The present invention relates to a forced protection switching method and a forced protection switching clearing method in an Ethernet ring network.
Due to an increase in Internet users, the rate at which traffic in a communication network has increased is high. Also, Internet users have demanded various types of services, such as a high-speed data service, an electronic commerce (e-commerce) transaction service, a telemedicine service, a virtual education service, and a real-time multimedia service.
Therefore, a management scheme of coping with a communication network that is malfunctioning or performing poorly is required to provide users with continuous services and to maximize efficiency of the communication network.
Methods of improving the survivability of a management scheme are mostly classified into protection switching and restoration. Protection switching refers to a method of rapidly restoring the communication network by presetting both a path and a bandwidth between nodes when faults in the communication network occur. Restoration refers to a method of restoring interrupted services to their original states using both available paths and a volume of the communication network after the faults in the communication network occur.
In more detail, protection switching is a technique that has been applied mainly to optical transmission equipment, such as synchronous digital hierarchy (SDH)/synchronous optical network (SONET).
A conventional Ethernet protection switching technique is to block a specific port when operating normally and to unblock the specific port when a fault is detected. Thus, an operator is not able to easily block a link that is temporarily operating to repair a transmission line of a specific node in an Ethernet ring network.
The present invention provides a forced protection switching method and a forced protection switching clearing method in an Ethernet ring network to assist an operator to easily block and clear a link corresponding to a specific node so as to provide usefulness of the Ethernet ring network.
According to an aspect of the present invention, there is provided a forced protection switching method applied in a node of an Ethernet ring network, including: receiving a forced switching (FS) command; blocking a port of a corresponding; forwarding a FS message indicating that the Ethernet ring network is forcedly switched; and flushing a filtering database (FDB).
According to another aspect of the present invention, there is provided a forced protection switching method applied in a node of an Ethernet ring network whose port is linked to an ring protection link (RPL) of the Ethernet ring network and is blocked, including: receiving a FS message indicating that the Ethernet ring network is forcedly switched; clearing the blocked port linked to the RPL; and flushing an FDB.
According to another aspect of the present invention, there is provided a forced protection switching method applied in a node of an Ethernet ring network, including: receiving a FS message indicating that the Ethernet ring network is forcedly switched; and flushing an FDB.
According to another aspect of the present invention, there is provided a forced protection switching clearing method applied in a node of an Ethernet ring network that has been forcedly switched, including: receiving a FS clear command; driving a timer; forwarding a clear message indicating that the node has been cleared of being forcedly switched; receiving a return message indicating that a port linked to an RPL of the Ethernet ring network has been blocked, after the timer ends; clearing the blocked port of the node; and flushing an FDB.
According to another aspect of the present invention, there is provided a forced protection switching clearing method applied in a node of an Ethernet ring network whose port is linked to an RPL of the Ethernet ring network and is cleared of being blocked, including: receiving a clear message indicating that the Ethernet ring network had been cleared of being forcedly switched; driving a timer; when the timer ends, blocking the port that is linked to the RPL; forwarding a return message indicating that the port linked to the RPL has been blocked; and flushing an FDB.
According to another aspect of the present invention, there is provided a forced protection switching clearing method applied in a node of an Ethernet ring network, including: receiving a clear message indicating that the Ethernet ring network had been cleared of being forcedly switched; receiving a return message indicating that a port linked to a RPL of the Ethernet ring network has been blocked; and flushing an FDB.
According to the present invention, when an operator temporarily forcedly blocks a specific link for maintenance and repair, such as inspections of states of links, etc., in an Ethernet ring network, the operator can maintain services that are being provided so as to provide flexibility of the Ethernet ring network.
The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
For example, when an operator gives a forced switching (FS) command to node “D” in order to block a link between nodes “D” and “E,” the node “D” blocks a port corresponding to the link between nodes “D” and “E”, bidirectionally forwards a FS message periodically, and initializes, i.e., flushes, its filtering database (FDB). Here, the FDB refers to a table that includes port numbers and node identification information, i.e., a database indicating which port a received packet is forwarded to.
When a node that is not an RPL Owner receives a FS message, the node flushes its FDB. Without a higher priority demand, when the RPL Owner receives a FS message, the RPL Owner unblocks a port blocked when the RPL Owner blocked the RPL in an initial stage, and initializes its FDB.
The node “D” bidirectionally forwards the FS message periodically so that the other nodes recognize that a ring is forcedly switched. Even if the other nodes receive the FS message from the node “D,” they do not re-initialize (re-flush) their FDBs after the first time the FS message is received. Service traffic resumes when the FDBs of the nodes are updated through a media access control (MAC) learning process.
When the node “D” receives the clear command, the node “D” drives a guard timer before flushing its FDB to prevent malfunctioning due to an unavailable FS message or return message that may be received from a neighboring node. Next, the node “D” bidirectionally forwards a clear message indicating that the clear command to clear FS has been given.
When the RPL Owner receives the clear message, the RPL Owner drives a Wait to Block (WTB) timer, and when the WTB timer expires, the RPL Owner re-blocks the port that had been unblocked and bidirectionally forwards a return message. The RPL Owner also flushes its FDB and bidirectionally forwards the return message periodically to indicate that a node of a ring is idle.
When the node “D” receives the return message, the node “D” clears the blocked right port and flushes its FDB when the guard timer expires. Even if the other nodes receive the return message, they do not re-initialize their FDBs after the first time, and service traffic resumes according to a MAC learning process.
Referring to
In operation S300, the node “D” receives the FS command. In operation S310, the node “D” blocks a Ring-Automatic Protection Switching (R-APS) channel and traffic from the specific link that is to be blocked. In operation S320, the node “D” bidirectionally forwards a FS message that indicates FS. In this state, the node “D” continues forwarding the FS message. In operation S330, the node “D” flushes its FDB.
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In operation S630, the node “D” determines whether the guard timer has expires. If the node “D” determines in operation S630 that the guard timer has expires, in operation S640, the node “D” determines whether the node “D” has received a return message that indicates that an RPL has been blocked from the RPL Owner. If the node “D” determines in operation S640 that the node “D” has received the return message, the node “D” clears a port that had been blocked by FS, in operation S650. In operation S660, the node “D” flushes its FDB.
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The invention can also be embodied as computer readable codes on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data that can be thereafter read by a computer system. Examples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.
While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The preferred embodiments should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.
Number | Date | Country | Kind |
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10-2008-0130444 | Dec 2008 | KR | national |
10-2009-0031258 | Apr 2009 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR09/02088 | 4/22/2009 | WO | 00 | 10/21/2010 |