Note: Descriptions are shown in the official language in which they were submitted.
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MANAGEMENT OF TERMINATIONS IN
A COMMUNICATIONS NETWORK
FIELD OF THE INVENTION
5 This invention relates to the management of connections in a large scale
heterogeneous communications network, such as those operated by
telecommunications
utility companies and utilised by different carriers and service providers. In
particular the
invention relates to a method and apparatus for selecting terminations for
connections in a
broadband network.
BACKGROUND TO THE INVENTION
The term "communications network" as used in the specification, is meant to
encompass networks suitable for voice telephony and for data communications.
Such
communications networks may be suitable for switching and transporting voice,
data,
15 sound and/or image traffic which might otherwise be referred to as
broadband or
"multimedia" communications.
Existing communications networks are characterised by a number of transmission
mediums using a variety of network technologies, protocols, software
applications and
equipment sourced from different vendors. Whilst much of the equipment
includes
2o management functions, such as monitoring, test and alarm features, the
centralising,
handling and controlling of network management functions in a complex mufti-
vendor
environment is a significant problem.
A further problem in a heterogeneous network - which might include customer
access technologies (ADSL, HFC), core network technologies (ATM, frame relay)
and
25 transmission technologies (SONET/SDH, WDM) - is that the management of end-
to-end
connections is typically conducted according to a lowest common denominator
philosophy.
The services provided by the network are limited to those able to be supported
by the least
capable equipment in the network. This philosophy is very ineffective in
utilising the full
capability of the diverse communications paths available in a network to meet
particular
3o service requirements of customers.
Conventional network management centres use several operation support systems
(OSS) for optimising the allocation of resources in a communications network.
Generally
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information on both the flow of communications traffic in the network and the
functional
capabilities provided by network switching elements, which together may be
referred to as
the 'network state', is accumulated at the network management centre.
Typically
information on the network state is maintained in a central database which
must be
5 periodically updated to reflect changes in the communications network. The
database may
be updated directly or by agent systems present in a distributed network.
Accordingly, the
network management centre can remotely monitor the network state for assessing
performance levels, detection of equipment failure, :rectification of circuit
outages and
network traffic.
to A significant problem associated with a central network state database is
the
overheads which are imposed on the communications network in keeping the
information
current such that appropriate resource allocations decisions might be taken.
This is
sometimes referred to as the problem of "synchronising" the information in the
network
management database with the availability of network elements, their
functional attributes
15 and real time state. This problem is particularly acute with respect to the
management of
individual terminations, being a large scale undertaking which impacts on
network
connectivity.
lossa
AAD: ATM access device
2o ADSL: asymmetric digital subscriber loop
ATM: asynchronous transfer mode
CMIP: common management information protocol
COR.BA: common object request broker architecture
DSL: digital subscriber
line
25 EMS: element management
system
HFC: hybrid fibre-optic
co-axial
NMS: network management
system
NTU: network terminal unit
OSS: operation support system
3o VPC: virtual path connection
SDH: synchronous digital hierarchy
SNMP: . simple network management protocol
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SONET: synchronous optical network
TCP/IP: transmission control protocol / Internet protocol
. TL/1: interface protocol for network management
VCI: virtual circuit identifier
VPI: virtual path identifier
WDM: wave division multiplexing
OBJECT OF THE INVENTION
It is an object of the present invention to provide a connection manager for
1o selecting terminations for a predetermined path in a communications network
that carries
broadband traffic between two locations in the network which ameliorates or
overcomes at
least some of the problems associated with the prior art.
It is another object of the invention to provide a method for selecting
terminations
for a predetermined path in a communications network thereby contributing to
cost
effective routing of broadband traffic between two locations in the network.
Further objects will be evident from the following description.
DISCLOSURE OF THE INVENTION
In one form the invention resides in a connection manager for selecting
2o terminations from a plurality of terminations for paths available in a
communications
network for carrying broadband traffic, wherein the connection manager
includes:
(a) a connection model that indicates functional features supported by each
path in the
network and locations of terminations for respective paths;
{b) an interface to control means which manage the feature specific functions
of the
terminations in the network; and
(c) processing means operative, in response to a request for termination of a
predetermined path in the network between two locations, for identifying from
the
connection model in light of termination features required for the
predetermined
path, appropriate control means; whereby
(d) selection of individual terminations for said path is delegated to the
identified
control means, which delegated selection involves:
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(i) determining whether an individual termination supporting the required
features is available at the location; and
(ii) if more than one termination supporting the required features is
available,
adjudicating amongst equivalent terminations.
s Preferably the functional features represented by the connection model
include one
or more of the following:
(i) communications protocol;
(ii) transmission rate;
{iii) availability of the path;
to (iv) average errar rate; and/or
(v) physical location.
