JP2002118580A - Ring protection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line protection method in which installation cost in ring network is reduced while exhibiting traffic containing efficiency and traffic protection capacity similar to those of a prior art BLSR. SOLUTION: In the ring protection method for maintaining a ring network performing communication service through datagram by switching a faulty transmission line, each node of the ring network is triggered by detection of a faulty section of its own apparatus or information of a faulty section from other apparatus to perform switching of a transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a ring network, and more particularly to a ring protection method for maintaining a failure network by switching the failure transmission path.

[0002]

2. Description of the Related Art Generally, a communication network is used to realize a transmission line protection function. 1. TSI control when switching path control function Bandwidth management function 3. It is necessary to implement a connection management function (misconnection avoidance control). The current backbone network is: 1. Connection-Oriented communication Since TDM transmission is assumed, the protection method (ITU-T G.841 / Bellco) realized in the backbone network is used.
re GR-1230-CORE) is a method specialized on the above premise. In this method, in order to prevent erroneous connection of traffic, it is necessary to perform communication between devices that perform switching and make transmission line switching timing uniform, but the protocol processing for determining transmission line switching timing is complicated.

On the other hand, when the traffic to be transmitted is a datagram (particularly an IP packet), the following features are characteristic. 1. 1. Autonomous reception processing by connection-less type communication (because a label indicating the destination is attached to each packet) Dynamic bandwidth control processing in upper layer (flow control by TCP, etc.) Therefore, a method of realizing the transmission line protection function by datagram-based reception processing in each device has also been proposed ("The SRP MAC Layer Proto").
col "draft-tsiang-srp-00.
txt (INTERNET DRAFT)). In this case, instead of simplifying the switching process, the datagram receiving process becomes a bottleneck in the switching operation time and cannot be applied to a large-capacity transmission network.

[0004] Therefore, it is expected that datagrams will be mainly used for traffic transmitted in the backbone network in the future.

[0005]

However, the conventional ring protection method has the following problems. When the traffic is a datagram, it can be said that the traffic misconnection prevention function is provided in the traffic itself as described above. Therefore, the connection-O is required for the network transmitting the datagram.
If the transmission line protection of the conventional method realized in the backbone network on the assumption of the oriented communication and the TDM transmission is applied, implementation of functions that are not necessarily required will cause an increase in device cost.

The present invention has been made in view of the above-mentioned problems in the prior art, and solves the above problems in a ring network, and has the same traffic accommodation efficiency and traffic protection capability as those of the conventional BLSR. The purpose is to provide a protection method.

[0007]

According to a first aspect of the present invention, there is provided a ring protection method provided to solve the above-mentioned problems, by switching a failure transmission path to a ring network which provides a datagram communication service. In the ring protection method for maintaining this, each node device of the ring network performs a transmission line switching process by using a failure section detection of the own apparatus or a failure section notification from another apparatus as a trigger.

When each node device of the ring network performs transmission path switching processing triggered by detection of a failure section of the own apparatus or notification of a failure section from another apparatus, the timing of transmission path switching with another apparatus is not adjusted, so that the transmission path is not adjusted. The process of determining the switching timing is simplified.

A ring protection method according to a second aspect of the present invention, which is provided to solve the above-mentioned problem, provides a ring protection method for maintaining a ring network for performing a communication service by datagram by switching a faulty transmission path. In the method, each node device of the ring network performs a transmission path switching process triggered by detection of a failure section of the ring apparatus or notification of a failure section from another apparatus, and sends a pattern indicating a transmission path abnormal state to the network for a predetermined time. It is characterized by doing.

[0010] Each node device of the ring network performs transmission path switching processing triggered by detection of a failure section of the own apparatus or notification of a failure section from another apparatus. The process of determining the switching timing is simplified. Also, by transmitting a pattern indicating a transmission path abnormal state to the network for a certain period of time, data reception processing during switching processing is suppressed, and as a result, the burden of data reception processing in the upper layer is reduced, and erroneous delivery of datagrams prevent.

A ring protection method according to a third invention of the present application provided to solve the above-mentioned problem is a ring protection method according to the first or the second invention of the present application, wherein the method for monitoring a transmission path of a physical layer of a network is provided. The fault section is used to perform fault detection, fault information transfer, and switch request transfer, and the fault section notification is performed.

