JP2009147653A - Communication system and ring node device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a communication system for quickly switching communication channels even when multiple failures occur. <P>SOLUTION: In the communication system for connecting RPR (Resilient Packet Ring) networks, a topology management part 55 of a node device 11A manages as in-system topology information first topology information on its own ring topology and second topology information on a ring in another system topology by mutually communicating the information between itself and the node device of another system ring. An RPR transmission/reception part discriminates an RPR frame to be sent to its own ring on the basis of a destination of the RPR frame and the in-system topology information. An aggregation SW part 51 discriminates an RPR frame to be transferred to a ring in another system on the basis of a destination of the RPR frame added in the RPR frame and the in-system topology information, and transfers it to the ring in another system. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system and a ring node device in which a plurality of RPR networks are connected through a predetermined path.

  With the recent complication of communication network systems, many line failures have occurred in communication networks. For this reason, it is desired to respond quickly and efficiently to a line failure in a communication network.

  As a network protocol technique capable of recovering a network failure at high speed, there is RPR (Resilient Packet Ring) defined by IEEE (Institute of Electrical and Electronics Engineers) 802.17, for example.

  In this RPR, each ring node (node device) as a ring network forms a bi-directional duplex ring, and each physical address is advertised on the ring network. Each ring node collects advertisement information and Recognizes the order (topology map). Each ring node transmits a packet by selecting a ring of a system close to the physical address of the destination with reference to the topology map when transmitting the packet on the ring network. In addition, each ring node can quickly detect the failure location on the ring network by constantly monitoring the failure information (information related to failures in the ring network) that each ring node periodically transmits. The function to switch the route according to the situation (failure bypass function at the time of ring failure, protection function) is provided.

  For example, there is a technique for configuring a ring network with high fault tolerance using RPR in a network that relays data at an OSI (Open Systems Interconnection) reference model second layer (layer 2) level. In such a network, a plurality of ring nodes constituting a ring network are connected to network nodes constituting another network in order to make a communication path redundant at a boundary connecting the ring network and another network. A redundant path is configured. Conventionally, STP (Spanning Tree Protocol) defined in IEEE802.1D is applied to the entire network to form a logically loop-free network topology.

  In this STP, a redundant ring network is logically made into a tree structure to eliminate a loop portion, and one forwarding path (communication path) adapted to a change in the network configuration is generated. The forwarding path is generated by each node putting STP information in a control frame (BPDU: Bridge Protocol Data Unit) and exchanging the information with each other. The synchronization of the STP information of each bridge is guaranteed by a protocol timer. A priority is given to each bridge, a cost is given to each link, and the bridge with the highest priority is set as a root bridge. This root bridge is used as the starting point of the tree structure, and a tree is constructed by selecting a low-cost route.

  Moreover, at least two inter-ring connecting devices described in Patent Document 1 are provided between rings to be connected in order to interconnect physical rings. Each inter-ring connecting device recognizes two rings as one virtual ring, and uses this virtual ring as a target of RPR protection.

International Publication No. WO 2004/095779 Pamphlet

  However, since the ring network described in IEEE802.17 is a single bidirectional double ring network, when two or more failures occur in the double ring network, the communication path is divided, and the ring network is broken. Communication was not possible in the section. As a countermeasure against this, there is a method using STP. However, since it is necessary to wait until the Max Age time of STP from the disconnection of a communication path due to the occurrence of a failure to the determination of another path, it takes a long time to recover the communication path. For this reason, there has been a problem that switching of communication paths cannot be performed quickly.

  Even in the method of recognizing two rings as one virtual ring, if two or more failures occur in each double ring network, the communication path is divided and communication is possible in some sections. could not. Also, IEEE 802.17 does not specify a technology related to a communication method that can secure a communication path when a plurality of failures occur.

  The present invention has been made in view of the above, and an object of the present invention is to provide a communication system and a ring node device that can quickly switch communication paths even when a plurality of failures occur in a dual ring network. And

  In order to solve the above-described problems and achieve the object, the present invention includes at least two RPR networks each having a plurality of ring node devices, and a ring node device of one of the RPR networks. In the communication system in which at least two sets of devices between the ring node devices of the other RPR network are connected by a predetermined path, each of the at least two sets of ring node devices is in the RPR network to which the own device belongs. An RPR transmission / reception unit that transmits / receives an RPR frame to / from another ring node device different from the own device in the own RPR network, and a ring in another RPR network that is another RPR network different from the own RPR network The node device is coupled via the predetermined path. A first topology information related to the topology of the own RPR network as an encapsulated RPR frame between an encapsulated transmission / reception unit that transmits and receives the encapsulated RPR frame and a ring node device in the other RPR network; A topology management unit that mutually notifies the second topology information related to the topology of the other RPR network, and manages the first topology information and the second topology information as in-system topology information. The RPR transmission / reception unit, based on the transmission destination information on the transmission destination of the RPR frame added in the RPR frame and the topology information in the system, the RPR frame that is the transmission source in the own RPR network, and An RPR file whose source is in another RPR network An RPR frame to be sent in the local RPR network and sent to the local RPR network, and the encapsulated transmission / reception unit transmits destination information on the transmission destination of the RPR frame added in the RPR frame, and Based on the intra-system topology information, the RPR frame to be transferred to the other RPR network is discriminated from the RPR frame that is the transmission source in the local RPR network and the RPR frame that is the transmission source in the other RPR network. Transferring to another RPR network.

  According to the present invention, based on the transmission destination of the RPR frame and the topology information in the system, the RPR frame to be sent to the local RPR network and the RPR frame to be transferred to the other RPR network are discriminated, and the local RPR network and the other RPR are respectively determined. Since it is sent to the network, it is possible to quickly switch the communication path even when a plurality of failures occur in the double ring network.

  Embodiments of a communication system and a ring node device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a communication system according to Embodiment 1 of the present invention. The communication system 10 is a system using a ring network that relays frames using RPR, and is an escape that connects two ring networks (RPR networks) 1 and 2 and the ring network 1 and the ring network 2. Pass (predetermined pass) 3.

