JP4980200B2 - Data communication system and transfer frame - Google Patents

Description

  The present invention relates to a technique capable of easily increasing the number of VPNs (Virtual Private Networks) in a wide area Ethernet network (Ethernet is a registered trademark).

  VPN is a service that can use a public line network provided by a telecommunications carrier as if it were a dedicated line between subscribers. This VPN is possible using VLAN (Virtual LAN) technology used in Ethernet. This VLAN is represented by a 12-bit VLAN-ID (sometimes abbreviated as “VID”), can identify 4096 or less VLANs, and can identify 4096 or less VPNs.

  Here, in the wide area Ethernet, it is assumed that a public line network provided by a communication carrier is used as a carrier backbone, and it is desired that more than 4096 VPNs can be provided.

  As a technology capable of providing more than 4096 VPNs, in addition to the conventional VLAN tag including VLAN-ID, a new VLAN tag is prepared, and the VLAN exceeding 12 bits included in the plurality of VLAN tags. A technology for identifying more than 4096 VLANs by ID (referred to as “VLAN stacking technology”) is considered. However, when the VLAN stacking technology is used, a special switch having a function extension corresponding to the VLAN stacking technology is used as a switch for configuring the wide area Ethernet network. Compared with the case of using this switch, the price for constructing the wide area Ethernet network becomes high, resulting in an increase in communication cost.

Edited by Akiyoshi Aruta, “Overview of Wide-area Ethernet Technology”, The Institute of Electronics, Information and Communication Engineers, June 1, 2005, p. 38-40, p. 130-142

  An object of the present invention is to solve the above-described problems of the prior art and provide a technique capable of providing more than 4096 VPNs even when a conventional switch that does not support the VLAN stacking technique is used. .

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A data transmission system for transmitting data from a source host included in a first user network to a destination host included in a second user network via a virtual private line provided in a wide area network,
The wide area network is:
A source edge switch to which the source host is connected;
A destination edge switch to which the destination host is connected;
A core network configured by one or more core switches and connecting between the source edge switch and the destination edge switch;
With
The source edge switch generates a transfer frame from the user frame when a user frame including the data arrives from the source host, transfers the generated transfer frame to the core network,
When the transfer frame arrives, the core switch in the core network transfers the transfer frame as it is,
The destination edge switch generates the user frame from the transfer frame when the transfer frame arrives, transmits the generated user frame to the destination host,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. an n-bit (n is an integer) virtual network identifier in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The data transmission system, wherein the virtual private line identifier is defined corresponding to the virtual network identifier.

  In the first application example, the second partial identifier included in the MAC address for the destination edge switch and the MAC address for the source edge switch constituting the header of the transfer frame that transmits the wide area network, and the first partial identifier, An m-bit virtual private line identifier can be represented, and more virtual private lines can be identified than an n-bit virtual network identifier. Therefore, for example, when the wide area network is a wide area Ethernet, the number of VPNs that can be provided using the Ethernet VLAN technology applied to the local area network is 4096 or less, but more than 4096 VPNs are provided. can do.

  Further, the MAC address for the destination edge switch, the MAC address for the source edge switch, and the first partial identifier of the virtual private line that constitute the header of the transfer frame are respectively the destination MAC that constitutes the header of the user frame. It is configured to correspond to an address, a source MAC address, and a virtual network identifier. Thus, for example, when the wide area network is a wide area Ethernet, it is possible to construct a wide area Ethernet using a conventional switch that does not support the VLAN stacking technique described in the related art.

[Application Example 2]
A data transmission system according to Application Example 1,
The source edge switch is for the destination edge switch composed of the destination edge switch identifier and the second partial identifier based on the destination MAC address and the virtual network identifier included in the user frame. A data transmission system comprising a table for obtaining a MAC address, the first partial identifier, and a destination port for transferring the transfer frame.

  In Application Example 2, the transmission source edge switch can be easily configured with the transmission destination edge switch identifier and the second partial identifier based on the transmission destination MAC address and the virtual network identifier included in the user frame. The MAC address, the first partial identifier, and the destination port for transferring the transfer frame can be obtained, and the transfer frame can be generated and transferred from the obtained destination port.

