JP2006352544A - Layer 2 network redundancy system - Google Patents

Abstract

Provided is a redundant system for a layer 2 network in which a non-redundant section of a layer 2 network is shortened and a path can be switched from an active system to a standby system in a short time when a network failure occurs.
Subscriber home bases A and B are connected to each other via a layer 2 network made redundant by multiplexing each switch. The layer 2 network converts CSWs 33 and 34 duplicated by the active system (m) and the standby system (s), ESWs 32 and 35 arranged at the boundary of the network, and converts layer 2 frames into optical signals. It is composed of net side M / Cs 31 and 36. Each of the customer bases A and B is selectively connected to the subscriber terminal with either the subscriber M / C 10 or 20 that is duplicated and either the active system or the standby system of each subscriber M / C. Port switching devices 11 and 21 are arranged.
[Selection] Figure 1

Description

  The present invention relates to a layer 2 network redundancy system, and more particularly to a layer 2 network redundancy system capable of switching a path from an active system to a standby system in a short time when a network failure occurs.

A redundant system in an Ethernet (registered trademark) -based layer 2 network is disclosed in Patent Document 1. FIG. 5 is a block diagram showing the configuration of a conventional layer 2 network redundancy system. The subscriber bases A and B of each subscriber communicating with each other are partially redundant by multiplexing core switches (CSW). Connected via a layered network. This layer 2 network includes a plurality of CSWs 33 and 34 that are duplexed by the active system (m) and the standby system (s), and edge switches (ESW) 32 and 35 that are arranged at the boundary of the network. And a pair of network media converters (M / C) 31 and 36 for converting the layer 2 frame into an optical signal. Each of the in-home bases A and B includes a subscriber side M / C 10 and 20 disposed opposite to the network side M / C 31 and 36, and a subscriber terminal A and a subscriber terminal A and B connected to the subscriber side M / C 10 and 20, respectively. B is arranged.
Japanese Patent Laid-Open No. 2004-304230

  In the above prior art configuration, only the CSWs 33 and 34 are multiplexed, and the ESWs 32 and 35 and the M / Cs 31 and 36 are not multiplexed. Therefore, there has been a technical problem that when a defect occurs in ESW or M / C, the replacement work is forced to be performed, so that the provided line is disconnected only for the time required for the replacement work.

  As for the ESWs 32 and 35 and the M / Cs 31 and 36 on the network side, if they are arranged in the station where the network manager resides, just by multiplexing them as in the case of the CSWs 33 and 34, A relatively quick recovery can be expected by placing the network administrator on the work of switching to the standby system.

  However, for the subscriber side M / Cs 10 and 20 in which the ESWs 32 and 35 and the M / Cs 31 and 36 are arranged in an unmanned station or the work by the network administrator cannot be expected, switching by the network administrator is performed manually. As a premise, simple recovery cannot be expected simply by multiplexing.

  The object of the present invention is to solve the above-described problems of the prior art, shorten the non-redundant section of the layer 2 network, and perform redundancy in the layer 2 network that can quickly switch the path from the active system to the standby system when a network failure occurs. Is to provide a system.

In order to achieve the above object, the present invention includes a layer 2 network and its edge switch, a subscriber-side and net-side media converter, and redundancy of the layer 2 network in which each switch and media converter are multiplexed. In the computerized system, the following measures are taken.
(1) Port switching means for switching the connection destination of the fixed port to which the subscriber terminal is connected to any of a plurality of selected ports to which the active and standby subscriber media converters are connected, and the active link Means for transmitting the down to the port switching means, the port switching means in response to the detection of the link down, the means for detecting the down of the adjacent link connected to the selected port of the active system, And a means for switching the connection destination of the fixed port to a backup selection port, and a means for resuming communication between the subscriber terminal and the subscriber-side media converter after the completion of the switching.
(2) The net-side media converter includes means for detecting a link down with the edge switch and notifying the subscriber-side media converter of the link down,

The subscriber-side media converter includes means for bringing down an adjacent link with the switching means in response to the link down notification.
(3) The subscriber-side media converter includes means for detecting down of the adjacent link with the network-side media converter and bringing down the adjacent link with the switching means.
(4) The port switching means is characterized in that each of the selected ports includes a pulse transformer, and includes simultaneous on prevention means for preventing a plurality of pulse transformers from being turned on simultaneously.