  The ring network 1 forms a bidirectional double ring (inner ring and outer ring), and includes five node devices (ring node devices) 11A to 15A on the ring A. In the ring network 1, the node devices 11A to 15A are connected to the outer ring in the clockwise direction in the order of the node device 15A, the node device 14A, the node device 13A, the node device 12A, and the node device 11A. The node devices 11A to 15A are connected to the inner ring in the order of the node device 11A, the node device 12A, the node device 13A, the node device 14A, and the node device 15A in the counterclockwise direction.

  The ring network 2 forms a bidirectional double ring (inner ring and outer ring), and includes five node devices (ring node devices) 21B to 25B on the ring B. In the ring network 2, the node devices 21B to 25B are connected to the outer ring in the clockwise direction in the order of the node device 21B, the node device 22B, the node device 23B, the node device 24B, and the node device 25B. Further, the node devices 21B to 25B are connected to the inner ring in the order of the node device 25B, the node device 24B, the node device 23B, the node device 22B, and the node device 21B in the counterclockwise direction.

  Then, the node device 11A and the node device 21B are connected by one escape path 3 to constitute one pair node, and the node device 12A and the node device 22B are connected by one escape path 3 to form one set. A pair node is configured. Further, the node device 13A and the node device 23B are connected by one escape path 3 to constitute one pair node, and the node device 14A and the node device 24B are connected by one escape path 3 to form one set. The node device 15A and the node device 25B are connected by a single escape path 3 to form a pair of pair nodes. As a result, the node devices 11A to 15A of the ring network 1 and the node devices 21B to 25B of the ring network 2 are connected to each other via the escape path 3, respectively.

  One to a plurality of terminals (terminal devices such as PCs) are connected to each of the node devices 11A to 15A and 21B to 25B. FIG. 1 shows a case where the terminal 31 is connected to the node device 21B and the terminal 32 is connected to the node device 25B. In FIG. 1, illustration of terminals connected to the node devices 11A to 15A and 22B to 24B is omitted.

  Here, the operation of the ring networks 1 and 2 when the ring network 1 and the ring network 2 operate independently without being connected by the escape path 3 will be described. Hereinafter, as a single operation of the ring networks 1 and 2, a topology map creation method, a ring failure detection method, and a protection method using RPR will be described. Since the node devices 11A to 15A in the ring network 1 and the node devices 21B to 25B in the ring network 2 perform the same operation, the operation of the node devices 11A to 15A in the ring network 1 is here. explain.

(1) Topology map creation method In the ring network 1, it is understood in which order each node device 11A to 15A is connected in the ring A (node order), and each node device 11A based on this node order. ˜15A creates a topology map of the ring network 1.

  Specifically, each of the node devices 11A to 15A transmits an RPR control frame called a TP (Topology and Protection) frame in both directions of the ring network 1 at a predetermined cycle. The TP frame has an initial value of 255 and a TTL (Time To Alive) that is decremented by 1 every time it is relayed. In a node device other than the node device (transmission source device) that transmitted the TP frame, The TTL of the TP frame is subtracted and relayed to the adjacent node device. Finally, the node device that transmitted the TP frame terminates the TP frame by discarding the TP frame itself. Each of the node devices 11A to 15A receives the TP frame, and grasps the position of the transmission source device of the TP frame (the number of relays of the node device) viewed from the own node device for each node device and creates a topology map. .

(2) Ring failure detection method When each node device 11A to 15A transmits / receives a TP frame in the ring network, a non-delivery of the keep alive frame sent from the immediately upstream node (upstream adjacent node device) And a failure between the links from the immediately upstream node to the own node device is detected by the own node reception failure.

  Each of the node devices 11A to 15A determines whether or not the transmission source of the Keep Alive frame is the immediately upstream node device based on the topology map created in (1). Information regarding the link state with the immediately upstream node device is transmitted in a TP frame. As a result, all receiving node devices including the immediately downstream node device (downstream adjacent node device) grasp the received link state of the TP frame transmission source device, and any link on ring A is in a failed state. Is mapped (creates link failure information).

(3) Protection Method When each node device 11A to 15A detects a link failure, it switches the transmission direction of the RPR data frame. Specifically, each of the node devices 11A to 15A has a small number of node relays until reaching the destination node based on the topology map created in (1) and the link failure information created in (2), and the ring failure The RPR data frame is transmitted by selecting a ring (inner or outer) where no occurrence has occurred.

  In RPR, there is a rule that the fault bypass time is a maximum of 50 milliseconds. For this reason, the protection function (protection unit 54 described later) included in each of the node devices 11A to 15A detects the failure location from the failure information and switches the RPR data frame transmission direction, and the failure bypass time is 50 mm. Execute at high speed to be within seconds.

  The RPR defines the specifications of the media access sublayer of the data link layer. The RPR can be any one of, for example, Ethernet (registered trademark) for packet communication and SDH (Synchronous Digital Hierarchy) for synchronous communication. It is applicable to the standard and has a feature that does not limit the physical layer.

  However, when the ring network 1 and the ring network 2 operate independently, a new communication path may not be ensured when a plurality of failures occur. Therefore, in the present embodiment, the ring network 1 and the ring network 2 of the communication system 10 are connected by the escape path 3 as shown in FIG. Further, in the communication system 10, the communication path is recovered using the virtual address without using the STP. Hereinafter, a topology map creation method, a ring failure detection method, and a protection method using RPR by the communication system 10 will be described.

  First, the configuration of the node devices 11A to 15A and 21B to 25B according to the first embodiment will be described. Since the node devices 11A to 15A and 21B to 25B have the same configuration, the configuration of the node device 11A will be described here.

  FIG. 2 is a diagram illustrating a configuration of the node device according to the first embodiment. The node device 11A includes a concentrator SW unit 51, an RPR interface transmission unit 52x, an RPR interface reception unit 52y, a protection unit 54, a topology management unit 55, an outer ring transmission unit 56x, an outer ring reception unit 56y, an inner ring transmission unit 58x, and an inner side. The ring receiver 58y, the outer ring drop determination unit 57, the inner ring drop determination unit 61, and the filtering unit 62 are provided.

  Here, the outer ring transmission unit 56x, the outer ring reception unit 56y, the inner ring transmission unit 58x, and the inner ring reception unit 58y correspond to the RPR transmission / reception unit described in the claims, and the concentration SW unit 51 here Corresponds to the encapsulated transmitter / receiver described in the claims. In the following description, the RPR data frame and the RPR control frame may be referred to as an RPR frame.