[Application Example 3]
A data transmission system according to Application Example 2,
The core switch includes a table for obtaining a destination port for forwarding the forwarding frame based on the destination edge switch identifier constituting the destination edge switch MAC address included in the forwarding frame. Characteristic data transmission system.

  In the application example 3, the core switch can easily determine the destination port for forwarding the transfer frame based on the destination edge switch identifier constituting the MAC address for the destination edge switch included in the transfer frame, The transfer frame can be transferred from the destination port for which it was obtained.

[Application Example 4]
A data transmission system according to Application Example 3,
The transmission destination edge switch includes the first partial identifier included in the transfer frame, and the second partial identifier configuring the transmission destination edge switch MAC address and the transmission source edge switch MAC address. Based on the virtual private line identifier represented and the destination MAC address included in the transfer frame, a virtual network identifier corresponding to the destination host and a destination port for transmitting the user frame are obtained. A data transmission system comprising a table.

  In Application Example 4, the transmission destination edge switch is represented by the first partial identifier included in the transfer frame, and the second partial identifier constituting the transmission destination edge switch MAC address and the transmission source edge switch MAC address. A virtual private network identifier corresponding to the destination host and a destination port for transmitting the user frame can be easily obtained based on the virtual private line identifier and the destination MAC address included in the transfer frame. The frame can be transmitted from the destination port from which the frame was obtained.

[Application Example 5]
The transmission source host of a data transmission system for transmitting data from a transmission source host included in the first user network to a transmission destination host included in the second user network via a virtual private line provided in the wide area network A source edge switch to which the destination host is connected, a destination edge switch to which the destination host is connected, and one or more core switches, and connects between the source edge switch and the destination edge switch A transmission frame generated from the user frame in the destination edge switch for transmitting a user frame including the data in a wide area network comprising a core network,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. an n-bit virtual network identifier in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits (m> n) identifying the virtual private line A first partial identifier of n bits of the virtual private line identifier, and a header including the user frame excluding the virtual network identifier,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The transfer frame according to claim 1, wherein the virtual private line identifier is defined corresponding to the virtual network identifier.

  If the transfer frame of Application Example 5 is applied to the data transmission system, the second part included in the MAC address for the destination edge switch and the MAC address for the source edge switch that constitute the header of the transfer frame that transmits the wide area network The identifier and the first partial identifier can represent an m-bit virtual private line identifier, and can identify more virtual private lines than an n-bit virtual network identifier. Therefore, for example, when the wide area network is a wide area Ethernet, the number of VPNs that can be provided using the Ethernet VLAN technology applied to the local area network is 4096 or less, but more than 4096 VPNs are provided. can do.

  Further, the MAC address for the destination edge switch, the MAC address for the source edge switch, and the first partial identifier of the virtual private line that constitute the header of the transfer frame are the destination MAC that constitutes the header of the user frame, respectively. It is configured to correspond to an address, a source MAC address, and a virtual network identifier. Thus, for example, when the wide area network is a wide area Ethernet, it is possible to construct a wide area Ethernet using a conventional switch that does not support the VLAN stacking technique described in the related art.

[Form 1]
The transmission source host of a data transmission system for transmitting data from a transmission source host included in the first user network to a transmission destination host included in the second user network via a virtual private line provided in the wide area network A source edge switch to which the destination host is connected, a destination edge switch to which the destination host is connected, and one or more core switches, and connects between the source edge switch and the destination edge switch A transmission frame generated from the user frame in the source edge switch for transmitting a user frame including the data in a wide area network comprising a core network,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. an n-bit (n is an integer) virtual network identifier in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits ( m is from n) identifying the virtual private line. A first integer identifier of n bits of a virtual private line identifier of a large integer ) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The transfer frame according to claim 1, wherein the virtual private line identifier is defined corresponding to the virtual network identifier.
[Form 2]
In a data transmission system for transmitting data from a transmission source host included in a first user network to a transmission destination host included in a second user network via a virtual private line provided in a wide area network, the transmission destination host A source edge switch connected to a destination edge switch to which the source host is connected via a core network composed of one or more core switches, to which the source host is connected,
When a user frame including the data arrives from the source host, a transfer frame is generated from the user frame, and the generated transfer frame is transferred to the transfer destination edge switch via the core switch in the core network,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. n bits (n is an integer virtual network identifier) in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The virtual private line identifier is defined corresponding to the virtual network identifier.
A source edge switch characterized by that.
[Form 3]
In the data transmission system for transmitting data from a transmission source host included in the first user network to a transmission destination host included in the second user network via a virtual private line provided in the wide area network, the transmission source host Is connected to a source edge switch to which is connected via a core network composed of one or more core switches, and is a destination edge switch to which the destination host is connected,
When a forward frame transferred from the source edge switch via the core switch in the core network arrives, a user frame including the data transmitted from the source frame to the source edge switch is generated from the forward frame. And transmitting the generated user frame to the destination host,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. n bits (n is an integer virtual network identifier) in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The virtual private line identifier is defined corresponding to the virtual network identifier.
A destination edge switch characterized by that.
If the transmission source edge switch of the first aspect and the transmission destination edge switch of the second aspect are used, the data transmission system of the application example 1 can be configured.
Note that the present invention is not limited to the device invention such as the data communication system described above, but can also be realized as a method invention such as a data communication method.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. Network configuration:
B. Data transfer operation:
B1. Overview of operation:
B2. Operation in edge switch (ingress edge switch):
B3. Operation in the core switch:
B4. Operation in edge switch (Egress edge switch):
C. Effect D. Variations:

A. Network configuration:
FIG. 1 is an explanatory diagram showing a network to which a data communication system of the present invention is applied. In this network, as shown in FIG. 1, a wide area Ethernet network provided by a telecommunications carrier is interposed between user networks (subscriber networks). There are many network devices in the wide area Ethernet network, and they are connected to each other by lines. In the example of FIG. 1, three edge switches ESW1 to ESW3 among the edge switches existing at the edge portion of the wide area Ethernet network are shown, and a ring-shaped core network among the core switches existing inside the wide area Ethernet network is formed. 4 core switches CSW1 to CSW4 are shown. In the following description, when the edge switches ESW1 to ESW3 are not particularly distinguished, they are simply referred to as edge switches ESW. Further, when the core switches CSW1 to CSW4 are not particularly distinguished, they are simply referred to as the core switch CSW.

  Each user network is connected to each other by connecting to an edge switch ESW existing at the edge of the wide area Ethernet network. In the example of FIG. 1, the user 1 network, the user 2 network, and the user 3 network are connected to the port 1, port 2, and port 3 of the first edge switch ESW1, respectively, and the third edge switch The user 4 network, the user 5 network, and the user 6 network are connected to the port 2, port 3, and port 4 of the ESW 3, respectively, and the user 7 network is connected to the port 2 of the second edge switch ESW2. ing. Further, as hosts in the user 1 network, the user 2 network, and the user 3 network, the host A1, the host A2, and the host A3 are connected to the first edge switch ESW1, respectively. Hosts A3, A4, and B2 are connected to the third edge switch ESW3 as hosts in the network 5 and the user 6 network, respectively, and a host A5 is connected as the host in the user 7 network. 2 edge switch ESW2.

  In the following description, the same symbol as the name of each host is used for the MAC address of each host. For example, the MAC address of the host A1 is represented as “A1”. However, these MAC addresses are examples for facilitating the explanation, and the present invention is not limited to these. In addition, like the hosts A1 to A5, the hosts represented by the same alphabetic symbols are connected to the same VPN defined by the same VLAN-ID.

  In FIG. 1, all network devices, lines, and user networks that are not necessary for the following description are omitted for easy understanding of the drawing. The same applies to the drawings described later.

  Here, the edge switch ESW and the core switch CSW are configured as shown in FIG.

  FIG. 2 is a block diagram showing a configuration of a switch that can be used as an edge switch or a core switch. As shown in FIG. 2, the switch 100 mainly includes a control unit 110 and a communication unit 120. Among these, the control unit 110 includes a CPU 112, a memory 114, and the like. The CPU 112 executes a program stored in the memory 114, thereby performing management of the entire apparatus, packet processing, and the like. The memory 114 stores the program, data, and a management table as necessary. The communication unit 120 includes a network interface 122 and the like, and performs packet relay processing and the like. Each network interface 122 is connected to a physical line (twisted pair cable, optical fiber, etc.) such as Ethernet (registered trademark) via a port (not shown).

