JPH10276215A - Switch node - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly process an OAM cell by receiving a response cell having hierarchy information which a terminal switch node returns in response to the OAM cell having hierarchy information which is increased at a high-order switch node and decreased at a low-order switch node and processing the cell based on hierarchy information. SOLUTION: The OAM processing part 12 of the switch node 10 is provided with a reference part 13a, an identification part 14a and a storage part 15a, which are provided from a multipoint route to a multipoint leaf. When the response cell having hierarchy information which the prescribed terminal switch node returns in response to the OAM cell having hierarchy information increased at the high-order switch node and decreased at the low-order switch node is received, the reference part 13a refers to hierarchy information contained in the response cell and the identification part 14a identifies whether the cell is to be transferred to the multipoint leaf or not. Thus, the DAM cell can smoothly be processed even in the communication network of the communication form of a point-to-multipoint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an OA for maintenance management.
The present invention relates to a switch node of an asynchronous transfer mode (ATM) communication network for transferring M (Operation Administration and Maintenance) cells, and particularly to a switch node suitable for a communication network having a point-to-multipoint communication mode.

[0002]

2. Description of the Related Art Conventionally, in various communication systems, O
A maintenance management function called AM is defined for each frame level and connection level.

[0003] Specifically, such an OAM retains a failure monitoring function when a failure occurs on a line between networks or between a terminal and a network, a continuity test function for confirming line continuity, and line quality. It defines a performance management function for checking whether or not there is

[0004] Incidentally, the communication mode in various communication systems is point-to-point.
, And a one-to-many communication mode called point-to-multipoint.

[0005] In a normal telecommunication system other than a LAN (Local Area Network), since the above-described one-to-one communication mode is assumed, one-to-one processing is performed even when the OAM function is realized. Become.

For example, the International Telecommunications Union (ITU)
TU-T: I. 610 (hereinafter referred to as “I.610”).
In the OAM in the wide area ISDN specified in the above, failure occurrence display information (AI) is provided at both the VP level and the VC level.
S), continuity check, RDI responding to AIS, and the like are defined.

FIG. 6 shows this I.D. OAM specified in 610
It is a figure showing the common format of a cell.

[0008] As shown in FIG.
Is a header (Header) 60a indicating the destination of the ATM cell.
An OAM type (OAM Type) field 60b indicating a function type such as fault management, performance management, or system management;
For example, a function type field 60c indicating the type of a detailed function belonging to the OAM type such as AIS in the OAM type of the fault management, and a function specific field (Function specific field) individually defined for each OAM type and function type ) 60d and a reserved field provided for future use (Reserved for f).
uct use) 60e and a validity assurance (EDC) field 60f that assures the validity of the information using the cyclic code.

As described above, the International Telecommunication Union uses the OAM cell having such a configuration to implement the OIS of the wide area ISDN.
The aim is to realize the AM function.

However, this international telecommunications union
I. In the OAM function recommendation to be standardized as 610,
At present, point-to-point as shown in FIG.
Only point-to-point connections are targeted,
Point-to-multipoint 1 shown in FIG.
There are no provisions for many-to-many connections.

For this reason, if the above OAM function recommendation is applied to a point-to-multipoint connection, not only the user cells expected to be broadcasted, but also the OAM cells are broadcasted, and independent maintenance and management can be performed for each connection end point. The problem of disappearing occurs.

More specifically, the above OAM function recommendation (I.6)
In 10), for example, when a failure occurs between switch nodes, a failure notification OAM cell (hereinafter, referred to as an “AIS cell”) called a VP-AIS must be transmitted from a failure detection point.

For this reason, when such a rule is applied to the multicast connection, a response cell called VP-RDI (hereinafter referred to as "RDI cell") is transmitted to a switch node completely unrelated to the failure. Becomes

For example, when a line failure for the switch node 102 occurs between the switch nodes 102 and 105 shown in FIG. 7B, as shown in FIG. AIS
Switch node 101 that has transmitted a cell and received it
Transmits an RDI cell by multicast in the opposite direction of the connection.

For this reason, this switch node 101
Not only the switch node 102, which is the failure route,
RD for switch node 103 unrelated to failure
The result is that an I-cell is transmitted.

The switch node 1 shown in FIG.
When a line failure for the switch node 102 occurs between the nodes 01 and 102, as shown in FIG. 9, the switch node 102 that has detected the failure generates an AIS by multicast connection in the downstream direction of the connection.
Send the cell.

That is, this AIS cell is transmitted to each route of the switch nodes 104, 105 and 106, and finally each connection end point, ie, the switch nodes 105, 107, 108, 109 and 11
Reach 0.

