JP3366825B2 - Transmission apparatus for BLSR network, BLSR network system, and traffic output control method in output path switching in case of failure - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to SONET (Sy
nchronous Optical Network
k) BLSR (Bidirectional Lin)
e Switched Ring) network device configuration.

[0002]

2. Description of the Related Art Currently, as a BLSR network, "Bellcore GR-1230 Issue" is used.
2-Fiber BLS as described in 2 ".
There are R and 4-Fiber BLSR. 2-Fib
The er BLSR connects each node in a ring shape with two optical fibers, performs bidirectional communication in the clockwise direction and the counterclockwise direction with each optical fiber, and halves the capacity in each line. One of the capacities is currently used and the other is used as a spare. Further, the 4-Fiber BLSR performs bidirectional communication in the clockwise direction and the counterclockwise direction with one optical fiber respectively, and also has a working line and a protection line respectively and four optical fibers between each node. Are connected with. In this Ring network, for example, STS-1 (S
ynchronous Transport Sign
Traffic is transferred in frame units called al-1), and these frames are time-division multiplexed at the positions of predetermined time slots and transmitted.

2-Fiber BLSR and 4-Fi
Both of the Ber BLSRs usually use a method of transmitting traffic using a working line and relieving traffic using a protection line when a failure occurs.

In the following, OC (Optical Car)
rier) -48 4-Fiber BLSR will be described as an example with reference to the drawings.

FIG. 2 shows a line usage example (1) of the BLSR network. In FIG. 2, 10 is B
The entire LSR network is shown, and the BLSR network 10 includes an optical fiber transmission line group 11 and a plurality of nodes 12. In FIG. 2, six nodes (A, B,
3 shows a BLSR network consisting of C, D, E and F).

The optical fiber transmission line group 11 is composed of two bidirectional optical fibers and four bidirectional optical fibers, and has a CW (Cloc).
k Wise) direction working line 13 and CW direction protection line 1
4 and CCW (Counter Clock Wis)
e) It is composed of the direction working line 15 and the CCW direction protection line 16. The plurality of nodes 12 are inserted into the optical fiber transmission line group 11 at intervals, each accommodates a low-order group device, and the traffic of each line between the low-order group device and the optical fiber transmission line group 11. (STS-1) is inserted (Add) or extracted (Drop).

In the example shown in FIG. 2, the STS-1 traffic is inserted at the node D using the time slot number # 1 of the working line 13 in the CW direction, and the nodes are sequentially passed through the nodes C, B and A. Extracted at F. The same time slot number is assigned to each node.

In the BLSR network system, FIG.
In, for example, when a failure occurs only in the working line between the nodes A and B, the path passing through the failed section is transmitted using the protection line 14. The configuration in this case is shown in FIG. In FIG. 3, when a failure occurs in the working line 13, the nodes A and B switch to transmit the time slot number # 1 transmitted by the working line 13 using the protection line 14 (this switching Below
Called span switch).

Further, in the BLSR network system, in FIG. 2, when a failure occurs in both the working line and the protection line between the nodes A and B, the path passing through the failure section is used as a protection line in the counterclockwise direction. Loop back to 16. The configuration in this case is shown in FIG. In FIG. 4, working line 13 and protection line 1 between nodes A and B
If both 4 and 4 fail, the node B determines the time slot number # 1 transmitted by the working line 13.
, And switches to transmit in the opposite direction using the protection line 16, and the node A loops the time slot number # 1 transmitted by the protection line 16 and transfers it to the working line 13 (in this case, the node The switching between A and B is hereinafter referred to as a ring switch). By this ring switch, the data of the time slot number # 1 of the working line 13 inserted in the node D is looped from the working line 13 to the protection line 16 in the node B via the node C and transferred. It is looped from the protection line 16 to the working line 13 at the node A via the nodes C, D, E, and F, transferred, and extracted at the node F.

In this way, it is the faulty end nodes (nodes A and B in this example) that execute the span switch or ring switch. Further, in the example illustrated in FIG. 4, the nodes C, D, E, and F pass the K-byte for indicating the protection line information and the switching control information transmitted and received between the nodes A and B, and the Full Pass Thr.
You are in the off state.

Next, the configuration of each node will be described. Figure 5
The structure of the node 12 is shown in FIG. Since all the nodes on the BLSR network have the same configuration, the configuration of one node is shown as a representative. In FIG. 5, the node 12 is
ADM (Add Drop Multiplexer)
Called CW working line 13, CW protection line 1
4, CCW direction working line 15 and CCW direction protection line 16, Add line 27 (line for inserting traffic from low-order group device) and Drop line 28 (extract traffic and output to low-order group device) Line) and to accommodate. The optical signals transmitted from other node devices are
The signal is received by the optical receiver (R) 21, is input to the overhead processing unit 23, and is subjected to overhead processing. The traffic from which the overhead is removed is TSI (Time Slot In) for each of the high-speed side traffic and the low-speed side traffic.
terchange) and TSA (Time Slo)
cross-connect unit 20 for performing tAssignment)
Are input to the STS-1 unit and are assigned to each direction. The distributed traffic is multiplexed, subjected to overhead processing by an overhead processing unit 23, converted into an optical signal by an optical transmitter (T) 22, and then converted into a CW direction working line 13 and a CW direction protection line 1.
4 and CCW direction working line 15 and CCW direction protection line 16
And the Drop line 28. For example, in the configuration shown in FIG. 2, STS-1 # 1
Traffic of the node D is the Add line 27 shown in FIG.
C of the transmission path to the node C in the cross-connect unit 20 via the overhead processing unit 23.
Allotted to the W direction working line 13, STS-1 # 1
Are multiplexed and output.