According to the present invention, the following effects are achieved.
(1) According to the invention of claim 1, when a failure occurs on the working path, the multiplexed edge switch and media converter are automatically switched from the working system to the standby system. Route switching at the time of occurrence can be performed in a short time.
(2) According to the second and third aspects of the present invention, it is possible to easily transmit a failure occurrence on the working path to the port switching means.
(3) According to the invention of claim 4, since it is possible to prevent a plurality of selected ports from being simultaneously turned on in the port switching means, it is possible to prevent the occurrence of a loop.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a redundant system for a layer 2 network according to the present invention. The same reference numerals as those described above represent the same or equivalent parts.

  The subscriber's home base A and home base B are connected via a layer 2 network made redundant by multiplexing each switch. The layer 2 network of the present embodiment includes a plurality of CSWs 33 and 34 that are duplexed by the active system (m) and the standby system (s), and a pair of duplexed networks that are arranged at the boundary of the network. ESWs 32 and 35, and a pair of redundant network side M / Cs 31 and 36 for converting layer 2 frames into optical signals. The ESWs 32 and 35 have a LAG (Link Aggregation) function, and the frames received from the network side M / Cs 31 and 36 are appropriately load-distributed and transmitted to the ports of the duplexed CSWs 33 and 34. To do.

  Each of the in-house bases A and B is arranged opposite to the network side M / Cs 31 and 36, and the duplicated subscriber side M / Cs 10 and 20 and the duplicated subscriber side M / C Port switching devices 11 and 21 that selectively connect either the active system (m) or the standby system (s) to the subscriber terminals A and B are arranged.

  The CSWs 33 and 34, ESWs 32 and 35, and M / Cs 10, 20, 31, and 36 have a MAC address learning function, and an FDB (Filtering Data Base) that associates a source MAC address of a received frame with an incoming port of the frame. After that, if the destination MAC address of the received frame is already registered in the FDB, the frame is transferred to the corresponding port. If the destination MAC address of the received frame is not registered in the FDB, it is transferred to all ports.

  The registered MAC address is held until the aging timeout. When a received frame whose source MAC address is already registered in the FDB is received from a port different from the registered content, the MAC address is considered to have moved, and the FDB entry is reregistered (overwriting for the destination port). An FDB entry is deleted when a frame is not received from the same source MAC address within a predetermined aging time. Also, when a port goes down, the entry related to the corresponding port on the FDB is deleted.

  FIG. 2 is a functional block diagram showing the configuration of the main part of the port switching device 11 (21) arranged at each home base A (B). The subscriber terminal A (B) is connected to the fixed port P0. Then, the duplicated subscriber side M / C 10 (20) is connected to the selected ports P1 and P2, respectively.

  The port changeover switch 41 is connected to the selection ports P1 and P2 via the pulse transformers 46 and 47, and switches the selection port from the working system to the standby system in response to an instruction from the port switching unit 43. The link down detection unit 42 detects that the working link is down and notifies the port switching unit 43 of it. The port switching unit 43 instructs the port switching switch 41 to switch ports in response to the link down notification. The simultaneous on prevention unit 44 controls the pulse transformers 46 and 47 so that the selected ports P1 and P2 are not turned on at the same time. In response to the completion of the port switching, the communication control unit 45 resumes communication between the fixed port P0 and the new active selection port.

  Next, the operation of this embodiment will be described with reference to the timing chart of FIG. Here, the description starts from a state in which the selected port P2 is selected as the active system by the port switching device 11 of the home base A, and communication is performed between the home bases A and B via the selected port P2. .

  On the layer 2 network, CSW and ESW periodically transmit / receive a link test pulse to / from the opposite node, and if the link test pulse can be received, the adjacent link to the opposite node is determined to be good.

  Here, as shown in FIG. 4, when a problem occurs in the active ESW 32 (m) of the layer 2 network, the link test pulse is detected at the adjacent network side M / C 31 (m) and CSW 33 (m). It is determined that the adjacent link is down. The network side M / C 31 (m) transmits a message to the effect that link down has been detected to the adjacent link L1 on the subscriber side. When the subscriber side M / C 10 (m) receives the link down message, the subscriber side M / C 10 (m) brings down the adjacent link L2 on the port switching device 12 side at time t1 in FIG.