Therefore, at each connection end point, an RDI cell responding to the AIS cell is transmitted to the switch node 102, and the OAM cell, which is generally considered to have little traffic, is connected to the connection branch point. You will concentrate as you get closer.

As a result, the switch node 101 located at a higher layer than the switch node 102 must receive a very large number of OAM cells, and the traffic adversely affects the traffic of the normal user cells.

[0020]

As described above, a conventional OA represented by the OAM function recommendation (I.610) is used.
When the M technology is applied to a system having a point-to-multipoint communication mode, RDI cells are transmitted to irrelevant switch nodes. There is a problem that cell traffic is adversely affected.

Therefore, the present invention solves the above problem,
OA with point-to-multipoint communication
It is an object of the present invention to provide a switch node suitable for a communication network having an M function.

[0022]

In order to achieve the above object, a first aspect of the present invention is to interpose between a first switch node located at an upper position and a plurality of second switch nodes located at a lower position, In a switch node of an asynchronous transfer mode communication network for transferring an OAM cell for maintenance received from any of the second switch nodes to the first switch node, a lower order switch node is added to a higher order switch node. O with hierarchical information that reduces in
Receiving means for receiving, from the first switch node, a response cell having the hierarchical information returned by a predetermined terminal switch node in response to an AM cell; and the receiving means receiving a response cell from the first switch node. And processing means for processing the response cell based on the hierarchical information included in the response cell.

Further, in the second invention, the processing means, when the receiving means receives a response cell from the first switch node, refers to the layer information included in the response cell, and Determining whether or not the response cell should be transferred to the switch node. If the determination means determines that the response cell should be transferred, the second source of the OAM cell corresponding to the response cell is determined. And a transfer means for transferring the response cell to the switch node.

The third aspect of the present invention is the first aspect, wherein
Asynchronous transfer that is interposed between the first switch node and a plurality of second switch nodes located below, and broadcasts the OAM cell for maintenance received from the first switch node to the second switch node In a switch node of a mode communication network, a response cell having the hierarchical information returned by a predetermined terminal switch node in response to an OAM cell having hierarchical information to be added in an upper switch node and reduced in a lower switch node is referred to as Receiving means for receiving from each of the second switch nodes, and, when the receiving means receives each of the response cells from the second switch node, representing the response cell based on hierarchical information included in each of the response cells. Transfer means for transferring the representative response cell to the first switch node.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment,
A case will be described in which a communication system having a point-to-multipoint communication mode shown in FIG.

FIG. 1 is a diagram showing a configuration of a switch node used in the present embodiment.

As shown in FIG. 1, this switch node 1
0 is a cell handling unit 11 for handling a cell
a and 11b and an OA that performs OAM processing according to the present invention
M processing unit 12.

The OAM processing unit 12 is a connection end point (hereinafter, referred to as a "multipoint leaf") to which a connection is branched from a connection connecting point (hereinafter, referred to as "multipoint route") where a plurality of routes are gathered. ), A reference unit 13a, an identification unit 14a, and a storage unit 15a, and a reference unit 13 provided for a multipoint route from the multipoint leaf.
b, the identification unit 14b and the storage unit 15b, and the storage unit 15
a and a collating unit 16 for collating the contents stored in 15b.

First, the multipoint route and the multipoint leaf will be described with reference to FIG.

In the present embodiment, the concept of subordination in the tree structure is applied to connection connecting points, and a connecting point that may perform multicast within a point-to-multipoint connection is called a “multipoint route”. A connecting point that is dependent on the multipoint route is called a “multipoint leaf”. Note that the range over which these dependencies are reached is simply referred to as a “leaf”.

FIG. 2 is a diagram showing the relationship between a leaf, a multipoint route, and a multipoint leaf in a communication system having a point-to-multipoint communication mode.

As shown in FIG. 2, each leaf is represented by a triangle consisting of a broken line. The switch node located at the vertex of each triangle is a multipoint route, and the switch node located along the bottom is a multipoint route. It is a multipoint leaf.

For example, switch nodes 102 and 103
Is a multipoint leaf for switch node 101, and switch node 102 is switch node 1
It is a multipoint route for 04, 105 and 106.

Since the switch node 107 and the switch node 106 do not exist in the same leaf, the switch node 107 is not a multipoint leaf of the switch node 106.

In this embodiment, the dependency between leaves is indicated by using the term "hierarchy".