Preferably said plurality of terminations are assigned to termination groups
in
accordance with their termination role.
The role of a termination group may include location, physical configuration
or
15 functional features supported by the terminations in the group.
Most preferably, terminations are managed by a hierarchy of control means
wherein
the individual terminations are at the lowest level in said hierarchy.
If required, the terminations are grouped in accordance with the hierarchy of
control means.
2o Suitably the delegated selection of individual terminations further
includes
traversing the hierarchy of control means to a control means managing
individual
terminations.
Preferably, adjudication amongst terminations is conducted by the control
means
on the basis of cost attributed to respective terminations.
25 In preference said control means report the identity of the individual
termination at
each of the two locations.
Preferably said interface to said control means includes network equipment
adaptors co-located with network switching, transmission and/or terminal
equipment.
Most suitably the processing means is operative, where a first termination has
been
3o selected, to delegate selection of a second termination that is connectable
to said first
termination.
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In another form the invention resides in a method for selecting terminations
for a
predetermined path in a communications network for carrying broadband traffic,
the
method including the steps of:
(a) creating a connection model that indicates functional features supported
by each
path in the network and locations of terminations for respective paths;
(b) providing an interface to control means which manage the feature specific
functions
of the terminations in the network;
(c) identifying, in response to a request for termination of a predetermined
path in the
network between two locations, from the connection model in light of
termination
to features required for the predetermined path, appropriate control means;
and
(d) delegating selection of individual terminations for said path to the
identified control
means, whereby delegated selection involves:
(i) determining whether an individual termination supporting the required
features is available at the location; and
~5 (ii) if more than one termination supporting the desired features is
available,
adjudicating amongst equivalent terminations.
Preferably said plurality of terminations are assigned to termination groups
in
accordance with their termination role.
The role of a termination group may include location, physical configuration
and
2o functional features supported by the terminations in the group.
Most preferably, terminations are managed by a hierarchy of control means
wherein
the individual terminations are at the lowest level in said hierarchy.
Suitably the step of delegating selection of individual terminations further
includes
traversing the hierarchy of control means to a control means managing
individual
25 terminations.
Preferably adjudication amongst terminations is conducted on the basis of cost
attributed to respective terminations.
In preference, the method includes a further step wherein the control means
report
the identity of the individual termination at each of the two locations.
3o The delegated selection suitably involves the following steps to traverse
the
hierarchy of control means, which steps are executed recursively:
(a) if a control means returns an individual termination,
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(i) then report the termination's identity to the connection manager;
(b) otherwise the control means,
. (i) delegates to a lower level control means in the hierarchy;
(ii) compares available terminations; and
s (iii) returns lowest cost termination.
The step of delegating selection may further include, where a first
termination has
been selected, selecting a second termination that is connectable to said
first termination.
BRIEF DETAILS OF THE DRAWINGS
l0 To assist in understanding the invention preferred embodiments will now be
described with reference to the following figures in which
FIG 1 is a diagram of a heterogeneous communications network including a
hierarchy of connection managers;
FIG. 2 is a diagram illustrating the structure of a connection manager of a
first
15 embodiment;
FIG. 3 is a diagram of a world view from the perspective of the abstract
connection
model of the first embodiment;
FIG. 4 is a diagram of a hierarchical tree structure of termination groups
which
may be present in a communications network;
2o FIG. 5 is a diagram illustrating fragments of the network of FIG. 4 with a
deployed
connection manager enabling delegated selection of terminations; and
FIG. 6 is a diagram showing a preferred method of delegating selection of
terminations in a network employing partial availability switching.
25 DETAILED DESCRIPTION OF THE DRAWINGS
The embodiment of the invention is described in the environment of a
heterogeneous communications network 10 as illustrated in FIG. 1. The
connection
manager of the embodiment participates in the service activation and service
assurance
processes of large communications networks. The connection manager is suited
to use in
30 relation to broadband communications products which have significant
complexity at the
"Network Layer" (as defined by the ITU-T layered management model) - such as
ATM,
SDH, IP and bundled broadband products. The connection manager supports
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configuration and security activities at the Network Layer and can cooperate
with other
systems performing these functions for subsets of the communications network.
