JP2006020036A - Layer 2 communication system and layer 2 communication device capable of detouring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the number of terminal which can be housed by alleviating a communication traffic load which passes the highest order device of a tree of layer 2 switch tree network. <P>SOLUTION: An extended L2 switch includes a subordinate tree transfer table which registers the correspondence of the address of a subordinate terminal to an output communication channel to the terminal, and a first message transfer means for transferring a communication message to a predetermined communication channel to a high order tree network when the subordinate tree transfer table does not have a corresponding entry. An extended L2 switch capable of detouring includes, in addition to the transfer table and a first message transfer means, a detour transfer table which registers the correspondence of the destination terminal address of a communication message to be detoured to the address of the second layer 2 communication device of a tree network to which the destination terminal belongs, and a second message transfer means for detour transferring the communication message having the destination terminal address registered to this detour transfer table based on the detour transfer table. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a layer 2 communication system in which a load of communication traffic passing through the highest switch of a tree is reduced in a layer 2 switch tree network in which layer 2 switches are arranged in a tree shape, and a bypassable layer used in the system 2 relates to communication equipment.

  In the conventional L2 (Layer 2) switch as described in Non-Patent Document 1, the MAC address of the MAC frame transmitted by the terminal is viewed, and the terminal MAC address and the output communication path are set in the MAC entry in the L2 switch. When learning and receiving a MAC frame from another terminal having the destination MAC address of the terminal, the MAC entry is searched using the destination MAC address as a key, and when this search is successful, the stored output communication The MAC frame is transferred to the road.

In this type of L2 switch,
1) When a MAC frame having a destination MAC address not learned in the MAC entry is received, the MAC frame is broadcast to all output communication paths.
2) When the number of terminals accommodated in the L2 switch network increases, the number of MAC entries of each L2 switch is exceeded, and MAC frames that exceed the entries are broadcast to all output communication paths.

  Further, in the conventional L2 switch network, when the terminal moves and the L2 switch to which the terminal is connected is frequently changed, the MAC entry before movement of all the L2 switches in the network is output to the new L2 switch after movement. In order to update the path, the new L2 switch must broadcast the MAC frame for entry update to all L2 switches in the network in response to an update request from the terminal.

Rich Seifert "LAN switching thorough explanation" Nikkei Business Publications, August 6, 2001, P58-P65, P78-P88 (transparent bridge)

  As described above, the conventional L2 switch network has a problem that the amount of communication traffic increases because broadcasting frequently occurs.

  In the L2 switch network, the L2 switches are configured in a tree shape by STP (Spanning Tree Protocol). Generally, however, in the tree configuration network, a load is easily generated in the L2 switches constituting the top of the tree. There was a problem that the exchange capacity of the L2 switch had to be increased and the cost was increased.

  The present invention has been made in view of the above, and suppresses the occurrence of broadcast in the L2 switch tree network and reduces the communication traffic load passing through the highest level device of the L2 switch tree network, thereby reducing the L2 switch tree. An object of the present invention is to obtain a layer 2 communication system capable of increasing the number of terminals that can be accommodated in the network and expanding the application scale of the L2 switch tree network and a bypassable layer 2 communication device used in the system.

  In order to solve the above-described problems and achieve the object, the present invention provides a plurality of first layer 2 communication devices connected to a communication path and a plurality of second layers connected to a bypass communication path in addition to the communication path. 2 layer 2 communication devices, and a plurality of tree networks in which the first and second layer 2 communication devices are connected in a tree shape are connected in a tree shape, and between the second layer 2 communication devices. Are connected to each other by a detour communication path, wherein the first and second layer 2 communication devices include the address of each terminal existing under its own and the output communication path to the terminal. The subordinate tree transfer table in which the correspondence relationship is registered, and the communication message to each terminal existing under the subordinate tree transfer table are transferred to the corresponding output communication path based on the subordinate tree transfer table, and the subordinate tree transfer table is compatible. Without own arrangement A first message transfer means for unicasting a communication message to a terminal that does not exist in the network to a predetermined default communication path reaching the upper tree network. A detour transfer table in which the correspondence between the partner terminal address and the address of the second layer 2 communication device of the tree network to which the partner terminal belongs is registered, and the partner terminal registered in the detour transfer table And a second message transfer unit configured to detour-transfer a communication message having an address to the address of the second layer 2 communication device registered in the detour transfer table via the detour communication path, respectively. To do.

  According to this invention, based on the subordinate tree transfer table, the communication message to each terminal existing under the subordinate tree is transferred to the corresponding output communication path, and the terminal that does not correspond to the subordinate tree transfer table and does not exist under the subordinate tree A communication message having a destination terminal address registered in the detour transfer table is registered in the detour transfer table with a second message that is unicast transferred to a predetermined default communication path that reaches the upper tree network. A detour transfer is made to the address of the layer 2 communication device via the detour communication path.

  According to this invention, based on the subordinate tree transfer table, the communication message to each terminal existing under the subordinate tree is transferred to the corresponding output communication path, and the terminal that does not correspond to the subordinate tree transfer table and does not exist under the subordinate tree A communication message having a destination terminal address registered in the detour transfer table is registered in the detour transfer table with a second message that is unicast transferred to a predetermined default communication path that reaches the upper tree network. Since the detour transfer is performed via the detour communication path with respect to the address of the layer 2 communication device, the occurrence of broadcast is suppressed, and the communication traffic load passing through the highest level device of the tree of the L2 switch tree network is reduced. As a result, the number of terminals that can be accommodated in the network is increased, and the application scale of the network can be expanded.

  Embodiments of a layer 2 communication system according to the present invention and a bypassable layer 2 communication device used in the system will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a layer 2 switch (hereinafter abbreviated as L2 switch) network according to a first embodiment to which the present invention is applied. The L2 switch network shown in FIG. 1 includes an upper tree network 171, a plurality of lower tree networks 172 to 175, and a bypass communication network 176. The upper tree network 171 includes a plurality of extended L2 switches 161 to 163 connected in a tree shape. The plurality of lower tree networks 172 to 175 are respectively configured by a plurality of extended L2 switches 121 to 144 connected in a tree shape. The extended L2 switches 121, 123, 126,... Constituting the tree ends of the lower tree networks 172 to 175 accommodate terminals 101 to 109 that perform L2 communication.

