JP4589059B2 - Redundant network and edge switch - Google Patents

Description

  The present invention relates to a redundant network constructed by combining a plurality of edge switches and a plurality of core switches, and an edge switch used for constructing such a redundant network.

  As is well known, in a so-called Ethernet network (a network in which communication according to the standard defined in IEEE802.3 is performed), in order to make the communication path redundant, as schematically shown in FIG. In addition, two paths that pass through the core switch (layer 2 to layer 4 switch) are provided between the two edge switches (layer 2 switch), respectively.

  In a network having such a configuration, the forwarding / blocking state of each port of each core switch is determined by exchanging BPDU (Bridge Protocol Data Unit) frames between edge switches (IEEE802.1D (Where the redundant path control is performed by the spanning tree protocol specified in) and the active / standby state of each core switch is determined by exchanging Hello packets between edge switches (unique to the network equipment manufacturer) Redundant path control is performed by the hot standby protocol).

  However, in any network in which redundant path control is performed, when a failure occurs in a part (circuit) related to the exchange of control information (BPDU frame, Hello packet) in the core switch, it is shown in FIG. (A state where the data frame loops infinitely). FIG. 9B shows a case where a failure occurs only in the part related to the exchange of control information of the core switch α, and as a result, it is erroneously recognized that the core switch α is not usable. It is the figure which showed the state of the network typically.

  Accordingly, an object of the present invention is to provide a redundant configuration network that does not cause the above-described problems, and an edge switch that can construct such a redundant configuration network.

In order to solve the above problems, the present invention, between Ji, respectively, the redundancy network is L 2 network including a portion in which a plurality of communication paths you through more than one core switch is provided, Cycles a process of detecting the number of links that are the total number of communicable edge switches and core switches connected to itself as each core switch, and notifying each edge switch connected to itself of the detected number of links using a switch for performing manner, as each edge switch for each core switch connected to its own, a control information including the number of most recent link notified from the core switch, via the core switch Storage means for storing control information not including information indicating whether or not the communication path to the other edge switch is valid; Update means for updating the number of links in the control information related to each core switch on the storage means with the number of links notified from each core switch, and one of the ports to which the communication path to the other edge switch is connected Port state control means for setting a port to a forwarding state and blocking each remaining port, and at least when a certain number of links from a certain core switch is notified, and a certain core switch Control on the storage means when the number of links is not notified for a predetermined time from
Determining the status of each port on the basis of the information, keep to that used the switch and a port state control means for performing port state control process of controlling the respective ports to the determined state.

  That is, the redundant configuration network of the present invention has a configuration in which path switching is performed by an edge switch, not a core switch. In addition, the edge switch required for the construction of the redundant configuration network of the present invention can be realized only by adding a function for performing path switching control to the edge switch whose original circuit configuration is simpler than that of the core switch. Therefore, the edge switch required for the construction of the redundant configuration network of the present invention has a probability that a problem will occur in the part that performs path switching control (the part related to the exchange of control information) rather than the existing core switch. It will be low. Therefore, the redundant configuration network of the present invention functions as a network that is less likely to cause a problem than the existing redundant configuration network in which the path is switched by the core switch.

In the edge switch used in the redundant configuration network of the present invention, the storage unit stores the control information for each core switch for each redundancy group to which the core switch belongs, and the port state control The port state control processing performed by the means is in a state in which frame transmission / reception performed via a certain core switch is performed via another core switch belonging to the same redundancy group as the core switch. It is also possible to use a switch that is a process for this purpose .

  Since the edge switch of the present invention can be used as a component of the redundant configuration network of the present invention, if the edge switch of the present invention is used, the redundant configuration network in which the path is switched by the existing core switch. As a result, it is possible to realize a redundant configuration network that is less likely to cause problems.

  According to the present invention, it is possible to construct a redundant configuration network that is less likely to cause a problem than an existing redundant configuration network in which paths are switched by a core switch.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  As schematically shown in FIG. 1, the redundant configuration network according to an embodiment of the present invention includes at least two edge switches and a plurality of core switches that connect the edge switches. It is a network.

  This redundant configuration network is a network in which path switching control is performed by an edge switch, not a core switch. However, the basic functions (functions not related to path switching control) of the edge switch and core switch constituting this redundant configuration network are the existing edge switch (layer 3 switch) and core switch (layer 2 to layer In the following, the configuration and operation of the edge switch and the core switch used in the redundant configuration network according to the present embodiment will be focused on the points different from the existing ones. Will be explained.