The
connection manager of the embodiment resides in a network management layer 30
between
the service layer 20 and the network element layer 40.
The service layer 20 typically includes service order systems 21 which
institute the
creation of new connections and facilitates the query, modification and
deletion of existing
connections and pre-sales systems 23 which support pre-sales activities
including enquiries
regarding available connection characteristics, connection cost and time
frame. Examples
of service layer systems include service order, customer network management
(CNM) or
1o wholesale gateway.
The network element layer 40 typically includes the hardware for providing
network services such as switching or transmission, for example ADSL/I~C
customer
access technologies 41, ATM core network broadband technologies 42, and
transport
technologies 43 such as SONET/SDH or WDM. The network element hardware may be
15 conceptually considered to reside in different "domains" and is typically
also proprietary in
nature. Accordingly, the network element hardware generally uses proprietary
or
compatible network element managers which act as proxies for many of the
network
elements.
Examples of network element managers are EMS systems 44 and 45 for the
2o ADSL/HFC hardware, the NMS 46 for the ATM core hardware and the vendor
specific
NMS 47, 48 for the transport domain. Although the network element managers
manage
many network elements, they expose each network element as an individual
entity. Thus in
other embodiments, the connection manager may interface directly to the
network
elements.
25 The network management layer 30 of the embodiment illustrates the
flexibility of
the connection manager. A first connection manager 31 is interfaced to the EMS
systems
44 and 45 for managing the customer access domain 40A. The functional
flexibility of the
connection manager arises from its ability to manage the different functional
requirements
of the switch matrix EMS 44 and the AAD EMS 45. A second connection manager 32
3o manages the core domain 40C and a third connection manager 33 is interfaced
to the
vendor NMS systems 47 and 48 in the transport domain 40T. The transport domain
illustrates the ability of the connection manager to handle disparate vendor
equipment.
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The connection managers include interfaces which communicate using the CMIP,
SNMP,
TL/1 or proprietary protocols as required. These interfaces may be adapted to
suit
particular vendors' equipment, current or future.
A fourth connection manager 34 is interfaced with the three domain connection
managers 31, 32 and 33 for the purpose of cross-domain connection management.
The
cross-domain manager 34 level accepts end-to-end connection instructions for
the entire
network, it determines which paths through the underlying networks are
available and
issues connection instructions to the domain connection managers as
appropriate. The
connection task is thus delegated to the appropriate domain connection
managers.
1o Although shown as four separate managers, the network management layer 30
may
be viewed as undertaking the overall connection management function for the
network,
with the cross-domain connection and domain connection being managed at
different
levels. Thus the network wide connection requirement is simplified step by
step so that
each level of connection management can be optimised to manage the portions of
the
15 network under its control. However, the separate connection managers
illustrate the
distributed nature of a network wide connection manager 35 which may be
geographically
distributed across a large number of sites and network operations centres.
Network Models
The connection manager provides flexible network modelling tools for
representing
2o a service provider or network owner's view of broadband connections. The
key concepts
for these representations are:
(i) "paths" which represent the owner's view of a connection, such as ATM
PVC;
(ii) "terminations" where the path is manifest outside of a network, such as
an
25 ATM VPI, VCI and cable, a network port or a customer NTU, and include
intermediate terminations which are conceptually manifestations of sub-
paths in sub-networks; and
(iii) "features" which are the external selectable characteristics of the path
visible at its terminations, such as quality of service, bit rate or path
3o diversity.
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Conceptually a path can negotiate many sub-networks, network elements and
protocols,
such as end-to-end SDH connections implemented using SDH switches and WDM
transmission.
Connection Mana~_ ear Structure
The structure of the connection manager 35 of the embodiment is described in
relation to FIG. 2, as it might be deployed in relation to a particular
network. A
connection model 36 is used to represent the network and its services, which
model may
be implemented by the core software 37. Network adapters 38 are provided to
interface
with network elements, EMS or other NMS. Service adaptors 39 are provided to
interface
to to existing service OSS.
The connection manager 35 supports several fundamental operations relating to
the
life cycle of a path. The network owner may instruct that a path be reserved,
created or
changed, which results in the automatic selection, allocation and
configuration of
appropriate network equipment to implement a connection with the specified
features
between specified terminations. A remove operation frees the allocated network
equipment.
The connection manager allows the determination of which features are
supported,
in what combinations and at what localities in the network. Terminations and
paths may
be searched and listed, and the termination which best supports a given set of
features in a
locality suggested by the connection manager. A create operation followed by a
change
operation suitably implements the connection.