That is, a switch node that is a connection end point and is a multipoint route is assumed to be at the highest hierarchy in this point-to-multipoint connection, and is a multipoint leaf of the multipoint route. In addition, it is assumed that the hierarchy becomes lower by one stage as it goes to the switch node which is a multipoint route of another leaf.

For example, the switch node 10 in FIG.
1 is the highest hierarchy, and the switch nodes 108 and 109
And 110 are the lowest hierarchy.

Further, in the present embodiment, even if a connection node is not actually branched in a point-to-multipoint connection, a switch node in which a connection branch may occur later due to addition of a connection branch destination or the like is also performed. It is called a multipoint route.

In other words, this is to prevent a situation in which the multipoint connection hierarchy information cannot be matched due to the temporal context of the addition of the branch destination due to the later addition of the connection branch.

Next, a detailed configuration of the OAM processing unit 12 shown in FIG. 1 will be described.

When the reference units 13a and 13b shown in FIG. 1 recognize that the cell received from the cell handling units 11a and 11b is an OAM cell, the reference units 13a and 13b refer to multipoint connection hierarchy information of the OAM cell, which will be described later. This is a processing unit.

The identification sections 14a and 14b are provided with a reference section 13a.
And a processing unit that performs queuing of OAM cells, identification of a transmission route, and the like based on the multipoint connection hierarchy information referred to by 13b and 13b.

The storage units 15a and 15b store the OA so that the OAM cell can be compared with the cell responding to the OAM cell.
A storage unit that stores part or all of the information of the M cell,
Specifically, when a multicast OAM cell is transmitted to a multipoint leaf, the OAM cell is stored in the storage unit 15a, and an OAM cell responding to the OAM cell returned from the multipoint leaf is stored in the storage unit 15a. 15b
To memorize.

When a multicast OAM cell is transmitted toward a multipoint route, the OAM cell is stored in the storage unit 15b, and an OAM cell responding to the OAM cell returned from the multipoint route is stored in the storage unit 1b.
5a.

The collation unit 16 collates the corresponding OAM cells stored in the storage units 15a and 15b.

The OAM processing unit 1 having the above configuration
2 operates especially on multipoint routes and OA
Each time the M cell passes through the multipoint route, the multipoint connection information inside the OAM cell is rewritten.

More specifically, in each multipoint route, it is possible to know whether the connection branches in the upper layer direction or the lower layer direction. Increments the multipoint connection layer information, and decrements the multipoint connection layer information when transmitting an OAM cell in a lower layer direction.

As described above, the switch node 10 increments or decrements the multipoint connection hierarchy information included in the OAM cell, and performs OAM based on the multipoint connection hierarchy information.
It performs cell queuing and identification of a transmission route.

Next, the data structure of the OAM cell used in this embodiment will be described.

FIG. 3 is a diagram showing a cell format of an OAM cell handled by the switch node 10 shown in FIG. 1 in comparison with a conventional cell format. However, since the cell format of the entire OAM cell has already been described with reference to FIG. 6, a function specification field (Function specifi
c field).

As shown in FIG. 3A, the function specifying field 30 of the present invention has a defect type (Defect Typ).
e) 30a, Defect Location 30
b, Multipoint connection hierarchy information (multipoin
t root counter) 30c and unused octets (Unuse
d octets) 30d.

The function specifying field 30 according to the present invention is set in the OAM function recommendation (I.6) shown in FIG.
Comparing with the conventional function specifying field 31 defined in 10), it can be seen that the multipoint connection hierarchy information 30c is added to the function specifying field 30 of the OAM cell used in the present invention as compared with the conventional one. .

Here, the multipoint connection hierarchy information 30c is information indicating a hierarchy relative to the point of failure, and is incremented or decremented each time a multipoint route is passed.

In this embodiment, a relative hierarchy is used. However, an absolute hierarchy such as a case where the multipoint route is set to zero hierarchy may be used.

Next, a specific description will be given of a line failure handling sequence when the switch node 10 shown in FIG. 1 is used. Here, the switch node 10 shown in FIG.
Here, a case where a failure occurs in the line for the switch node 102 between 2 and 105 and a case where a failure occurs in the line for the switch node 102 between the switch nodes 101 and 102 will be described.

First, as shown in FIG. 4A, when a failure occurs in the line for the switch node 102 between the switch nodes 102 to 105, as shown in FIG. AI having multipoint connection hierarchy information '0' for node 101
An S cell (hereinafter referred to as “AIS (0)”) is transmitted.

That is, the switch node 101, which is the connection end point, can know the leaf layer in which a failure has occurred by referring to the multipoint connection layer information included in the AIS (0).