The Line switching control unit 25 shown in FIG.
Determines whether to execute the ring switch or the span switch according to the state of the transmission path (fiber breakage, etc.) or an instruction from the OS that is the management device for the entire system, and instructs the cross-connect unit 20 to perform the switching instruction. The cross-connect unit 20 is in a state (ring switch, span switch, Full) in response to the switching command from the Line switching control unit 25.
The transmission path is switched by using Pass Through. The switching command is defined in the node in advance.

Table 1 shows a table of switching commands (states) that the Line switching control unit 25 instructs the cross-connect unit 20.

[0014]

[Table 1]

In Table 1, West and East indicate cases where a failure occurs on the West side and the East side of the node shown in FIG. 5, respectively. Br (Bridge
d) indicates that the traffic output to the working line is switched to the protection line, and Sw (Switched) indicates that the traffic input from the working line is switched to input from the protection line. Idle indicates that switching is not performed. Further, according to GR-1230, the span switch can be executed on both sides of the node, and therefore the numbers 14 to 22 indicate the case of execution on both sides.

Table 1 shows the state in the case of the 4-fiber BLSR, but in the case of the 2-fiber BLSR, the span switch is not executed, so the item regarding the span switch is excluded. According to this figure, 4-Fiber
In the case of BLSR, each node needs to control 25 switching states.

Next, erroneous line connection will be described. In FIG. 2, between the A and the node B and between the C and the node D, when the fiber of the working line and the protection line is cut as shown by the mark X in FIG. 7, the node D shown in FIG.
STS-1 # 1 traffic from node to node F is looped back at D without passing through nodes B and C, and CCW
It passes through the nodes E and F using the STS-1 # 1 of the protection line 16 in the direction, is looped back at the node A, and is extracted at the node F.

On the other hand, FIG. 8 shows another line usage example (No. 2) in the BLSR network shown in FIG. Figure 8
, The traffic inserted at node E, passed through node D, and extracted at node C, and the traffic inserted at node C, passed through nodes B and A, and extracted at node F are both STS. -1 # 2 is used for transmission. In FIG. 8, as in FIG. 7, A-
When the fibers of the working line and the protection line are cut between the nodes B and between the nodes C and D as shown by the crosses, as shown in FIG. Traffic is STS-1
Since # 2 is used, the traffic is inserted in the node E, and the line is erroneously connected. In order to prevent such a situation, in the GR-1230 Issue2, in the node A performing the loopback, the path AIS (Alarm I) is set.
Ndification Signal) to this STS-
It is specified that the operation of inserting the 1 # 2 traffic at the specified position is performed. The operation of inserting the path AIS is called squelch. Path A
The traffic in which the IS is inserted is discarded in the low-order group device connected to the node.

FIG. 10 shows another line usage example (3) in the BLSR network shown in FIG. In FIG. 10, the traffic that is inserted at node E, passes through node D, and is extracted at node C; the traffic that is inserted at node C, passes through node B, and is extracted at node A; The traffic inserted and extracted at the node F is shown to be transmitted using STS-1 # 3, respectively. In FIG. 10, as in FIG. 7, when a fiber disconnection between the working line and the protection line occurs between A and node B and between C and node D, as shown in FIG. 11, as shown in FIG. If loopback is performed in the same manner as in 7, traffic that is extracted at node A will be erroneously connected. Therefore, node A also inserts the path AIS into the extracted traffic.

Therefore, the operation for performing squelch, that is, the operation for inserting the path AIS must be performed for each path. For example, as shown in FIGS. 2, 8 and 10, STS
-1 If the line settings of # 1, # 2, and # 3 are set, A
-When a failure occurs between the nodes B and C-node D, in the node A, the STS-1 # 1 received from the failure avoidance protection line 16 loops back as it is (see FIG. 7), but the failure avoidance side S received from the protection line 16
A path AIS is inserted in TS-1 # 2 and STS-1 # 3 (see FIGS. 9 and 11).

Bellcore GR-1230 Is
According to sue2, each node is
Ring Top showing the order of node IDs in the ring
The logic Map and the STS SquelchM that indicates at which node the traffic that passes through, is inserted into, or is extracted from the own node is inserted and at which node the traffic is extracted.
hold ap and.

FIG. 12 shows an example of Ring Topology Map of the BLSR network shown in FIG. FIG. 12 shows that in the CW direction in the BLSR network, D,
The nodes are arranged in the order of C, B, A, F, and E. Although six nodes are described in FIG. 12, BLSR allows up to 16 nodes.

