JP2007104512A - Loop detection and avoiding function in redundancy line function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method in which loops are detected between adjacent apparatuses caused by misconfiguration of link aggregation, the loops are avoided using a degeneracy function of link aggregation functions, and communications are continued between terminals. <P>SOLUTION: When a frame is transmitted, the transmitter MAC address of a frame transmitted from a link aggregation is stored. If a frame is received which has a MAC address stored from the same link aggregation as a transmitter MAC address, a loop is detected and communications are operated with only one of integrated lines using the degeneracy function of the link aggregation functions to avoid the loop and continue communications between terminals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a network communication apparatus that connects a plurality of networks at a layer 2 level, and a processing method of the apparatus. In particular, the present invention relates to a technique for detecting a loop between adjacent devices connected by a redundant line and avoiding such a loop.

  As a technique for detecting and correcting a loop, there is a method of monitoring rewriting of a spanning tree protocol (see, for example, Non-Patent Document 1) and FDB (Filtering Data Base) (see, Patent Document 1).

  The spanning tree protocol detects a loop with a control frame BPDU (Bridge Protocol Data Unit), and the method of monitoring the FDB rewrite detects the loop by monitoring the FDB rewrite frequency. When each loop is detected, the logical line causing the loop is changed to a blocking state (a state in which no frame is relayed), and the loop is logically cut off.

  FIG. 1 shows an example of a network configuration diagram in a loop configuration. A loop occurs as in 100. When the loop prevention function is applied to this configuration, the loop is logically blocked by shifting the line 103 side of the network communication device 101 to the blocking state. By blocking the loop in this way, communication from the terminal 104 to the terminal 105 is performed via the network communication devices 106, 107, and 102, and the loop does not occur.

  On the other hand, there is a function called link aggregation (see Non-Patent Document 2). This is a technology that aggregates a plurality of lines and handles them as a single logical line, and has a degeneration function that can continue operation on the remaining lines when a failure occurs in the aggregated lines. The link aggregation function is a technique used between adjacent devices, and it is necessary to match the settings of the devices at both ends. LACP (Link Aggregation Control Protocol) is defined as a control protocol for dynamically assembling this aggregation setting.

JP 2005-33360 A IEEE802.1D IEEE802.3ad

  By the way, in the LACP of the link aggregation function, since control frames are periodically exchanged in both seconds on both lines to be aggregated, the performance may deteriorate. Some devices do not support LACP. In such a case, LACP is not used.

  The link aggregation function needs to be set between both apparatuses in advance, but when setting manually without using LACP, a loop may be caused as shown in FIG. 2 due to a setting error. In FIG. 2, the network communication device 302 can recognize the lines 305, 306, and 307 as the link aggregation 309, but the network communication device 303 does not recognize that the lines 305, 306, and 307 are link aggregation. In this state, the frame transmitted from the link aggregation 309 by the network communication device 302 is flooded (relayed to all lines other than the received line) by the network communication device 303, so that the network communication device returns as shown by 310 in FIG. It returns to 302 and becomes a loop.

  Here, when the above-mentioned spanning tree protocol and the technique of Patent Document 1 are used, a loop is detected by the network communication device 302 as shown in FIG. 3, and the link aggregation 309 is put into a blocking state, and communication between terminals is performed. It will block.

  Therefore, it is possible to provide a technique for detecting a loop between adjacent devices as shown in FIG. 2 and using the degeneration function of the link aggregation function at the time of detecting the loop so as to avoid the loop and continue communication between terminals. One purpose.

  In solving the above problem, for example, when the transmission source MAC address of the frame transmitted from the link aggregation is retained and a frame having the same MAC address as the MAC address retained from the same link aggregation is received. In other words, when the transmitted frame returns, one link is used in the same way as when all but one of the aggregated links has failed using the link aggregation degeneration function. Provide technology that can be operated by itself and avoid loops.