Then, the switch node 101 that has received the AIS (0) responds to the AIS (0) with the RD
Although the I cell is returned, when such an RDI cell is transmitted by multicast, the RDI cell is transmitted not only to the switch node 102 but also to the switch node 103.

However, this RDI cell has the AIS
The RDI cell received by the switch node 103 is discarded because the information is valid only for the switch node 102 that is a multipoint leaf that has transmitted (0) and is completely unnecessary for the switch node 103. .

In this embodiment, in order to facilitate such discarding, the multipoint connection hierarchy information of the AIS cell is transmitted by including it in the RDI cell. The information is decremented so that a failed leaf hierarchy can be identified.

Specifically, the switch node 101 transmits the RDI including the multipoint connection hierarchy information “0”.
A cell (hereinafter referred to as “RDI (0)”) is transmitted to each of the switch nodes 102 and 103, and the own node
In the switch node 102 which is the source of the cell, an RD
I (-1) is transmitted.

On the other hand, the switch node 103 that has not transmitted the AIS cell discards the RDI (0) when confirming that the multipoint connection hierarchy information is “0”, and discards the RDI (0). 0) is not transmitted to other switch nodes. As a result, the RDI cell can be transmitted only to the expected route.

Note that multipoint leaves corresponding to all connection end points are not always connected in the same number of layers.

For this reason, in the multipoint route of the source of the AIS cell that has received the RDI cell for which the multipoint connection layer information is “0”, the RDI cell is transmitted among the routes connected in a layer lower than the layer. No RDI cell is transmitted except for what should be done.

When the connection is made in a higher layer than the above layer, the multipoint connection layer information is
Before it becomes 0 ', it becomes a connection end point and R
Since it is determined that the route does not require DI, the RDI cell is discarded.

As described above, the AIS cell and the RDI cell having the multipoint connection hierarchy information are exchanged between the switch nodes, and the route for transmitting the RDI cell is specified based on the multipoint connection hierarchy information. RDI to switch nodes not related to
Transmission of a cell can be suppressed.

Next, as shown in FIG. 5A, a sequence when a failure occurs in a line between the switch nodes 101 to 102 and directed to the switch node 102 will be described.

As shown in FIG. 5B, in this case,
First, the switch node 102 is the switch node 10
AIS (0) is transmitted to 4, 105 and 106.

The switch node 104 sets the AIS (−) obtained by decrementing the multipoint hierarchy information.
1) to the switch node 107, and the switch node 106 transmits the AIS (-1) to the switch node 108,
Send to 109 and 110.

The switch node 106, which is a multipoint route,
RD responding to AIS (-1), respectively
If I (-1) is received, RDI (0) is transmitted to switch node 102.

Each time the switch node 106 receives the RDI (-1) from each of the switch nodes 108, 109 and 110, the switch node 102
, The RDI (0) is transmitted in a form representing the leaf.

That is, if the RDI cell is transmitted to the multipoint route every time the RDI cell is received as in the related art, the concentration of traffic by the RDI cell to a specific switch node occurs, and the traffic of the user cell is adversely affected. Because it has an effect.

As described above, in the present embodiment, when the multipoint connection hierarchy information of the RDI cell received by the switch node of the multipoint route is 0 or less, the RDI cell from another multipoint leaf waits. Or after confirming the state of the route,
If a DI cell is transmitted and the multipoint connection hierarchy information is positive, no waiting or status confirmation is performed.

As described above, in the present embodiment,
When the RDI cell having the multipoint connection hierarchy information is received from the multipoint route, the reference unit 13a refers to the multipoint connection hierarchy information included in the RDI cell, and the identification unit 14a stores the RDI cell in the multipoint leaf. Since it is configured to determine whether or not to transfer, the following effects can be obtained.

1) OAM cells can be processed smoothly even in a communication network having a point-to-multipoint communication mode.

2) OAM can be performed efficiently without transferring unnecessary response cells to other switch nodes.

When the RDI cell having the multipoint connection hierarchy information is received from each multipoint leaf, the reference unit 13b refers to the multipoint connection hierarchy information included in the RDI cell, and the identification unit 14b checks the multipoint connection hierarchy information. Representative RD on point route
Since the configuration is such that the I cell is transferred, it is possible to reduce the influence of the concentration of the RDI cells on the traffic of the user cells.

In the present embodiment, the case where the OAM cell itself waits has been described. A as defined in 610
An IS state and an RDI state may be defined for each route, and the state may be referred to.