Further, FIG. 13, FIG. 2, FIG. 8 and FIG.
The receiving side of the CW direction working line 13 held by the node A when the line is set as shown in FIG.
An example of the STS Squelch Map on the side) is shown. FIG. 13 shows that STS-1 # 1 transmitted from the node B via the CW direction working line 13 is inserted in the node D and extracted in the node F as shown in FIG. Further, STS-1 # 2 is inserted in the node C and extracted in the node F as shown in FIG. Similarly, STS-1 # 3 is inserted in node C and extracted in node A as shown in FIG. In the case of OC-48 4-Fiber BLSR, STS-1 # 1 to STS-1 # 48 are described. In addition to CCW working line 13, CC
Similarly for the W-direction working line 15, STS Sq
Holds the uelch Map.

In order to prevent erroneous connection as shown in FIGS. 7, 9 and 11, each node is equipped with the squelch control unit 26 shown in FIG. The squelch control unit 26 uses Li
The switch state is received from the ne switching unit 7, and an instruction to insert the path AIS into the STS-1 traffic requiring the squelch operation is issued to the cross connect unit 20.

FIG. 14 shows an example of a flowchart for executing squelch in the squelch control unit 26. When this flowchart is executed, first, at step 51, it is determined whether or not the own node is executing Ring Bridge & Switch. Ring is the squelch
Since this is the node executing Bridge & Switch, the process ends if it is not executing. Next step 5
K-byte and Ri input from obstacle avoidance side in 2
ng Topology Map by Missing
Specify the Node. The Missing Node is a node that is separated from its own node. In addition, the K-byte input from the obstacle avoidance side is
In the case of node A in FIGS. 7, 9 and 11, C
It is a K-byte from the protection line 16 in the CW direction. In the cases shown in FIGS. 7, 9 and 11, K-byte is emitted from the node D and input to the node A using the CCW direction protection line 16. The node between the node issuing this K-byte and its own node is Mi.
Since it is a SSH Node, referring to the Ring Topology Map as shown in FIG. 12, when viewed from the node A in FIGS. 7, 9 and 11, the node between the node D and the node A, that is, the node B. And the node C is determined to be the Missing Node.

Next, the Missin specified in step 52.
The traffic emanating from the g Node is identified (step 54), and the traffic emanating from the Missing Node is squelched, that is, the path AIS is inserted (step 55). When viewed from the node A of FIGS. 7, 9 and 11, STS-1 # 1 is Missin.
Since STS Squelch Map shows that it is not inserted in g Node (B, node C), squelch does not occur and STS-1 # 2 and STS-1 # 3 are Mi.
STS-1 # 2 and ST that are input from the fault avoidance side protection line 16 because they are inserted at the SSing Node
Squelch S-1 # 3. Similarly, OC-
In case of 48, this squelch operation is performed in steps 53, 5
6, 57 depending on STS-1 # 1 to STS-1 # 48
Up to 48 times.

[0027]

As described above, the BL
In the SR network, there are various types of switching operations for each node as shown in Table 1. GR-1230
According to the report, 50m from the state without obstacles to the end of switching
It is stipulated that all lines should be switched within 100 ms when avoiding double failures. When the switching is executed by the firmware, it is necessary to grasp the state from the switching control unit and determine the connection status of the path, so that it becomes difficult to satisfy the time regulation as the transmission capacity increases.

According to the above-mentioned conventional method, when performing squelch, the Missing Node is first specified, and then the traffic to be squelched is determined. Therefore, when the number of Missing Nodes increases, the insertion node becomes Miss in all the traffic.
It is necessary to judge whether or not it is an ing Node. In this case, for example, Missing Node is 1
If there are 0 nodes, Missing Node is 1
Compared with the case of the node, the comparison processing must be performed up to 10 times. This kind of processing is performed by the CP in the node.
Ring Top when U does by software processing
logic Map and STS Squelch M
Since processing is performed while referring to ap, it takes a considerably long time to generate the path AIS.

The present invention is to solve the above problems, and provides a BLSR network transmission device, a network system, and a switching method capable of executing switching in a simple procedure with a simple hardware configuration. With the goal. Another object of the present invention is to provide a transmission device for a BLSR network that can execute squelch with a simple hardware configuration.

[0030]

SUMMARY OF THE INVENTION The present invention is a B which is connected to a plurality of optical fiber transmission lines and which houses a low-order group device.
LSR (Bidirectional Line Sw)
A transmission device for a BLSR network, which inserts and extracts traffic between the low-order group device and the optical fiber transmission line in an An output control unit that controls the output of the traffic is provided for each route, and the output control unit holds the input traffic and a control unit that performs access control of the holding unit. Storage means for storing a storage area of traffic held in the holding means corresponding to the order of traffic to be output from the output route for each switching state of the route at the time of occurrence of the fault; A switching control means for instructing the switching of the route at the time of occurrence, the control means according to the switching instruction of the route instructed by the switching control means. In stage, in the order of the traffic to be output from the holding means reads the traffic to be outputted, to the output path, then outputs the read traffic, the output control unit, route of when the failure occurs Off
Depending on the replacement status, it corresponds to the order of the traffic to be output.
The squelch to indicate whether the traffic is invalid.
Squelch storage means for storing control information, and the traffic
The squelch storage means when outputting the signal to the output route.
According to the squelch control information stored in the path AIS (A
larm Indication Signal)
BLS further comprising insertion means for insertion into traffic
An R network transmission device is provided.