The connection manager 35 of the embodiment preferably uses a COR.BA IIOP
architecture to interface to both the service layer and the network layer. The
service layer
interface and the network model can be adapted to present some standard data
models,
2s such as ETSI 600-653 or ATM Forum M4, or adapted to existing service layer
interfaces.
All connection manager objects can be annotated with the names and identifiers
required
by external systems, for example customer circuit identifiers.
The connection manager is a high-availability system supporting on-line
changes to
configuration with back-out, on-line database backup, replicated databases and
redundant
3o hardware. Depending on configuration, the connection manager will support
10,000
transactions per hour on one mid-range server machine (for example a Hewlett-
Packard
"J-class" server). This typically corresponds to a network with 50 million
installed paths
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with a typical operational latency is 0.3 seconds. The connection manager will
typically
process 10 network alarms per second on one mid-range server. This typically
corresponds to 1 million to 5 million installed paths.
One connection manager installation can be distributed, as indicated above,
over a
5 number of server machines. A distributed installation on up to 10 machines
would be
typical, as transaction processing scales approximately linearly over this
range. Such
installation can suitably support HP UXTM or Solaris~ on StJN Sparc~,
Microsoft's
NT~ on Intel or PA-RISC operating systems.
FIG. 3 shows a view of the world from the perspective of a connection model,
1o considered in the abstract. The connection mode! is a framework for
describing
communications systems involving connections. In particular, the abstract
connection
model 50 of the embodiment is a distributed, object oriented way of
representing the state
and operations required to manage the network layer 30 of a broadband
communications
network. The service layer 20 is effectively the driver for the connection
model in that
providing function to the service layer is the role of the connection model.
In order to address requests from the service layer the connection model
delegates
to either the network element layer 40 - in the form of either network
elements 53 or
network element managers 54 or other providers at the network management layer
- for
example workflow managers 51, network managers 52, other connection managers
SS or
2o network service provider (NSP) 56. The choices involved in performing
delegation
include: (a) to which subordinates are functions delegated? (b) how are super-
functions
mapped to subordinates? (c) what is the sequencing of subordinate operations?
and (d)
what actions occur when a subordinate operation fails?
The abstract connection model 50 must be instantiated for operational use,
with the
2s instantiation depending on:
(i) the particular networking technology employed by the network owner;
(ii) the network owner's engineering rules; and
(iii) the network owner's service level requirements.
It is the model's instantiation 36 that gives meaning to the components of the
model, such
3o as path, feature and termination. When a connection model is instantiated,
each of the
abstract concepts that it presents will have a precise meaning. Furthermore, a
model
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instantiation will have objects instantiated against it which objects will
conform to both the
abstract connection model and the instantiated model.
The development of a connection manager application normally includes the
following three stages:
5 ~ Network analysis and design - the focus at this stage is to define the
architecture of
the network to be managed and to analyse the characteristics of each component
of
the network.
~ Connection manager installation - the focus of this stage is to use the
mechanisms
supported by the core software to specify how the network should be managed.
1o The installation is the outcome of this stage.
~ Run time - once a connection management system is installed, paths can be
created
through the network to provide communications services.
Basic Concepts
The basic concepts for connection management used by the connection model are
15 the path-termination-feature concepts, as introduced briefly above. A
feature is a
characteristic of a path that is required by a client or customer, and is
manifest to the client
of the path. Typical features include data transfer protocol, bandwidth,
reliability and error
rate; for example: ATM protocol, 64kb/s data rate and unavailability for less
than 1
minute/year. Characteristics of paths such as routing via a particular network
element, or
2o implementation using a particular technology are not features, because the
client cannot
detect those characteristics. Features may apply to particular terminations of
a path or
installed on connections, which often requires feature values. The feature
Maximum Bit
Rate has a value specifying what the maximum bit rate is, for example Maximum
Bit Rate
= 256kb/s. A feature with values applied to a connection is referred to as an
installed
25 feature.
A path is provided by a network and is fully characterised by the installed
features
of the path (the path features), a set of terminations exposed to the client
and a set of
installed features for each termination (the termination features). A path may
be
permanent, that is the ability to transmit exists at all times after the path
is established by a
3o connection manager, until it is torn down by the connection manager. A path
may be
switched, in which case there are two phases, "configuration" and
"signalling". The
signalling phase initiates and finalises the ability to transfer data.