  The bypassable extended L2 switches 151 to 154 are located at the top of the lower tree network, manage addresses of all terminals in the lower tree network, and when communication between the lower tree networks occurs, Relay communication to other subtrees using the communication network. In this L2 switch network, the term “extended L2 switch” is used for each L2 switch constituting the tree network. The meaning of the extension will be described later.

  The extended L2 switches 121 to 144 in the lower tree networks 172 to 175 are connected by communication paths 201 to 224. The extended L2 switches 161 to 163 in the upper tree network 171 are connected by communication paths 231 to 236.

  Further, detour communication paths (tunnels) 241 to 243 are communication paths when the detourable expansion L2 switches 151 to 154 realize detour communication to other detourable expansion L2 switches. Depending on the type of the detour communication network, these tunnels include connection type tunnels such as MPLS LSP (Label Switching Path), or MAC non-connection type tunnels such as MAC MAC in MAC and IP L2TP (Layer 2 Tunneling Protocol). Etc. When MPLS (MultiProtocol Label Switching) is adopted as the communication format of the bypass communication network, the MAC frame is encapsulated with a frame with a SHIM label corresponding to the MPLS destination communication device (L2-VPN encapsulation), and MACinMAC Is used, the MAC frame is further encapsulated with a MAC frame used in the bypass communication network (MACinMAC encapsulation), and when IP L2TP is adopted, the MAC frame is encapsulated with an IP frame ( L2TP encapsulation).

  Each extended L2 switch other than the detourable extended L2 switches 151 to 154 in the L2 tree network may belong to either the upper tree network 171 or the lower tree networks 172 to 175, and the terminal MAC address and the lower extended L2 switch A subordinate tree transfer table 401 in which data indicating the correspondence relationship with the communication path is registered. FIG. 4A shows an example of the subordinate tree forwarding table 401 in the extended L2 switch 122. The subordinate tree forwarding table 401 shows the correspondence between the MAC address A of the terminal 101 and the output communication path 201, and the terminal 102. The correspondence between the MAC address B and the output communication path 202 is registered. Registration in the subordinate tree forwarding table 401 is performed when a terminal registration message to be described later is transmitted.

  On the other hand, the bypassable extended L2 switches 151 to 154 include a bypass transfer table 402 in addition to the subordinate tree transfer table 401 similar to the above. In the detour transfer table 402, data indicating the correspondence between the terminal MAC address and the communication path to the detour destination extended L2 switch is registered. FIG. 4B illustrates an example of the subordinate tree transfer table 401 and the detour transfer table 402 provided in the bypassable extended L2 switch 151. In the subordinate tree transfer table 401, the correspondence between the MAC address A of the terminal 101 and the output communication path 203, the correspondence between the MAC address B of the terminal 102 and the output communication path 203, the MAC address C of the terminal 103 and the output communication path 206, The correspondence of is registered. Further, in the detour transfer table 402, the correspondence between the MAC address D of the terminal 104 and the detour communication path 241, the correspondence between the MAC address G of the terminal 107 and the detour communication path 242, the MAC address I of the terminal 109 and the detour communication path 243 Correspondence with is registered. The registration in the detour transfer table 402 is performed when a normal communication message is transmitted from the terminal and a detour response message described later is transmitted from the detour destination extended L2 switch, as will be described later.

  Next, the operation will be described. First, in this L2 switch network, when each terminal is connected to this L2 switch network and physical L1 communication means between the terminal and the L2 switch is established, each terminal or an L2 switch (edge switch) that accommodates the terminal is established. ), A terminal registration message including the MAC address of the terminal is transmitted to the L2 tree network. By this terminal registration message, each L2 switch is registered in the subordinate tree forwarding table 401 described above.

  FIG. 6 shows the operation of each extended L2 switch when a terminal registration message is received from the lower communication path. When each extended L2 switch receives the terminal registration message from the lower communication path (step S1), the correspondence between the MAC address of the terminal and the received communication path is assigned to the subordinate tree forwarding table 401 based on the received terminal registration message. Is registered (step S2), and the received terminal registration message is transferred to the default upper channel (step S3).

  FIG. 2 shows a state where the terminal 101 (MAC address: A) and the terminal 109 (MAC address: I) are transmitting terminal registration messages 251 and 252 as indicated by broken line arrows. The terminal registration messages 251 and 252 may be transmitted on the terminal side, or may be transmitted by an L2 switch (in this case, 121 and 140) that accommodates the terminal.

  In FIG. 2, the terminal registration message 251 from the terminal 101 is transmitted along with the terminal address of each received communication path (terminal 101, 201, 203, 232) in the extended L2 switches 121, 122, 151, 162 on the way. While being stored in the tree transfer table 401, it is output to each of the default output communication paths 201, 203, 232, and 231 set in advance toward the uppermost extended L2 switch 161 of the L2 tree network, and finally L2 It reaches the uppermost extended L2 switch 161 of the tree network. Similarly, the uppermost extended L2 switch 161 registers the correspondence between the received communication path 231 and the terminal address in the subordinate tree forwarding table 401.

  Similarly, the terminal registration message 252 from the terminal 109 side finally reaches the uppermost extended L2 switch 161 of the L2 tree network via the extended L2 switches 140, 143, 153, and 163.

  In this way, all extended L2 switches in the L2 tree network register the relationship between the addresses of all terminals under their switch and the output communication path in the subordinate tree forwarding table 401 when the terminal registration message is transferred. To do.

  In order to delete registration information from the subordinate tree forwarding table 401, a terminal registration deletion message is transmitted from the terminal or the L2 switch that accommodates the terminal. FIG. 7 shows the operation of each extended L2 switch when the terminal registration deletion message is received from the lower communication path. When each extended L2 switch receives a terminal registration deletion message from the lower communication path (step S10), the corresponding entry information is deleted from the subordinate tree forwarding table 401 based on the received terminal registration deletion message (step S11). Further, the received terminal registration deletion message is transferred to the above-mentioned default upper channel (step S12).

