JP2000201157A - Method for switching transfer route in atm connectionless network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a transfer route switching method in an ATM connectionless network which can quickly switch an end-to-end transfer part to a normal link to aid it. SOLUTION: Plural edge nodes 10 to 17 are arranged on boundary points between a backbone network 1 and respective access networks 2 to 5, the backbone network sides of respective edge nodes 10 to 17 are connected to junction noes 6 to 9 and their access network sides are connected to respective access switches 18 to 21 to form duplex structure between the access switches 18 to 21 and the junction nodes 6 to 9 through the edge nodes 10 to 17 and attain double belonging connection between the edge nodes 10 to 17 and the junction nodes 6 to 9. When a fault occurs in a certain junction node, each of the edge nodes 10 to 17 changes the entry of an intra-network packet transfer route solving information table for transferring an intra-network packet to the network 1 by autonomous processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM connectionless network in which an edge node is arranged at a boundary point between a backbone network and an access network, and the edge node transfers a monitoring packet in the direction of the backbone network. If it is determined that the link connected to the edge node and the relay node accommodated in the backbone network are abnormal, an entry in the intra-network packet transfer route resolution information table for transferring the intra-network packet to the backbone network Is switched by an autonomous process in an ATM connectionless network.

[0002]

2. Description of the Related Art With regard to a data communication network platform represented by the Internet, as a carrier, IP
(Internet Protocol) Native and ATM (Asynchronous Transfer)
Mode) There are two native approaches. However, they each have advantages and disadvantages, as described below. First, the characteristics of the former IP native will be described.

(1). Features of IP native (IPv4
When a network is configured on the basis), the address system is restricted by the network design in IPv4. That is, (a). Advanced technology is required to realize security; (b). VLAN (Virtual Local Ar)
ea Network) is complicated, (c). A large processing load of a routing protocol processed by each node; (d). The network scales, (e). High affinity for external connections, etc.

(2). ATM native features (ATM
(When a network is configured on the base), (a). SVC (Switched Virtual)
Connection) has a large initial delay when setting a shortcut. (B). A large processing load of a routing protocol processed by each node; (c). Because network management is complicated, (a). QoS (Quality Of Service)
e) routing is applicable; (b). VLAN construction is possible, and so on.

[0005]

As described above, since the IP native and the ATM native each have advantages and disadvantages, an intermediate platform for solving each disadvantage is required. Also, in the ATM connectionless network, when a failure occurs in a transfer path for transmitting a packet in the network, the output transfer path is switched, and in order to promptly restore the transfer path, an early state of the packet transfer path resolution information table in the network is required. Update is required. However, in the conventional configuration, since the detected failure information is once notified to the management system and is updated for the first time under the control of the management system, it takes time to update the table, and as a result, it takes time to recover from the failure. There is a problem that it takes time.

Japanese Patent Application Laid-Open No. 09-46351 (connectionless system) describes that a virtual connection having the number of hooks is generated between a start point exchange and an end point exchange performing connectionless communication, and one of them is created. The starting point exchange that performs connectionless communication as an operation connection uses the bandwidth usage of each link used by the operation connection for each virtual connection, the bandwidth usage of each link used in the entire connectionless communication, and the connectionless of each link. It is disclosed that information such as the remaining bandwidth usage of communication is periodically collected and the operation connection is switched to another virtual connection. However, even in the case of this publication, the above-mentioned problem has not been solved yet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. When an abnormality occurs in a link and a relay node, end-to-end (end-to-end) is performed by an apparatus autonomous process. It is an object of the present invention to provide a transfer path switching method in an ATM connectionless network that can perform switching and rescue of a transfer path to a normal link in a short time.

[0008]

In order to achieve the above object, a transfer path switching method in an ATM connectionless network according to the present invention comprises: an access network relayed by an access switch; and a backbone net relayed by a relay node. And an edge node having an ATM interface to the access network and the backbone network, respectively, is arranged at the boundary of the above, transfers a monitoring packet from the edge node toward the backbone network, and connects the link connected to the edge node and the link. The presence or absence of a failure of the relay node is determined by the edge node,
When the edge node determines that a failure has occurred, the entry in the intra-network packet transfer route solution information table for transferring the intra-network packet to the backbone network is changed to autonomous processing.

According to the present invention, the presence or absence of a failure in the link connected to the edge node and the relay node accommodated in the backbone network by transferring the monitoring packet in the direction of the backbone network by the edge node. To monitor. As a result of this monitoring, if it is determined that the link and the relay node are abnormal, the entry in the intra-network packet transfer route solution information table for transferring the intra-network packet to the backbone network is changed by autonomous processing.