[0031]

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 15 shows the structure of the cross-connect unit in the node shown in FIG. 5 according to the embodiment of the present invention. Figure 1
In the cross-connect unit 20 shown in FIG. 5, the traffic input from each transmission line is sorted and input to the output control units 101 to 105 provided for each output transmission line. Each traffic is selected by one of the selectors 31 controlled by the address control memory (ACM) 1 in each output control unit, and the squelcher 8 selects a path AI if necessary for each STS-1 traffic.
S is input and output. In the present embodiment, traffic means data stored in a time slot of a path in STS-1 units.

FIG. 1 shows the configuration of one output control section in the cross-connect section shown in FIG. The transmission line 6 indicates each input transmission line, and identification information is added to each input transmission line in advance. Each traffic is stored in the area corresponding to the STS number in the data memory 7 through the transmission line 6. The input data is temporarily stored in the data memory 7. Further, the data to be stored in the area corresponding to the STS number of the input transmission line designated by the command of the ACM 1 is selected and output, and the squelcher 8 inserts the path AIS if necessary and is output from the output transmission line 9. . A
The CM 1 corresponds to the order of the traffic to be output (output STS number) and the state-based map group 2 that indicates the input route (read transmission line) and the input traffic number (read STS number) for each switch state. , A squelch map group 3 for each outgoing node indicating whether or not squelch should be performed for each traffic. The ACM 1 instructs the selector 31 to select the data in the data memory 7 in accordance with the data stored in the state-based map group 2 selected by the selector 32, and also determines whether to insert the path AIS 8 into the squelcher 8. Control.

The state-based map group 2 is, in the order of the traffic to be output, for all the states shown in Table 1 described above, the input route of the traffic (read transmission line, in this case, the data memory shown in FIG. 1). 7) and its traffic number (STS #, in this case, it may be the address of the data memory 7 shown in FIG. 1) are defined in advance. One state-based map 4 is selected. FIG. 17
19 and FIG. 19 specifically show the map group 2 for each state. FIG. 17 shows a read transmission line and a read ST in the order of output STS numbers.
It shows that the S number is stored and stored in all the states shown in Table 1. In addition, FIG.
Normal time (No. 1) shown in Table 1 and East side Span Br & Sw (No. 13) shown in Table 1 at the time of failure and E
16 shows an example of a map group 2 by state in the ACM 1 corresponding to the CW direction working line output 13 shown in FIG. 15 with ast side Ring Br & Sw (number 7). ACM1 is
According to the switching instruction from the Line switching control unit 25, the state-based map 4 is selected, and the read STS of the read transmission line is read according to the order of # 1 to # 192 of the read STS numbers stored in the selected state-based map. The selector 31 can be instructed to select the traffic data corresponding to the number. When the ACM 1 directly instructs the output of the traffic data stored in the data memory 7 by the selection and the address of the data memory 7, the selector 31 is not provided and the data output from each of the data memories 7 is not provided. You may make it input directly into the squelcher 8. For example, as shown in FIG. 17, as the output STS number # 1 of the state-by-state map 4 in the normal state, the read transmission line is the CW direction working line CW (W), and the read STS number is 1.
Since the number is # 1, the CW direction working line CW (W)
The data # 1 of the data memory 7 corresponding to No. 13 is read out and output to the CW-direction working line CW (W) on the output side. Similarly, the traffic is output in order from the output STS numbers # 2 to # 192, and then the output STS number #
Return to 1.

Further, the squelch map group 3 is created in advance for each ring division state in a possible failure, and one squelch map is generated according to the source node ID of the failure avoidance side input K-byte from the squelch control unit 26. Is selected. The squelch map has a squelch flag indicating whether or not to squelch for each traffic. 18 and 20 specifically show the squelch map group 3. As shown in FIGS. 18 and 20, the output S
A squelch flag indicating whether squelch is required (Yes) or not (No) in the order of TS numbers is stored for each traffic. The squelch map is provided for each case where squelch is unnecessary (FIG. 20 (1)) and for each ring division state (FIGS. 20 (2) to 20 (6)). According to GR-1230, the ring split state is determined by the source node of the K-byte input from the fault avoidance side, so in FIG. 18 and FIG.
The squelch flag is stored for each source node of yte. For example, if a failure as shown in FIG.
Since it is necessary to insert the AIS into TS-1 # 2, the squelch flag is set in the area corresponding to this traffic. In this case, in node A, node D
Since the K-byte output from is received,
The squelch map of the output node = D as shown in (4) is selected, and the squelch flag of the output STS number # 2 is YES.
Since it is set to, the AIS is inserted in the traffic to the output STS number # 2.