  First, a control frame exchanged between adjacent switches for path switching control in the redundant configuration network will be described.

  The redundant configuration network is a network in which routes are switched by periodically exchanging control frames having the configuration shown in FIG. 2 between adjacent switches.

  The TYPE (IEEE802.1Q VLAN tag) field and TCI field included in this control frame indicate that the own frame is transmitted / received by the VLAN (transmitted / received by another LAN from the data frame). This is a field in which information is set. The Padding field is a field in which dummy data is set in order to set the frame length of the control frame to the shortest frame length (64 bytes).

  The Sender_Group-ID field, Sender_Priorty field, Sender_Link_Count field, and Sender_HelloTime field respectively relate to the core switch (which is directly connected to the edge switch that transmits this control frame) that exists on the path to which this control frame is transmitted. As information, this is a field in which Group-ID, Link-Count, Priority, and HelloTime managed (stored internally) by the edge switch that transmits this control frame are set.

  Here, HelloTime is information specifying the transmission period of this control frame, and Group-ID is a core switch directly connected to an edge switch, a redundant group (communication to the same edge switch) This is information to be classified into a set of core switches that can be used for

  This Group-ID is information that can be determined for each core switch as schematically shown in FIG. 3 (a) or as schematically shown in FIG. 3 (b). ing.

  That is, the Group-ID is information (FIG. 3 (a)) that classifies each core switch into a redundancy group only by which edge switch is used for relaying frames between the edge switches. This information can also be used as information (FIG. 3 (b)) that is classified into a redundancy group depending on which edge switch is used for relaying the frame and the purpose / purpose of the relayed frame. .

  Priority is used to enable an edge switch to determine one core switch to be actually used from among a plurality of core switches that can be used for communication with other core switches (details will be described later). In addition, it is numerical information whose value is determined for each Group-ID. Link-Count is the total number of switches that are guaranteed to reach the target edge switch among the layer 2 / core switches connected to each core switch. That is, this Link-Count is information that is “2” for the core switch α of the redundant configuration network as shown in FIG. 4 and “3” for the core switch β, for example. .

  The four Receiver_XXX (XXX = Group-ID, Priority, Link_Count, HelloTime) fields provided in the control frame (Fig. 2) are the control frames received last time from the destination edge switch of this control frame. This is a field in which information set in the Sender_XXX (XXX = Group-ID, Prior, Link_Count, HelloTime) field is set.

  That is, the edge switch / core switch according to the present embodiment, for each other adjacent switch, Group-ID, Priority, Link_Count, and HelloTime (hereinafter referred to as information of these four types of information) transmitted from the switch. This is a switch having a function of managing control information to be transmitted to the switch. In addition, each switch according to the present embodiment exchanges a control frame including these two types of control information periodically with each other switch in the form schematically shown in FIG. It also has a function to do. In FIGS. 5A and 5B, the control information A described above the switch A is control information managed by the switch A as to be transmitted to the switch B. The control information B described above A is control information that the switch A manages as received from the switch B. The control information B described above the switch B is control information managed by the switch B as information to be transmitted to the switch A, and the control information A described above the switch B. Is control information managed by the switch B as received from the switch A.

  Furthermore, the core switch according to the present embodiment has a function of detecting the number of switches actually linked to the own switch and transmitting a control frame including a Link-Count indicating the detected number. ing.

  Then, when the edge switch according to the present embodiment receives a control frame in which the Link-Count is changed, all the ports are set in a blocking state, and the Link-Count in each corresponding control information is received. After changing the setting in the control frame, the port state control process of the procedure shown in FIG. 6 is performed for each Group-ID stored as an element of control information in the own switch. It is configured. An edge switch is also used when a control frame is not received within a predetermined time (time corresponding to HelloTime), when the content of the received control frame is invalid, or when there is a link with the core switch. When down is detected, all ports are set to the blocking state, the corresponding control information is cleared, and the port state control processing (for each Group-ID stored as an element of the control information in its own switch ( 6).

  That is, the edge switch that has started the port state control process first receives the attention Group-ID (in the figure, attention G-ID: the Group-ID that is the target of this process) and the Group-ID (in the figure, G -ID) is investigated (step S101), and if the number of control information with the same Group-ID and Group-ID is equal to 0 (step S101; none), all ports This port state control process is terminated without entering the forwarding state. Then, when there is an unprocessed Group-ID, the edge switch starts a port state control process for the Group-ID.

