Reference Architecture 2C
Figure 17/M.3017 每 Reference Architecture 3C
Figure 18/M.3017 每The Layer Network Architecture of HCPNs
Figure 19/M.3017 每 Integrated Management of HCPNs Option 1
Figure 20/M.3017 每 Integrated Management of HCPNs Option 2
Figure 21/M.3017 每 Integrated Management of HCPNs Option 3
Figure 22/M.3017 每 Integrated Management of HCPNs Option 4
ITU-T Recommendation M.3017
Framework for the Integrated Management of Hybrid
Circuit/Packet Networks
(2003)
This Recommendation is a part of a series of Recommendations defining the TMN paradigms for management of large-scale carrier networks. It is the scope of this Recommendation to provide an overview of:
The evolving telecommunications networks
architectures that provide for multi-service
networking over packet-switched networks (e.g. IP and ATM).
The interworking architectures and scenarios to allow interworking between traditional circuit-switched and HCPNs.
The services and applications to be provided over the above architectures (e.g. Voice over IP).
Management paradigms employed in managing IP Networks.
Considerations for the extension of TMN toward the management of HCPNs.
Connections across administrative domains are included in the scope, however in this
Recommendation no explicit provisions are made for these.
The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is published regularly.
- ITU-T, G.805 (2000), Generic Functional Architecture of Transport Networks.
- ITU-T, G.872 (2001), Architecture of Optical Transport Networks.
- ITU-T, M.3020 (2000), TMN Interface Specification Methodology.
- ITU-T, M.3010 (2000), Principles for a Telecommunications Management Network.
- IETF RFC 1901 (1996), Introduction to Community-based SNMPv2
- IETF RFC 3411 (2002), An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks
-
ITU-T
X.720 (1992), Management information model
- ITU-T X.722 (1992), Guidelines for the definition of managed objects
- ITU-T Q.812 (1997), Upper layer protocol profiles for the Q3 and X interfaces
- ITU-T Q.811 (1997), Lower layer protocol profiles for the Q3 and X interfaces
- OMG Document formal/99-10-07, The Common Object Request Broker: Architecture and Specification, Revision 2.3.1.
- ITU-T X.780 (2001), TMN guidelines for defining CORBA managed objects
- ITU-T Q.816 (2001), CORBA-based TMN services
-
ITU-T Q.816.1 (2001), CORBA based TMN
services: Extensions to support coarse-grained interfaces
- ITU-T Q.814 (2000), Specification of an electronic data interchange interactive agent
- ITU-T Q.815 (2000), Specification of a security model for whole message protection
For the purposes of this Recommendation, the following definitions apply.
-
access
group;
-
connection;
-
layer
network;
-
link;
-
link
connection;
-
subnetwork;
-
subnetwork
connection protection;
-
trail.
This Recommendation defines the following
terms:
A paradigm is a set of management functionalities that includes a protocol and
associated services, as well as a supporting information definition
language. It can be used to produce
collections of management information including relationships among the management
information to accomplish a given management objective. A paradigm must have mechanisms to
support the definition of a library of management information.
A Hybrid
Circuit/Packet IP Network is a network
composed of both circuit-switched and IP packet-based layer (sub) networks.
See
Section 6.2.1 for details.
A Technology-Specific Network(TSN) is a
single layer network of the layer-based network model, which is only concerning
about one technology, e.g. IP, ATM, SDH or Optical network.
For the
purpose of providing multiple services, assuring QoS and reducing operating
costs, the core networks of
service providers are usually composed of several technology-specific
communication networks. There are various relations between these
networks, and they may cooperate with each other to provide services. In this
Recommendation, core networks composed of several interacting TSNs belonging
to the same operator, are called Multi-Technology Networks(MTS).
Integrated Network Management System (INMS) is the managing system performing the
integrated management of MTN.
It is responsible for analyzing and processing of the management information
collected from TSNs, and the
integrated management of topology, configuration, fault and performance of several
TSNs.
Technology-specific Network Management System (TS-NMS) is
the managing system performing
the management of a TSN,
including the management of the sub-networks and their relations. TS-NMS
provides INMS the management information of topology, configuration, fault and
performance of this TSN.
