Note: Descriptions are shown in the official language in which they were submitted.
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GR 98 P 1698
Description
Method and communications system for processing state
information in a management network having a number of
management levels
The invention relates to a method and a
corresponding communications system for processing
state information in a management network having a
number of management levels, the state information
being transmitted between an agent of one management
level and at least one manager of a next higher
management level for a state realignment.
The principles of a management network, which
are also called TMN (Telecommunications Management
Network) principles, define a number of management
levels for the management of a communications system -
for example a mobile communications system, each level
having a dual function. In the managing system, each
level, apart from the lowest one, has a manager
function for the level below. In the managed system,
each level, apart from the topmost one, has an agent
function for the next higher level.
The management of state information (state
management) represents one of a number of TMN function
areas which characterizes the state of a managed
object. A managed object is a logical abstraction of a
resource in the communications system. A distinction is
made here between hardware-related managed objects
which describe a manufacturer-related implementation of
a function, and function-related managed objects which
are in each case the abstraction of a manufacturer-
independent functionality. In an object-oriented
environment - such as between manager and agent in a
mobile communications system - each agent functionality
is provided by a particular object - as instance of an
object class - which is
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known both to the agent and to the manager. The
management state of an object can be described by means
of state information according to the ITU-T X.731
>standard. In this arrangement, each change of the state
of a managed object is transmitted by the agent to the
manager in corresponding messages.
If the connection between the two management
levels, that is between agent and manager, is no longer
guaranteed for a particular period, the agent must
temporarily store the changes in the state which have
occurred during this interval, in order to ensure that,
after the communication capability has been restored,
the manager is provided as rapidly as possible with an
overview of thecurrent state of the object. For this
purpose, a state realignment is performed between agent
and manager - for example during the setting up of a
new connection after a connection termination or after
an initialization of the agent or of the manager. In
principle, the manager plays the active role by
triggering the state realignment and requesting and
receiving the state information for each existing
object from the agent. Requesting and transmission is
always done for all agent objects, i.e. independently
of the content of the respective state information at
the time of the request by the manager. In the case of
a relatively large number of managed objects, the
signaling load is considerable and leads to the
alignment procedure taking an undesirably long time.
It is the object of the invention to specify a
method and communications system for processing state
information in a management network having a number of
management levels for improved state realignment.
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In accordance with one aspect of this invention,
there is provided a method for processing state information
in a communication system by means of a management network
exhibiting a number of management levels (A, B, C), the
state information being transmitted between an agent (AG) of
one management level (B, C) and at least one manager
(MA1, MA2) of a next-higher management level (A, B) for a
state realignment, in which method the manager (MA1, MA2)
sends a request message (staAS) for performing the state
realignment to the agent (AG), the agent (AG) checks the
state information with regard to deviations from a normal
state, and the agent (AG) sends changes in the state
information to the manager (MA1, MA2) in one or more
successive messages (staCN).
In accordance with another aspect of this
invention, there is provided a communication system for
processing state information in a management network having
a number of management levels (A, B, C), the state
information being transmitted between an agent (AG) of a
management level (e.g. B) and at least one manager
(MA1, MA2) of a next higher management level (e.g. A) for a
state realignment, comprising facilities (M-CTR) in the
manager (MA1, MA2) for sending a request message (staAS) for
performing the state realignment to the agent (AG), and
facilities (A-CTR) in the agent (AG) for checking the state
information with regard to deviations from a normal state
and for sending changes in the state information to the
manager (MA1, MA2) in one or more successive messages
(staCN).
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The invention is based on the fact that state
information is transmitted between an agent of one
management level and at least one manager of a next
higher management level for a state realignment.
According to the subject matter of the invention, the
manager sends a request message for performance of the
state realignment to the agent. The agent checks the
state information with respect to deviations from a
normal state and sends changes in the state information
to the manager in one or a number of successive
messages.
As a result of the subject matter of the
invention, the state realignment is only performed when
changed state information is present so that the
manager is informed by the agent on request of
deviations from the normal state. In consequence, not
all state information is automatically transmitted,
irrespective of whether it has changed or not. This
results in a reduced information flow between agent and
manager which represents a considerable gain for the
manager if there is a large number of managed objects.