  The outer ring receiving unit 56y receives an RPR frame from the outer ring and checks whether there is an error in the received RPR frame. The outer ring reception unit 56y sends the received RPR frame to the outer ring drop determination unit 57.

  The inner ring receiving unit 58y receives the RPR frame from the inner ring and checks whether there is an error in the received RPR frame. The inner ring reception unit 58y sends the received RPR frame to the inner ring drop determination unit 61.

  The outer ring drop determination unit 57 determines whether to relay or drop the RPR frame received by the outer ring reception unit 56y based on the TTL of the RPR frame. The outer ring drop determination unit 57 transmits the RPR frame determined to be relayed to the outer ring transmission unit 56x with TTL minus 1, and transmits the RPR frame determined to be dropped to the RPR interface reception unit 52y.

  The inner ring drop determination unit 61 determines whether to relay or drop the RPR frame received by the inner ring reception unit 58y based on the TTL of the RPR frame. The inner ring drop determination unit 61 transmits the RPR frame determined to be relayed to the inner ring transmission unit 58x with TTL minus 1, and transmits the RPR frame determined to be dropped to the RPR interface reception unit 52y.

  The outer ring transmission unit 56x schedules both traffic of an RPR frame to be added to the outer ring and a reception frame to be transferred by the outer ring. The outer ring transmission unit 56x transmits the RPR frame that the outer ring drop determination unit 57 determines to relay to its own ring (ring node device) or the RPR frame transmitted from the RPR interface transmission unit 52x to the outer ring (node device). 15A).

  The inner ring transmission unit 58x schedules both traffic of the RPR frame to be added to the inner ring and the reception frame to be transferred by the inner ring. The inner ring transmission unit 58x transmits the RPR frame determined by the inner ring drop determination unit 61 to relay to the own ring or the RPR frame transmitted from the RPR interface transmission unit 52x to the inner ring (node device 12A). .

  The concentrator SW unit 51 transmits and receives MAC frames via a path 72 to and from a terminal connected to the node device 11A. Further, the line concentrator SW unit 51 transmits and receives MAC frames to and from the node device 21A of the ring network 2 connected via the escape path 3. The concentrator SW unit 51 performs switching of MAC frames transmitted and received between the terminal and the node device 21A. The concentrator SW unit 51 transmits and receives MAC frames using an escape passport for ring B (on the other ring side) when transmitting and receiving MAC frames to and from the node device 21B.

  The RPR interface transmission unit 52x is connected to the line concentrator SW unit 51, the protection unit 54, the topology management unit 55, the outer ring transmission unit 56x, and the inner ring transmission unit 58x. The RPR interface transmission unit 52x generates an RPR data frame or an RPR control frame by adding an RPR header to the MAC frame that has arrived at the concentrator SW unit 51. Further, the RPR interface transmission unit 52x transmits the topology information of the other ring (other RPR network) managed by the topology management unit 55 (information on the topology for creating a TTL table or a virtual TTL table described later) to the RPR. An RPR control frame is generated by adding the control frame.

  The RPR interface transmission unit 52x has a function of selecting a transfer destination (either the inner ring or the outer ring or both) of the generated RPR data frame or RPR control frame. The RPR interface transmission unit 52x selects a ring to which an RPR frame is added based on topology information managed by the topology management unit 55 and failure information from the protection unit 54.

  The RPR interface transmission unit 52x determines whether the MAC frame transmitted from the line concentration SW unit 51 is a frame that has passed through the escape path 3 from the other system ring, and is a frame from the other system ring. In some cases, the RPR frame is extracted from the encapsulated frame. Further, when the extracted RPR frame is an RPR data frame, the RPR interface transmission unit 52x determines the RPR frame based on the ring ID of the RPR frame (destination information for identifying the inner ring and the outer ring serving as transmission destinations). Select a ring (inner ring or outer ring) to add.

  The RPR interface transmitter 52x sends the RPR frame to the inner ring transmitter 58x when adding the RPR frame to the inner ring, and sends the RPR frame to the outer ring transmitter 56x when adding the RPR frame to the outer ring. Send to. When the extracted RPR frame is an RPR control frame including topology information of another system ring, the RPR interface transmission unit 52x delivers the RPR control frame to the topology management unit 55.

  The RPR interface reception unit 52y is connected to the filtering unit 62, the protection unit 54, the topology management unit 55, the outer drop determination unit 57, and the inner ring drop determination unit 61. The RPR interface reception unit 52y determines whether the RPR frame received from the inner ring or the outer ring is an RPR data frame or an RPR control frame, and notifies various functional modules to each functional module according to the determination result.

  When the RPR frame received from the inner ring or the outer ring includes a MAC frame, the RPR interface reception unit 52y extracts the MAC frame from the RPR frame and passes the extracted MAC frame to the filtering unit 62. Further, when the RPR interface reception unit 52y determines that the RPR frame is a frame to be transferred to the escape path 3, the RPR frame is MAC-encapsulated and passed to the filtering unit 62.

  The topology management unit 55 is connected to the outer ring drop determination unit 57 and the inner ring drop determination unit 61. The topology management unit 55 creates and stores topology information of the own ring based on the TP frames received from the node devices 12A to 15A in the own ring by the inner ring receiving unit 58y and the outer ring receiving unit 56y. . In addition, the topology management unit 55 stores the topology information of the other ring received by the concentrator SW unit 51 from the node device 21B via the escape path 3.

  The topology management unit 55 uses the communication path of the other ring (ring network 2) through the escape path 3 before the failure point when the communication path is divided due to the occurrence of multiple failures on the own ring. In order to take over the frame relay, the topology information of the other ring is added to the topology information of the own ring and managed. The topology management unit 55 according to the present embodiment is created using the topology information of the own ring created using the real address for identifying each of the node devices 11A to 15A and the virtual address identifying the pair of pair nodes. Stored topology information. The virtual address is an address used when a plurality of failures occur in the communication system 10 and a new communication path is set.