This Recommendation uses the following abbreviations:
AAA |
Authorization
Authentication Accounting |
ADM |
Add and Drop
Multiplexer |
ATM |
Asynchronous Transfer Mode |
BLSR |
Bidirectional Line Switched Ring |
CMIP |
Common Management
Information Protocol |
COPS |
Common Open Policy Service |
CORBA |
Common Object Request
Broker Architecture |
DCS |
Digital
Crossconnect System |
DEN |
Directory Enabled Networking |
EDI |
Electronic Data Interchange |
|
Element Management System |
FCAPS |
Fault management,
Configuration management, Accounting management, Performance management,
Security management |
GSM |
Global System for
|
HCPN |
Hybrid Circuit/Packet Network |
HTTP |
HyperText Transfer Protocol |
IIOP |
Internet
Inter-ORB Protocol |
IMS |
IP Multimedia
Subsystem |
INML |
Integrated Network Management sub-Layer |
INMS |
Integrated Network Management System |
IP |
Internet Protocol |
LC |
Link Connection |
LDAP |
Lightweight
Directory Access Protocol |
MS SPRING |
Multiplex Section Shared Protection Ring |
MTN |
Multi-Technology
Networks |
NE |
Network Element |
NML |
Network
Management Layer |
NMS |
Element Management System |
OS |
Operations System |
OSI |
Open System Interconnection |
OTN |
Optical Transfer
Network |
POTS |
Plain Old
Telephone Service |
PSTN |
Public Switched
Telephone Network |
QoS |
Quality of
Service |
RMI |
Remote Method
Invocation |
SDH |
Synchronous
Digital Hierarchy |
SMS |
Service
Management System |
SNCP |
Sub-Network Connection Protection |
SNMP |
Simple Network
Management Protocol |
SONET |
Synchronous
Optical Network |
SS7 |
Signalling System
No.7 |
STM-N |
Synchronous
Transport Module (level) N |
TCP |
Transfer Control
Protocol |
TMN |
Telecommunications Management Network |
TSN |
Technology-Specific
Network |
TS-NML |
Technology-Specific
Network Management sub-Layer |
UDP |
User Datagram
Protocol |
UML |
Unified Modeling
Language |
UPSR |
Unidirectional Path Switched Ring |
USM |
User-based
Security Model |
VC |
Virtual Circuit |
VP |
Virtual Path |
WDM |
Wavelength-Division
Multiplexing |
XC |
Cross Connect |
XML |
eXtensible Markup
Language |
This Recommendation describes a framework for the integrated management of Hybrid Circuit/Packet Networks (HCPN). It begins in Section 6, with a description of the network environments in an HCPN that need to be supported within the integrated management framework. This description includes reference architectures and topologies. Section 7 describes Service environment, namely the relationship between technology-specific networks in the HCPN environment. Section 8 describes the management environment itself.
This section proposes transport network architectures for use as a
description of the network environment applicable to integrated management of HCPNs. The focus is on the transport
view of network architectures.
Signaling
and control architectures are beyond the scope of this version of the Recommendation. Transport
services for the control plane are supported by the transport architectures.
A set of reference architectures is provided. The architectures were developed on the basis of collective architectural input from service providers and are intended to provide the basis for multi-technology network architectures subject to study by the service providers.
Each reference architecture captures a grouping of technologies and configurations. The set of architectures exhibit a progression from current technology networks to future networks that will be based on technologies that in some cases are just now beginning to emerge. Due to the ample options allowed in the reference architectures, refinements will generally be needed to define use cases for specific network management functions.
Each reference architecture is constructed by overlaying a physical architecture with a layer domain architecture. The physical architecture identifies relationships among network elements and transport media; the layer domain architecture identifies specific adaptation relationships among transport layer domains. Four reference architectures are defined building on three distinct physical architectures.
Section 6.2 provides an
overview concepts pertaining to generic network topology. Section 6.3 presents the reference architectures including an explanatory
overview, a description of three physical architectures, and descriptions of
the four reference architectures.