  According to the above means, it is possible to detect and avoid a loop between adjacent devices due to a link aggregation setting error, and to prevent communication between terminals from being interrupted.

  A preferred embodiment for implementing the present invention will be described. However, the present invention is not limited to this embodiment.

  First, an outline of the present embodiment will be described with reference to FIG. FIG. 4 shows an example of a network configuration for explaining the operation of a network communication device having a loop avoidance function. Consider a case where there is a link aggregation setting error in the network communication device 303 of FIG.

  First, the network configuration will be described. The network communication devices 302 and 303 are connected by lines 305, 306, and 307, and the link aggregation function is used to aggregate these three lines. However, the network communication device 303 has a setting error in the link aggregation function. Therefore, the network communication device 303 recognizes the lines 305, 306, and 307 instead of link aggregation. Two terminals are connected to each of the network communication devices 302 and 303, and all the devices are connected at the layer 2 level.

  With this configuration, it is considered that a frame is transmitted from the terminal 300 to the terminal 301 in a state where neither the network communication devices 302 and 303 have learned a MAC address.

  The network communication device 302 receives the frame transmitted from the terminal 300, and the network communication device 302 relays the frame to the link aggregation 309 (in this case, it is assumed that the frame is transmitted from the line 305). An address and a destination link aggregation 309 are held.

  Since the network communication device 303 receives the frame transmitted from the network communication device 302 to the line 305 and the network communication device 303 does not recognize the link aggregation, flooding to the lines 306, 307, and 308 (relay to a line other than the reception line) )

  The frame relayed to the lines 306 and 307 is received again by the network communication device 302, and when viewed from the network communication device 302, it appears that the frame has been received from the link aggregation 309.

  The network communication device 302 compares the source MAC address of the received frame with the received logical line (link aggregation 309) pair and the information held at the time of transmission, and if there is a matching entry, It is determined that the frame transmitted from the link aggregation has returned, that is, it is determined that the loop is between adjacent devices due to a setting error of the link aggregation function of the adjacent device, and the link aggregation function 309 is used using the degeneration function of the link aggregation function. Only one of the aggregated lines (here, only the line 305) is operated.

  Since the link aggregation 309 is degenerated and operated using only the line 305, the network communication apparatus 302 does not receive frames from the lines 306 and 307 even if the network communication apparatus 303 floods the lines 306 and 307. Will be able to avoid. In addition, communication between the terminals 300 and 301 can be performed correctly without being interrupted.

  Next, details of the apparatus for realizing FIG. 4 will be described with reference to FIGS.

  FIG. 5 is a block diagram illustrating details of the network communication device 302 of FIG.

  The functional block added in this embodiment is the loop monitoring control unit 500 in particular. In this functional block, a table 501 for holding the source MAC address, a table management unit 502 for holding the source MAC address in the table at the time of frame transmission, a check processing unit 503 for checking the source MAC address at the time of frame reception, and a loop It is divided into an execution processing unit 504 that instructs a link aggregation degeneration process at the time of detection.

  In addition, interface control units 508, 509, 510, and 511 for transmitting and receiving frames, a relay processing unit 505 that relays frames, a transmission processing unit 506 that performs frame transmission processing, and frame reception processing are performed in the relay processing unit 505 The reception processing unit 507 is divided. The interface control units 509, 510, and 511 correspond to the link aggregation 309 in FIG. In addition, although not shown, the link aggregation setting unit stores a link aggregation function setting (number of lines or interface control units aggregated by link aggregation, group name of link aggregation, and the like).

  FIG. 6 shows the contents of the address management table 501 held in the present invention. Consists of source MAC address, link aggregation group, and aging value (time to keep entries). When sending a frame from link aggregation, holds the source MAC address of the frame and the link aggregation to be sent and sets the aging value I do. This retained entry is deleted from the table at the aging-out opportunity. This link aggregation group is acquired from the link aggregation setting unit.