  The topology management unit 55 creates the topology map of the own ring using the topology information of the own ring created using the real address, and uses the topology information of the communication system 10 created using the virtual address. Thus, a topology map of the communication system 10 is created. Based on the failure status on ring A notified from protection unit 54, topology management unit 55 determines the number of HOPs to destination node devices 11A to 15A on the local ring in a predetermined information table (TTL table, virtual It is registered and stored in the (TTL table). The TTL table and the virtual TTL table are information tables for creating a topology map created based on the topology information and the TP frame, respectively.

  The protection unit 54 grasps the failure status in the communication system 10 based on the TTL table or virtual TTL table of the topology management unit 55 and notifies the topology management unit 55 of the failure information.

  When the MAC frame transmitted from the RPR interface reception unit 52y is a MAC frame transferred to the escape path 3, the filtering unit 62 prioritizes transmission (transfer) priority added to the MAC frame. Check the information. The filtering unit 62 passes only MAC frames with high priority information (predetermined value or more) to the concentration SW 51 side, and discards MAC frames with low priority information.

  FIG. 3 is a diagram for explaining a real address set in each node device. In FIG. 3, the numerical values shown in each of the node devices 11A to 15A and 21B to 25B are real addresses for identifying the node devices, and are set without duplication in each node device.

  The node devices 11A, 12A, 13A, 14A, and 15A have real addresses “101”, “102”, “103”, “104”, and “105”, respectively.

  Further, the node device 21B, the node device 22B, the node device 23B, the node device 24B, and the node device 25B have real addresses “201”, “202”, “203”, “204”, and “205”, respectively.

  In the present embodiment, the clockwise direction of the ring network 1 is West-span, and the counterclockwise direction is East-span. Further, the counterclockwise direction of the ring network 1 is defined as West-span, and the clockwise direction is defined as West-span.

  Next, inter-ring connection information notification processing and acquisition processing using virtual addresses in the communication system 10 will be described. FIG. 4 is a diagram for explaining a real address and a virtual address set in each node device. In FIG. 4, the upper numerical values shown in the node devices 11A to 15A and 21B to 25B are real addresses, and the lower numerical values are virtual addresses.

  In the communication system 10, the same virtual address is set for the pair nodes connected by the escape path 3. The node device 11A and the node device 21B have a virtual address “001”, and the node device 12A and the node device 22B have a virtual address “002”. Further, the node device 13A and the node device 23B have a virtual address “003”, the node device 14A and the node device 24B have a virtual address “004”, and the node device 15A and the node device 25B have virtual addresses. “005”.

  Each of the node devices 11A to 15A and 21B to 25B according to the present embodiment manages a TTL table as information for creating a topology map and manages a virtual TTL table as information for creating a virtual topology map. ing. FIG. 4 shows a TTL table and a virtual TTL table of the node device 13A, and a TTL table and a virtual TTL table of the node device 23B as examples of the TTL table and the virtual TTL table managed by each node device. In FIG. 4, the TTL table and the virtual TTL table are collectively described, but the TTL table and the virtual TTL table may be separate tables.

  The TTL table is set in the TTL value (the number of HOPs), the real address and the virtual address set in the node device in the West direction (West-in), and the node device in the East direction (East-in). It is an information table in which real addresses and virtual addresses are associated with each other.

  In the TTL table of the node device 13A, the West-in node device in which the TTL is “0” has the real address “103” and the virtual address “003”. In addition, the West-in node devices with TTLs “1” to “4” have real addresses “102”, “101”, “105”, and “104”, respectively, and virtual addresses “002”. , “001”, “005”, and “004”.

  Similarly, in the TTL table of the node device 13A, the East-in node devices whose TTLs are “0” to “4” have real addresses “103”, “104”, “105”, “101”, “102” and the virtual addresses are “003”, “004”, “005”, “001”, and “002”, respectively.

  In the TTL table of the node device 23B, the West-in node devices having TTLs “0” to “4” have real addresses “203”, “202”, “201”, “205”, “ 204, and the virtual addresses are “003”, “002”, “001”, “005”, and “004”, respectively.

  Similarly, in the TTL table of the node device 23B, the East-in node devices whose TTL are “0” to “4” have real addresses of “203”, “204”, “205”, “201”, “202”, and the virtual addresses are “003”, “004”, “005”, “001”, and “002”, respectively.

  In the present embodiment, in order to grasp the entire topology of rings A and B even when multiple failures occur, a virtual model simulating two pair nodes connected to both ends of escape path 3 with a virtual address for one unit. A topology map is generated by each of the node devices 11A to 15A and 21B to 25B.

  Here, a virtual topology map generation process by each of the node devices 11A to 15A and 21B to 25B will be described. Each of the node devices 11A to 15A and 21B to 25B holds a virtual address in advance in the topology management unit 55 together with the real address assigned to the RPR interface. In the communication system 10, each topology management unit 55 is set so that pair nodes have the same virtual address.

  Each of the node devices 11A to 15A and 21B to 25B periodically transmits an ATT_SECONDARY_MACS type frame of an ATD (Attribute Discovery) frame, which is one of RPR control frames, to the inner ring and the outer ring. The ATT_SECONDARY_MACS type frame is generated by the topology management unit 55. The ATT_SECONDARY_MACS type frame is transmitted to the outer ring via the outer ring drop determination unit 57 and the outer ring transmission unit 56x, and is transmitted to the inner ring via the inner ring drop determination unit 61 and the inner ring transmission unit 58x. Thereby, the node devices 11A to 15A advertise the virtual address of the own node device on the ring A as the secondary address, and the node devices 21B to 25B advertise the virtual address of the own node device on the ring B as the secondary address. .

  Each of the node devices 11A to 15A and 21B to 25B receives a virtual address (RPR control frame) from another node device by the outer ring receiving unit 56y and the inner ring receiving unit 58y. This virtual address is sent to the RPR interface receiver 52y via the outer ring drop determination unit 57 and the inner ring drop determination unit 61, respectively. The RPR interface reception unit 52y sends the virtual address to the topology management unit 55.

  The topology manager 55 of each of the node devices 11A to 15A and 21B to 25B generates a virtual TTL table (topology information) using the virtual address received from the other node device. This virtual TTL table is a node list using virtual addresses in which the TTL values are in descending order, and is generated for each span. The virtual TTL table is an information table of a part composed of virtual addresses in the TTL table shown in FIG. 4. The TTL value, the virtual address set in the West-in node device, and the East- It is an information table in which virtual addresses set in in node devices are associated with each other.

