Data communication device and the method thereof

Abstract

When the provider edge PE1 detects the occurrence of a failure at the access line AL1, it sends the label withdraw message to the virtual circuit VC1, and when the provider edge PE2 receives the label withdraw message sent via the virtual circuit VC1, the access line AL2 is put to a link down state, and when the customer edge CE2 detects the link down state of the access line AL2, it switches from the normal path to the redundant path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory drawing showing a network for which the data communication system is applied as the first embodiment of this invention. FIG. 2 is a block diagram showing the constitution of the switch that can be used as the customer edge and the provider edge. FIG. 3 is an explanatory drawing showing the operation contents during access line failure occurrence for the first embodiment of this invention. FIG. 4 is a flow chart showing the process operation of the provider edge PE2 for the first embodiment of the invention. FIG. 5 is an explanatory drawing showing one example of the configuration information to be set in the provider edge PE2. FIG. 6 is an explanatory drawing showing the operation contents during access line failure occurrence for the second embodiment of the invention. FIG. 7 is a flow chart showing the process operation of the provider edge PE2 for the second embodiment of the invention. FIG. 8 is an explanatory drawing showing the operation contents during access line failure occurrence for a variation example. FIG. 9 is a flow chart showing the process operation of the provider edge PE2 for a variation example. FIG. 10 is an explanatory drawing showing an example of a network using a typical VPWS. FIG. 11 is an explanatory drawing showing an example of a network for which a redundant structure is built for a VPWS network.

Claims

1. A data communication system for performing data communication between a second and third network via a first network, the data communication system comprising: a first edge of the first network;a second edge of the first network connected to the first edge via a first virtual circuit of the first network;a third edge of the first network;a fourth edge of the first network connected to the third edge via a second virtual circuit of the first network;a fifth edge of the second network connected to the first edge via a first access-line and connected to the third edge via a third access line; anda sixth edge of the third network connected to the second edge via a second access line and connected to the fourth edge via a fourth access line;wherein a path that passes through the fifth edge, the first edge, the second edge, and the sixth edge is constituted as a normal path, and a path that passes through the fifth edge, the third edge, the fourth edge, and the sixth edge is constituted as a redundant path,the first edge sends a virtual circuit withdraw message to the first virtual circuit when the first edge detects an occurrence of failure at the first access line,the second edge puts the second access line into a link down state when the second edge receives the virtual circuit withdraw message sent via the first virtual circuit, andthe sixth edge switches from the normal path to the redundant path when the sixth edge detects the link down of the second access line.

2. A data communication system for performing data communication between a second and third network via a first network, the data communication system comprising: a first edge of the first network;a second edge of the first network connected to the first edge via a first virtual circuit of the first network;a third edge of the first network;a fourth edge of the first network connected to the third edge via a second virtual circuit of the first network;a fifth edge of the second network connected to the first edge via a first access line and connected to the third edge via a third access line; anda sixth edge of the third network connected to the second edge via a second access line and connected to the fourth edge via a fourth access line;wherein a path that passes through the fifth edge, the first edge, the second edge, and the sixth edge is constituted as a normal path, and a path that passes through the fifth edge, the third edge, the fourth edge, and the sixth edge is constituted as a redundant path,at least the BFD (Bidirectional Forwarding Detection), which is the reachability verification protocol, is operated between the first edge and the fifth edge and is operated between the second edge and the sixth edge,the first edge sends a virtual circuit withdraw message to the first virtual circuit, when a failure occurs at the first access line and the first edge detects the failure occurrence by the BFD,the second edge stops sending of the BFD echo/control packet to the second access line when the second edge receives the virtual circuit withdraw message sent via the first virtual circuit, andthe sixth edge switches from the normal path to the redundant path when the sixth edge detects timeout of the BFD echo/control packet for the second access line.

3. The data communication in accordance with claim 2, wherein the second edge sends a notification of a down state by the BFD control packet to the second access line rather than stopping the sending of the BFD echo/control packet when the second edge receives the virtual circuit withdraw message sent via the first virtual circuit, andthe sixth edge switches from the normal path to the redundant path when the sixth edge receives the notification of the down state by the BFD control packet from the second access line rather than detecting the timeout of the BFD echo/control packet.