  Next, the operation of bypass communication at the time of normal communication message transmission will be described with reference to FIGS. 3, 5-1 to 5-5, and FIGS. 8 to 13. FIG. 3 is a diagram for explaining bypass communication when the calling terminal 101 transmits a communication message to the called terminal 109, 301 is a MAC communication message transmitted by the terminal 101, and 302 is a bypassable extension L2. A MAC communication message with a detour request identifier transmitted by the switch 151, 303 is a MAC communication message transmitted by the detourable extended L2 switch 153, 304 is a detour response message, and 305 is a detour communication message. FIG. 5A illustrates the MAC communication message 301 transmitted from the terminal 101 or the MAC communication message 303 transmitted from the bypassable extended L2 switch 153, and FIG. 5B illustrates the bypass request identifier transmitted from the bypassable extended L2 switch 151. 5-3 shows a bypass response message 304, FIG. 5-4 shows a bypass communication message 305 encapsulating the MAC communication message 301, and FIG. 5-5 shows a bypass bypass message 306. Show.

  Hereinafter, a bypass communication operation when the calling terminal 101 transmits a communication message to the called terminal 109 will be described. When the calling terminal 101 communicates with the called terminal 109, the calling terminal 101 transmits a communication message 301 as shown in FIG. 5A to the extended L2 switch 121. This communication message 301 includes a communication header part including a destination MAC address (in this case, the MAC address I of the terminal 109), an originating MAC address (in this case, the MAC address A of the terminal 101), and a higher-level protocol identifier, and communication data. It consists of a payload part.

  Upon receiving such a communication message 301, the extended L2 switch 121 executes a process as shown in FIG. FIG. 8 shows an operation procedure when a normal communication message in the extended L2 switch other than the bypassable extended L2 switch is received from the lower communication path. When the extended L2 switch 121 receives the communication message 301 from the lower-level communication path (step S20), the extended L2 switch 121 searches the subordinate tree transfer table 401 using the destination MAC address (in this case, the MAC address I of the terminal 109) in the communication message 301 as a key. (Step S21). If there is an entry in the subordinate tree transfer table 401 as a result of this search (step S22), the communication message 301 is transmitted to the corresponding lower-level communication path (step S23), and no entry exists in the subordinate tree transfer table 401. (Step S22), the communication message 301 is transferred to its default output communication path (in this case, the communication path 201). In this case, since the terminal 109 is not under the control of the extended L2 switch 121, there is no entry in the subordinate tree transfer table 401, and the extended L2 switch 121 transfers the communication message 301 to its default output communication path 201. Become.

  The extended L2 switch 122 that has received the communication message 301 from the communication path 201 performs the same operation as described above with the extended L2 switch, and as a result, transfers the communication message 301 to the default communication path 203.

  When the bypassable expansion L2 switch 151 receives the communication message 301, the bypassable expansion L2 switch 151 executes a process as shown in FIG. FIG. 9 shows an operation procedure when a normal communication message in the bypassable extension L2 switch is received from the lower communication path. When the bypassable extended L2 switch 151 receives the communication message 301 from the lower-level communication path (step S30), the subordinate tree forwarding table 401 uses the destination MAC address (in this case, the MAC address I of the terminal 109) in the communication message 301 as a key. Is searched (step S31). If there is an entry in the subordinate tree transfer table 401 as a result of this search (step S32), the communication message 301 is transmitted to the corresponding lower-level communication path (step S33), and no entry exists in the subordinate tree transfer table 401. Next (step S32), the bypass transfer table 402 is searched using the destination MAC address as a key (step S34).

  If there is an entry in the bypass transfer table 402 as a result of this search (step S35), the bypassable extended L2 switch 151 transmits a communication message 301 to the corresponding bypass communication path (step S36), and the bypass transfer table 402 If there is no entry (step S35), the communication message 302 is inserted with the detour request identifier 501 and the address 502 (N1) necessary for performing communication to the own switch on the detour communication network 176 in the communication message 301. It is generated (step S37), and the generated communication message 302 with the detour request identifier is transferred to its own default output communication path (in this case, the communication path 232 of the L2 upper tree network 171) (step S38).

  FIG. 5-2 shows a communication message 302 with a detour request identifier, in which a detour request identifier 501 is inserted in the communication header portion, and a detour source address 502 (on the detour communication network of the detourable extension L2 switch 151) in the payload portion. MAC address N1) is inserted. In this case, the upper protocol identifier present in the communication header portion in the communication message 301 is moved to the payload portion in the communication message 302 with the detour request identifier.

  In this case, the bypassable extended L2 switch 151 cannot find the destination MAC address in the communication message 301 from either the subordinate tree transfer table 401 or the bypass transfer table 402. A communication message 302 with a request identifier is created, and the created communication message 302 with a detour request identifier is transmitted to the L2 upper tree network 171.

  The extended L2 switch 162 of the L2 upper tree network 171 performs processing as shown in FIG. 8 using the received MAC address (in this case, the MAC address I of the terminal 109) in the received communication message 302 with the detour request identifier as a key. , The subordinate tree forwarding table 401 is searched, but since the corresponding output communication path cannot be found in this case as well, the received communication message 302 with the detour request identifier is further transmitted via the default output communication path 231. Transfer to upper extended L2 switch 161.

  Since the highest-level extended L2 switch 161 has received the terminal registration message from all the terminals in all the L2 tree networks 172 to 175, the subordinate tree transfer table 401 in which data relating to the addresses of all the terminals in the network is registered is displayed. have. Therefore, the highest-order extended L2 switch 161 can determine that the destination terminal 109 exists on the output communication path 234 side by performing the processing as shown in FIG. The communication message 302 is transmitted to the lower extended L2 switch 163 via the output communication path 234.