FIG. 16 is a more specific block diagram of the output control section shown in FIG. In FIG. 16, a read transmission path and a read STS number are written in each state-based map of the state-based map group 2 in the order to be output. A
The CM 1 controls the data memory 7 and the selector 31 so as to select the data from the data memory 7 in this order. In addition, a squelch flag indicating whether or not to perform squelch is written in each squelch map of the squelch map group 3, and if the squelch is sequentially required for the data output from the selector 31, the squelch flag is inserted. Control eight. The squelcher 8 passes the path AI to the traffic of the STS-1 number designated by the instruction of the ACM1.
It has a role of a filter that inserts S and allows traffic that is not instructed by ACM1 to pass through as it is. Counter circuit 30
Controls the timing of reading the data of the data memory 7, the selected state-based map 4, and the selected squelch map 5. In the state-based map group 2, read transmission paths and STS numbers to be read are created in advance for all states, and one state-based map is selected according to the state from the line switching control unit 25. The squelch map group 3 is created in advance for each ring division state of BLSR when squelch is required.
One squelch map is selected according to the source node ID of the obstacle avoidance side input K-byte from. The state-based map group 2 is all created when the normal cross-connect map is distributed or updated. Further, the squelch map group 3 is all created when the Ring Topology Map or STS Squelch Map is distributed or updated. The state-based map group 2 and the squelch map group 3 are created in advance before the system operates.

In the following, as shown in FIGS. 2, 8 and 10, the node according to the present embodiment is used in the normal time and the failure when the lines of STS # 1, # 2 and # 3 are set. The configuration and operation of the cross-connect unit related to the output of the CW working line 13 of A will be described.

FIG. 19 shows the normal time (No. 1) shown in Table 1.
And at the time of failure, the East side Span Br & shown in Table 1
Sw (number 13) and East side Ring Br & Sw
(No. 7) and CW direction working line output 13 shown in FIG.
The example of the map group 2 classified by state in ACM1 corresponding to is shown. Actually, the state-based map group 2 has all the state-based maps for the states shown in Table 1. As described above, all the state-based map groups 2 are created when the normal cross-connect map is distributed or updated. Also, an ACM provided for each output transmission line
The same processing is performed in the selector 1, selector 31 and squelcher 8.

FIG. 20 shows the CW direction working line output 1
The squelch map group 3 in ACM1 corresponding to 3 is shown. The squelch map group 3 is Rin as described above.
gTopology Map or STS Squel
Created when ch Map is distributed or updated.

FIG. 21 shows an example of the structure of a part of the cross-connect section shown in Table 1 at the normal time. 21, the line switching control unit 25 instructs the selector 32 to select the normal map (see FIG. 19A) from the state-based map group 2. The selector 32 selects the normal state-based map 4 from the state-based map group 2. Further, the squelch control unit 26 does not need squelch control during normal operation, and therefore instructs the selector 33 to select the squelch map 5 (see FIG. 20A) that does not require squelch from the squelch map group 3. The selector 33 selects a map that does not require squelch during normal operation. Each of the data (D11 to D16) input from each transmission line is STS-
The data is sequentially written into the data memory 7 in units of 1 to be stored in the position corresponding to the STS number. The ACM 1 selects the selector 31 according to the information of the selected state-based map 4 and the selected squelch map 5.
The data written in the data memory 7 is selected in sequence by controlling the data output, and the data is output to the transmission path.

For example, when the counter circuit 30 is incremented, as shown in FIG. 19 (1), as the output STS number # 1 of the selected state-specific map 4, the read transmission line is the CW direction working line CW ( W) and the read STS number is # 1, so the CW-direction working line CW (W) 13
Is instructed to read the # 1 data (D11) of the data memory 7, and the selector 31 outputs the data D11 of the CW-direction working line CW (W). next,
As shown in FIG. 20 (1), in the selected squelch map 5, the output STS number # 1 does not require squelch (N
Therefore, the squelcher 8 does nothing and outputs the data D11 as it is. Next, the counter circuit 30
Is incremented, the selected state map 4
Is the # 2 of the CW-direction working line CW (W), so C
D12 which is the data of # 2 of the working line CW (W) in the W direction
Is read and output. Since the output STS number # 2 of the selected squelch map 5 also does not require squelch (No), the squelcher 8 does nothing and outputs D12 as it is. Next, when the counter circuit 30 is incremented, the output STS number # 3 of the selected state-based map 4 is output.
Is the # 1 of the Add line, the selector 31
D14 which is the data of the d line # 1 is output. Since the output STS number # 1 of the selected squelch map 5 also does not require squelch (No), the squelcher 8 does nothing and outputs D14 as it is. As a result, the output side CW
For direction working line CW (W) 13, D to STS-1 # 1
11, D12 for STS-1 # 2, D for STS-1 # 3
Data is output in the order of 14. Therefore, # 1 of the output side CW direction working line CW (W) 13 is connected to the input side CW direction working line CW (W) # 1, and # 2 of the output side CW direction working line CW (W) 13 is the input side. CW direction Working line CW
(W) Connected to # 2, output side CW direction working line CW
(W) 13 # 3 is connected to the Add line # 1.