Signalling emanates from
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network equipment connected to the path. The configuration phase is performed
by a
connection manager and establishes the bounds of data transfer that can be
requested by
signalling. For example, configuration may allow data transfer anywhere within
a national
network, with speed up to 20Mb/s. This would prevent signalling requesting an
international transfer, or a 100Mb/s transfer.
A path typically has two terminations, but may have one or many. Examples of
paths are ATM PVCs and SVCs, SDH connections, or customer access networks (ie.
local
loop). The term path as used herein includes the ITU-T concepts of connection
and trail,
as well as further concepts such as Switched Virtual Connection.
1o A network represents the ability to manage paths and is used to create new
paths
and list existing paths. Paths are always totally contained within exactly one
network. A
network may be conceptualised as a factory of paths, and a collection of the
paths that it
has created. It is also a collection of the terminations at which the paths
will or could be
manifest. Example networks include an ATM switch, a Main Distribution Frame, a
SONET ring, a ATM domain manager, a regional SDH network manager. The term
"network" includes the ITU-T concepts of network, sub-networks and network
element.
A network is typically implemented by calling on the services of other
networks,
termed sub-networks. For example, an ATM network may use the services of a DSL
and
CORE ATM network. The term "sub-network" may imply a client-server
relationship
2o between the network and the sub-network. Generally, there is nothing
inherent in a
network that makes it a sub-network. All sub-networks are fully fledged
networks in their
own right. Therefore all the properties and functions of networks are also
properties and
functions of sub-networks.
A termination is where a path is, or may be, manifest to the client of a
network. A
termination can also include a grouping of terminations. A termination
grouping may or
may not be capable of establishing paths. Example terminations may be an
physical port, an
ATM VPI on a physical port, or a cable pair at a customer's premises. The term
"termination" includes the ITU-T concepts of trail termination point,
connection
termination point and access group. A termination can participate in a finite
number of
3o paths, typically one, but potentially more.
A path in a network will have one or more (usually two) terminations. Single
termination paths may represent loop-back and multiple terminations may
represent
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multiple drop (for example CSMA) or a closed user group (for example a voice
private
network). Paths may share terminations, this may express a multi-serving
capacity (such
as the set of customers using a billing server).
Connection Manaeer
5 The connection manager 35 presents an architecture for assembling a working
network management system. The core software 37 provides a connection model
that
reflects the characteristics of the particular network equipment deployed by
the network
owner. The operative connection model 3 6 can also reflect the business and
engineering
policies of the service provider or network owner, in other words, the
knowledge that a
1o human operator would apply if they were performing the connection manager
functions
manually. The core software 37 assumes that the interface to the network
supports the
connection model 36, preferably expressed in CORBA.
The network adaptors 38 are developed typically using stack products, such as
those vended by Vertel and Hewlett-Packard, in order to provide simple
interfaces into
15 complex protocols such as CMIS or TL/l.
The service adaptors 39 provide an interface between the network's service
management layer OSS. Existing operation support systems generally have a
proprietary
interface, although there are some emerging standards including the US Federal
Communications Commission's "Gateway". Printed paper or a character terminal
are
2o common interfaces. The deployed connection manager 3 S preferably has an
adaptor to
automate the interface between the service management layer and the core
software 37.
Distributed Object Model
As the connection manager is a network layer manager, it is only concerned
with
modelling network-level concepts. The first network level concept is
"connection". The
25 connection model 36 ofthe embodiment is a distributed object model,
preferably expressed
in CORBA interface definition language (IDL). In accordance with the concepts
introduced earlier, there are three types of objects, namely:
(i) path objects that represent connections;
(ii) termination objects that represent where the connections are physically
30 manifest; and
(iii) network objects which are the fabric that can create connections.
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Link objects may be optionally included in order to model connectivity between
networks
or sub-networks.
Network Objects
The network object is a container of path objects and termination objects.
Network objects form a hierarchy, where some network objects are superior to
others.
Network objects will typically form a strict containment hierarchy, though the
connection
manager allows any non-cyclic structure. Network objects can represent:
individual
network element instances, groups of network elements organized by some owner
determined criteria, such as geographic domains or fi~nctional domains; sub-
networks that
1o are managed by some other NMS, such as a vendor NMS; cross-domain networks
that
aggregate several domain network objects, such as those identified 40A(ccess),
40C(ore)
and 40T(ransport) in FIG. 1.
Network objects support the following operations: listing the capabilities of
the
network object; listing the characteristics of the paths that the network
objects can create;
creating paths having specified terminations and features; previewing path
creation;
searching for paths, terminations and sub-networks having specified
characteristics.