The manager, however, is only interested in the changes
in the state information which are necessary for the
state realignment, it is consequently only provided
with these deviations in accordance with the subject
matter of the invention. In consequence, the
transmission of state information for which the agent
has found no deviation from the normal state can be
omitted.
According to a further development of the
invention, state attributes and/or status attributes
are used as state information. The normal state is
preferably defined by means of predeterminable values
for the state attributes and/or status attributes. Due
to the above attributes, detailed information on the
changed state of each
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existing object can be called up by the manager and
provided by the agent.
State attributes for characterizing the
operational readiness, the manageability and the use of
a resource supported by the agent in the communications
system are preferably used as state information.
Furthermore, status attributes which specify, for a
resource supported by the agent in the communication
system, whether it is in an unknown state, in an alarm
state or in a state of availability, are preferably
used as state information. Due to the transmission of
only the changed attributes, the manager only receives
the detailed information required as a minimum in order
to produce the state realignment between manager and
agent.
It has been found to be advantageous if the
manager, in the request message, also sends a
correlation information item for correlating the
respective request with the messages containing the
changed state information received from the agent. As a
result, a number of requests for state realignment can
run simultaneously or serially. The parallel solution
has the advantages of an even better utilization of the
transmission resources at the interface of the
agent/manager relation and a faster provision of the
changed state information for the next higher
management level. Due to the correlation by means of
the unambiguous correlation intormation issued by the
manager, there is the additional possibility of
allocating the incoming responses of the agent,
containing the changed state information, to the
correct request even if the order is not maintained.
Successively initiated requests can mutually overtake
each other, for example when a packet data network is
traversed between agent and manager. The agent can
process a number of requests in parallel and
immediately thereafter send back the state information
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to the manager or managers for state realignment
without regard to the order of the started requests.
A further advantageous development of the
invention provides that a correlation information item
for a correlation of the subsequently transmitted
messages containing the changed state information with
the state realignment started in each case is also sent
by the agent in a message to start the state
realignment. The unambiguous correlation information
issued by the agent guarantees that the changed state
information items of various state realignments running
simultaneously or in series reach the manager which in
each case is processing the received state information
further, independently of the time when they are sent
out by the agent.
According to a particularly advantageous further
development of the invention, the manager controls the
state realignment in dependence on at least one
parameter sent to the agent. The advantage of a state
realignment which can be parameterized compared with the
base functionality lies in that only certain state
information is transmitted on the basis of the parameter
transmitted. This provides the manager with a selection
function for a subset of all state information. In
particular, the possibility of a controlling influence
on the realignment by simple means and by using
standardized messages increases the flexibility of the
manager and additionally reduces the message and
information flow. Due to the parameterizable alignment
functionality for processing the state information it is
possible, for example, to achieve a selection of
resources and/or an active control of the order of the
requested information. In particular, the combination of
the base functionality - transmission of only the
changes of the state on the basis of deviations compared
with the normal state - with the parameterizable
alignment functionality leads to a particularly
effective method and communications system
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which results in optimum utilization of transmission
resources at the interface of the agent/manager
relation and the fastest possible provision by the
agent of only the state information requested by the
manager for the next higher management level.
According to a further development of the
invention, the manager sends a parameter by means of
which the state realignment is automatically initiated
by the agent. Thus, the state realignment can be
controlled by the manager in such a manner that it is
triggered automatically by the agent at certain times.
According to further advantageous developments
of the invention, the parameterization can take place
with one or more of the following parameter values, in
each case set by the manager. Thus, a parameter is
provided by the manager with parameter values which
specify a starting time for the automatic state
realignment and/or an end time for the automatic state
realignment. Other parameter values define
- a time interval for a repetition of the automatic
state realignment,
- selected resources for which changed state
information is to be transmitted by the agent,
- the termination of a running state realignment.
In the text which follows, the invention will
be explained in greater detail with reference to
illustrative embodiments and referring to the figures,
in which:
Figure 1 shows the block diagram of a management
network for a mobile communications system
with agent/manager relation between an
operations and maintenance center and one or
more network management centers,
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Figure 2 shows the block diagram of the management
network according to Figure 1 with agent/
manager relation between a base station
system and an operations and maintenance
center for performing at least two
applications for the base station system,
Figure 3 shows the block diagram of agent and manager
for processing the state information for
parameterizable state realignments according
to the invention, and
Figure 4 shows the message flow between the manager
and the agent for controlling the state
realignment.