Next, when a failure as shown in FIG. 3 occurs,
The operation when the state is switched to Span Br & Sw will be described with reference to FIG. FIG. 22 shows a partial configuration example of the cross-connect unit when Span Br & Sw is activated between the nodes A and B as shown in FIG. 22, the line switching control unit 25 selects the map of the East Span Br & Sw (see FIG. 19 (2)) from the state-based map group 2 so that the selector 3 can select the map.
Instruct 2. The selector 32 selects a map of East Span Br & Sw from the map group 2 for each state.
Further, since the K-byte is not issued when the span switch is executed, squelch control is not necessary, and the squelch control unit 26 selects the squelch-free squelch map 5 (see FIG. 20 (1)) from the squelch map group 3. To the selector 33. The selector 33 selects a map that does not require squelch during normal operation. Each of the data (D21 to D26) input from each transmission line is sequentially written in the data memory 7 in units of STS-1 to be stored in the position corresponding to the STS number.
Similar to FIG. 21, the ACM 1 follows the information of the selected state-based map 4 and the selected squelch map 5 as follows.
By controlling the selector 31, the data written in the data memory 7 is sequentially selected and the data is output to the transmission path.

For example, when the counter circuit 30 is incremented, as shown in FIG. 19B, the output STS number # 1 of the selected state-specific map 4 is # of the CW-direction protection line CW (P). Since it is 1, the selector 31 selects and outputs the data D21 of the CW-direction protection line CW (P). Next selected squelch map 5
Since the output STS number # 1 of No. 1 does not require squelch (No), this data is not processed by the squelcher 8 and the data D21 is output as it is. Next, the counter circuit 3
When 0 is incremented, the output STS number # 2 of the selected state-specific map 4 is the CW-direction protection line CW (P).
No. 2 of the CW-direction protection line CW (P), the selector 31 outputs D22, which is the data of # 2.
Since the output STS number # 2 of the selected squelch map 5 also does not require squelch (No), the squelcher 8 does nothing and outputs D22 as it is. Next, when the counter circuit 30 is incremented, the output STS number # 3 of the selected state-based map 4 is # 1 of the Add line, so that the selector 31 outputs data D of the Add line # 1.
24 is output. Since the output STS number # 3 of the selected squelch map 5 also does not require squelch (No), the squelcher 8 does nothing and outputs D24 as it is. As a result, the output side CW direction working line CW (W) 13
To STS-1 # 1, D21 to # 2, D22 to # 2, and D24 to # 3. Therefore, # 1 of the CW-direction working line CW (W) 13 is the CW-direction protection line CW.
(P) Connected to # 1, output side CW direction working line CW
# 2 of (W) 13 is connected to the CW-direction protection line CW (P) # 2, and the output-side CW-direction working line CW (W) 13 #
3 is connected to the Add line # 1.

Next, when a failure as shown in FIG. 7 occurs,
The operation when the state is switched to East Ring Br & Sw will be described with reference to FIG. FIG. 23 shows an example of a partial configuration of the loss connect unit when a fiber cut or the like occurs between the nodes A and B and between the nodes C and D as indicated by the crosses as shown in FIGS. 7, 9 and 11. Is shown. In FIG. 23, the line switching control unit 25
Is from East State Br &
The selector 32 is instructed to select the Sw map (see FIG. 19C). The selector 32 selects the state-based map 4 of EastRing Br & Sw from the state-based map group 2. Further, since the source node of the K-byte input from the failure avoidance side (West side) is the node D, the squelch control unit 26 selects the squelch map 5 (source node = D (see FIG. 20 (4))). The selector 33 is instructed to do so. Selector 33 outputs source node = D
The squelch map 5 of is selected. Each of the data (D31 to D36) input from each transmission line is sequentially written in the data memory 7 in units of STS-1, and is stored in the position corresponding to the STS number. As shown in FIG. 23, the ACM 1 sequentially selects the data written in the data memory 7 by controlling the selector 31 in accordance with the information of the selected state-based map 4 and the selected squelch map 5. , Output data to the transmission line.

For example, when the counter circuit 30 is incremented, as shown in FIG. 19 (3), the output STS number # 1 of the selected state-specific map 4 is # 1 of the CCW direction protection line CCW (P). Therefore, the selector 31
The data D31 of the CCW direction protection line CCW (P) # 1 is selected by and output. Next, as shown in FIG. 20 (4), the output STS of the selected squelch map 5
Since the number # 1 does not require squelch (No), the squelcher 8 does nothing and outputs the data D31 as it is. Next, when the counter circuit 30 is incremented, the output STS number # 2 of the selected state-based map 4 is # 2 of the CCW-direction protection line CCW (P), so that the selector 31 outputs D32. The output STS number # 2 of the selected squelch map 5 requires squelch (Ye
s), the AIS is inserted by the squelcher 8. Next, when the counter circuit 30 is incremented, the output STS number # 3 of the state-based map 4 selected is Ad.
Since it is the # 1 data of the d line, the selector 31 outputs D
34 is output. Since the output STS number # 3 of the selected squelch map 5 does not require squelch (No), the squelcher 8 does nothing and outputs D34. Therefore, the output side CW direction working line CW (W) is STS-1
D31 for # 1, STS-1 for AIS, STS-1 for # 2
Data is output to # 3 in the order of D34. as a result,
Output side CW direction Working line CW (W) # 1 is input side CC
Connected to W-direction protection line CCW (P) # 1 and output side C
AIS is inserted in # 2 of the W-direction working line CW (W),
The output side CW direction working line CW (W) # 3 is connected to the Add line # 1.