In order to compare network topologies and examine the interactions of topologies across different technologies it is necessary to agree upon some generic terminology. ITU-T Recommendation G.805 Generic Functional Architecture of Transport Networks provides a good model for examining topology, allowing networks to be decomposed into layer networks that handle the different characteristic information. However, common usage architectural terms, such as SDH MS SPRING, (Multiplex Section Shared Protection Ring) while containing topological terms, such as ring, are not solely topological terms, but describe a combination of connectivity (topology) and equipment functionality across multiple layers (i.e., a ring configuration of physical links, Multiplex Section protection switching, ability to inhibit protection switching on selected Administrative Units). In order to relate common usage terms from different technologies to one another, a set of common terms needs to be agreed upon.
In this Recommendation, Topology is defined as the principle arrangement or relations of the objects/components used in describing a network to one another without regard to their actual occurrence in any real network.G.805 defines topological component as an architectural component, used to describe the transport network in terms of the topological relationships between sets of points within the same layer network.
G.805 describes four topology component types: layer network, sub-network, link, and access group. These terms can be used and in some cases simplified for our purposes.
A layer network refers to resources that support a specific characteristic information (e.g., STM-1). A layer network*s transport entities are identified by links, and its transport processing functions are identified by sub-networks and access groups. A lower, server layer network provides connectivity for higher, client layer networks at its access groups. Access groups indicate where paths may be terminated in a layer network. Each layer network has the potential to have its own unique topology.
G.805 allows portions of a layer network to be aggregated into larger sub-networks. However, when considering a layer network*s complete topology, we generally need to decompose all sub-networks to their lowest level, which correspond to fabrics.
Links represent fixed connectivity for a particular layer network. They are established by setting up trails between termination functions in a lower server layer network.
G.805 divides layer networks into two types:
-
Transmission
media layer network - a "layer network" which may be media
dependent and which is concerned with the transfer of information between
transmission media layer network "access points" in support of one or
more "path layer networks".
-
Path
layer network - a "layer network" which is independent of the
transmission media and which is concerned with the transfer of information
between path layer network "access points".
For use in considerations of network management, it is useful to define two types of views of network architecture that are in the spirit of G.805 but with hooks into some of the more tangible elements of a network:
-
Physical architecture 每 the
configuration of 1) transport media and 2) Network Elements(NEs) or other devices that provide the
ability to terminate physical transport layer signals.
-
Layer network topology 每 the
configuration of links connecting cross-connect fabrics (or sub-networks) or
termination points (access groups) within a given transport layer.
The physical architecture is analogous to the configuration of transmission media layer network combined with specification of network elements. It is noted that in the transmission media layer for an optical transport network (in terms of fibers, not WDM optical paths, which are associated with a separate layer network) all paths are point-to-point between devices, or network equipment. The layer network topology is basically the topological configuration of a path layer network.
Having defined different topological components, we need to agree on some generic terms for topology types. While these terms are familiar, they are often not well defined in common usage. The following definitions for generic topology types are proposed. Where possible, they are based on discrete mathematics terminology.
The simplest topology is point-to-point (see Figure 1) which is comprised of a link
connecting two nodes.
Figure 1/M.3017
每 Point-to-Point
Topology
Stringing several nodes
together serially with point-to-point links forms a linear chain topology (see Figure 2). The intermediate nodes
provide cross-connect as well as termination functionality.
Figure 2/M.3017 每 Linear Chain Topology
In a star topology (see Figure 3) all other nodes in the topology are only connected to one hub node. Only the hub node needs to provide cross-connect functionality; however, all connectivity is lost if the hub node is removed.
Figure 3/M.3017 每 Star Topology
Sometimes in common usage the term ※tree§ is used to imply
hierarchical routing. But in terms of connectivity it just indicates that there
is only one route between any two nodes in the topology. Linear chain and star
topologies are sub-classes of tree topology
(see Figure 4), but any node in
a generic tree topology may have links to more than two other nodes.
Figure 4/M.3017 每 Tree Topology
A ring topology
(see Figure 5)
differs from the previous
topologies in that it provides route diversity. Specifically, in a ring
topology each node has exactly two links connected to it, so that the links
form a ring. Thus, there are exactly two paths between any two nodes. (Logical
rings may not have physical route
diversity because of the underlying layer network topologies.)