  The node devices 11A to 15A and 21B to 25B exchange virtual TTL tables (mutual notification) with each pair node. The topology management unit 55 of each of the node devices 11A to 15A and 21B to 25B sends the created virtual TTL table to the RPR interface reception unit 52y as an RPR frame. Specifically, the RPR interface receiving unit 52y encapsulates the virtual TTL table created as an RPR frame and sends it to the concentrator SW unit 51. The concentrator SW unit 51 transmits the encapsulated RPR frame via the escape path 3 to the pair node. Send to.

  Each of the node devices 11A to 15A and 21B to 25B that are paired nodes receives the encapsulated RPR frame by the line concentration SW unit 51. The encapsulated RPR frame is sent to the RPR interface transmission unit 52x, and the RPR interface transmission unit 52x extracts the RPR frame. The extracted RPR frame is sent to the topology management unit 55.

  The topology management unit 55 extracts the virtual TTL table of the pair node from the RPR frame. The topology management unit 55 synthesizes the virtual TTL table of the local ring and the virtual TTL table received from the pair node to generate a new virtual TTL table (intra-system topology information), and creates the new virtual TTL table. Based on this, a virtual topology map is generated. In the virtual topology map, the number of HOPs from the own node device with respect to the destination address (address of another node device on the ring) is registered, and the registration order of the destination address and the number of HOPs is opposite to that of the TTL table.

  When each of the node devices 11A to 15A and 21B to 25B generates a virtual topology map, the following processing is executed. That is, when the topology management unit 55 adds an RPR frame to the own ring, the topology management unit 55 searches the virtual topology map using the destination address as a key, and sets the number of HOPs acquired from the virtual topology map as the initial value of the TTL. The RPR frame in which this TTL is set is transmitted to the outer ring via the outer ring drop determination unit 57 and the outer ring transmission unit 56x, and is transmitted to the inner ring via the inner ring drop determination unit 61 and the inner ring transmission unit 58x. Is done.

  Each of the node devices 11A to 15A and 21B to 25B receives the RPR control frame from the other node device by the outer ring receiving unit 56y or the inner ring receiving unit 58y. The RPR control frame is sent to the RPR interface reception unit 52y via the outer ring drop determination unit 57 or the inner ring drop determination unit 61, respectively. Then, the RPR interface reception unit 52y sends the RPR frame to the topology management unit 55.

  In the topology management unit 55, when there is information (virtual address for TTL) acquired from the virtual TTL table notified from the node device of the other system, the information is marked.

  The protection unit 54 detects the ring failure of the own node device based on the virtual TTL table of the topology management unit 55. Specifically, in the virtual TTL table, the protection unit 54, when there is no virtual node device common to both spans, the last entry of the span with the smaller (closer) side of the final TTL value (the lowest level of the virtual node table). It is determined that a failure has occurred at the end of the node device registered in (1).

  Next, the operation of the communication system 10 when the communication path to the destination node is divided due to the occurrence of multiple failures will be described. In the communication system 10, when the communication path to the destination node is divided due to the occurrence of multiple failures, the following method is used to acquire the topology information ahead of the division via the other system ring.

  That is, the topology management unit 55 of each of the node devices 11A to 15A and 21B to 25B sets a virtual TTL table held by itself in an ATT_ORG_SPECIFIC type ATD frame, and further, this ATD frame is received by the RPR interface reception unit 52y. Encapsulate and transfer to escape path 3. The transmission of the ATD frame to the escape path 3 is performed at a predetermined cycle. When the topology of the own system ring is changed due to a failure or the like and the TTL table is regenerated, an ATT_ORG_SPECIFIC type ATD frame is immediately transmitted from the escape path 3 to the pair node.

  5 and 6 are diagrams for explaining the operation of each node apparatus when multiple failures occur in the communication system. The TTL table shown in FIG. 5 is a TTL table and a virtual TTL table when a multiple failure occurs (immediately after), and the TTL table shown in FIG. 6 is a virtual table acquired from another system ring after the occurrence of multiple failures. It is a new virtual TTL table created using addresses. Here, as an example of multiple failures, the location where the failure occurs is between node device 11A and node device 12A in ring A, between node device 13A and node device 14A in ring A, and node device 21B in ring B. And the node device 22B, and between the node device 24B and the node device 25B in the ring B will be described. First, the TTL table and the virtual TTL table immediately after the occurrence of multiple failures (before the mutual notification of the virtual TTL table) will be described with reference to FIG.

(Node device 11A)
In this case, in the TTL table of the node device 11A, the West-in node devices whose TTLs are “0”, “1”, and “2” have real addresses “101”, “105”, and “104”, respectively. is there. Further, in the TTL table of the node device 11A, the East-in node device in which the TTL is “0” has the real address “101”.

  In the virtual TTL table of the node device 11A, the West-in node devices with TTL “0”, “1”, and “2” have virtual addresses “001”, “005”, and “004”, respectively. is there. In addition, in the virtual TTL table of the node device 11A, the East-in node device in which the TTL is “0” has the virtual address “001”.

(Node device 13A)
Further, in the TTL table of the node device 13A, the West-in node devices with TTL “0” and “1” have real addresses “103” and “102”, respectively. In the TTL table of the node device 13A, the East-in node device with TTL “0” has the real address “103”.

  In the virtual TTL table of the node device 13A, the West-in node devices with TTL “0” and “1” have virtual addresses “003” and “002”, respectively. In the virtual TTL table of the node device 13A, the East-in node device with TTL “0” has a virtual address “003”.

(Node device 14A)
In addition, in the TTL table of the node device 14A, the West-in node device in which the TTL is “0” has the real address “104”. In the TTL table of the node device 14A, the East-in node devices with TTL “0”, “1”, and “2” have real addresses “104”, “105”, and “101”, respectively. .

  In the virtual TTL table of the node device 14A, the West-in node device with TTL “0” has a virtual address “004”. In the virtual TTL table of the node device 14A, the East-in node devices with TTL “0”, “1”, and “2” have virtual addresses “004”, “005”, and “001”, respectively. is there.

(Node device 21B)
In the TTL table of the node device 21B, the West-in node devices with TTL “0” and “1” have real addresses “201” and “205”, respectively. Also, in the TTL table of the node device 21B, the real address of the East-in node device in which the TTL is “0” is “201”.