The squelch map 2 shown in FIG. 20 when squelch is required is selected by the Ring Br & S.
Only in the state of w, and in other cases, the map without squelch shown in FIG. 20 (1) is selected.

As described with reference to FIGS. 21, 22 and 23, according to the present embodiment, when the state changes, the line switching control unit 25 selects the state-based map according to the state. It is possible to switch routes for each traffic only by control. Further, the squelch operation that needs to be performed for each traffic can be executed only by the control of the squelch control unit 26 for selecting the squelch map according to the source node of the K-byte input from the obstacle avoidance direction. In this embodiment, the working line 1 in the CW direction is used.
Although only the configuration related to the output of No. 3 has been described, switching and squelch operation can be performed by having the same configuration for each of the other transmission line outputs.

Next, a second embodiment will be described. Figure 6
2 shows the device configuration according to the second embodiment of the present invention. In the second embodiment, the state-based map group 2 and the squelch map group 3 shown in FIG.
A configuration in which the outputs of the ACMs 110 and 120 are selected under the control of the ne switching control unit 25 and the squelch control unit 26 will be described. In FIG. 6, the ACM 110 has an input route (read transmission line) and an input traffic number (read ST) in the traffic order to be output for each state shown in Table 1.
S number) and are stored. The ACM 120 also stores, for each source node, whether or not squelch should be performed for each traffic. The Line switching control unit 25 selects any of the ACMs 110 by instructing any of the states shown in Table 1, and the squelch control unit 26 controls the K-by at the time of failure.
One of the ACMs 120 is selected according to the source node of te. Thus, as in the first embodiment, Lin
The e-switch control unit 25 can switch the route for each traffic only by controlling the selection of the state-based map according to the state. Further, the squelch operation that needs to be performed for each traffic can be executed only by the control of the squelch control unit 26 for selecting the squelch map according to the source node of the K-byte input from the obstacle avoidance direction.

In the first and second embodiments, the O
Although C-48 4-Fiber BLSR is taken as an example, a general OC-N 4-Fiber or OC-N 2 is used.
-It can also be applied to Fiber BLSR networks. In the 2-Fiber BLSR, half of the entire band is currently used and the other half is reserved, so that the embodiment of the present invention can be applied assuming that the band allocated for protection is a protection line.

[0051]

According to the present invention, in a BLSR network transmission device, switching can be executed by a simple procedure with a simple hardware configuration. Also, if squelch is required due to ring division etc., pass A with a simple procedure.
IS can be inserted. Further, this switching and squelch operation only selects data, so the time until switching or squelch operation can be shortened.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a node according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a line setting example in 4-Fiber BLSR (No. 1)

FIG. 3 is an explanatory diagram showing an example of restoration by a span switch in a line setting example (1).

FIG. 4 is an explanatory diagram showing an example of restoration by the ring switch in the line setting example (1).

FIG. 5 is an explanatory diagram showing an example of a node configuration in 4-Fiber BLSR.

FIG. 6 is an explanatory diagram showing a configuration of a node according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of restoration at the time of ring division in the line setting example (1).

FIG. 8 is an explanatory diagram showing an example of line setting in 4-Fiber BLSR (Part 2).

FIG. 9 is an explanatory diagram showing a restoration example at the time of ring division in the line setting example (No. 2).

FIG. 10 is an explanatory diagram (part 3) showing a line setting example in 4-Fiber BLSR.

FIG. 11 is an explanatory diagram showing a restoration example at the time of ring division in the line setting example (3).

FIG. 12 is an explanatory diagram showing an example of Ring Topology Map.

FIG. 13 is an explanatory diagram showing an example of STS Squelch Map.

FIG. 14 is an explanatory diagram showing an example of a flowchart for executing squelch.

FIG. 15 is a configuration diagram of a cross-connect unit according to the embodiment of the present invention.

FIG. 16 is a configuration diagram showing the configuration shown in FIG. 1 more specifically.

FIG. 17 is an explanatory diagram showing a state-based map group according to the embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a squelch map group according to the embodiment of the present invention.

FIG. 19 is an explanatory diagram (1) showing an example of a state-based map group.
(3)

FIG. 20 is an explanatory diagram (1) showing an example of a squelch map group.
(6)

FIG. 21 is an explanatory diagram showing an operation example in a normal state according to the embodiment of the present invention.