[0012] By using the transmission path monitoring method of the physical layer (Layer 1) of the network, switching occurs without depending on the upper layer, and simple switching processing is performed.

According to a fourth aspect of the present invention, there is provided a ring protection method according to the first to third aspects of the present invention, wherein the ring network is an SDH / SON.
It is characterized by conforming to ET.

The ring network is an SDH / SO
By complying with the NET, when a datagram service is provided in such a network, a switching function can be realized with a lower cost implementation than usual. here,
The SDH is Synchronous Digital
HIRARCHY (international standard for high-speed relay speed systems), and the SONET is a Synchronous O
optical network (a multiplex communication system for a backbone transmission network).

[0015] A ring protection method according to a fifth invention of the present application provided to solve the above-mentioned problem is characterized in that, in the ring protection method according to the fourth invention of the present application, the ring network is a BLSR.

When the ring network is a BLSR, the protection function of the BLSR can be used.

According to a sixth aspect of the present invention, there is provided a ring protection method according to the sixth or fifth aspect of the present invention, wherein the ring protection method according to the fourth or fifth aspect of the present invention comprises a network having a pattern representing the transmission path abnormal state. AIS (Alarm Indica)
(Signal Signal).

The transmission of the pattern indicating the abnormal state of the transmission path to the network is performed by AIS (Alarm Indicati).
On Signal), the transmission path abnormal state can be easily displayed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the ring protection method according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a normal state of a ring network according to the present invention. As shown in FIG. 1, the ring network to which the ring protection method of the present embodiment is applied is a two-fiber ring with four nodes. Switching unit is Line in SONET
As a unit, a half band of the transmission path is reserved in advance as a standby system. The channel selection at the time of switching is 2 fibers
It shall conform to BLSR.

Message transmitted by each node when switching occurs
“age” is Message = {switching status notification; transmission source node; status notification; transfer path}, and is described as follows. Here, source node = I uniquely assigned to each device constituting the ring
D. Switching state notification = FS (forced switching) SF (switching due to Signal Fail equivalent failure) SD (switching due to Signal Degrad equivalent failure) MS (manual switching) WTR (failure recovery / switching standby state) RR (switch response) NR (switching) None) Status notification = IDLE (no switching) Switched (during switching) Transfer route = Short (a route that crosses a switching section) Long (a path that does not cross a switching section). In addition, “transmission path abnormal state” includes SDH / SO
AIS (Alarm Indicati) at NET
on Signal).

Next, the operation of one embodiment of the ring protection method according to the present invention will be described below with reference to the drawings. 2 to 9 are block diagrams showing the operation of the ring protection method according to one embodiment of the present invention. First, the switching operation will be described. FIG.
As shown in FIG. In the normal state, each node has ｛NR, its own node,
Short, IDLE｝ is transmitted (FIG. 1). 2. If the node B detects a failure between A and B, the node B
Sends a pattern indicating "transmission path abnormal state" in the direction of node C (FIG. 2). The “transmission line abnormal state” pattern is indicated by a bold broken line in the figure. 3. The node B performs transmission path switching, and the SF on the Short side, Node_B, Short, Swi
tched｝, Long side ｛SF, Node_
B, Long, Switched} is transmitted (FIG. 3). Further, a pattern indicating “transmission path abnormal state” is transmitted in the direction of the node C. 4. ｛SF, Node_B, Short, Sw
The node A that has received the “ｅｄ” sends a pattern representing “transmission path abnormal state”. At the same time, the transmission line is switched, and ＳRR, Node_
A, Short, Switched｝, Long
側 SF, Node_A, Long, Sw on the side
transmitted (FIG. 4). 5. The node C transmits the node {SF, Nod
When e_B, Short, Switched} is received, the message is transferred to the D side. Similarly, node D transmits {SF, Node_
B, Short, Switched}, the message is transferred to the A side (FIG. 4). 6. The pattern indicating the “transmission line abnormal state” is transmitted for a time sufficient for the switching operation to be completed in the entire ring (FIG. 5).