  Further, in the virtual TTL table of the node device 21B, the West-in node devices with TTL “0” and “1” have virtual addresses “001” and “005”, respectively. Also, in the virtual TTL table of the node device 21B, the East-in node device with TTL “0” has a virtual address “001”.

(Node device 23B)
Further, in the TTL table of the node device 23B, the West-in node devices with TTL “0” and “1” have real addresses “203” and “202”, respectively. In the TTL table of the node device 23B, the East-in node devices with TTL “0” and “1” have real addresses “203” and “204”, respectively.

  Further, in the virtual TTL table of the node device 23B, the West-in node devices with TTL “0” and “1” have virtual addresses “003” and “002”, respectively. In addition, in the virtual TTL table of the node device 23B, the East-in node devices whose TTL is “0” have virtual addresses “003” and “004”, respectively.

(Node device 24B)
Further, in the TTL table of the node device 24B, the West-in node devices having TTL “0”, “1”, and “2” have real addresses “204”, “203”, and “202”, respectively. . In the TTL table of the node device 24B, the East-in node device in which the TTL is “0” has the real address “204”.

  Further, in the virtual TTL table of the node device 24B, the West-in node devices having TTL “0”, “1”, and “2” have virtual addresses “004”, “003”, and “002”, respectively. is there. In the virtual TTL table of the node device 24B, the East-in node device with TTL “0” has a virtual address “004”.

  Next, a new virtual TTL table created by mutual notification of the virtual TTL table after the occurrence of multiple failures will be described with reference to FIG. Each of the node devices 11A to 15A and 21B to 25B generates a virtual TTL table and a virtual topology map by acquiring the virtual TTL table of the pair node notified from the pair node. Specifically, each of the node devices 11A to 15A and 21B to 25B grasps position information of each node device in a normal range (a range in which no communication failure occurs) by a TP frame transmitted / received in the own system ring. is doing.

  For example, the node device 11A reflects the virtual TTL table (second topology information) received from the node device 21B, which is a pair node, in the virtual TTL table (first topology information) held by the node device. The node device 11A here has the contents of the virtual TTL table received from the node device 21B in the virtual TTL table held by itself, so the virtual TTL table is not updated.

  Further, the node device 24B reflects the virtual TTL table received from the node device 14A that is a pair node in the virtual TTL table that the node device 24 owns. The virtual TTL table of the node device 24B exists upstream in the east direction, and the TTL does not have virtual addresses corresponding to “1” and “2”. On the other hand, the virtual TTL table received from the node device 14A exists upstream in the East direction, and has virtual addresses corresponding to TTL “1” and “2”. Therefore, “005” and “001” are added to the East-in as virtual addresses corresponding to TTL “1” and “2” in the virtual TTL table of the node device 24B.

  Further, the node device 24B relays the virtual TTL table received from the node device 14A into the ring B. Specifically, the node device 24B receives the virtual TTL table transmitted as a frame encapsulated from the node device 14A by the line concentration SW unit 51. The concentrator SW unit 51 sends the frame to the RPR interface transmitter 52x. The RPR interface transmission unit 52x extracts an RPR frame from the encapsulated frame. Then, the RPR interface transmission unit 52x selects a ring for adding the RPR frame based on the extracted ring ID of the RPR frame. Then, the RPR interface transmitter 52x transfers the RPR frame to the inner ring transmitter 58x and the outer ring transmitter 56x according to the selected ring. The inner ring transmission unit 58x and the outer ring transmission unit 56x transmit the virtual TTL table received from the node device 14A as an RPR frame to the inner ring and the outer ring.

  Here, since a failure has occurred between the node device 24B and the node device 25B in the ring B, a virtual TTL table (RPR frame) is sent from the node device 24B to the node device 23B via the inner ring. The node device 23B receives the virtual TTL table from the node device 24B by the concentrator SW unit 51, and reflects the received virtual TTL table in the virtual TTL table held by the own node device. At this time, since the node device 24B receives the virtual TTL table from the ring of its own system, 1 is added to each TTL value of the received virtual TTL table and the result is reflected in the virtual TTL table held by the own node device. To do. As a result, the virtual TTL table (virtual TTL table used for reflection) from the node device 23B that the node device 24B reflects in the virtual TTL table of its own node device has TTL “1”, “2”, and “3”. The East-in node devices have virtual addresses “004”, “005”, and “001”, respectively.

  The virtual TTL table of the node device 23B exists upstream in the East direction, and the TTL does not have virtual addresses corresponding to “2” and “3”. On the other hand, the virtual TTL table used for reflection exists upstream in the East direction, and has virtual addresses corresponding to TTL “2” and “3”. Therefore, “005” and “001” are added to the East-in as virtual addresses corresponding to TTL “2” and “3” in the virtual TTL table of the node device 24B. Note that a new virtual address is not overwritten on a TTL whose virtual address is already registered in the virtual TTL table.

  Further, the node device 13A reflects the virtual TTL table received from the node device 23B, which is a pair node, in the virtual TTL table held by the node device. The virtual TTL table of the node device 13A exists upstream in the East direction, and does not have virtual addresses corresponding to TTL “1”, “2”, and “3”. On the other hand, the virtual TTL table received from the node device 23B exists upstream in the east direction and has virtual addresses corresponding to TTL “1”, “2”, and “3”. Therefore, “004”, “005”, and “001” are added to the East-in as virtual addresses corresponding to TTL “1”, “2”, and “3” in the virtual TTL table of the node device 13A.

  Then, the topology management unit 55 of the node device 13A generates a virtual topology map based on the newly created virtual TTL table. Thereby, the topology management unit 55 of the node device 13A recognizes that the ring A has the topology shown in FIG.

  In the topology of FIG. 7, the node devices with virtual addresses “101”, “102”, “103”, “104”, “105” are sequentially connected in the counterclockwise direction, and the virtual address is “ The topology in the case where a communication failure has occurred between the node devices “101” and “102” is shown.

  At this time, the topology management unit 55 marks the virtual addresses “001”, “004”, and “005” acquired from the virtual TTL table of the pair node as newly added virtual addresses. When there is no virtual node common to both spans in the newly created TTL table, the protection unit 54 has a Span (West-in side) on the side with the smaller final TTL (the one with the lower TTL value). The RPR protection operation is performed on the assumption that a failure has occurred at the end of the last entry (the West side of the node device 12A).