FIG. 22 is a Span Br according to an embodiment of the present invention.
Explanatory diagram showing operation example when executing & Sw

FIG. 23 is an explanatory diagram showing an operation example at the time of executing Ring Br & Sw with ring division according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Address control memory (ACM) 2 ... State-based maps 3 ... Squelch map group 4 ... Selected state map 5 ... Selected squelch map 6 ... Input transmission path 7 ... Data memory 8 ... Squelcher 9 ... Output transmission path 10 ... BLSR network 11 ... Optical fiber transmission line group 12 ... Node 13 ... CW direction working line 14 ... CW direction protection line 15 ... CCW direction working line 16 ... CCW direction protection line 20 ... Cross connect part 21 ... Optical receiver 22 ... Optical transmitter 23 ... Overhead processing unit 25 ... Line switching control unit 26 ... Squelch control unit 27 ... Add line 28 ... Drop line 30 ... Counter circuit 31-33 ... Selector.

─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takashi Mori 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division (56) Reference JP-A-5-91103 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 12/437

Claims (5)

(57) [Claims] 1. A BLSR (Bidirect) that is connected to a plurality of optical fiber transmission lines and accommodates a low-order group device.
Ional Line Switched Ring)
A transmission device for a BLSR network, which inserts and extracts traffic between the low-order group device and the optical fiber transmission line in a network system and switches the route when a failure occurs, for each output route In, having an output control unit for controlling the output of the traffic, the output control unit, holding means for temporarily holding the input traffic, control means for performing access control of the holding means, For each switching state of the route at the time of failure occurrence, in accordance with the order of the traffic to be output from the output route, storage means for storing the storage area of the traffic held in the holding means, and when the failure occurs and a switching control means for performing a switching instruction of route, the control means, in accordance with the switching instruction of route instructed by the switching control means, in said storage means, the output The order of the traffic to be, from the holding means reads the traffic to be outputted, to the output path, then outputs the read traffic, the output control unit, the switching state of the route when the fault occurs, the output Should
The traffic is invalid according to the traffic order.
Squelch note that stores squelch control information indicating whether or not
The storage means and the schedule when outputting the traffic to the output route.
According to the squelch control information stored in the memory unit,
AIS (Alarm Indication Sign)
al) and an insertion means for inserting the traffic into the traffic.
A transmission device for a BLSR network provided . 2. The BLSR network transmission device according to claim 1, wherein the squelch storage means corresponds to a switching state of a route when the fault occurs.
Predefined, ring splits in the network
According to the order of the traffic to be output,
A transmission apparatus for a BLSR network, comprising: a squelch map storing the squelch control information . 3. The BLSR network transmission device according to claim 1, wherein the BLSR corresponds to a switching state of a route when the failure occurs.
Predetermined ring split state of the network
Is transmitted from the other device on the failure avoidance side.
A transmission device for a BLSR network , further comprising squelch control means for making a determination according to the transmission source of the . 4. Connected to a plurality of optical fiber transmission lines,
In addition, BLSR (Bidirect) that accommodates low-order group devices
Ional Line Switched Ring)
In the network system, the traffic between the low-order group device and the optical fiber transmission line is
Inserting and extracting a link, and switching the route when a failure occurs
A plurality of BLSR network transmission devices to perform , each of the BLSR network transmission devices
An output control unit that controls the output of the traffic for each road
The output control unit has a holding unit that temporarily holds the input traffic.
And a control means for performing access control of the holding means , and whether the output route is changed depending on the switching state of the route at the time of occurrence of the failure.
Corresponding to the order of the traffic to be output from
Storage means for storing a storage area for traffic held in stages
And a switching control means for instructing switching of the route when the failure occurs
And the control means follows a route switching instruction instructed from the switching control means.
Te, you Keru in the storage means, the order of the traffic to be output
First, read the traffic to be output from the holding means.
And output the read traffic to the relevant output route.
The output control unit determines the output to be output depending on the switching state of the route when the failure occurs.
The traffic is invalid according to the traffic order.
Squelch note that stores squelch control information indicating whether or not
The storage means and the schedule when outputting the traffic to the output route.
According to the squelch control information stored in the memory unit,
AIS (Alarm Indication Sign)
al) is inserted into the traffic concerned, and a BLSR network system is provided. 5. Connected to a plurality of optical fiber transmission lines,
In addition, BLSR (Bidirect) that accommodates low-order group devices
Ional Line Switched Ring)
In the network system, the low-order group device and the
Insertion and extraction of traffic due to the optical fiber transmission line
The BLSR network that performs and switches routes when a failure occurs
In switching the output route when there is a failure in the transmission device for
A traffic output control method for each output route, the switching state of the route at the time of the occurrence of the failure
For each, in the order of the traffic to be output from the output route
Correspondingly, clarify the storage area of the traffic to be held.
It should be memorized and output according to the switching state of the route at the time of the failure.
The traffic is invalid according to the traffic order.
Squelch control information indicating whether or not
Every time, the input traffic is temporarily retained, and it is possible to switch routes for each output route when the failure occurs.
Yes, the order of the stored traffic to be output
Read the traffic to be output, which was held,
When the read traffic is output to the output route and the traffic is output to the output route, the memory is stored.
According to the squelch control information, the path AIS (Alar
m Indication Signal) the tiger
Output route in the event of a failure, characterized by being inserted into a hit
Traffic output control method in switching.