The illustrative embodiment describes the
invention by means of a TMN concept for the management
of a mobile communication system which, for example,
exhibits network facilities of a mobile radio network
according to the GSM standard. The invention is not
restricted either to the GSM standard or to mobile
radio networks but can be applied to telecommunication
networks of any type and operation which use a TMN
management network.
A mobile communications system is a
hierarchically structured system of various network
facilities, in which the lowest hierarchy stage is
formed by the mobile stations. These mobile stations
communicate with the radio stations forming the next
hierarchy level, which are called base stations, via a
radio interface. The, for example, mobile stations in a
radio area of base stations supplying a radio cell are
preferably combined for covering a relatively large
radio area and connected to higher-level network
facilities, the base station controllers. The base
stations and base station controllers belong to a base
station subsystem of the mobile communications system.
The base station controllers communicate via defined
interfaces with
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one or more switching facilities, the mobile switching
centers, via which, among other things, the transition
to other communication networks also takes place. The
mobile switching centers, together with a plurality of
data bases, form the switching subsystem of the mobile
communications system.
Apart from the above network facilities, there are
one or more operation and maintenance centers which are
used for, among other things, configuring and
monitoring the network facilities. For this purpose,
monitoring measures and configuration measures are in
most cases remotely controlled from the operation and
maintenance center which are usually arranged in the
area of the mobile switching centers. In this
arrangement, an operation and maintenance center in
each case communicates with a base station subsystem or
switching subsystem via a defined interface. A further
task of the operation and maintenance center is the
management of state information (state management)
which represents one of a number of management function
areas and characterizes the state of a managed object.
A managed object is a logical abstraction of a physical
resource - i.e. a network facility - in the mobile
communications system. In this context, a distinction
is made between hardware-related managed objects which
describe a manufacturer-related implementation of a
function, and function-related managed objects which
are in each case the abstraction of a manufacturer-
independent functionality.
For the management of the mobile communications
system, the TMN principles define a number of levels,
of which, in the present example, three levels will be
explained in the text which follows, referring to
Figures 1 and 2.
Figures 1 and 2 in each case show three levels
A, B and C of the management network, of which
management level C contains the network element level
comprising a number of
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base station subsystems BSS11, BSS12...BSS1N and BSS21,
BSS22...BSS2M. Management level B characterizes the
network element management level in which the operation
and maintenance centers OMC1 and OMC2 in each provide
the manufacturer-related management functionality for
individual subsystems such as, in the present example,
the operation and maintenance center OMC1 for the base
station subsystems BSS11, BSS12...BSS1N and the
operation and maintenance center OMC2 for the base
station subsystems BSS21, BSS22...BSS2M. Management
level A characterizes the network management level in
which the network management centers NMC1 and NMC2 in
each case implement an integrated manufacturer-
independent management functionality. In this
arrangement, a number of network management centers can
have access to the same network facility of the next-
lower management level B, in the present example
network management centers NMC1 and NMC2 of the next-
higher management level C to the operation and
maintenance center OMC1 of the next-lower management
level B. Between the network facilities of different
management levels, defined interfaces are provided for
information transfer.
The difference in the illustrations according
to Figure 1 and Figure 2 lies in the fact that there is
an agent/manager relation for processing state
information for one or more state alignments in
Figure 1 between the operation and maintenance center
OMC1 (agent) and a network management center NMC1
(manager) or a number of - physically separate -
network management centers NMC1, NMC2 (manager) and, in
Figure 2, between the base station subsystem BSS11
(agent) and two different applications OF1 and OF2
(manager) in the operation and maintenance center OMC1
or between the operation and maintenance center OMC1
(agent) and two different applications NF1 and NF2
(manager) in the network management center NMC1. In
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order to secure an overview of the state of managed
objects at any time in the network management centers
NMC1, NMC2, the operation and maintenance
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center OMC1 provides the state information - stored on
the basis of events and states which have occurred, for
example, within the supported base station subsystems
BSS11...BSS1N, and sends them on request in parallel to
both managers. This is done preferably after a
disconnection or after an initialization of the agent
or of the manager. Similarly, a number of requests can
also be directed successively to the agent, e.g. the
operation and maintenance center OMC1, by a single
manager, e.g. the network management center NMC1.