Figure 5/M.3017 每 Ring Topology
The term ※mesh§ is particularly ill defined in common usage, being neither a discrete mathematics term, nor a clear pictorial description. It is often used to mean a fully connected topology (described below), but sometimes it is just used to describe a more complex topology that cannot be described using one of the more restrictive terms defined above. In this Recommendation a mesh topology (see Figure 6) is defined simply as one in which there are two or more paths between at least two of its nodes. Using this definition, a mesh topology is one that contains a loop, so that it is not a type of tree topology, but may contain other links than those that form a single loop, which would be a ring. A simple mesh topology can be thought of as a conglomeration of several of the topologies above.
Figure 6/M.3017 每 Mesh Topology
A fully connected
mesh topology (see Figure 7) is sometimes referred to
simply as a mesh topology; however, it is much more specific. There is a direct
link between each node and every other node in this topology. No cross-connect functionality is required to
connect any of the nodes, and should a point-to-point link fail, there is a
high degree of route diversity to ensure continued connectivity. Fully
connected mesh topologies do not scale
well because N*(N-1)/2 links are required for N nodes.
Figure 7/M.3017 每 Fully Connected Mesh Topology
There is another type of mesh that is of interest in terms
of survivability. A highly connected mesh topology (see Figure 8) is defined as one
that has at least two paths between each node and every other node. In such a
topology, loss of any single link would not cause loss of potential
connectivity between any of the nodes, and loss of any single node would not cause loss of potential connectivity
between any of the other nodes. The simplest form of such a topology would of
course be a ring.
Figure 8/M.3017 每 Highly Connected Mesh Topology
What many people may consider as topologies, such as SDH MS SPRING or VC virtual ring, may be more accurately be described by the more generic terms, architectures or transport architectures, because they have implications on both topological (connectivity) and transport network functionality. G.805 defines an architectural component as any item used to generically describe transport network functionality.
For example, an SDH MS SPRING can be described as being composed of a ring physical architecture (point-to-point fiber terminating on successive pairs of ADMs arranged to form a ring) that supports a ring logical topology (comprised of e.g. point-to-point STM links connecting successive pairs of STM/VC cross-connect fabrics).
Note that in SDH/SONET, the term link refers to a bundle of pre-provisioned point-to-point link connections between two endpoints; in ATM (in a topology context) it more accurately represents a quantity of bandwidth between two endpoints.
An SDH VC virtual ring provides an example of how topologies at different layers are somewhat independent. An SDH VC virtual ring architecture does not define a particular physical topology, which could be a mesh (as in Figure 9) or even a linear chain. In the linear case, diverse routing is not achieved since the ring is collapsed. In the case of a DCS physical mesh, a ring could be configured through the mesh in conjunction with DCS ring functionality; diverse routing would need to be guaranteed by selection of non-overlapping ring segments.
A virtual ring topology could be formed in the VC-3 Path Layer, for example, by creating point-to-point VC-4 trails as clients of the STM-4 and STM-1 layers to form a ring. If Sub-Network Connection Protection (SNCP) switching functionality is available at the VC-3 layer, the virtual ring could operate as a protection ring.
Continuing with the example in Figure 9, assume that all of the equipments have ATM VP termination capability and the equipment on the STM-4 ring also have ATM VP cross-connect capability. VC-3 trails were created from each node to the one on the far left then the ATM VP layer network would have a star topology. If instead, VC-3 trails were created among all of the nodes on the STM-4 ring then the ATM VP layer would have a fully connected mesh network. The other equipment would not appear at the ATM VP layer because there was no connectivity provided to them by VC-3 trails.
Figure 9/M.3017 每 Topologies at Physical and Logical Layers
In this section, four
reference architectures are presented. Each reference
architecture consists of two views of a network:
- Physical Architecture 每 the configuration of physical transport media and NEs. The possible types of NEs that may be included are identified. NE types are defined in terms of the types of cross-connect or switching fabric(s) supported and may include supported adaptations of transport layers at trail terminations.
- Layer Domain Architecture 每 the configuration of transport layers related through adaptation of server layer bandwidth to client layer connections. This view indicates support of flexible connections or inflexible connections within each transport layer. In addition, it shows mappings of services to layer domains
Each reference architecture
is formed by associating a
specific layer domain architecture with one of three physical
architectures.