Therefore, according to the present invention, when an abnormality occurs in a link and a relay node, switching to a normal link can be relieved in a short time by device autonomous processing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transfer path switching method in an ATM connectionless network according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ATM connectionless network applied to a first embodiment of a transfer path switching method in an ATM connectionless network according to the present invention. The platform which is the background of the present invention is based on an ATM connectionless network, which is one of them, and assigns addresses closed in the network (addresses in the network) to each node, encapsulates user packets, and closes the network. A packet (intra-network packet) is generated and forwarded in the network.

A network is constituted by the backbone network 1 and a plurality of access networks 2 to 5 in FIG. The plurality of access networks 2 to 5
Are a plurality of user terminals 22 to 25, 26 to 29, respectively.
It is an undercarriage network for accommodating 30-33 and 34-37. The backbone network 1 is a network for interconnecting a plurality of access networks 2 to 5.

At the boundary between the backbone network 1 and the access networks 2 to 5, edge nodes 10 to 1
7 are interconnected between the access networks 2 to 5 and the backbone network 1. The edge nodes 10 to 17 are the edge nodes 10 and 1
Two units are arranged, such as 1, 12 and 13, 14 and 15, and 16 and 17.

Relay nodes 6 and 8 are connected to the backbone network 1 side of the edge nodes 10 and 11, and 12 and 13, respectively. Edge nodes 14 and 15, 1
Relay nodes 7 and 8 are connected to the backbone network 1 sides 6 and 17, respectively. The relay nodes 6 and 8 are mutually connected to the relay nodes 7 and 8, respectively.

The access nodes 2 of the edge nodes 10 and 11 are connected to an access switch 18.
The access networks 3 of the edge nodes 12 and 13 are connected to an access switch 19. The access networks 4 of the edge nodes 14 and 15 are connected to an access switch 20. The access networks 5 of the edge nodes 16 and 17 are connected to an access switch 21.

The access networks 2 to 5 are relayed by access switches 18 to 21, respectively. Further, the backbone network 1 includes the relay nodes 6 to 9
Is relayed by ATM connectionless network 5 accommodating these relay nodes 6-9, edge nodes 10-17, and access switches 18-21.
FIG. 2 shows a part of the portion related to 0 extracted. The portion of the ATM connectionless network 50 will be described in further detail with reference to FIG.

In FIG. 2, edge nodes 55 and 5
6, 57 and 58 (corresponding to the parts of the edge nodes 10 to 14 in FIG. 1) are access networks 66 and 67 (corresponding to the parts of the access networks 2 and 3 in FIG. 1) and the backbone network 65 (the backbone network in FIG. 1). 1), each of which has an ATM interface, and is arranged at the boundary between the backbone network 65 and the access networks 66 and 67. The edge nodes 55 to 58 resolve the addresses in the destination network from the IP destination addresses of the user packets received from the access networks 66 and 67.

Further, the edge nodes 55 to 58 resolve the output transfer route (port, VPI, VCI) to the backbone network 65 from the address in the destination network, encapsulate the IP packet into a packet in the network, and The address is transferred to the backbone network 65 with the internal address added. Further, the edge nodes 55 to 58 remove the destination network address of the intra-network packet received from the backbone network 65 and output transfer routes (ports / ports) from the destination IP address to the access network 65.
VPI / VCI) and access network 6
Transfer to 6,67 side.

The edge nodes 55, 56, 57, 58
Each of the relay nodes 51 and 52 is double-attached (securing a plurality of transfer routes to the backbone network 65 for the purpose of distributing traffic and securing a detour in the event of a failure). The relay nodes 51 and 52
The backbone network 65 has an ATM interface and is arranged in the backbone network. The relay nodes 51 and 52 resolve the output transfer path (port, VPI, VCI) from the destination network address to the backbone network 65 for the network packet received from the backbone network 65, and transfer the received network packet as it is. I do.

The relay nodes 51 and 52 face the access switches 53 and 54, respectively, and perform termination processing for network duplication. Access switches 53, 54
Has an ATM interface on the access networks 66 and 67 and is arranged in the access networks 66 and 67. The access switches 53 and 54 provide input ports VPI and VCI for the received user packets, respectively.
Then, the output ports VPI and VCI corresponding to 1: 1 are resolved and the transfer processing is performed.