Next, the switching back operation will be described. As shown in FIG. 1 and FIG. 6 to FIG. When the failure is recovered, the Node B sends the ｛WTR, Node_B, Short, S to the Short side.
switched｝, Long side WTR, N
mode_B, Long, Switched} (FIG. 6). 2. ｛WTR, NOde_B, Short, S
The node A that has received the switched @
RR, Node_A, Short,
Switched｝, Long side ｛WTR,
Node_A, Long, Switched} is transmitted (FIG. 7). 3. After the release of the WTR timer, the node B releases the switching, and 両 側 NR, Node_B, Short,
IDLE} is transmitted (FIG. 8). 4. Node A has ｛NR, Node_B, Sho
When rt, IDLE # is received, the switching is released,
ＮＲ NR, Node_A, Short, IDLE
｝ Is transmitted to both sides (FIG. 9). 5. Nodes C and D are ｛NR, *, Sh from both sides.
ort, IDLE}, ｛NR,
The own node ID, Short, and IDLE are transmitted to both sides (FIG. 1).

As described above, the failure detection, the failure information transfer, and the switching request transfer are performed by using the transmission path monitoring method of Layer 1, and the switching is performed due to the failure section notification from the other device. Then, by transmitting a pattern indicating "transmission path abnormal state" for a certain period of time after transmission path switching, data reception processing during switching processing due to transmission path failure is suppressed, and erroneous delivery of datagrams between service devices is prevented. . Since the transmission line switching timing is not matched with that of another device, the process of determining the transmission line switching timing is simplified.

[0024]

As described above, according to the ring protection method of the present invention, switching is realized not in datagram units but in units of aggregating traffic of paths and sections. I do. In addition, the datagram receiving process in the service device connected downstream is suppressed to reduce the load of the erroneous delivery datagram discarding process. Further, when the present invention is applied to the SDH / SONET TDM transmission, a protection function having the same traffic protection capability as that of the conventional method can be realized more easily.

[0025]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a normal state in an embodiment of a ring protection method according to the present invention.

FIG. 2 is a block diagram showing a state at the time of switching in an embodiment of the ring protection method according to the present invention.

FIG. 3 is a block diagram showing a state at the time of switching in an embodiment of the ring protection method according to the present invention.

FIG. 4 is a block diagram showing one state at the time of switching in an embodiment of the ring protection method according to the present invention.

FIG. 5 is a block diagram showing a state at the time of switching in an embodiment of the ring protection method according to the present invention.

FIG. 6 is a block diagram showing a state at the time of switching back in one embodiment of the ring protection method according to the present invention.

FIG. 7 is a block diagram showing one state at the time of switching back in one embodiment of the ring protection method according to the present invention.

FIG. 8 is a block diagram showing a state at the time of switching back in one embodiment of the ring protection method according to the present invention.

FIG. 9 is a block diagram showing one state at the time of switchback in one embodiment of the ring protection method according to the present invention.

Claims (6)

[Claims] In a ring protection method for maintaining a ring network that provides a communication service using datagrams by switching a failure transmission path, each node device of the ring network detects a failure section of its own device or A ring protection method, wherein a transmission path switching process is performed by using a failure section notification from another device as a trigger. 2. A ring protection method for maintaining a ring network that provides a communication service using datagrams by switching a faulty transmission path, wherein each node device of the ring network detects a faulty section of its own device. A ring protection method comprising: performing a transmission line switching process by using a failure section notification from another device as a trigger; and transmitting a pattern indicating a transmission line abnormal state to a network for a predetermined time. 3. The method according to claim 1, wherein failure detection, failure information transfer, and switching request transfer are performed by using a transmission path monitoring method of a physical layer of the network, and the failure section notification is performed. 3. The ring protection method according to item 2. 4. The system according to claim 1, wherein the ring network is an SDH (Sy
nchronous Digital Hilarch
y) / SONET (Synchronous Optical)
4. The ring protection method according to claim 1, wherein the ring protection method is compliant with (a. 5. The method according to claim 4, wherein the ring network is a BLSR. 6. The transmission of the pattern indicating the abnormal state of the transmission path to the network is performed by an AIS (Alarm Indic).
6. The ring protection method according to claim 4, wherein the ring protection method is an application signal.