  On the other hand, when the number of pieces of control information having the same Group-ID and Group-ID is “1” (step S101; one piece), the edge switch is forwarding the port specified by the control information. (Step S103). Further, when there are a plurality of control information having the same Group-ID and Group-ID (step S101; plural), the edge switch selects the control information with the largest Link-Count from among the control information. When all are specified (step S102) and only one piece of such control information can be specified (step S102; one), the port specified by the control information is set to the forwarding state (step S103). Then, the edge switch that has finished the process of step S103 finishes the port state control process, and if necessary, starts the port state control process for the next Group-ID.

  On the other hand, when a plurality of pieces of control information with the maximum Link-Count can be specified (step S102; a plurality), the edge switch performs the control with the highest priority among the plurality of pieces of control information with the largest Link-Count. The port specified by the information is set to the forwarding state (step S104). Then, the edge switch ends the port state control process.

  As is clear from the above description, the redundant configuration network is a network in which paths are switched as follows.

  For example, consider the case where the link between the core switch α and the edge switch B in the redundant configuration network whose configuration and state are shown in FIG. That is, it is a redundant configuration network composed of edge switches A and B and two edge switches α and β having two Group-IDs (G-IDs in the figure) that are “1” connecting them. Consider a case where a failure occurs between the core switch α and the edge switch B in a redundant configuration network that is operating in a state where the route via the core switch α (α route in the figure) is a priority route. .

  In this case, the edge switch B that has detected the occurrence of the failure, as schematically shown in FIG. 7B, sets all the ports to the blocking state and manages the control information related to the core switch α. To clear.

  Further, when receiving a control frame from the edge switch A, the core switch returns a control frame including a Link-Count that is smaller by “1” to the edge switch A.

  Then, the edge switch A that has received this control frame puts all the ports into the blocking state and schematically manages them as related to the core switch α as shown in FIG. 7C. Change Link-Count to the one set in the received control frame.

  Thereafter, the edge switch A performs the port state change process (FIG. 6) for Group-ID = 1. In this case, as is clear from FIG. A branch will be taken. Therefore, as schematically illustrated in FIG. 7D, the edge switch A starts operation in a state where the port # 1 is in the blocking state and the port # 2 is in the forwarding state. .

  The edge switch B that detects the occurrence of a failure with the edge switch B also performs the port state change process. In this case, branching to “one” side is performed in step S101. Therefore, as schematically shown in FIG. 7D, the edge switch B starts operation in a state where the port # 1 is in the blocking state and the port # 2 is in the forwarding state. . Since the edge switches A and B start the operation in the state as described above, the redundant configuration network is in a state where the route passing through the core switch β (β route in the figure) is a priority route. The operation will start.

  Further, consider a case where a failure occurs between the core switch β and the edge switch B in the redundant configuration network whose configuration and state are shown in FIG.

  In this case, the edge switch B that has detected the occurrence of the failure places all the ports in the blocking state, and clears each control information managed as related to the core switch β. The edge switch B performs the port state change process (FIG. 6) for each of Group-ID = 1, 2. In this case, branching to one side is performed in step S102 during each process. Therefore, the edge switch B starts the operation in the state where the port # 1 is in the forwarding state for both Group-ID = 1 and 2, as schematically shown in FIG. Will do.

  In addition, as schematically shown in FIG. 8B, the edge switch A starts the operation in the state where the port # 1 is in the forwarding state for both Group-ID = 1 and 2. Will do.

  This is because, in this case, when receiving the control frame from the edge switch A, the core switch β returns a control frame including a Link-Count that is smaller by 1 to the edge switch A. The edge switch A that has received this control frame sets all the ports in the blocking state, and sets the Link-Count in each control information managed as related to the core switch β in the received control frame. Change to what you have. After that, the edge switch A performs the port state change process for each of Group-ID = 1, 2. In this case, at the time of the port state change process for each of Group-ID = 1, 2, “one” is performed in step S102. This is because branching to the “side” is performed.