B. Data transfer operation:
In the following, with respect to the data transfer operation executed in the network shown in FIG. 1, when an Ethernet frame is transmitted from the host A1 in the user 1 network belonging to the same VPN to the host A3 in the user 4 network, (1) An operation outline, (2) operation in an edge switch as an ingress edge switch, (3) operation in a core switch, and (4) operation in an edge switch as an egress edge switch will be described in this order.

B1. Overview of operation:
First, it is assumed that the host A1 transmits an Ethernet frame (hereinafter referred to as “user frame”) according to the format shown in FIG. 3 to the host A3.

  FIG. 3 is an explanatory diagram showing the format of the user frame. As shown in the figure, the user frame has a 6-byte (byte) destination (destination) MAC address (DA) field, a 6-byte transmission source MAC address (SA) field, a 4-byte VLAN-TAG field, and 2 bytes. Each TYPE field and Payload field are arranged in this order.

  The VLAN-TAG field is further divided into a 2-byte TPID field and a 2-byte TCI field. The TCI field is further divided into a 3-bit PRI field, a 1-bit CFI field, and 12-bit CFI field. It is divided into bit VLAN-ID (VID) fields.

  When data is transmitted from the host A1 to the host A3, the MAC address “A1” of the host A1 is stored in the source MAC address field, and the MAC address “A3” of the host A3 is stored in the destination MAC address field. Inserts “1”. Note that “1” inserted in the VLAN-ID field indicates the VPN to which the host group represented by the symbol “A” belongs. The VLAN-ID indicating the VPN to which the host group represented by the symbol “B” belongs is represented by “2”. Note that these VLAN-IDs are examples for facilitating the explanation, and the present invention is not limited to these.

  When the user frame transmitted from the host A1 reaches the first edge switch ESW1 (referred to as “ingress edge switch”), the edge switch ESW1 transmits the reached user frame to the Ethernet according to the format shown in FIG. A frame (hereinafter referred to as a “transfer frame”) is transmitted from a destination port obtained as described later.

  The frame format is defined by, for example, IEEE 802.1Q.

  FIG. 4 is an explanatory diagram showing the format of the transfer frame. As shown in the figure, the transfer frame includes a 6-byte destination PMAC address (PDA) field, a 6-byte source PMAC address (PSA) field, a 2-byte TPID field, a 2-byte TCI field, and a 2-byte TYPE field. , Payload fields are arranged in this order.

  The destination PMAC address field is further divided into a 5-byte DSID field and an 8-bit VPN-U field. The DSID field is a field indicating an identifier of an edge switch as an egress edge switch to which a destination host represented by a destination MAC address is connected (hereinafter referred to as “destination switch identifier”). The VPN-U field is a field indicating the upper part of 8 bits (1 byte) of the 20-bit VPN-ID that is the identifier of the VPN.

  Similarly to the destination PMAC address field, the source PMAC address field is further distinguished into a 5-byte SSID field and an 8-bit VPN-U field. The SSID field is a field indicating an identifier of an edge switch as an ingress edge switch to which a transmission source host represented by a transmission source MAC address is connected (hereinafter referred to as “transmission source switch identifier”).

  Similar to the TCI field in the user frame, the TCI field is classified into a 3-bit PRI field, a 1-bit CFI field, and a 12-bit VPN-D field. The VPN-D field is a field indicating the lower part of 12 bits of the VPN-ID.

  The Pyload field is a field indicating a user frame excluding the VLAN-TAG field.

  For example, when data is transmitted from the host A1 to the host A3, if the identifier of the edge switch ESW1 is “ESW1” in the edge switch ESW1, the identifier “ESW1” of the edge switch ESW1 is displayed in the SSID field of the source PMAC address field. Is inserted. If the identifier of the edge switch ESW3 is “ESW3”, the identifier “ESW3” of the edge switch ESW3 is inserted into the DSID field of the destination PMAC address field. Furthermore, the upper part of 8 bits of the 20-bit VPN-ID is inserted into the VPN-U field, and the lower part of 12 bits of the VPN-ID is inserted into the VPN-D field. The Insertion of data into each of these fields is actually obtained by searching the management table of the edge switch ESW1 shown in FIG. 1 using the VLAN-ID and destination MAC address included in the user frame as keys. . The operation of the edge switch ESW1 as an ingress edge switch using this management table will be described later.