Figure 1 shows the structure for requests for state
realignment sent out a number of times according to the
invention, which, in the present example, are running
in parallel between management level B in which the
agent in the form of the operation and maintenance
center OMC1 is located, and the next-higher management
level A in which the managers are formed by at least
two separate network management centers NMC1, NMC2.
To secure an overview of the state situation at
any time also at management level B, e.g. in the
operation and maintenance center OMC1, the base station
subsystem BSS11 provides the state information - stored
on the basis of events and states occurring, for
example, within the supported base stations and base
station controllers - and sent in parallel to at least
two managers of the operation and maintenance center
OMC1 in the form of the different applications OF1 and
OF2, both of which are executed by one and the same
physical facility OMC1. This is also preferably done
after a disconnection or after an initialization of the
agent or of the manager. A serial transmission of
requests initiated several times by a single manager,
e.g. the operation and maintenance center OMC1, to the
agent, e.g. the base station subsystem BSS11, is also
possible. As an alternative, or additionally, an
agent/manager relation can also exist between the
operation and maintenance center OMC1 (an agent) and
the network management center NMC1 (a manager)
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for the serial exchange of requests and state
information or for the parallel exchange of requests
and state information for at least two different
applications NF1 and NF2 (two managers) in the network
management center NMC1. Figure 2 shows the structure
for state realignments running in parallel according to
the invention between management level B, in which the
managers are located as applications OF1 and OF2, and
the next-lower management level C in which the agent is
located.
As soon as an internal interface which has
failed in management level C is operational again, the
state realignment, also called realignment procedure or
realignment method, is started on request of the
manager/managers, and only the state information which
has changed due to deviations compared with a normal
state is transmitted by the agent according to the
invention. In the present example, the state
realignment begins initially between the base station
subsystem, e.g. BSS11, and the applications OF1, OF2 in
the operation and maintenance center OMC1 in parallel
and then continues in parallel between the operation
and maintenance center OMC1 and the higher-level
network management centers NMC1, NMC2. At the end of
these procedures, the state situation is updated again
both in the OMC and in the NMCs and aligned with one
another. Naturally, the realignment method can be
limited to the updating of the state information
between the agent and managers in two immediately
adjoining management levels, e.g. level B and level A.
Figure 3 diagrammatically shows the
configuration of agent AG and managers MA1, MA2 with
the facilities required for carrying out state
realignment procedures running simultaneously - in the
case of two or more managers - or serially - with only
one manager. Each manager MA1, MA2 and agent AG has a
controller M-CTR and, respectively, A-CTR which can
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generate and evaluate the messages for the state
realignment.
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Similarly, they have transceivers - not shown in
greater detail - for sending and receiving the messages
and storage facilities for storing the state
information and other user and signalling information.
The controller M-CTR of the manager then
generates a request message by means of which the agent
is called up to transmit the state information, and
preferably inserts into this request message a
correlation information item used for correlating the
request with messages transmitted subsequently. This
correlation information item issued by the controller
M-CTR is unambiguous. The request message is
transmitted to the agent via the transceivers. For
controlling the state realignment, the M-CTR facility
of the manager also includes one or more parameters par
in the respective request message in order to
selectively request certain state information from
selected network facilities. The respective request
message is sent together with the parameters par to the
agent AG. In particular, the state realignment or
realignments can be automated by means of a parameter
par so that the controller A-CTR of the agent
automatically repeatedly triggers the realignment
process within periods defined by a time interval. The
parameterizable alignment functionality with regard to
the processing of state information makes it possible
to achieve, for example, a selection of the resources
and/or an active control of the order of the requested
information.
The controller A-CTR of the agent AG receives
the request message containing the parameters par,
evaluates them and checks the state information with
respect to any deviations from a normal state. If this
is so, the controller A-CTR generates one or more
messages in which only the changes of the state
information for at least one existing object are
successively sent back
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to the manager MA1, MA2 or, respectively, the
controller M-CTR. The state information of managed
objects preferably comprises a number of state
attributes of which, for example, the attributes OST
(operational state), AST (administrative state) and UST
(usage state) for identifying the operational
readiness, the manageability and the use of a resource
supported by the agent and associated with the object
in the communication system are specified. The state
information preferably also comprises a number of
status attributes, of which the attributes UNS (unknown
status), ALS (alarm status) and AVS (available status)
are defined. In this context, they specify for the
respective object or, respectively, for the respective
resource in the communication system whether it is in
an unknown state (UNS), in an alarm state (ALS) or in a
state of availability (AVS).