Other network views may
be overlaid on a reference architecture comprised of these components. It is
expected that the reference architectures described in this Recommendation will be refined via additional specifications
when applied to specific use cases. These refinements may include:
- Specific combinations of NEs and NE connectivity
- Protection architecture of the physical transport layer
- Subnetwork topologies and protection architectures of logical transport layers
- Subnetwork topologies specific to component transport layers within a technology layer
- Specific connections between termination points
- Specific segment of the network (e.g. long haul, metropolitan area, secondary/access)
Subnetwork topology gives the configuration of transport bandwidth and cross-connect/switching resources representing the potential connections within a single transport layer. An example of component transport layers within a technology layer is STM regenerator section, STM multiplex section, VC-11, VC-12, VC-2, VC-3, VC-4 component layers within the aggregate SDH layer.
Three physical architectures are described.
They are presented in the time order in which they will likely appear in
implementations. For each physical architecture, the
potential NE types are listed and the configuration of physical transport media
is identified. An example configuration is constructed for
each architecture and is shown in a figure. It is noted that the figures
are intended to depict example configurations to help visualize the
architectures; they should not be viewed as excluding other example
configurations. In particular it is noted that hybrid NEs may include
cross-connect or switching fabrics for any combination of technologies
supported by a given architecture. The use of the term SDH in the figures below is meant to refer to either SDH or SONET.
This physical architecture has the following properties:
- Physical topology is based on SDH/SONET ring 每 either MS SPRING (SONET BLSR) or SONET UPSR(Unidirectional Path Switched Ring).
- NE types connected by ring include: SDH/SONET ADMs and DCS; hybrid SDH/SONET/ATM/IP NEs are possible.
- Ring interconnection via DCSs or ADMs via dual node interconnection.
- SDH/SONET ring protection plus ATM protection mechanisms possible.
An example configuration is shown in Figure 10.
Figure 10/M.3017 每 Example
Physical Configuration of SDH/SONET Ring-based
Physical Architecture
Although the DCS is included in this ring scenario, it does not have widespread acceptance as a viable SDH/SONET ring element. It is noted that a variety of protection architectures are possible for protecting services in the ATM layer.
This physical architecture has the following properties:
- OTN (Optical Transport Network) - architecture based on ITU-T G.872
- Physical topology is a fiber optic ring transporting multiple wavelengths
- NEs on the fiber optic ring include OTN ADMs and hybrid ADMs comprised of any combination of OTN/SDH/ATM/IP
- Dual interconnection to other subnetworks
- Variety of protection methods possible
An example configuration is shown in Figure 11.
Figure 11/M.3017 每 Example
Physical Configuration of Optical ADM Ring-based
Physical Architecture
The standards basis in G.872 is referenced as a goal, with the understanding that pre-standard implementation agreements are allowed. An OTN ADM can add/drop Optical Channel signals each of which is transported as a distinct wavelength.
This physical
architecture has the following properties
- OTN - architecture based on ITU-T G.872
- Physical topology is a fiber optic mesh; fiber carries multiplexed wavelengths
- NEs on the optical mesh include OTN Cross-Connect(XC) and hybrid NEs based on OTN and any combination of SDH, ATM, and/or IP.
- A variety of protection and restoration methods are possible.
An example configuration is shown in Figure 12.
Figure 12/M.3017 每 Example
Physical Configuration of Optical Mesh
-based Physical Architecture
An OTN XC can cross-connect Optical Channel signals each of which is transported as a distinct wavelength.
The legend used in the
reference architecture diagrams is described in the following text and in Figure 13. A
technology layer domain is indicated by an oval shape. The downward thick arrow
indicates an adaptation relationship between a client transport layer on top and a
server layer below. A client layer may be supported by several server layers.
Mappings of services (rectangular boxes) to layer domains are identified.
Different symbols are used to indicate flexible transport layers and fixed
transport layers. A flexible layer allows flexible routing of connections via
cross-connect or switching functionality.