  For example, when the network communication device 302 transmits a frame from the terminal 300 from the link aggregation 309, the network communication device 302 generates and holds the entry 550 in the figure, and the network communication device 302 transmits the frame from the terminal 311 to the link aggregation 309. When transmitting from, entries 551 in the figure are generated and held.

  In addition, the standard of the aging value is a short time from when a frame is transmitted to when it returns via an adjacent device. If information is held for a long time, a loop may be erroneously detected as follows.

  For example, consider the case where the terminal 311 is physically moved from the network communication device 302 to the network communication device 303 in FIG. 4 when the link aggregation function of the network communication device 303 is correctly set. FIG. 7 shows an image diagram at this time. At this time, if the network communication device 302 holds the entry 551 in FIG. 6, the network communication device 302 stores that the frame having the transmission source MAC address of the terminal 311 is transmitted from the link aggregation 309. In this state, when the network communication device 302 receives a frame transmitted from the terminal 311 to the terminal 300, it is assumed that the frame transmitted by the own device has returned from the same link aggregation, and is determined to be a loop. In order to prevent such erroneous loop detection, it is not desirable to set a very long time for the aging value. However, even if a loop is mistakenly detected, the link aggregation degeneration function is used to avoid the loop, and only one of the aggregated lines is operated, so communication between terminals is blocked. It will never be done.

  The address management table 501 is an area for storing which frame is transmitted from which link aggregation.

  Next, processing until the network communication device 302 detects and avoids a loop using the configuration and data described in FIGS. 5 and 6 will be described using a flowchart.

  FIG. 8 is a flowchart showing an outline of a flow from reception of a frame to transmission in the network communication device 302.

  The interface control unit receives the frame from the line (800), and passes the received frame to the reception processing unit 507 (801). Here, the loop monitoring control unit 500 performs a check process at the time of reception (details will be described later). (802) It is determined whether or not it is a loop based on the check result (803). If a loop is detected, the frame is discarded (808), the processing of this frame ends here, and no transmission processing is performed.

  If it is determined that it is not a loop, then the reception processing unit 507 passes the frame to the transmission processing unit 506 in order to perform frame transmission processing (804).

  Before transmitting the frame, the loop monitoring control unit 500 performs address holding processing at the time of transmission (805), and the transmission processing unit 506 passes the frame to the destination interface control unit (806). A frame is transmitted to (807).

  Further, detailed processing of the loop monitoring control unit 500 will be described using a flowchart. Since the present invention detects the loop by holding the frame information transmitted at the time of transmission and checking at the time of reception, here, the process at the time of transmission and the process at the time of reception will be described first.

  FIG. 9 is a flowchart of detailed processing of the address holding processing at the time of transmission 805 in FIG.

  The table management unit 502 checks whether or not the link destination logical line of the frame is set to link aggregation in the link aggregation setting unit (600). If the link aggregation is not set, nothing is done and the link aggregation is performed. Is set in the address management table 501 with the set of the transmission source MAC address and the transmission destination link aggregation of the frame (601), and if there is a matching entry, that is, already registered If there is no matching entry, the source MAC address of the frame and the link aggregation of the destination are held in the address management table 501 (602), and an aging value is set.

  FIG. 10 is a flowchart of detailed processing of the check processing at the time of reception 802 in FIG.

  The check processing unit 503 first sets loop undetected as a return value to be used after the end of this check processing (700), and whether or not the reception logical line of the frame is set to link aggregation in the link aggregation setting unit. Is checked (701). If link aggregation is not set, nothing is performed. If link aggregation is set, the following check processing is performed.

  Check whether there is an entry in the address management table 501 that matches the frame's transmission source MAC address and received link aggregation pair (702). If there is no matching entry, do nothing and if there is a matching entry Is determined to be a loop between adjacent devices, and the execution processing unit 504 performs a loop avoidance process.