Network objects may be configured as follows: assigning identity, description
and
meaning; defining the relationships between the network objects (for example,
a
containment tree structure); defining the connections between subordinate
network
objects; and the characteristics of the paths they can create.
Path Ob'~ects
Path objects represent the connections formed by network objects. They
correspond to some real-world connection concept. This could be for example:
(i) a physical connection, such as a bearer distribution frame;
(ii} a switched connection, such as an ATM virtual circuit; or
(iii) some abstract relationship, such as the relationship between a customer
and
their Internet service provider (ISP).
A path object is always contained within one network object. When network
objects form
a hierarchy, a network object may implement that path by delegating portions
of the
3o implementation to sub-paths in its subordinate networks. Paths are
characterised by
terminations and features. Terminations describe where the path is manifest,
features
describe externally visible characteristics. A path generally has two
terminations.
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A feature has a name and optionally a value. Features are applied to either
the path
itself, or terminations on the path. This permits termination- specific
features to be
modelled - as required for asymmetrical paths. It is common for features to
interact - that
is the existence of one feature affects the ability of a path to support
another feature.
5 Paths support life-cycle type operations, such as creating and deleting.
This allows
for several levels of completeness of the path's implementation. The levels of
implementation are:
(a) design - The path consumes no resources, other than those minimally
needed to record its characteristics. Design state paths need not obey any
rules.
10 (b) reserve - The path is fully implemented, except the last step which
would
enable service.
(c) installed - The path is implemented into the equipment to enable service.
(d) deleted - The path no longer exists, but the memory of it is kept for
audit
purposes.
1s Paths have a cost, which represents the amount of resource required to
implement this
path. The cost allows a client to rationally choose between several candidate
paths, each
of which is capable of supporting their needs. Path objects support the
following
operations: deletion; changing the features or terminations; preview
operations for the
above; and listing the path attributes.
2o Link Objects
Link objects are used to model the connectivity between networks. They usually
represent the next-lowest-layer in the network protocol stack. For example,
links in an IP
network may be ATM; whilst links in an ATM network may be SDH. A link has
termination groups at either end on different sub-networks. It may also
specify one or
25 more path objects that implement the link. For example, an ATM network may
specify a
link between two regional ATM sub-networks as being implemented using a path
from an
SDH network.
Link objects have a cost and can model the available capacity and used
capacity of
the interconnection they represent.
3o Link objects support the following operations: change implementing paths;
delete
the link; describe the link; and show link 'used' and 'available' capacity.
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Termination Objects
Termination objects represent where path objects are (or may be) manifest.
They
. correspond to some real-world concept for example: a physical termination,
such as a
cable; one channel multiplexed over some bearer such as an ATM virtual circuit
or SDH
s container; a grouping of multiplexed channels, such as an ATM virtual path.
A network
may express an effectively infinite number of terminations, for example an ATM
network
may model each VPI or VCI as a termination. Even coarser grained modelling
than the
ATM example will have large numbers of terminations. To allow these to be
easily
managed, the connection manager typically supports the grouping of
terminations into
to "termination groups".
Termination Groups
The connection model preferably manages the commonality of terminations
through the use of termination groups. In the embodiment, the termination
groups of one
network object preferably form a containment tree 60, such as illustrated in
FIG. 4. There
15 is a root node 61 that includes all termination groups that otherwise have
_no container.
The upper layers of the tree are generally abstract groupings, typically based
on physical
location, such as city 62 or central office building and switching equipment
63. The lower
layers of the tree are typically more concrete, such as interface card 64 or
cable 65. The
leaves of the tree are the lowest level of modelled termination, such as
cable, IP address
20 66, virtual channel 67, or similar technical constructs.
The use of termination groups for equipment such as switch N2 is as follows:
~ all ATM VCIs appear as terminations in VPI termination group 2;
~ the VPIs that appear in the same cable are the CABLE 2 group;
~ the cables terminating on a particular card are grouped on CARD 2; and
25 ~ finally into the group for switching stage N2.
The connection manager makes no clear distinction between termination and
termination
group - termination groups appear higher in the tree and individual
terminations occur
toward the leaves. The network objects indicate those ievels in the
containment tree it is
prepared to establish connections between - typically this may only be the
leaf nodes. The
3o meaning of terminations, and the structure of termination groups is
specifted by
configuration of the core software.