  Then, the transfer frame transmitted from the edge switch ESW1 as an ingress edge switch passes through the core switch CSW in the wide area Ethernet network and is connected to the edge switch ESW3 (“Egress edge switch”) to which the host A3 as the destination is connected. To be called).

  Here, each core switch CSW in the wide-area Ethernet network searches the management table using only the identifier of the edge switch inserted in the DSID field of the destination PMAC address field in the transfer frame as a key, thereby searching for the transfer frame. A transmission port (hereinafter referred to as “destination port”) is determined, and a transfer frame is transmitted from the determined destination port. The operation of the core switch CSW using this management table will be described later.

  The edge switch ESW3 as the egress edge switch extracts the user frame included in the received transfer frame and transmits it to the host A3 corresponding to the destination MAC address. Actually, the corresponding VLAN-ID and destination port are obtained by searching the management table using the VPN-ID represented by VPN-U and VPN-D and the destination MAC address as keys. Then, the user frame is extracted by inserting the VLAN-TAG including the obtained VLAN-ID into the user frame inserted in the Pyload of the transfer frame and from which the VLAN-TAG is removed. Send. The operation of the edge switch ESW3 as an egress edge switch using this management table will be described later.

B2. Operation in edge switch (ingress edge switch):
FIG. 5 is an explanatory diagram showing an operation in the edge switch ESW1 as an ingress edge switch. The edge switch ESW1 has a management table as shown in the figure. This management table is searched using the VLAN-ID (VID) and the destination MAC address (DA) as keys, and includes a 20-bit VPN-ID, a 6-byte destination PMAC address (PDA), and a 12-bit VPN-ID. The lower part VPN-D and the destination port are managed as information related to the VLAN-ID and the destination MAC address. The destination PMAC address is further divided into a 5-byte destination switch identifier (DSID) and a VPN-ID 8-bit (1 byte) upper part VPN-U. However, in the management table, in the static entry portion, the data included in the received user frame is the destination information with the information related to the VLAN-ID and the destination MAC address included in the received user frame. If the information used for transfer to the destination indicated by the MAC address (hereinafter also referred to as “corresponding information” in this section) is not stored in the dynamic entry portion, information for flooding has already been constructed. Prepared for each VPN.

  In the management table of the figure, the VLAN-IDs corresponding to the VPNs to which the hosts represented by the symbols “A” and “B” are connected are “1” and “2”. In this example, VPN-IDs corresponding to the VLAN-ID represented by “2” are “0x05001” and “0x06001”, respectively. Further, the switch identifiers of the edge switches ESW1, ESW2, ESW3 are “02: 00: 00: 00: 11”, “02: 00: 00: 00: 12”, “02: 00: 00: 00: 13”, respectively. "Is shown. These assumptions are the same in the following descriptions. However, in order to simplify the explanation and illustration, each switch identifier may be indicated by using the codes “ESW1”, “ESW2”, and “ESW3” of the respective edge switches. Also, “DC” in the management table is masked and treated as “Do n’t Care”. For flooding, information for each already constructed VPN is prepared in the static entry portion via the wide area Ethernet network.

  When data is transmitted from the host A1 to the host A3, as described in the above preconditions, the corresponding VLAN-ID is “1” and the destination MAC address is “A3”. Search the management table as a key. At this time, as described below, the corresponding information is learned and exists in the dynamic entry part of the management table, and the corresponding information is not learned and exists in the dynamic entry part of the management table. The operation will be different depending on the case.

(1) If you have already learned:
If the information corresponding to the received user frame has already been learned and the learned information is stored in the dynamic entry portion of the management table, the corresponding entry number in the dynamic entry portion can be retrieved by searching the management table. In the example, the information of entry number “1” is hit. At this time, “02: 00: 00: 00: 13 (corresponding to“ ESW3 ”)” as the destination switch identifier DSID included in the destination PMAC address (PDA) in the hit information is included in the source PMAC address. “02: 00: 00: 00: 11 (corresponding to“ ESW1 ”) as the source switch identifier SSID,“ 05 ”as the upper part VPN-U of the VPN-ID, and the lower part VPN-D of the VPN-ID “001” is used to construct the transfer frame shown in FIG. 4 and is transmitted from the destination port “4” to the wide area Ethernet network.