The state attribute OST can assume the values
"enabled" or "disabled", this state information being
readable but not changeable from the point of view of
the manager. The state attribute AST can assume the
values "unlocked by the manager" or "locked by the
manager" or "shutting down", the last-mentioned state
value having the significance that no further new
services will be accepted by the resource in the case
of a currently terminated operation. This state
information is readable and changeable from the point
of view of the manager. The state attribute UST can
assume the values "active, free capacity" or "busy, no
free capacity" or "idle", this state information being
only readable but not changeable from the point of view
of the manager. The normal state, which is used for
checking the presence of deviations and thus of changed
state information is adjustable by means of a default
value which is the result of a combination of the above
individual values, for example "enabled", "unlocked by
the manager" and "idle". This means that
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only the changed state information of managed objects,
the state of which differs from the normal state
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defined above is transmitted from agent to manager. All
other state information, i.e. of objects in the normal
state, remains unconsidered and is not transmitted.
Apart from these state attributes, the status
attributes UNS, ALS and AVS define in more detailed
form the state of the resource associated with the
object with regard to operational readiness, current
use and manageability. Thus, the status attribute UNS
is set to the value "true" if the state attribute OST
or the state attribute AST is not supported. The value
of the respective state attribute OST, AST is
irrelevant in this context. The status attribute ALS
represents an overall indicator for the alarm state of
a resource and is only readable by the manager but
cannot be influenced by it. The attribute assumes the
binary value "one" in the case of an alarm state and a
binary value "zero" in the case of the normal state.
The status attribute AVS can assume either no value or
a number of values from a defined set of individual
values and can also only be read by the manager. The
normal state is characterized by an empty set of
values.
The state information entered in the storage
device of the agent AG is checked by the controller A-
CTR and only the changed state information CST (changed
status) is sent to the controller M-CTR of the manager.
The unambiguous correlation information entered
in the request message by the controller M-CTR of the
manager MA1, MA2 is then used for correlating the
requests whilst any further correlation information
item correlates the messages subsequently sent by the
agent (state change notifications) with the state
realignment started in each case. The correlation
information issued by the agent AG or, respectively,
its controller A-CTR, is also unambiguous and is sent
to the next-higher management
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level preferably in the respective message together
with the changed state information cst. Using the
correlation information provides for unambiguous
correlation of state realignments performed
simultaneously or serially with a number of managers or
a single manager.
In the agent AG, a number of filter functions
EFD1, EFD2 (event forwarding discriminators), which can
in each case be associated with the managers MA1, MA2
and controlled by them, having filter criteria for the
messages generated by the agent AG, can also be used so
that the messages with the changed state information
cst are only routed to the managers MA1, MA2 when the
filter criteria are met. The controller M-CTR of the
manager is capable of setting up and deleting such
filter functions in the agent AG and of establishing
the filter criteria in order to be able to control the
message flow in dependence on its individual
requirements. The case may therefore occur that the
filter function setting is different from manager to
manager so that state information with different
content is processed by the realignment procedures
running simultaneously.
Figure 4 shows the message flow between an
agent AG - the operation and maintenance center OMC1 in
the example according to Figure 1 shown or the base
station subsystem BSS11 in the example of Figure 2
shown - and the manager MA1, MA2 - the different
network management centers NMC1, NMC2 in the example
according to Figure 1 or the various applications OF1,
OF2 in the example of Figure 2.
The message flow preferably takes place by
means of standardized M-EVENT-REPORT Services and an M-
CREATE Service initiated at the beginning. These are
generic CMISE (common management information service
element) standardized procedures which are defined
according to ITU-T X.710. ITU-T X.731 defines the
management of a standardized transmission of
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state information which is performed in accordance with
the M-EVENT-REPORT services. The correlation
information is entered in the messages or,
respectively, in particular message fields.
Furthermore, the managers MA1, MA2 provide the
parameters for controlling the state realignment with
certain parameter values and enter them individually or
in multiples into the respective request message. The
example in Figure 4 shows the message flow by means of
individual messages which can be transmitted in
parallel between the agent AG and the managers MA1, MA2
or -serially between the agent AG and the individual
manager MA1.