  Next, operations of data frame transmission processing and data frame relay processing by the node devices 11A to 15A and 21B to 25B will be described. In this embodiment, a layer 2 network is targeted, and data frame transmission within a ring is premised on RPR flooding. However, the same operation is performed even when an RPR spatial reuse operation is performed.

  The protection unit 54 of each of the node devices 11A to 15A and 21B to 25B confirms the virtual topology map held by itself when the data frame is added, and sets both node devices sandwiching the failure point (Clear Point) as the destination node Is specified. Then, the protection unit 54 sets the number of HOPs up to the destination node in the RPR header of the data frame as the initial value of TTL, and transmits this data frame to both the spans from the inner ring transmission unit 58x and the outer ring transmission unit 56x.

  Further, each of the node devices 11A to 15A and 21B to 25B receives the data frame from the upstream node device by the outer ring receiving unit 56y and the inner ring receiving unit 58y when the data frame is relayed. The data frames are sent to the outer ring drop determination unit 57 and the inner ring drop determination unit 61, respectively. The outer ring drop determination unit 57 and the inner ring drop determination unit 61 subtract one TTL in the RPR header and relay the result from the outer ring transmission unit 56x and the inner ring transmission unit 58x to the downstream node device.

  Thereby, in the rings A and B, when relaying the data frame, the TTL of the RPR header is subtracted by each of the node devices 11A to 15A and 21B to 25B, and relayed to the destination node where the TTL becomes the minimum value. It becomes.

  At this time, in the outer ring drop determination unit 57 and the inner ring drop determination unit 61 of each of the node devices 11A to 15A and 21B to 25B, when relaying a data frame, the TTL value reaches the arrival of the own ring in the relay direction. If it is larger than the possible range, the received data frame is sent to the RPR interface receiver 52y. The RPR interface reception unit 52y encapsulates this data frame and transfers it as a MAC frame to the escape path 3 via the line concentration SW unit 51.

  In the node device on the receiving side (other system ring), the MAC frame transmitted via the escape path 3 is received by the line concentration SW unit 51 and transmitted to the RPR interface transmission unit 52x. The RPR interface transmission unit 52x determines that the MAC frame is a frame that has passed through the escape path 3 from another system ring, and extracts the RPR frame from the encapsulated frame. At this time, since the entire data frame is encapsulated, the RPR interface transmission unit 52x checks the ring ID field of the RPR header of the data frame. Then, the RPR interface transmission unit 52x selects a ring (outer or inner ring) corresponding to the ring ID of the RPR frame.

  The RPR interface transmission unit 52x sends the extracted RPR frame to the outer ring transmission unit 56x or the inner ring transmission unit 58x according to the selected ring. The outer ring transmission unit 56x transfers this RPR frame to a node device located on the downstream side of the outer ring. Further, the inner ring transmission unit 58x transfers the RPR frame to the node device located on the downstream side of the inner ring.

  Further, when relaying the data frame, each of the node devices 11A to 15A and 21B to 25B relays the data frame as it is to the own ring if the TTL value is equal to or less than a predetermined value.

  Specifically, when the outer ring drop determination unit 57 relays the data frame, if the TTL value is smaller than or equal to the number of node devices in the reachable range of the local ring in the relay direction, the data frame Is relayed to the node device located downstream of the outer ring via the outer ring transmitter 56x.

  Further, when relaying the data frame, the inner ring drop determination unit 61 determines that the data frame is transferred to the inner ring if the TTL value is smaller than or equal to the number of node devices in the reachable range of the local ring in the relay direction. It relays to a node device located downstream of the inner ring via the transmitter 58x.

  In the present embodiment, the case where each of the ring networks 1 and 2 has five node devices has been described. However, the ring networks 1 and 2 have at least two pairs of nodes so that they can be configured. It is only necessary to have two node devices.

  Moreover, although the case where the communication system 10 has two ring networks 1 and 2 has been described in the present embodiment, the communication system 10 may be configured to have three or more ring networks.

  As described above, according to the first embodiment, the topology information is exchanged between the rings A and B by using the escape path 3 that connects the ring A and the ring B, so that each of the node devices 11A to 15A, 21B to 25B can generate topology information obtained by integrating the topology information of the own ring and the topology information of the other ring. In the communication system 10, when multiple failures occur, the communication path can be quickly switched based on the integrated topology information. Therefore, even when a multiple failure occurs, the recovery time of the communication path can be shortened, and a new communication path can be secured easily and quickly.

  In addition, since the frame distribution unit 81 transfers only a predetermined MAC frame to the other ring according to the transfer priority, the MAC between the ring networks 1 and 2 without squeezing the bandwidth of the escape path 3. It is possible to transmit and receive frames.

  In addition, since a virtual topology map simulating two pair nodes connected to both ends of the escape path 3 with one virtual address is generated in each of the node devices 11A to 15A and 21B to 25B, multiple failures occur. Sometimes it becomes possible to grasp the entire topology of the rings A and B.

Embodiment 2. FIG.
Next, Embodiment 2 of the present invention will be described with reference to FIG. In the communication system 10 according to the first embodiment, assuming that there is one escape path 3 connecting the pair nodes and the use bandwidth of the escape path 3 is insufficient, each of the node devices 11A to 15A and 21B to 25B is high. A function (filtering unit 62) for passing only frames of priority to the escape path 3 was provided.

  However, a frame transferred from both the inner and outer rings to the escape path 3 may pass through the escape path 3 at the maximum for the RPR transmission band plus the overhead for encapsulation.

  For this reason, in this embodiment, in order to increase the bandwidth of the escape path 3, each pair node is connected by the escape path 3 of a plurality of lines. That is, in the communication system 10 of the first embodiment, the escape paths 3 between the node devices 11A to 15A and 21B to 25B are connected by one escape path 3, respectively. In the system 10, the escape paths 3 between the node devices 11A to 15A and 21B to 25B are connected by a plurality of escape paths 3, respectively. Further, each node device 11A to 15A, 21B to 25B according to the present embodiment, when transferring a frame to the escape path 3, assigns to which escape path 3 the frame is transferred (a frame distribution unit described later) 81).