  The execution processing unit 504 uses the degeneration function of the link aggregation 309 to operate only one of the aggregated lines (703), and does not perform subsequent frame relay processing on the other lines. . For example, any one of a plurality of lines set as link aggregation in the link aggregation setting unit or a line corresponding to the interface control unit that transmitted or received the frame is effectively maintained, and link aggregation and setting are performed. The setting of the relay processing unit 505 is changed so as to invalidate other lines among the plurality of lines that have been set. The port corresponding to the line may be powered off or the received frame may be ignored.

  Further, if necessary, a report indicating that a loop has been detected by the link aggregation is reported to a manager using a console message, a SYSLOG message, a SNMP (Simple Network Management Protocol) trap packet, or the like (704).

  Finally, the return value is changed to loop detection (705), and this check process is terminated.

  Note that the administrator can correctly set the link aggregation causing the problem, remove the loop, and then cancel the degeneration of the link aggregation using a manual maintenance command or the like to restore it. Alternatively, after a certain period of time after degeneration, the degeneration may be automatically canceled and loop monitoring may be performed again. If the link aggregation setting is not yet correct and the loop has not been removed, the link aggregation is degenerated again and the loop is avoided.

Network configuration diagram of a typical loop configuration example Network configuration diagram for an example of a loop configuration between adjacent devices Example network configuration using the conventional loop prevention function Network configuration diagram for explaining an operation example of a network communication device having a loop avoidance function Functional block diagram of an example of a network communication device with a loop avoidance function Example of address management table contents Network configuration diagram for explaining an operation example when a terminal registered in the address management table moves Flow chart of processing example from frame reception to transmission Flow chart of an example of address holding processing performed before frame transmission Flow diagram of check processing example after frame reception

Explanation of symbols

100 Flows in which frames are looped 101, 102 Network communication device 103 Line 104 connecting network communication devices Frame transmission source terminal 105 Frame transmission destination terminal 106, 107 Network communication device 300, 301 Terminal 302 Network communication devices 304 to 308, which are neighboring devices of the network communication device 303 302 having a loop avoidance function by the line 309, which connects the terminal and the network communication device, and the link aggregation 310 of the network communication device 302. 312 Terminal 313 Link aggregation 500 loop monitoring control unit of network communication device 303 (functional block added in the present invention)
501 Address management table 502 Table management unit 503 Check processing unit 504 Execution processing unit 505 Relay processing unit 506 Transmission processing unit 507 Reception processing units 508 to 511 Interface control units 550 and 551 Entry information 600 to 602 in address management table 501 Loop monitoring control unit processing 700 to 705 Loop monitoring control unit processing 800 to 803 frame transmission processing 800 to 803 Frame reception processing 804 to 807 Frame transmission processing 808 Frame discard processing upon loop detection

Claims (5)

A loop avoidance method executed by a data communication device that transmits and receives data by connecting to a plurality of network lines,
Receiving first data from a first network line;
Determining whether the first network line is configured as link aggregation;
When the link aggregation is set, it is determined whether a set of the link aggregation setting and the transmission source address of the first data is stored,
When stored, it is determined as a loop. A loop avoidance method executed by a data communication device that transmits and receives data by connecting to a plurality of network lines,
Determine whether the first network line that transmits the first data is set as link aggregation,
When the link aggregation is set, it is determined whether the set of the link aggregation setting and the source address is stored,
When not stored, the set of the link aggregation and the source address are stored,
Receiving second data from the second network line;
Determining whether the second network line is configured as link aggregation;
When the link aggregation is set, it is determined whether a set of the link aggregation setting and the transmission source address of the second data is stored,
When stored, it is determined as a loop. The loop avoidance method according to claim 1, further comprising:
The link aggregation set including the first network line determined to be a loop is degenerated. The loop avoidance method according to claim 1, further comprising:
A part of a plurality of network lines belonging to the link aggregation set including the first network line determined to be a loop is blocked. The loop avoidance method according to claim 2, further comprising:
The stored set of link aggregation and source address is deleted after a predetermined time.

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