  In the port switching device 11 at the home base A, the link down detection unit 42 periodically monitors the state of the adjacent link L2 connected to the selected port P2, and when link down is detected at time t2. Thereafter, monitoring is continued for a predetermined time Δt so that a mere momentary interruption is not erroneously determined as link-down. If the link-down state continues for the predetermined time Δt or more, it is determined that the link is down at time t3, and the port switching unit 43 is notified of the link-down. In response to the link down notification, the port switching unit 43 instructs the port switching switch 41 and the simultaneous on prevention unit 44 to perform port switching.

  In response to the port switching instruction, the port selector switch 41 switches the selected port from the active system (P2) to the standby system (P1) at time t4. The simultaneous on prevention unit 44 operates the pulse transformers 46 and 47 exclusively so that the selected ports P1 and P2 are not simultaneously turned on. When the communication control unit 45 confirms that the selected port has been switched from the active system to the standby system by the port switch 41, the communication control unit 45 resumes communication at time t5.

  In the layer 2 network, MAC address relearning is performed periodically (for example, 300 seconds) for each CSW, ESW, and M / C, and the FDB is incomplete because of the aging timeout during the link down described above Even so, from the time t5 to the time t6 when the predetermined MAC relearning period elapses, the MAC address relearning is completed, and normal data communication can be resumed. The MAC relearning period depends on application settings in each subscriber terminal.

  In the above-described embodiment, the path switching procedure has been described by taking the link down due to the malfunction of the ESW 32 (m) as an example, but the same applies when the link between the ESW 32 (m) and the ESW 31 (m) is disconnected. The route is switched by the following procedure. Further, even when the links L1 and L2 are disconnected or a malfunction occurs in the M / C 10 (m), the port switching device 11 can similarly detect the link down of the active system, so that the path switching can be performed in the same procedure. Done.

1 is a block diagram of a layer 2 network redundancy system according to the present invention. FIG. It is a functional block diagram of a port switching device 3 is a timing chart showing the operation of an embodiment of the present invention. It is the block diagram which showed the operation | movement of one Embodiment of this invention. It is a block diagram of the conventional layer 2 network redundancy system.

Explanation of symbols

10, 20 ... Subscriber side media converter (M / C)
11, 21 ... Port switching device 31, 36 ... Net side media converter (M / C)
32, 35 ... Edge switch (ESW)
33, 34 ... Core switch (CSW)

Claims (4)

A layer 2 network and its edge switches;
A subscriber-side media converter located on the subscriber side;
A net-side media converter disposed between the subscriber-side media converter and an edge switch;
In the layer 2 network redundancy system in which each switch, edge switch and each media converter of the layer 2 network are multiplexed,
Port switching means for switching the connection destination of the fixed port to which the subscriber terminal is connected to any one of a plurality of selected ports to which the subscriber-side media converters of the active system and the standby system are connected;
Means for transmitting down of the working link to the port switching means,
The port switching means is
Means for detecting that the adjacent link connected to the selected port of the active system is down;
In response to detection of the link down, means for switching the connection destination of the fixed port to the selection port of the standby system,
A redundancy system for a layer 2 network, comprising: means for resuming communication between a subscriber terminal and a subscriber-side media converter after completion of the switching. The net side media converter includes means for detecting down of an adjacent link with an edge switch and notifying the subscriber side media converter of the link down;
The layer 2 network redundancy system according to claim 1, wherein the subscriber-side media converter includes means for bringing down an adjacent link with the switching means in response to the link down notification.   3. The layer according to claim 1, wherein the subscriber-side media converter includes means for detecting that an adjacent link with the net-side media converter is down and causing the adjacent link with the switching means to go down. 4. 2 network redundancy system.   4. The port switching means according to claim 1, further comprising simultaneous on prevention means for preventing the plurality of pulse transformers from being simultaneously turned on, wherein each of the selected ports includes a pulse transformer. The layer 2 network redundancy system described.

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