The user terminals 59 to 61 and 62 to 64 have ATM interfaces, respectively, and are arranged at the end points of the access networks 66 and 67. User terminal 5
9-61 and 62-64 are PC (Personal C)
a terminal such as an input / output (WS) / WS (Workstation), and a router / switch that further accommodates a network under the terminal.

FIG. 7 is an explanatory diagram showing an in-network packet transfer route solution information table 101 managed by the edge nodes 55 and 56 and 57 and 58. The intra-network packet transfer route solution information table 101 includes a destination network address 102 and an output transfer route number 103. This table is used to resolve the output transfer path number 103 from the destination network address 102 of the packet when transferring the intra-network packet toward the backbone network 65 at the edge nodes 55, 56, 57, 58. (Not shown) is fixedly set in advance. This intra-network packet transfer route resolution information table 10
1 in an ATM connectionless network,
Information necessary for determining a transfer route for transferring a packet in the network toward the backbone network 65 is stored.

Next, the operation of the first embodiment according to the transfer path switching method in the ATM connectionless network of the present invention will be described based on the ATM connectionless network shown in FIG. (1). Normal Transfer FIG. 3 is an explanatory diagram showing a transfer path at the time of normal transfer of a packet in the network. In FIG. 3, it is shown that the intra-network packet is transferred on the transfer path 71 indicated by a thick line. The in-network packet from the user terminal 60 to the user terminal 63 is first transferred from the user terminal 60 to the access switch 53. In the access switch 53, the transfer route from the edge node 55 to the relay node 51 is resolved by the intra-network packet transfer route resolution information table 101,
Will be transferred. Thereafter, the access switch 54 is transferred to the transfer path 71 via the relay node 51 and the edge node 57.
To the user terminal 63.

(2). Backbone Network Monitoring FIG. 4 is an explanatory diagram of the status of a transfer route monitoring packet when monitoring the backbone network. As shown in FIG. 4, a double belonging connection is established between the edge node 55 and the relay nodes 51 and 52. This is set so that the traffic load is appropriately distributed to the relay nodes 51 and 52 in the initial state by the setting of the intra-network packet transfer route solution information table 101.

However, when a failure or the like occurs in any of the relay nodes, it is necessary to perform another process of switching the output transfer path in order to secure a detour path in the event of a failure, which is another object of the double belonging connection. is there. Therefore, the edge node 55 periodically transmits the transfer path monitoring packet 72 toward the relay node 51 and the transfer path monitoring packet 73 toward the relay node 52 in order to monitor the state of the output transfer path. Transfer route monitoring packet 7
For the addresses in the destination network of 2, 73, their own addresses are set. Therefore, since the data is forwarded to the relay nodes 51 and 52, it is determined that the packet is normal by receiving the transfer route monitoring packets 72 and 73.

In this state, as shown in FIG.
In the case where a node failure has occurred, since the relay node 51 cannot receive the transfer route monitoring packet 72, the edge node 55 retransmits the transfer route monitoring packet 72 several times. As a result, the transfer route monitoring packet 72
Is received by the relay node 51, the edge node 5
5 judges that a failure has occurred in the relay node 51.

(3). Switching of Intra-Network Packet Transfer Route Resolution Information Table 101 When a failure occurs in the relay node 51, the edge node 5
In the intra-network packet transfer route solution information table 101 managed by the network node 5, the output transfer route number 103 is
All entries pointing in one direction are stored in the relay node 52.
It is updated by autonomous processing so as to indicate the direction.

(4). Transfer Path after Switching Since the same switching processing is also performed by the edge node 57, as a result, the data is transferred on the transfer path 76 as shown in FIG.

[0029]

As described above, according to the present invention, when a failure occurs, the contents of the intra-network packet transfer route solution information table are updated by autonomous processing of the device that has detected the failure. Once notification of the conventional failure occurrence information to the management system, by the control from the management system,
As compared with the process of updating the in-network packet transfer route solution information table, there is an effect that the end-to-end transfer path can be relieved in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an ATM connectionless network applied to a first embodiment of a transfer path switching method in an ATM connectionless network according to the present invention.

FIG. 2 is a block diagram showing a part of the ATM connectionless network of FIG. 1 in more detail.

FIG. 3 is an explanatory diagram of a transfer path at the time of normal transfer of an intra-network packet in the first embodiment of the transfer path switching method in the ATM connectionless network of the present invention.