In this embodiment, the case where the AIS cell and the RDI cell are transferred has been described. However, the present invention is not limited to this, and the continuity check (Continui
(ty Check) It can also be applied when handling cells and the like.

When waiting for a loopback cell, a loopback cell to be waited for can be specified by additionally storing a correlation tag defined by a conventional OAM cell.

[0081]

As described above in detail, according to the first aspect of the present invention, a predetermined terminal switch node responds to an OAM cell having hierarchical information in which a higher-order switch node adds and a lower-order switch node decreases. Since the response cell having the returned hierarchical information is received from the upper switch node, and when the response cell is received, the response cell is processed based on the hierarchical information included in the response cell. -OAM cells can be processed smoothly even in a communication network having a multipoint communication mode.

Further, according to the second invention, when a response cell is received from an upper switch node, it is determined whether or not the response cell should be transferred to the lower switch node by referring to the hierarchical information included in the response cell. If it is determined that the response cell should be transferred, the response cell is transferred to the second switch node that is the source of the OAM cell corresponding to the response cell. OAM can be performed efficiently without transferring cells to other switch nodes.

The third invention provides a response cell having hierarchical information returned by a predetermined terminal switch node in response to an OAM cell having hierarchical information which is added in an upper switch node and reduced in a lower switch node. Are respectively received from the lower switch nodes, and when each of the response cells is received, the representative response cell representing the response cell is transferred to the upper switch node based on the hierarchical information included in each response cell. Therefore, it is possible to reduce the influence of the concentration of the response cells on the traffic of the user cells.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a switch node used in this embodiment.

FIG. 2 is a diagram showing a connection mode of a communication system used in this embodiment.

FIG. 3 is a diagram showing a cell format of an OAM cell handled by the switch node shown in FIG. 1 in comparison with a conventional cell format.

FIG. 4 is a diagram showing an example of a processing sequence when a line failure occurs between the switch nodes shown in FIG. 2;

FIG. 5 is a view showing a processing sequence when another line failure occurs between the switch nodes shown in FIG. 2;

FIG. 6: International Telecommunication Union I. FIG. 6 is a diagram showing a common format of a conventional OAM cell defined in FIG.

FIG. 7 is a diagram showing an example of a point-to-point and point-to-multipoint connection mode.

FIG. Point to the OAM function specified in 610
The figure which shows an example of the sequence at the time of applying to the two-multipoint line fault.

FIG. Point to the OAM function specified in 610
The figure which shows the sequence at the time of applying to another line fault of two-multipoint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Switch node 11a, 11b Cell handling part 12 OAM processing part 13a, 13b Reference part 14a, 14b Identification part 15a, 15b Storage part 16 Collation part 101-110 Switch node 30, 31 Function specification field 30a Defect type 30b Defect position 30c Multi Point connection layer information 30d Unused octet 60 OAM cell 60a Header 60b OAM type field 60c Function type field 60d Function specification field 60e Reserved field 60f Validity assurance field

Claims (3)

[Claims] An OAM for maintenance management interposed between a first switch node located at a higher level and a plurality of second switch nodes located at a lower level and received from one of the second switch nodes. In a switch node of an asynchronous transfer mode communication network for transferring a cell to the first switch node, a predetermined termination switch is provided in response to an OAM cell having hierarchical information added in an upper switch node and reduced in a lower switch node. Receiving means for receiving, from the first switch node, a response cell having the hierarchical information returned by the node; and when the receiving means receives a response cell from the first switch node, the response cell is included in the response cell. Processing means for processing the response cell based on hierarchical information. 2. The processing unit, when the receiving unit receives a response cell from the first switch node, refers to layer information included in the response cell, and sends the response to the second switch node. Determining means for determining whether to transfer a cell; and determining, by the determining means, that a response cell should be transferred, to a second switch node which is a source of an OAM cell corresponding to the response cell. 2. The switch node according to claim 1, further comprising a transfer unit that transfers the response cell. 3. The OAM cell for maintenance that is interposed between a first switch node located at a higher level and a plurality of second switch nodes located at a lower level and received from the first switch node is stored in the OAM cell. In a switch node of an asynchronous transfer mode communication network that broadcasts to a second switch node, a predetermined terminal switch node responds to an OAM cell having hierarchical information to be added in an upper switch node and reduced in a lower switch node. Receiving means for receiving each of the returned response cells having the hierarchical information from the second switch node; and when the receiving means receives each of the response cells from the second switch node, the response cell is included in each of the response cells. Transfer means for transferring a representative response cell representing the response cell to the first switch node based on the hierarchical information. Switch nodes, characterized in that Bei was.