  When the lower extended L2 switch 163 receives the communication message 302 with the detour request identifier via the output communication path 234, the process as shown in FIG. 10 is executed. FIG. 10 shows an operation procedure when a normal communication message in the extended L2 switch other than the bypassable extended L2 switch is received from the upper communication path. When the extended L2 switch 163 receives the communication message 302 with the detour request identifier from the upper communication path (step S40), the extended L2 switch 163 uses the destination MAC address (in this case, the MAC address I of the terminal 109) in the communication message 302 as a key. The subordinate tree transfer table 401 is searched (step S41). If there is an entry in the subordinate tree transfer table 401 as a result of this search (step S42), the communication message 302 with the detour request identifier is transmitted to the corresponding lower communication path (step S44), and the subordinate tree transfer table 401 is displayed. If there is no entry (step S42), the received packet is discarded (step S43). In this case, since the terminal 109 is under the extension L2 switch 163, an entry exists in the subordinate tree forwarding table 401. Therefore, the extension L2 switch 163 communicates with its default output communication path 236 with a bypass request identifier. The message 302 will be transferred.

  When receiving the communication message 302 with the detour request identifier, the detourable extended L2 switch 153 executes processing as shown in FIG. FIG. 11 shows an operation procedure when a normal communication message in the bypassable extension L2 switch is received from the upper communication path. When the bypassable extended L2 switch 153 receives the communication message 302 with the bypass request identifier from the higher-level communication path (step S50), the destination MAC address in the communication message 302 (in this case, the MAC address I of the terminal 109) is used as a key. The subordinate tree forwarding table 401 is searched (step S51). If no entry exists in the subordinate tree forwarding table 401 as a result of this search (step S52), the received packet is discarded (step S53).

  On the other hand, if there is an entry in the subordinate tree forwarding table 401, the bypassable extended L2 switch 153 next determines whether or not a bypass request identifier exists in the received message (step S54). If the detour request identifier does not exist in the received message, the received message is transferred to the corresponding lower communication path obtained from the subordinate tree transfer table 401 (step S57).

  However, in this case, since the bypass request identifier exists in the received message, the bypassable extended L2 switch 153 determines that the bypass request identifier 501 and the bypass source address 502 (from the received communication message 302 with the bypass request identifier By acquiring the MAC address N1 on the bypass communication network of the bypassable extended L2 switch 151) and deleting these extension header parts (the bypass request identifier 501 and the bypass source address 502), the original information shown in FIG. The communication message 303 is restored (step S55). The restored communication message 303 is transferred to the corresponding lower-level communication path 222 obtained from the subordinate tree transfer table 401 (step S57).

  The communication message 303 finally reaches the destination terminal 109 via the extended L2 switches 143 and 140 when the extended L2 switches 143 and 140 perform the processing shown in FIG.

  On the other hand, the detour destination expansion L2 switch 153 creates the detour response message 304 shown in FIG. 5-3 after performing the process of step S55, and creates the detour response message 304 via the detour communication path 243. The data is transmitted to the L2 switch 151 (step S56). Specifically, as shown in FIG. 5C, the detour destination extended L2 switch 153 sets the source address as its own MAC address N2, and the destination address as the extended L2 switch indicated by the detour source address in the communication message 302. Create a detour response message 304 with address N1 (502), a communication header part with a detour response identifier 503 added, and the payload part of the MAC address I of the destination terminal 109 indicated as the destination MAC address in the communication message 302 Then, the created detour response message 304 is transmitted to the detour source extended L2 switch 151 via the detour communication path 243.

  As shown in FIG. 12, when the bypass source extension L2 switch 151 receives the bypass response message 304 via the bypass communication channel 243 (step S60), the communication channel from the received bypass response message 304 to the bypass destination extension L2 switch Information (MAC address N2 on the detour communication network 176 of the detour destination extended L2 switch 153 that is the source address in the detour response message 304) and the MAC address I of the destination terminal 109 (payload part in the detour response message 304) are acquired. Then, the acquired information is newly registered in the bypass transfer table 402 (step S61).

  As a result, the communication message 301 to the destination terminal 109 that has arrived at the detour-source extension L2 switch 151 from the lower communication path thereafter is detoured at steps S34 and S35 in the flowchart of FIG. The search of the transfer table 402 will be hit.

  As described above, the communication message 301 hit in the search of the detour transfer table 402 of the detour source extended L2 switch 151 is changed into a communication message 305 as shown in FIG. 5-4, for example, according to the communication format of the corresponding detour communication path 243. Encapsulated. In FIG. 5-4, the received communication message 301 is used as the payload portion of the encapsulated communication message 305, and this payload portion uses the MAC address of the bypass source extended L2 switch 151 as the source address, and the bypass destination extended L2 The MAC address of the switch 153 is a destination address, and is further encapsulated by a communication header portion having a bypass communication identifier. The detour source extended L2 switch 151 directly transfers the created encapsulated communication message 305 to the detour destination extended L2 switch 153 via the detour communication path 243. As described above, as the encapsulation, a connection type tunnel such as MPLS LSP, or a non-connection type tunnel such as MAC MACinMAC or IP L2TP is adopted.

  The detour-destination extended L2 switch 153 that has received the encapsulated communication message 305 via the detour communication path 243 executes processing as shown in FIG. When receiving the encapsulated communication message 305 from the detour communication path 243 (step S71), the detour destination extended L2 switch 153 decapsulates the encapsulated communication message 305 and restores it to the original communication message 303. After this restoration, the detour destination extended L2 switch 153 searches the subordinate tree forwarding table 401 using the destination MAC address in the decapsulated communication message 303 (in this case, the MAC address I of the terminal 109) as a key (step S72). . If there is a transfer entry as a result of this search (step S73), the decapsulated communication message 303 is transferred to the corresponding lower-level communication path (in this case, the communication path 222) obtained from the subordinate tree transfer table 401 (step S73). S74). The communication message 303 finally reaches the destination terminal 109 via the extended L2 switches 143 and 140 when the extended L2 switches 143 and 140 perform the processing shown in FIG.