FIG. 4 is an explanatory diagram of a transfer route of a packet in the network at the time of monitoring the backbone network in the first embodiment of the transfer route switching method in the ATM connectionless network of the present invention.

FIG. 5 is an explanatory diagram of a transfer path of a packet in the network when a relay node has failed in the first embodiment of the transfer path switching method in the ATM connectionless network of the present invention.

FIG. 6 is an explanatory diagram showing a state in which a transfer path is switched when a relay node fails in the first embodiment of the transfer path switching method in the ATM connectionless network of the present invention.

FIG. 7 is an explanatory diagram showing an intra-network packet transfer route solution information table managed by an edge node in the ATM connectionless network shown in FIG. 2;

[Explanation of symbols]

1,65 ... backbone network, 2-5,6
6,67 access network, 6-9,51,5
2 ... relay node, 10 to 17, 55 to 58 ... edge node, 18 to 21, 53, 54 ... access switch, 22 to 37, 59 to 64 ... user terminal, 50 ...
ATM connectionless network, 71, 76 ...
Transfer bus, 72-75 transfer path monitoring packet, 10
1... Intra-network packet transfer route solution information 102... Destination network address 103... Output transfer route program.

Claims (14)

[Claims] An edge node having an ATM interface to said access network and said backbone network is arranged at a boundary between an access network relayed by an access switch and a backbone net relayed by a relay node, respectively. The edge node determines whether or not a failure has occurred in the link connected to the edge node and the relay node by transferring a monitoring packet in the direction of the backbone network. Changing the entry in the intra-network packet transfer route solution information table for transferring the intra-network packet to the network to autonomous processing, wherein the transfer in the ATM connectionless network is performed. Route switching method. 2. The ATM connectionless network according to claim 1, wherein said edge node connects said backbone network side to said relay node, and connects said access network side to said access switch. Transfer path switching method. 3. The edge node resolves an IP address in a destination network from an IP destination address of a user packet received from the access network, and resolves an output transfer path from the destination network address to the backbone network to obtain an IP packet. 2. The transfer path switching method in an ATM connectionless network according to claim 1, wherein the packet is encapsulated in a network packet, an address in a destination network is added, and the packet is transferred to a backbone network. 4. The edge node according to claim 1, further comprising: removing an intra-network address of the intra-network packet received from the backbone network, resolving an output transfer route from the destination IP address to the access network, and transferring the packet to the access network side. The method according to claim 1, wherein the transfer path is switched in an ATM connectionless network. 5. The transfer path switching method in an ATM connectionless network according to claim 1, wherein said edge nodes are arranged two by two and are double-affiliated connected to said relay node. 6. The transfer path switching method in an ATM connectionless network according to claim 5, wherein the access switch and the relay node have a network duplex configuration with the two edge nodes interposed therebetween. 7. The transfer path switching method in an ATM connectionless network according to claim 1, wherein said relay node has an ATM interface in said backbone network and is arranged in said backbone network. 8. The relay node resolves an output transfer route from a destination network address to the backbone network for a network packet received from the backbone network, and transfers the received network packet as it is. The transfer path switching method in an ATM connectionless network according to claim 1, wherein 9. The access switch according to claim 1, wherein the access switch has an ATM interface in the access network and is located in the access network.
The transfer path switching method in the ATM connectionless network described in the above. 10. The ATM according to claim 1, wherein said access switch resolves an output port corresponding to 1: 1 from an input port of a received user packet.
A transfer path switching method in a connectionless network. 11. The intra-network packet transfer route solution information table is composed of a destination network address and an output transfer route. When the edge node transfers the packet toward the backbone network, the output transfer is performed from the destination network address of the packet. 2. The transfer path switching method in an ATM connectionless network according to claim 1, wherein the method is used to resolve a path number. 12. The ATM connection according to claim 1, wherein said intra-network packet transfer route solution information table stores information for determining a transfer route for transferring data in a direction of a backbone network in an ATM connectionless network. Transfer route switching method in wireless networks. 13. The edge node periodically transmits a transfer path monitoring packet to the relay node, and determines whether the relay node is normal based on whether the transfer path monitoring packet is received by the relay node or not. The transfer path switching method in an ATM connectionless network according to claim 1, wherein the determination is made. 14. The edge node, when detecting the occurrence of a failure in the relay node, stores all entries in the intra-network packet transfer path resolution information table in which the output transfer path number is in the direction of the failed relay node. 2. The transfer path switching method in an ATM connectionless network according to claim 1, wherein updating is performed by an autonomous process so as to indicate a direction.