The composition of a domain may be based upon a single
transport layer (e.g., Virtual Path) or a grouping of layers such as that
included within a technology (e.g., ATM, including both VP and VC). The term layer is used in the G.805 sense,
referring to transport of signals of a given
characteristic information (e.g. VC-3 path). It is useful to select a domain
based on collective behaviour, for example, common capabilities for connection
set up. For the purposes of developing reference architectures, aggregate
layers associated with a given technology are used without splitting out component
transport layers.
Figure 13/M.3017 每 Legend for Reference Architecture Figures
In the reference architecture figures below, colour coding is used to match NEs in the physical architecture with the supported transport layers in the layer domain architecture (not visible in black and white/grayscale editions).
This reference architecture combines Physical Architecture 1
with a layer domain architecture that transports ATM and IP over SDH and
carries circuit-switched services over ATM and SDH.
Figure 14/M.3017
每 Reference Architecture 1A
This reference architecture combines Physical Architecture 1
with a layer domain architecture that transports ATM and IP over a flexible SDH
infrastructure and over an (inflexible) SDH framing mechanism. In addition,
this architecture enables IP to be transported over ATM. Circuit-switched
services are carried over ATM and SDH as in the previous architecture.
Figure 15/M.3017
每 Reference Architecture 1B
This reference architecture combines Physical Architecture 2
with a layer domain architecture that builds on the capabilities of layer
domain architecture B. Wavelength (l) services are supported via the
flexible OTN layer. Circuit-switched services may be carried over SDH, ATM,
and/or IP. IP may be transported via ATM, SDH framing, and/or directly over the
OTN, assuming suitable digital framing/wrapper is provided. ATM traffic may be
carried over a flexible SDH network, SDH framing, or directly over the OTN.
Both flexible and inflexible (point-to-point) SDH signals may be transported
over OTN.
Figure 16/M.3017
每 Reference Architecture 2C
This reference architecture combines Physical Architecture 3
with the layer domain architecture C described in the previous reference
architecture. It is noted that protection may be provided via OTN mesh
techniques, SDH rings, and/or ATM and IP layer methods depending upon the
protection strategy implemented.
Figure 17/M.3017
每 Reference Architecture 3C
According to the provided functions, telecommunication networks in the HCPN environment may be divided into several TSNs, such as IP network, ATM network, SDH network, and Optical network. There are bearing or interworking relationships between these TSNs, as shown in Figure 18.
Figure 18/M.3017 每The Layer Network Architecture of HCPNs
A service layer network is composed of several service sub-networks. The relationship between service sub-networks can be client/server or peer/peer. GSM, PSTN and SS7 are examples of the service sub-networks, where SS7 provides signalling transmission service for GSM and PSTN. A service layer network can be borne by Optical transport network, SDH transport network, ATM transport network, and IP transport network.
In an
HCPN environment, the bearing relationship is the most important vertical
association among related TSNs.The bearing relationship indicates that a client
layer service is actually carried by a server layer network. Figure 18 shows some applicable bearing relations in HCPN
environment. A server layer network may have more than one client layer
network. For example, both IP and ATM networks may be supported by SDH transport
networks, and SDH itself can also be borne by Optical network.
In the
future, interworking relations among MTNs are
expected. When two
interworking TSNs do not have a client/server relationship, they are peers from the services point of view.
There are some typical examples of interworking relations between TSNs: an IP network interacts with a circuit
switching network, and a GSM network interacts with a PSTN network. The inter-connection between two TSNs is usually implemented by gateways.
Figures 19-22 show different possible scenarios that may be used to configure management functionality. It should be noted that the approaches assume that a management layer approach is used to configure network management capabilities.
A Semantic mediator function acts to
normalize the information model between the two types of networks. In these logical architectures, the
existence of a semantic mediator embedded in an operations system is implicit
at the point where the management of the two networks is integrated. Only external semantic mediators are
shown explicitly.
Figure 19/M.3017 每 Integrated Management of HCPNs Option 1
Figure 19 shows the first option of the integrated management
of HCPNs. In this figure, the NEs may be classified into three kinds, the
circuit-switched NEs, the packet-switched NEs and the interworking NEs, which
can be viewed as bridges between circuit-switched and packet-switched NEs.
The Infrastructure
EMS is the Element Management Layer systems that are responsible mainly for
managing the circuit-switched NEs and interworking NEs through interface 1A.