  If the forwarding entry corresponding to the destination MAC address in the decapsulated communication message 303 does not exist in the subordinate tree forwarding table 401 as a result of the search in step S72 (step S73), the detour destination extended L2 switch 153 -5, a bypass impossible message 306 is transmitted to the bypass source extended L2 switch 151 via the bypass communication path 243 (step S75), and the encapsulated communication message 305 received via the bypass communication path 243 is further transmitted. Discard (step S76). As shown in FIG. 5-5, the non-routable message 306 is a communication header part in which the originating address is its own MAC address N2, the called address is the originating address N1 in the encapsulated communication message 305, and the detour deletion identifier 505 is added. And the MAC address I of the destination terminal 109 indicated as the destination MAC address of the payload part in the encapsulated communication message 305 is the payload part.

  As shown in FIG. 14, when the bypass source extension L2 switch 151 receives the bypass impossible message 306 via the bypass communication path 243 (step S80), the destination MAC address existing in the payload portion (in this case, the terminal 109) The entry corresponding to the MAC address I) is deleted from the detour transfer table (step S81).

  As described above, the communication message related to the destination terminal registered in the detour transfer table of the detour source extended L2 switch is transferred to the destination terminal via the detour communication path without passing through the upper tree network. .

  As described above, in the first embodiment, the extended L2 switch is configured in a tree shape, and the terminal issues a terminal registration message to the highest-order extended L2 switch, so that all extended L2 in the upper and lower L2 tree networks can be obtained. The switch registers the correspondence relationship between all the terminals existing under the tree of its own switch and its output communication path in the subordinate tree forwarding table, and routes the MAC frame to the destination terminal by unicast based on this subordinate tree forwarding table. As a result, broadcasting to destination terminals existing under the tree of the own switch can be suppressed. Further, a communication message to a destination terminal that does not exist in the subordinate tree forwarding table is output by unicast to the default output communication path of the extended L2 switch, transferred to the upper level of the tree, and finally has an entry in the subordinate tree forwarding table. Since it reaches the L2 switch and loops back to reach the destination terminal, all unnecessary broadcasts can be suppressed in the entire upper and lower L2 tree networks.

  Further, the detour source extended L2 switch detects the correspondence between the destination terminal address and the detour destination extended L2 switch 153 using the detour forwarding table, and then transmits a communication message directly to the detour destination extended L2 switch using the detour communication network. As a result, the communication load generated in the extended L2 switch of the upper L2 tree network, particularly the uppermost extended L2 switch, can be greatly reduced, and the number of terminals that can be accommodated in the entire L2 tree network can be increased. . Further, the detour source extended L2 switch transmits a communication message with a detour request identifier, and the detour destination extended L2 switch detects the communication message with the detour request identifier, thereby including data to be registered in the detour transfer table. By sending the detour response message to the detour source extension L2 switch, the detour source extension L2 switch can grasp the address of the detour destination extension L2 switch. The processing time required for searching can be shortened, and efficient bypass communication can be realized. Furthermore, since the detour extension L2 switch directly makes a detour notification to the detour source extension L2 switch, dynamic information given by the detour destination expansion L2 switch, for example, when the detour communication network is realized by L2-VPN In addition, there is an effect that information such as a label paid out by the detour destination expansion L2 switch to the detour source expansion L2 switch can be added.

  In the upper L2 tree network 171, a communication message with a detour request identifier is transferred in a unicast manner from the detour source extended L2 switch to the detour destination extended L2 switch, whereby a detour communication path to the detour destination extended L2 switch and the destination terminal. Therefore, it is possible to communicate by unicast without generating unnecessary broadcast that occurs in the virtual private LAN service (VPLS) even in the bypass communication network, and the amount of communication traffic in the bypass communication network Can be reduced, and even in a situation where only one-way communication from the originating terminal to the destination terminal occurs, it can be reliably transmitted to the destination terminal by unicast.

  Furthermore, in the detour transfer table 402 of the detour source extended L2 switch, a correspondence entry between the destination terminal address and the detour destination expanded L2 switch address is created only when a communication request to the destination terminal occurs and detour is executed. There is no need to register terminal addresses in all L2 tree networks in advance in the detour-source extended L2 switch, and the number of necessary entries in the detour transfer table 402 can be greatly reduced.

  Further, the detour-source extended L2 switch transmits only the message received from the communication path of the lower subtree having no corresponding entry in the subordinate tree transfer table 401 and having the corresponding entry in the detour transfer table 402 to the detour communication path. In the extended L2 switch, only a message received from the detour communication path and having a corresponding entry in the subordinate tree transfer table 401 is transmitted to the communication path of the lower subtree, and there is no corresponding entry in the subordinate tree transfer table 401 Is discarded so that the entire upper and lower L2 tree networks are kept loop-free, eliminating the need to operate the STP (Spanning Tree) protocol and reducing the amount of communication messages and processing load required for STP protocol operation. There is also an effect that can be done.

  In this system, the term “extended L2 switch” is used for each L2 switch constituting the tree network. As described above, the extended L2 switch creates the subordinate tree forwarding table based on the terminal registration message transmitted from the terminal or the edge switch that accommodates the terminal, and the subordinate tree transfer is performed for the communication message from the lower communication path. If there is no entry in the table, it is unicast to a predetermined default communication path leading to the upper tree network, and if there is an entry in the subordinate tree forwarding table, it is unicast to the corresponding lower communication path and a communication message from the upper communication path. As for the message, if there is no entry in the subordinate tree forwarding table, the message is discarded, and if there is an entry in the subordinate tree forwarding table, the message is transferred so as to be unicast to the corresponding lower channel. Since such message transfer is performed, in the present L2 tree network, the detour source extended L2 switch can know the detour destination extended L2 switch address uniquely specified and the output communication path to the destination terminal.

  On the other hand, in the normal L2 switch, until all the L2 switches learn the output communication path to the destination terminal by packet transmission from the destination terminal, the above-described uniquely specified detour destination extended L2 switch address and the destination terminal Cannot be realized in the detour source expansion L2 switch. In other words, a normal L2 switch cannot broadcast to all output communication paths of the L2 switch or learn all terminals in the network until the output communication path to the destination terminal is learned by packet transmission from the destination terminal. Since the broadcast occurs when the MAC entry overflows, the above function cannot be obtained.