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Each termination preferably exposes to clients a cost for supporting paths
with
particular features. This allows clients to make a rational choice between
several possible
terminations, each of which could meet their needs. In some cases where cost
is not an
issue, it might be appropriate to adjudicate amongst equivalent terminations
by making a
5 random selection, or perhaps on the basis of physical sequence in associated
network
equipment.
Termination objects can support the following operations: describe the
termination;
describe the termination group structure; navigate through the termination
group structure;
and find, within a termination group, the lowest cost free termination capable
of supporting
to a particular set of features. As there are a huge number of terminations in
a typical
network, most deployments will configure terminations at the level of a
termination group.
The characteristics of the individual terminations will be derived from the
network
equipment adaptors. Termination group objects support the following
configuration: the
termination group structure and (optionally) the cost of members of the group.
15 Termination Roles
Each termination (and any corresponding termination group) has a purpose which
is referred to as a "termination role". Examples of termination roles 70 are
indicated on
FIG. 4 and may include location 71, switch 72, card 73, cable 74, IP Address
75, ATM
VPI 76 and ATM VCI 77. There is no specific requirement for a termination
group to
2o have an enumerable number of members or a fixed number of members, as the
members
may reflect some dynamic characteristic of a network. In a typical hierarchy
of termination
groups, termination roles tend to reflect location at upper levels and tend to
merge with
function at lower levels. With reference to FIG. 4, a request for a free
termination in the
termination group "Sydney" with role "ATM VPI" to the connection manager could
return
25 for example:
"Sydney.North. SwitchN2. Card2. Cable2.1 "
The connection manager can use whatever level of termination grouping is
desired
by the service provider or network owner. Using the above example, the
connection
manager may allocate paths at the interface card level 64, delegate
interconnection to the
3o cable level 65, whilst the validity of features could be handled at the
switch level 63. The
levels may be mixed, for example costs may be specified at the card and cable
levels. In
some instances the termination group may correspond to a customer network
terminal unit
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(NTi.l7. It is important that the scheme for termination groups selected by
the network
owner or communications engineer is not ambiguous for any individual
termination.
Network Interface
The connection manager can inter-work with equipment in the network in a
s number of different modes. The connection manager can be interfaced direct
to a network
element, typically via SNMP, TL/1 or CMIS systems; it can be interfaced into a
vendor's
element manager, where it sees the individual network elements; it can be
interfaced into a
vendor's domain manager, where the domain manager is used to establish sub-
paths in that
domain or it can be interfaced into another network owner's wholesale network.
The
io connection manager uses a published CORBA IIOP interface to the network to
expose the
life-cycle, model, state, search and sub-function operations described above
on page 10.
To deploy the connection manager, it is usually necessary to provide a network
equipment
adaptor from the IIOP interface to whatever interface the network layer
presents.
Examples
15 In order to explain the selection of terminations in accordance with a
preferred
system and method of the invention, reference is made to the network fragments
illustrated
in FIG. 5 in conjunction with the diagram illustrating the termination groups
in FIG. 4.
FIG. 5 shows the equipment associated with switch N2 and switch E2 which
include the
respective adaptors in North Sydney and East Melbourne, along with the
interconnections
2o to a connection manager located at a telecommunications company's national
network
management centre. In the example, a client requests an ATM virtual channel
between
North Sydney and East Melbourne with features maximum bit rate l.SMbps and
unavailable less than 4 minutes per year, which results in the connection
manager allocating
a path which is routed, from the North Sydney sub-network (N), over the
Central Sydney
25 sub-network (C), over the Canberra network, and then to the East Melbourne
sub-network
For ease of discussion, the connection manager 35 is illustrated as a single
entity in
FIGS, although it should be appreciated it is generally implemented in a
distributed fashion
over a number of computer sites as discussed above (such as capital city
management sites
3o at Sydney and Melbourne). In response to the request for termination of the
path between
the North Sydney and East Melbourne locations with termination features for
supporting
an ATM virtual channel, the processor 41 identifies from connection model 36
the
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termination group North corresponding to the North Sydney exchange 80 and the
termination group East corresponding to the East Melbourne exchange 90.
In accordance with a preferred method for selecting terminations, the
connection
manager 3 5 delegates selection of a suitable termination at North Sydney to
the switch
manager 81, by communicating with network adaptor 44 interfacing the switch
manager to
a CORBA compliant virtual bus 42. The switch manager 81, which controls
operation of
each of the switches N1, N2 and N3, determines that only termination group N2
associated
with the respective switch supports the functional features required for
termination of the
ATM channel. Accordingly selection of terminations from within termination
group N2 is
to delegated by switch manager 81 to the ATM port manager 82, via a second
network
adaptor 43.