Here the ellipse of
The IP EMS is
responsible for the element layer management for packet-switched NEs as well as
interworking NEs through Interface 1B, which is different from Interface 1A
(for example, Interface 1B may be an SNMP-based interface).
Both Infrastructure
EMS and IP EMS provide Interface 3 to an NMS, and the NMS performs the network
layer integrated management functions of HCPNs, and may manage several
technology-specific networks. The NMS
also provides Interface 5 to Service Management System (SMS).
Figure 20/M.3017 每 Integrated Management of HCPNs Option 2
Option
2 (see Figure
20) is the same as option 1,
except that it is that in this case, the circuit-switched NEs shall also
provide Interface 1B to the appropriate Infrastructure EMS, which is the
same interface as provided by packet-switched NEs. The packet-based NEs only
provide a typical interface for the IP EMS.
Figure 21/M.3017 每 Integrated Management of HCPNs Option 3
Option 3 (see Figure 21) is the same as option 1, except
that there is an explicit semantic mediation function
in-between the packet-switched NEs and the infrastructure NEs.
This option
releases the burden of packet NEs, which may just provide the same interface to
EMSs of different kind; while the ※Semantic Mediator§ becomes a complex
function for implementors.
Figure 22/M.3017 每 Integrated Management of HCPNs Option 4
Option 4 (see Figure 22) is the same as option 1, except
that the semantic mediation function has been moved up in the management layer.
While option 1 shows a single NMS providing the semantic mediation function to
the separate EMSs, option 4 shows separate NMS feeding into an additional NMS
that is providing the semantic mediation function.
Option 4 shows the possibility of integrated management of an HCPN in a layer-based approach in which the network management layer(NML) can be divided into two sub-layers: the technology-specific network management sub-layer (TS-NML) and the integrated network management sub-layer (INML). These sub-layers differ in management scope, management objectives and management functions.
The Infrastructure EMS and IP EMS are EML OSs and provide Interface 3A and Interface 3B to the Infrastructure NMS and IP NMS respectively.
The Integrated Network Management System(INMS) is an INML OS which mainly manages the relations between TSNs. The Infrastructure NMS and IP NMS are TS-NML OSs, each of which manages a single technology-specific network, and provides the necessary management information to INMS through Interface 4. There are not necessarily any interfaces between different TS-NML OSs. Based on the management information collected form Interface 4, INMS provides the provisioning of transmission service across two or more TSNs, maintains the end-to-end view of MTN facilities and supports the management of services involving two or more TSNs, and analyses the source fault or/and predicts the future performance trends involving two or more TSNs. The TS-NMS does not need to provide all the resources to INMS through Interface 4. Generally, only the resources connecting two or more TSNs are visible to INMS. In cases where special purpose management operations are required, such as a specific protection assignment for a bearing network, more resources information should be stored in INMS to achieve this goal, which may show information of two adjacent layers in different TSNs.
The service management system (SMS) just interacts with the
INMS in HCPN environment through Interface 5, which avoids the potential costs
of an SMS interacting with several TS-NML OSs. The main purpose for this
management architecture is to decrease the coupling of related TSNs in HCPN
environment, and to provide operators
a cross-border view of an HCPN.
The INMS is responsible to maintain the relationship information among TSNs,
and does the work which one single TS-NML OS cannot achieve. It works as a coordinator for cross-network border management
activities.
In its simplest
form, the IP-based management architecture can be described as management
protocols providing for the exchange of messages which convey management
information between the managed elements and the management stations. RFC1901
In IP-based management, the management station does not always have as clear a
distinction between
While management is
not always formally discussed in terms of Fault, Configuration, Accounting,
Performance and Security (FCAPS), these areas are all present in varying
degrees. Given the connectionless nature of IP routing, monitoring functions
have historically placed more emphasis on performance management compared with
other functions. Other areas such as alarm management, have received more
attention in recent years, though.
RFC3411 defines an SNMP management system
as containing:
- several (potentially many) nodes, each with an SNMP entity containing command responder and notification originator applications, which have access to management instrumentation (traditionally called agents);
- at least one SNMP entity containing command generator and/or notification receiver applications (traditionally called a manager) and,
- a management protocol, used to convey management information between the SNMP entities.