  As described above, the redundant configuration network according to the present embodiment employs a configuration in which the path is switched by the edge switch instead of the core switch, and thus may occur in the existing redundant configuration network. It is a network in which a certain problem (problem that occurs due to a failure in a part / circuit related to the exchange of control information in the core switch; see FIG. 9) cannot occur. In addition, the edge switch required for the construction of this redundant configuration network has a function for performing path switching control (a function for transferring control information and a port state change process) to an edge switch having a simpler circuit configuration than the core switch. This can be realized only by adding a function for Therefore, the edge switch required for the construction of the redundant configuration network has a lower probability of occurrence of a problem in the part related to the path switching than the existing core switch, and as a result, the redundancy switch according to the present embodiment. The configuration network functions as a network that is less likely to cause problems than the existing redundant configuration network in which paths are switched by the core switch.

<Deformation>
The redundant configuration network according to the above-described embodiment can be variously modified. For example, the redundant configuration network may be modified to use a core switch that does not have a function of returning a control frame whose Link-Count value is changed. In the case of such a modification, the above-described edge switch can be used as it is, or a modification that does not make a determination regarding the Link-Count value can be used.

  In addition, it will not be possible to guarantee that frames can be exchanged between edge switches where a communication failure has occurred, but Group-ID can be easily determined. When building a redundant network, the Link-Count value can be the total number of switches connected to each switch.

It is explanatory drawing of the structure of the redundant structure network which concerns on one Embodiment of this invention. It is explanatory drawing of the control frame exchanged between the edge switches contained in the redundantly configured network according to the embodiment. It is explanatory drawing of Group-ID set in a control frame. It is explanatory drawing of Link-Count set in a control frame. It is a figure for demonstrating the transmission / reception operation | movement of the control frame in an edge switch. It is a flowchart for demonstrating the content of the port state control process which an edge switch performs. It is explanatory drawing of operation | movement of the redundantly configured network which concerns on embodiment. It is explanatory drawing of operation | movement of the redundantly configured network which concerns on embodiment. It is explanatory drawing of the problem which arises in the existing redundant structure network.

Claims (4)

A redundant configuration network that is an L2 network including a portion in which a plurality of communication paths via one or more core switches are provided between two edge switches,
Each core switch on the plurality of communication paths is
A switch that periodically detects the number of links that are the total number of communicable edge switches and core switches connected to itself, and notifies each edge switch connected to itself of the detected number of links. And
Each of the two edge switches is
For each core switch connected to itself, is the control information including the latest number of links notified from the core switch, and whether the communication path to the other edge switch via the core switch is valid Storage means for storing control information not including information indicating whether or not;
Updating means for updating the number of links in the control information regarding each core switch on the storage means with the number of links notified from each core switch;
Port state control means for setting one port among the ports connected to the communication path to the other edge switch to a forwarding state and blocking each remaining port from a certain core switch. and when it is notified number of links value different from the past, from one core switch, for a predetermined time, to the case where the number of links is not notified Zhou of each port on the basis of the control information on the storage means A port state control means for performing a port state control process for determining a state and controlling each port to the determined state;
A redundant network characterized by being a switch comprising: The storage means
For each core switch, means for storing the control information for each redundant group to which the core switch belongs,
The port state control process performed by the port state control means includes:
This is a process for setting a state in which frame transmission / reception performed via a certain core switch is performed via another core switch belonging to the same redundancy group as the core switch. The redundant configuration network according to claim 1. A function that periodically detects the number of links that are the total number of communicable edge switches and core switches connected to itself and notifies each edge switch connected to itself of the number of detected links. An edge switch used in combination with a plurality of core switches having
For each core switch connected to itself, is the control information including the latest number of links notified from the core switch, and is the communication path to the other edge switch via the core switch valid? Storage means for storing control information not including information indicating whether or not;
Updating means for updating the number of links in the control information regarding each core switch on the storage means with the number of links notified from each core switch;
Port state control means for setting one port among ports connected to communication paths to other specific edge switches to a forwarding state and blocking each remaining port, at least a certain core switch Each of the ports based on the control information on the storage means when the number of links having a different value from the previous one is notified and when the number of links is not notified from a certain core switch for a predetermined time. A port state control means for performing a port state control process for determining a state of the port and controlling each port to the determined state;
An edge switch comprising: The storage means
For each core switch, means for storing the control information for each redundant group to which the core switch belongs,
The port state control process performed by the port state control means includes:
This is a process for setting a state in which frame transmission / reception performed via a certain core switch is performed via another core switch belonging to the same redundancy group as the core switch. The edge switch according to claim 3.