The ATM port manager 82 controls allocation of ATM ports available on the
cables attached to interface cards 83 for switch N2. Thus the port manager is
associated
with the termination groups having the termination roles card 73, cable 74 and
ATM
virtual port (VPI} 76 and channel (VCI) 77. The port manager 82 searches
through the
termination groups until the lowest cost "leaf' or individual termination,
namely the ATM
virtual channel identified as "Sydney. North.N2.Card2.Cable2.2.1", is returned
to the
connection manager. Suitably, the recursive search algorithm employed in the
preferred
method may be represented by the following pseudo-code:
if you are a leaf termination,
then
return self
else
pass to lower level terminations
compare returned results
return lowest cost termination
The connection manager also initially delegates selection of a termination at
East
Melbourne to switch manager 91, by communicating with network adaptor 45
interfacing
3o the switch manager to the CORBA compliant virtual bus 42. The switch
manager 91,
which controls operation of each of the switches E1 and E2, determines that
both
termination groups E1 and E2 associated with the respective switch have the
functional
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features required for termination of the ATM channel. However, E 1 has a much
lower
cost for the particular feature of l.SMbps bit rate. Accordingly selection of
terminations
from within termination group E1 is delegated to the ATM port manager 92, via
a second
network adaptor 46.
5 The delegation process may be repeated by the connection manager 35 for each
of
the intermediate sub-paths over the central Sydney and Canberra networks, in
the case that
the sub-paths require termination.
The diagram of FIG. 6 illustrates how the method of the invention may be
implemented in the case of a sub-network 100 which includes partial
availability switching.
to A requirement 102 for a path from a suitable termination in Sydney
supporting a
transmission rate of 1.2 Mbps to a specific termination Tx in Melbourne is
received by a
connection manager 101. The connection manager 101 is associated with an
access
domain manager 103 which is in turn responsible for a series of DSL
multiplexers A,, AZ,
... A", which are shown schematically as an access connection model 104. The
connection
15 manager 101 is further associated with an ATM domain manager 105 which is
in turn
responsible for a set of ATM switches S,, S2, S3 and S4, which are similarly
shown
schematically as an ATM connection model 106.
The requirement 102 is processed by connection manager 101 and delegated to a
first control means in the form of access domain manager 103 as a request 107
for an input
2o termination in Sydney supporting the feature 1.2 Mbps. The domain manager
determines
that any of the input terminations T" through T"" for multiplexers A support
1.2Mbps, and
T,4 is randomly selected from those terminations presently available. The
identity of input
termination T~4 is then returned 108 by the access manager 103 to the
connection manager
101. The connection manager then delegates a request 109 for an output
termination
which is connectable to T" to access manager 103, which returns 110 output
termination
To6
The connection manager 101 is aware from its connection model 112 that DSL
multiplexers managed by access manager 103 provide terminations for a link 113
between
A and ATM switches S managed by ATM manager 105, and that TI6 is the
corresponding
3o termination to termination Tob. The connection manager 101 oversights
installation of the
path connecting T,4 to Tob and the path connecting T~6 to TX.
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Summary
The connection manager of the invention operates at several levels. The cross-
domain management level can accept end-to-end connection instructions across
an entire
network, determines the path through the underlying sub-networks available to
it,
delegating the connection task to a number of network domain connection
management
layers. A network domain connection manager is cognisant of the termination
roles of
relevant termination groups, but delegates the selection of individual
terminations to
subordinate control systems managing feature specific functions. The
connection manager
need not keep track of information about the availability of network elements
and the real
1o time state and functionality of associated individual terminations, thereby
reducing
management information flows.
By automating the routing and configuration of connections across complex
networks, the connection manager substantially reduces the need for manual
management
at the network and element levels. The real time state of the network is
determined
15 dynamically as needed, ameliorating the onerous requirement for
synchronising a central
network management database. Connections can be provisioned in real time and
the
connection manager will scale to process increasing volumes of new connections
as
broadband communications networks grow.
The approach to object oriented modelling in the connection manager, wherein
the
2o abstract connection model is differentiated from the connection model
instantiations
resulting in a high degree of reuse of clients and servers. This approach also
allows for,
but does not enforce, very flexible client and server implementations, which
can match a
rapidly changing business scenario.
Throughout the specification the aim has been to describe the preferred
25 embodiments of the invention without limiting the invention to any one
embodiment or
specific collection of features.