RFC3411 defines
managed elements as devices such as hosts, routers, terminal servers, etc.,
which are monitored and controlled via access to their management
information.
SNMPv1 defines the
following protocol operations: get, get-next, set and trap and allows for many
simple data types based on integer and strings. SNMPv2c added get-bulk, 64bit counters and changed the PDU format. SNMPv3
added security and introduced new terminology.
Management
information consists of ※managed objects§ which are individual data items,
e.g., integers and strings, defined using the Structure of
Management Information (SMI). These are accessed via a virtual information
store, termed the Management Information Base (MIB). The scope of the MIB is
typically one managed entity. Managed objects are organized into simple groups
or into tables.
In this Recommendation, TMN management paradigms are classified as general purpose paradigms (suitable for all management applications) and special purpose paradigms (designed to satisfy some specific management application(s)).
To be considered as a general purpose paradigm, the paradigm must satisfy the following criteria:
-
Scalability (106 每 107 objects)
- Compatibility with existing models
- Support for multiple managers
- Support for query capabilities
- Support for data modification capabilities
- Support operations on set valued attributes
- Support multiple object access
- Selective access of attributes
- Support operations on multiple objects
- Support of autonomous notifications
- Subscription to receipt of autonomous notifications
- Well defined notifications
- Support for modeling of the containment relationship
- Support of unique names
- Support of creation and deletion semantics
Special purpose paradigms will be accompanied by a description of the management space that they are addressing.
Special purpose paradigms will exist because for their particular application they may offer a performance advantage or economic benefit.
For example it may be possible to classify HTTP, SNMP, XML and JINI as special purpose protocols and CMIP, IIOP and Java RMI as general purpose protocols. The special purpose protocols would be associated with information models that are semantically consistent with the general purpose protocols and the protocol and functional transformations would be done at a gateway. For instance, SNMP may run to a gateway, provide none of the event filtering capabilities required, be collected via traps at the gateway and then filtered and further processed at the gateway.
General-purpose paradigms support the overall functioning of
the TMN. They can be used at both
Qx and X interfaces. They
support a common object oriented semantic model of resources. They provide protocols and services that
allow these resources to be managed.
The OSI System Management paradigm is based on the
architecture of systems management found in ITU-T Recommendation X.720. The resources are modeled using the
notation of ITU-T Recommendation X.722 (GDMO). The protocols specified in ITU-T
Recommendation Q.812 for the Upper Layer Protocol Specification of the OSI
Paradigm are used. These protocols
may use a variety of lower layer protocols specified in ITU-T Recommendation
Q.811 including Internet Protocols.
OMG CORBA can be used in a variety of ways within TMN. When used as a general purpose
paradigm the guidelines found in ITU-T Recommendations X.780 and/or X.780.1 are
followed. In addition the services
found in ITU-T Recommendations Q.816 and/or Q.816.1 are
used. The protocol used is
found in ITU-T Recommendation Q.812 in
the section on the protocol profile for CORBA based services. This protocol profile uses the Internet
Protocol profile found in ITU-T Recommendation Q.811.
EDI/EDIFACT may be used at the TMN X interface to support
TMN service layer interactions. The
protocol profile used to support EDI/EDIFACT is found in ITU-T Recommendation
Q.812 in the section on Protocol Profile for EDI/EDIFACT
Based Services. This protocol
profile used ITU-T Recommendation Q.814 to the Interactive Agent protocol and,
if needed, ITU-T Recommendation Q.815 to provide whole message security. This protocol used the Internet Protocol
lower layers specified in ITU-T Recommendation Q.811.
SNMP is suitable for use in interfaces between Network
Elements and Element Management Systems. The details for using this protocol
are part of Q.811/Q.812
The fundamental reason that SNMP is not available as a
general purpose paradigm is that it may not support the existing models. There does not seem to be a prescriptive
way of mapping the existing models into SNMP. It is also the case that a paradigm must be capable of being used in
an object-oriented manner, and capable of multiple object addressing and
multiple object operations.
In addition, support for
modeling of the containment relationship, unique names, and creation and
deletion semantics is conceivable, but not trivial.
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