Embodiment 2. FIG.
Next, Embodiment 2 will be described with reference to FIG. In the first embodiment, the upper tree network 171 and the bypass communication network 176 are physically separated. However, in the second embodiment, these two networks are multiplexed on the physically same network. However, this is realized by logically separating the upper tree network and the bypass communication network.

  FIG. 15 shows a network configuration diagram of the second embodiment showing multiplexing of the upper tree network and the bypass communication network. The L2 switch network shown in FIG. 15 has a physical communication network 662, a logical upper tree network 661 and a logical bypass communication network 663 multiplexed on the physical communication network 662.

  The physical communication network 662 includes a plurality of physical communication devices 611 to 620 and physical lines 621 to 631 that connect the physical communication devices 611 to 620. The logical upper L2 tree network 661 includes detourable extended L2 switches 601 to 604, extended L2 switches 605 to 607, and extended L2 inter-switch logical lines 641 to 646. On the other hand, the logical bypass communication network 663 is configured by the bypassable extended L2 switches 601 to 604 and the bypass communication paths 651 to 656, and is configured on the same physical communication network 662 as the logical upper tree network 661. Has been.

  In the configuration of the second embodiment, the upper L2 tree network 661 and the bypass communication network 663 are multiplexed on the same physical network 662. For example, the physical communication devices 611 to 620 on the physical communication network 662 are configured by commercially available VLAN (virtual private LAN) compatible L2 switches, and VLAN operations are performed on the L2 switches. This is realized by separating the logical bypass communication network 663.

  When the diversion source / diversion-destination extended L2 switches 601 and 603 perform the creation process of the subordinate tree forwarding table 401 by the terminal registration message and the MAC communication message forwarding process based on the subordinate tree forwarding table 401 described in the first embodiment Performs the extended L2 switch communication operation with the logical extended L2 switches 605 to 607 using the logical lines 641 to 644 between the extended L2 switches using the logical upper tree network 661.

  Further, the detour-source / detour-destination-capable extension L2 switches 601 and 603 are configured to transmit the detour response message 304 described in Embodiment 1 and the detour communication message 305 encapsulating the MAC communication message 301 based on the detour forwarding table 402. When performing the transmission process, the logical bypass communication network 663 is used, and the logical bypass communication operation is performed using the bypass communication path 655.

  As described above, according to the second embodiment, since the upper tree network and the bypass communication network are logically configured on the same physical communication network, the configuration cost of the physical communication network can be reduced. is there.

Embodiment 3.
Next, Embodiment 3 will be described with reference to FIG. In the second embodiment, the logical upper tree network and the bypass communication network are configured on the same physical communication network. However, in the third embodiment, the upper tree network and the bypass communication network are constructed on different physical communication networks. In addition, the fault tolerance is improved by using each other as a backup network.

  FIG. 16 shows a network configuration diagram of the third embodiment, where the upper tree network 701 and the bypass communication network 702 are physically separated. In the detour communication network 702, detour communication address resolution servers 711 to 712 for resolving detour communication addresses of the detourable expansion L2 switches 741 to 744 are installed. These detour communication address resolution servers 711 to 712 operate as a replication distributed database, and registration in a detour communication address resolution server is reflected in all detour communication address resolution servers.

  Next, the operation will be described. First, for example, the extended L2 switches 731, 741, 733, and 734 learn the output communication path to the terminal 722 with the reception of the terminal registration message 761 transmitted by the terminal 722 in the lower L2 tree network as a trigger. . That is, registration to the subordinate tree transfer table 401 is performed by the extended L2 switches 731, 741, 733, and 734.

  Further, triggered by the reception of the terminal registration message 761, the bypassable extended L2 switch 741 transmits the terminal registration including the MAC address B of the terminal 722 and the address N2 on its own bypass communication network to the bypass communication address resolution server 712. The message 762 is transmitted, and the correspondence relationship between the MAC address B of the terminal 722 and the address N2 on its own bypass communication network is registered in the bypass communication address resolution server 712.

  Next, for example, when the bypass source extended L2 switch 743 normally receives a communication message, the communication message 302 shown in FIG. 5-2 is first shown to the upper L2 tree network 701 in the same manner as in the first embodiment. The same communication message 751 is transmitted. Thereafter, the detour source extension L2 switch 743 receives a detour response message 763 similar to the detour response message 304 shown in FIG. 5-3 from the detour destination expansion L2 switch 741, and then uses the detour communication network 702 as shown in FIG. A communication message 752 similar to the communication message 305 shown in FIG. This communication message 752 reaches the destination terminal 722 in the same manner as in the first embodiment. In such a normal time, an inquiry to the bypass communication address resolution server does not occur.

  On the other hand, when the bypass source extended L2 switch 743 is notified or detects the occurrence of a failure in the upper L2 tree network 701 by some means, the bypass source extended L2 switch 743 uses the MAC address of the destination terminal 722 as a key for address resolution. The request 764 is acquired by the bypass communication address resolution server 711. As described above, in this case, since the correspondence between the MAC address B of the terminal 722 and the address N2 on the bypass communication network 702 of the bypass destination extended L2 switch 741 is registered in the bypass communication address resolution server, The detour source extended L2 switch 743 acquires from the detour communication address resolution server 711 the address N2 (765) on the detour communication network 702 of the detour destination extended L2 switch 741 corresponding to the MAC address B of the destination terminal 722. Therefore, the bypass source extension L2 switch 743 transmits the communication message 752 to the bypass destination extension L2 switch 741 via the bypass communication network 702 using the acquired address N2 of the bypass destination extension L2 switch 741. This communication message 752 reaches the destination terminal 722 in the same manner as in the first embodiment.