4. The data communication system in accordance with claim 1, wherein the first network is a VPWS (Virtual Private Wire Service) network.

5. The data communication system in accordance with claim 4, wherein the virtual circuit withdraw message is a label withdraw message stipulated by the LDP (Label Distribution Protocol) which is the label distribution protocol.

6. A network device that is used as an edge of a first network, the network device being connected to another edge of the first network via a virtual circuit and being connected to an edge of the second network via an access line, and the network device putting the access line into a link down state when a virtual circuit withdraw message sent from the another edge via the virtual circuit is received.

7. A network device that is used as an edge of a first network, the network device being connected to an other edge of the first network via a virtual circuit and being connected to an edge of the second network via an access line, and in the case where the BFD (Bidirectional Forwarding Detection), which is the reachability verification protocol, is operated between the network device and the other edge, the network device stopping sending of the BFD echo/control packet to the access line when a virtual circuit withdraw message sent from the other edge via the virtual circuit is received.

8. The network device in accordance with claim 7, wherein the network device sends a notification of a down state by the BFD control packet to the second access line, instead of stopping the sending of the BFD echo/control packet, when a virtual circuit withdraw message sent from the another edge via the virtual circuit is received.

9. A data communication method for performing data communication between a second and third network via a first network, the data communication method comprising the steps of: (a) providing a first edge of the first network, a second edge of the first network connected to the first edge via a first virtual circuit of the first network,a third edge of the first network,a fourth edge of the first network connected to the third edge via a second virtual circuit of the first network,a fifth edge of the second network connected to the first edge via a first access line and connected to the third edge via a third access line,a sixth edge of the third network connected to the second edge via a second access line and connected to the fourth edge via a fourth access line,a path which passes through the fifth edge, the first edge, the second edge, and the sixth edge and is constituted as a normal path, anda path which passes through the fifth edge, the third edge, the fourth edge, and the sixth edge and is constituted as a redundant path;(b) causing the first edge to send a virtual circuit withdraw message to the first virtual circuit when the first edge detects an occurrence of failure at the first access line;(c) causing the second edge to put the second access line into a link down state when the second edge receives the virtual circuit withdraw message sent via the first virtual circuit; and(d) causing the sixth edge to switch from the normal path to the redundant path when the sixth edge detects the link down of the second access line.

10. A data communication method for performing data communication between a second and third network via a first network, the data communication method comprising the steps of: (a) providing a first edge of the first network, a second edge of the first network connected to the first edge via a first virtual circuit of the first network,a third edge of the first network,a fourth edge of the first network connected to the third edge via a second virtual circuit of the first network,a fifth edge of the second network connected to the first edge via a first access line and connected to the third edge via a third access line,a sixth edge of the third network connected to the second edge via a second access line and connected to the fourth edge via a fourth access line,a path which passes through the fifth edge, the first edge, the second edge, and the sixth edge and is constituted as a normal path, anda path which passes through the fifth edge, the third edge, the fourth edge, and the sixth edge and is constituted as a redundant path;(b) operating at least the BFD, which is the reachability verification protocol, between the first edge and the fifth edge and between the second edge and the sixth edge;(c) causing the first edge to send a virtual circuit withdraw message to the first virtual circuit, when a failure occurs at the first access line and the first edge detects the failure occurrence by the BFD;(d) causing the second edge to stop sending of the BFD echo/control packet to the second access line when the second edge receives the virtual circuit withdraw message sent via the first access line; and(e) causing the sixth edge to switch from the normal path to the redundant path when the sixth edge detects timeout of the BFD echo/control packet for the second access line.

11. The data communication method in accordance with claim 10, the data communication method, instead of the steps (d) and (e), further comprising the steps of: (h) causing the second edge to send a notification of a down state by the BFD control packet to the second access line when the second edge receives the virtual circuit withdraw message sent via the first access line; and(i) causing the sixth edge to switch from the normal path to the redundant path when the sixth edge receives the notification of the down state by the BFD control packet.