  First, the configuration of the node devices 11A to 15A and 21B to 25B according to the second embodiment will be described. Since the node devices 11A to 15A and 21B to 25B have the same configuration, the configuration of the node device 11A will be described here.

  FIG. 8 is a diagram illustrating a configuration of the node device according to the second embodiment. Among the constituent elements in FIG. 8, constituent elements that achieve the same functions as those of the node device 11 </ b> A of the first embodiment shown in FIG. 2 are given the same numbers, and redundant descriptions are omitted. 11 A of node apparatuses which concern on Embodiment 2 have the frame distribution part 81 instead of the filtering part 62 compared with 11 A of node apparatuses which concern on Embodiment 1. FIG.

  The frame distribution unit 81 performs an encapsulation process when a frame is transferred to the escape path 3 performed by the RPR interface reception unit 52y in the node device 11A of the first embodiment. Furthermore, the frame distribution unit 81 according to the present embodiment executes link aggregation for the number of escape paths 3 on the frame transferred to the escape path 3.

  As described above, according to the second embodiment, each pair node is connected by a plurality of escape paths 3, and the frame distribution unit 81 executes link aggregation. Therefore, the communication band between the pair nodes can be expanded.

  As described above, the communication system and the ring node device according to the present invention are suitable for securing a new communication path when multiple failures occur.

It is a figure which shows the structure of the communication system which concerns on Embodiment 1 of this invention. 2 is a diagram illustrating a configuration of a node device according to Embodiment 1. FIG. It is a figure for demonstrating the real address set to each node apparatus. It is a figure for demonstrating the real address and virtual address which are set to each node apparatus. FIG. 5 is a diagram (1) for explaining the operation of each node device when multiple failures occur in the communication system. FIG. 6B is a diagram (2) for explaining the operation of each node device when multiple failures occur in the communication system. FIG. 7 is a diagram showing a virtual topology map after the multiple failure shown in FIGS. 5 and 6 occurs. FIG. 4 is a diagram illustrating a configuration of a node device according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Ring network 3 Escape path 10 Communication system 11A-15A, 21B-25B Node apparatus 31, 32 Terminal 51 Concentration SW part 52x RPR interface transmission part 52y RPR interface reception part 54 Protection part 55 Topology management part 56x Outer ring transmission part 56y outer ring receiving unit 57 outer ring drop determining unit 58x inner ring transmitting unit 58y inner ring receiving unit 61 inner ring drop determining unit 62 filtering unit 81 frame distributing unit

Claims (5)

At least two RPR networks having a plurality of ring node devices are provided, and a predetermined distance between devices between the ring node device of one RPR network and the ring node device of the other RPR network among the RPR networks is predetermined. In a communication system in which at least two sets of paths are connected,
The at least two sets of ring node devices are:
An RPR transmission / reception unit that transmits / receives an RPR frame to / from another ring node device different from the own device in the own RPR network, which is an RPR network to which the own device belongs,
An encapsulated transmission / reception unit that transmits / receives an encapsulated RPR frame to / from a ring node apparatus in another RPR network which is another RPR network different from the own RPR network;
First topology information related to the topology of the local RPR network and second topology information related to the topology of the other RPR network, as an RPR frame encapsulated between ring node devices in the other RPR network, And a topology management unit that manages the first topology information and the second topology information as in-system topology information;
With
The RPR transmission / reception unit, based on transmission destination information on the transmission destination of the RPR frame added in the RPR frame and topology information in the system, the RPR frame that is the transmission source in the own RPR network and the other Among the RPR frames whose source is the RPR network, the RPR frame to be sent to the own RPR network is determined and sent to the own RPR network,
The encapsulated transmission / reception unit, based on the transmission destination information on the transmission destination of the RPR frame added in the RPR frame and the topology information in the system, the RPR frame that is the transmission source in the own RPR network and the other A communication system comprising: determining an RPR frame to be transferred to the other RPR network out of RPR frames having a transmission source in the RPR network, and transferring the determined RPR frame to the other RPR network.   A filtering unit that causes the encapsulated transmission / reception unit to transfer an RPR frame having a priority higher than a predetermined value to the other RPR network based on information on transfer priority added to the RPR frame. The communication system according to claim 1. The predetermined path comprises a plurality of lines,
A distribution unit that distributes the encapsulated RPR frame to any one of the plurality of lines, wherein the encapsulated transmission / reception unit distributes the encapsulated RPR frame via the line distributed by the distribution unit; The communication system according to claim 1, wherein the communication is transferred to the other RPR network.   The first topology information and the second topology information are each based on a virtual address common to a pair of ring node devices connected by the predetermined path and a real address unique to each ring node device. The communication system according to claim 1, wherein the communication system is generated information. In a ring node device that is arranged in an RPR network and connects to another RPR network different from the RPR network by a predetermined path,
The own RPR network and the other RPR network in which the own device is arranged have at least the predetermined path between devices between the ring node device of the own RPR network and the ring node device of the other RPR network. It is arranged in a communication system with two sets connected,
An RPR transmission / reception unit that transmits / receives an RPR frame to / from another ring node device different from the own device in the own RPR network, which is an RPR network to which the own device belongs,
An encapsulated transmission / reception unit that transmits / receives an encapsulated RPR frame to / from a ring node apparatus in another RPR network which is another RPR network different from the own RPR network;
First topology information related to the topology of the local RPR network and second topology information related to the topology of the other RPR network, as an RPR frame encapsulated between ring node devices in the other RPR network, And a topology management unit that manages the first topology information and the second topology information as in-system topology information;
With
The RPR transmission / reception unit, based on transmission destination information on the transmission destination of the RPR frame added in the RPR frame and topology information in the system, the RPR frame that is the transmission source in the own RPR network and the other Among the RPR frames whose source is the RPR network, the RPR frame to be sent to the own RPR network is determined and sent to the own RPR network,
The encapsulated transmission / reception unit, based on the transmission destination information on the transmission destination of the RPR frame added in the RPR frame and the topology information in the system, the RPR frame that is the transmission source in the own RPR network and the other A ring node apparatus characterized by distinguishing an RPR frame to be transferred to the other RPR network from among RPR frames having a transmission source in the RPR network and transferring it to the other RPR network.

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