  Further, when a failure occurs in the bypass communication network 702, the bypass extension L2 switch 743 cannot receive the bypass response message 763 that the bypass extension L2 switch 741 notifies the bypass extension L2 switch 743 using the bypass communication network 702. The occurrence of a failure in the bypass communication network 702 can be detected. When the occurrence of a failure in the bypass communication network 702 is detected, the bypass source extended L2 switch 743 transmits a communication message 751 using the upper L2 tree communication network 701 while the failure occurs in the bypass communication network 702. Thus, the communication message is transmitted to the required destination terminal 722.

  As described above, according to the third embodiment, since the bypass communication address resolution server for resolving the bypass address is installed, even if a failure occurs in the upper tree network, the bypass source extended L2 switch can be used as the address resolution server. The address of the detour extension L2 switch is resolved for the network, and the communication can be continued using the detour communication network. Even if a failure occurs in the upper tree network, the communication can be continued. Can be increased. Further, when a failure occurs in the bypass communication network, it is detected that the bypass response message does not reach the bypass source extension L2 switch from the bypass destination extension L2 switch, and the bypass source extension L2 switch uses the bypass communication network based on this detection. However, since communication is switched to communication using the upper tree network, communication can be continued even if a failure occurs in the bypass communication network, and fault tolerance can be improved. In addition, since a plurality of bypass communication address resolution servers are arranged to distribute the load and the number of hops from the bypass source extended L2 switch is shortened, the waiting time of the response message that the bypass source extended L2 switch obtains from the bypass communication address resolution server is reduced. There is also an effect that it can be shortened.

Embodiment 4.
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the above embodiment, the bypassable extended L2 switch reduces the communication load of the upper L2 tree network as much as possible by always using the bypass communication path when the bypass communication path is usable. 4, when the administrator or the management device controls the use of the bypass communication path, when the L2 switch of the upper L2 tree network is not overloaded, communication is performed using the upper L2 tree network. When the L2 switch is in an overload state, switching is performed so that communication is performed using a bypass communication network.

  FIG. 17 is a network configuration diagram for realizing the fourth embodiment. Extended L2 switch of the upper L2 tree network In this case, the highest extended L2 switch 834 is connected to the detour management device 861. Under the control of the bypass management device 861, the extended L2 switch 834 normally bypasses the same communication message 851 as the communication message 302 including the bypass request identifier shown in FIG. 5-2 transmitted from the bypass source extended L2 switch. The request identifier is deleted, a communication message 852 with the bypass request identifier deleted is transmitted, and the bypass processing between the bypass source extended L2 switch 843 and the bypass destination extended L2 switch 841 is not executed.

  Next, the operation will be described. The extended L2 switch 834 of the upper L2 tree network notifies the detour management device 861 of the statistical information 862 of traffic passing through the extended L2 switch 834 for each address of the detour request source extended L2 switch at regular intervals. The detour management device 861 determines the load state of the extended L2 switch 834 based on the notified traffic statistical information 862. If it is determined that the extended L2 switch 834 is in an overload state, the detour request identifier is deleted. The extended L2 switch 834 is notified to stop (863).

  By this notification 863, the extended L2 switch 834 transmits the communication message 851 with a detour request identifier without deleting the detour request identifier. As a result, the detour destination extended L2 switch 841 receives the communication message 851 with the detour request identifier, and deletes the detour request identifier from the communication message 851 and transmits it to the destination terminal 822 as in the first embodiment. At the same time, the detour response message 853 shown in FIG. 5-3 is transmitted to the detour source extended L2 switch 843. The detour source extended L2 switch 843 that has received this detour response message 853 performs a detour operation via the detour communication network 802 by the same operation as in the first embodiment.

  As described above, in the fourth embodiment, when the L2 switch 834 of the upper L2 tree network is not overloaded, the bypass management device 861 performs communication using the upper L2 tree network, and the L2 switch 834 of the upper L2 tree network. Is switched so that communication is performed using the bypass communication network when the network is in an overload state, traffic increase in both the upper L2 tree network and the bypass communication network is prevented, and the upper L2 tree is prevented. The network and the bypass communication network can be used efficiently.

  When the detour communication network is connection-type, the detour management device 861 monitors the continuation time (continuity) of traffic between terminals, and performs communication for sporadic traffic using the upper L2 tree network for a predetermined time. If switching is performed so that communication is performed using the bypass communication network for the traffic that continues as described above, it is possible to reduce the load of connection setting processing of the bypass communication network due to sporadic traffic.

  As described above, the layer 2 communication system according to the present invention is useful for a layer 2 switch tree network in which layer 2 switches are arranged in a tree shape.

It is a figure which shows the L2 switch network of Embodiment 1 to which this invention is applied. 6 is a diagram illustrating a transfer state of a terminal registration message in the L2 switch network according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating a transfer state of various communication messages in the L2 switch network according to the first embodiment. It is a block diagram which shows the registration content of the subordinate tree forwarding table in an extended L2 switch. It is a block diagram which shows the registration content of a subordinate tree transfer table and a detour transfer table in a detour expansion L2 switch. It is a figure which shows the MAC communication message which a terminal transmits / receives. It is a figure which shows the MAC communication message with the detour request identifier which a detourable extended L2 switch transmits. It is a figure which shows a detour response message. It is a figure which shows the detour communication message which encapsulated MAC communication message. It is a figure which shows a message which cannot be bypassed. It is a flowchart which shows the operation | movement at the time of the terminal registration message reception in an extended L2 switch and a bypassable extended L2 switch. It is a flowchart which shows the operation | movement at the time of the terminal registration deletion message reception in an extended L2 switch and a bypassable extended L2 switch. It is a flowchart which shows operation | movement when a MAC communication message is received from the low-order communication path in an extended L2 switch. It is a flowchart which shows operation | movement when a MAC communication message is received from the low-order communication path in a bypassable expansion L2 switch. It is a flowchart which shows operation | movement when a MAC communication message is received from the high-order communication path in an extended L2 switch. It is a flowchart which shows operation | movement when a MAC communication message is received from the high-order communication path in a detour expansion L2 switch. It is a flowchart which shows operation | movement when the detour response message in a detour expansion L2 switch is received. It is a flowchart which shows operation | movement when the communication message from the detour communication path in a detour expansion L2 switch is received. It is a flowchart which shows an operation | movement when the bypassing impossible message in a bypassable expansion L2 switch is received. It is a figure which shows the L2 switch network of Embodiment 2 to which this invention is applied. It is a figure which shows the L2 switch network of Embodiment 3 to which this invention is applied. It is a figure which shows the L2 switch network of Embodiment 4 to which this invention is applied.