As soon as the communication between a manager
MA1, MA2 and the agent AG is restored after an
interruption of the connection, each manager MA1, MA2
sends a request message staAS (start Alignment
Scheduler) according to the M-CREATE Service for
transmitting the state information to the agent AG for
the state realignment. The correlation information
staAH (state Alignment Handle) defined by the manager
MA1, MA2 is preferably also sent - for example in the
defined message field "action information" - which
characterizes a direct correlation of the request with
the agent messages subsequently received. By this
means, the current request can also be allocated to the
respective manager in the case of a number of managers
so that the parallel realignments of the managers can
be initiated, performed and ended independently of one
another.
The request message staAS also contains
parameter values for the subsequent sequence of
functions, entered by the manager. The parameterization
can preferably be performed with one or more set
parameter values of which the values begT (begin Time),
endT (end Time), int (interval), admST (administrative
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state) and relEN (related entities) are specified by
way of example. The specific parameter values describe:
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- a starting time (begT), for example date and clock
time, for an automatic state realignment and/or an end
time (endT), for example date and clock time, for the
automatic state realignment,
- a time interval (int), for example in minutes, hours,
days etc. for repeating the automatic state
realignment,
- selected resources (relEN) for which the changed
state information is to be transmitted by the agent,
- the discontinuation (admST) of a running state
realignment, a recontinuation of the alignment
procedure also being possible with the value admST=
unlock. The parameter values begT...admST are contained
in a message field, predetermined in accordance with
the standard, of the M-CREATE service so that
preexisting and defined fields can also be used.
Following the evaluation of the parameters in
the received request message staAS, the agent checks
whether there are changes in the state information by
means of deviations compared with the normal state and
edits the changed state information for each managed
object which is not in the normal state. This is
preferably done by means of the state and status
attributes according to the description relating to
Figure 3. The agent AG continues the state realignment
by generating a start message stSA (start State
Alignment) and inserting the correlation information
aliNI (alignment Notification Id) defined by it into
this message. The correlation information item staAH
issued and transmitted by the manager is also contained
in a particular message field of the start message
stSA. The correlation information aliNI is entered, for
example, in the standardized message field
"notification identifier" of the message stSA. Both
information items staAH, aliNI are sent out together in
the message stSA to the managers MA1, MA2 by the agent
AG. As a result, "alignment-related" M-EVENT-REPORT
messages of different M-CREATE requests
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can be distinguished from one another but also from
regular
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M-EVENT-REPORT messages which have nothing to do with
the state realignment. This is because an alignment
procedure does not necessarily stop other M-EVENT-
REPORT messages which occur spontaneously during the
alignment procedure and are sent to the manager or
managers.
After the automatic start of the state
realignment - preferably controlled by the manager MA1,
MA2 by means of at least one parameter - the agent AG
only returns the edited changed state information cst
to the requesting manager MA1, MA2 in successive staCN
(state Change Notification) messages by using the M-
EVENT-REPORT service. In a staCN message, only the
state changes found for an object and its associated
resource are preferably transmitted so that in the case
of a number of objects which may be different, a number
of staCN messages are also needed. In this context,
each staCN message exhibits the correlation information
item aliNI - for example in the defined message field
"correlated notifications". After the last M-EVENT-
REPORT message of each state realignment, the agent AG
generates an end message endA (end alignment) which
contains the correlation information item aliNI. In a
case where all managed objects are in the normal state
at the time of the M-CREATE Service or when the
messages with the state changes are filtered out by the
current filter settings, the end message endA directly
follows the start message stSA. The above message flow
is repeated for each state alignment until the end of
the automatic state realignment is reached which can be
seen from the parameter value endT. Even if the example
described with respect to Figure 4 relates to parallel
realignments with a number of managers, the message
flow can naturally also be applied to a number of
requests, triggered successively by a single manager,
for processing state information in accordance with the
"state alignment". This has the
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advantage that, due to the unambiguous correlation by
means of the correlation
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information, the individual manager has the capability
of being able to allocate the incoming responses of the
agent unambiguously to the requests - for example
different applications in the manager - even if the
order is not maintained. Successively sent requests may
overtake each other, for example if a packet network is
traversed between agent and manager.