Explanation of symbols

101-109 terminal 121-144 extended L2 switch 151-154 bypassable extended L2 switch 161-163 extended L2 switch 171 upper tree network 172-175 lower tree network and 176 bypass communication network 201-224 communication path 231-236 communication path 241 ~ 243 Detour communication path (tunnel)
251,252 Terminal registration message 301-302 Communication message 304 Detour response message 305 Encapsulated communication message (detour communication message)
306 Non-routable message 401 Subordinate tree transfer table 402 Diverted transfer table 661 Logical upper L2 tree network 662 Physical communication network 663 Logical detour communication network 711, 712 Detour communication address resolution server 861 Detour management device.

Claims (8)

A plurality of first layer 2 communication devices connected to the communication path, and a plurality of second layer 2 communication devices connected to the bypass communication path in addition to the communication path, and the first and second layers A layer 2 communication system configured by connecting a plurality of tree networks in which two communication devices are connected in a tree shape and connecting the second layer 2 communication devices by a detour communication path;
The first and second layer 2 communication devices are
A subordinate tree forwarding table in which the correspondence between the address of each terminal existing under its own and the output communication path to the terminal is registered;
Based on this subordinate tree forwarding table, the communication message to each terminal existing under its own is transferred to the corresponding output communication path, and the communication message to the terminal that does not correspond to the subordinate tree forwarding table and does not exist under its own subordinate First message transfer means for unicast transfer to a predetermined default communication path leading to the upper tree network;
With each
The second layer 2 communication device is:
A detour transfer table in which a correspondence relationship between a destination terminal address of a communication message to be bypassed and an address of a second layer 2 communication device of a tree network to which the destination terminal belongs is registered;
A second communication message having the destination terminal address registered in the detour transfer table is detoured via the detour communication path to the address of the second layer 2 communication device registered in the detour transfer table; Message transfer means,
A layer 2 communication system comprising:   The first and second layer 2 communication devices perform data registration in the subordinate tree forwarding table based on receiving a terminal registration message including a MAC address of the terminal issued by the terminal. The layer 2 communication system according to 1. The first message transfer means of the second layer 2 communication device that is the detour creates a communication message in which the detour request identifier indicating the detour request and its own address are inserted into the received communication message from the originating terminal. Forward to the default channel,
Upon receiving the communication message in which the detour request identifier and the address of the detour source second layer 2 communication device are inserted, the detour second second layer 2 communication device receives the detour source second via the detour communication path. Send a detour response message including its own address and the address of the partner terminal to the layer 2 communication device,
3. The layer 2 communication system according to claim 1, wherein the second layer 2 communication device that is a bypass source performs data registration in the bypass transfer table based on reception of the bypass response message.   When the detour destination second layer 2 communication device receives the communication message in which the detour request identifier and the address of the detour source second layer 2 communication device are inserted, the detour request identifier and the detour source first The address of the second layer 2 communication device is deleted, and the communication message from which the detour request identifier and the address of the second layer 2 communication device of the detour source are deleted is transferred to the counterpart terminal based on the subordinate tree forwarding table. The layer 2 communication system according to claim 3. The second message transfer means of the second layer 2 communication device as the detour source encapsulates the communication message received in the first communication format in the second communication format when detouring the communication message to the detour communication path. Forward and
The second layer 2 communication device of the detour destination decapsulates the communication message encapsulated in the second communication format received via the detour communication path into the communication message of the first communication format, and decapsulates the communication message. The layer 2 communication system according to any one of claims 1 to 4, characterized in that: is transferred to a counterpart terminal based on a subordinate tree forwarding table.   If the destination terminal address included in the decapsulated communication message is not registered in the subordinate tree forwarding table, the second layer 2 communication device of the detour destination discards the communication message and also transmits the second detour source second communication device. 6. The layer 2 communication system according to claim 5, wherein a non-routable message for instructing deletion of registration from the detour transfer table is transmitted to the layer 2 communication device via the detour communication path.   Among the first layer 2 communication devices, a predetermined layer 2 communication device positioned higher in the tree includes a detour request identifier transmitted from the detour source second layer 2 communication device and a detour source second layer 2 When receiving the communication message in which the address of the communication device is inserted, the communication message in which the address of the detour request identifier and the second layer 2 communication device of the detour source is inserted is transferred as it is, or the detour request identifier and the detour source The layer 2 communication system according to any one of claims 3 to 6, further comprising switching means for switching whether to delete the address of the second layer 2 communication device for transmission. Connecting a plurality of layer networks connected in a tree shape to a plurality of layer 2 communication devices connected to the communication path and a plurality of bypassable layer 2 communication devices connected to the bypass communication path in addition to the communication path A detourable layer 2 communication device used in a layer 2 communication system configured and configured by connecting detourable layer 2 communication devices via a detour communication path,
A subordinate tree forwarding table in which the correspondence between the address of each terminal existing under its own and the output communication path to the terminal is registered;
Based on this subordinate tree forwarding table, the communication message to each terminal existing under its own is transferred to the corresponding output communication path, and the communication message to the terminal that does not correspond to the subordinate tree forwarding table and does not exist under its own subordinate First message transfer means for unicast transfer to a predetermined default communication path leading to the upper tree network;
A detour transfer table in which a correspondence relationship between a partner terminal address of a communication message to be bypassed and an address of a detourable layer 2 communication device of a tree network to which the partner terminal belongs is registered;
A second communication message having a destination terminal address registered in the detour transfer table is detoured via the detour communication path to the detourable layer 2 communication device address registered in the detour transfer table. Message transfer means;
A detourable layer 2 communication device comprising:

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