(2) In case of not learning:
When the information corresponding to the received user frame is not learned and the learned information is not stored in the dynamic entry part of the management table, the corresponding entry number in the static entry part In the example, the information of the entry number “1001” is hit. At this time, “UN” (“EE: EE: EE: EE: EE” is registered in the non-hit entry as the destination switch identifier DSID of the destination PMAC address (PAD) in the hit information. Is a dedicated identifier that means “destination unknown”.), “02: 00: 00: 00: 11 (corresponding to“ ESW1 ”) as the source switch identifier SSID included in the source PMAC address, VPN The transfer frame shown in FIG. 4 is configured using “05” as the upper part VPN-U of ID and “001” as the lower part VPN-D of VPN-ID, and the wide area from the destination port “4” Send to the Ethernet network. Note that the identifier “EE: EE: EE: EE: EE” meaning that the destination is unknown is an example, and other values may be used.

  The edge switch ESW1 receives the response information corresponding to the above-described flooded transfer frame, and learns the corresponding information and stores it in the dynamic entry portion of the management table.

B3. Operation in the core switch:
Similarly to the edge switch ESW1 as an ingress edge switch, the operation in the core switch has learned information for transferring the received transfer frame (hereinafter referred to as “corresponding information” in this section) and stores it in the management table. It depends on whether it is done or not. Therefore, in the following, the operation of the core switch CSW will be described separately for cases where the information for transferring the received transfer frame has been learned and has not yet been learned.

(1) If you have already learned:
FIG. 6 is an explanatory diagram showing an operation in the core switch CSW in which information corresponding to the received transfer frame has been learned. The core switch CSW also has a management table like the above-described edge switch ESW1. FIG. 6 shows a management table of the first core switch CSW1 that first receives the transfer frame from the edge switch ESW1. This management table includes a destination switch identifier DSID as a destination PMAC address (PDA) and an upper part VPN-U of VPN-ID and a lower part VPN-D of VPN-ID as destination keys. It is managed as information related to the destination PMAC address and the lower part VPN-D of the VPN-ID. However, among the information stored in the dynamic entry part, the upper part VPN-U of the VPN-ID and the lower part VPN-D of the VPN-ID are “DC”. That is, the destination port for transmitting the transfer frame is managed only by the destination switch identifier DSID. In the static entry part, the received transfer frame is transferred to the edge switch as the egress edge switch represented by the destination switch identifier DSIS with information related to the destination switch identifier DSID included in the received transfer frame. Information for performing flooding (hereinafter also referred to as “corresponding information” in this section) is not stored in the dynamic entry portion, but information for performing flooding is prepared for each VPN that has already been constructed. Has been.

  When the information corresponding to the received transfer frame has been learned and the learned information is stored in the dynamic entry portion of the management table, when the management table is searched, the corresponding entry number in the dynamic entry portion In the example, the information of entry number “2” is hit. At this time, the received transfer frame is transferred as it is from the destination port “2” in the hit information.

  Similarly, the other core switches CSW2 and CSW3 have the management table, and when the corresponding information is learned and stored in the dynamic entry portion of the management table, the first core switch Similarly to CSW1, the destination port included in the information of the entry number that has been hit, in the example of the figure, the destination port [3] in the second core switch CSW2 and the destination port “2” in the third core switch CSW3 The received transfer frame is transferred as it is.

  As described above, the transfer frame is transferred to the edge switch as the egress edge switch corresponding to the destination switch identifier DSID included in the transfer frame, in this example, the third edge switch ESW3.

(2) In case of not learning:
When the information corresponding to the received transfer frame is not learned, the operation in the core switch CSW is performed by the edge switch ESW1 as the ingress edge switch described above and the transfer frame is based on unicast. It depends on whether EWS1 is unlearned and the transfer frame is due to flooding.

  FIG. 7 is an explanatory diagram illustrating an operation in the core switch CSW in which information corresponding to the received transfer frame is not learned when a unicast transfer frame is received. In this case, each core switch CSW has a management table in which information corresponding to the received transfer frame has not been learned and is not in the dynamic entry portion. In the figure, a management table of the first core switch CSW1 is shown.

  If the information corresponding to the received transfer frame is not learned and the learned information is not stored in the dynamic entry part, the management table is searched, and the corresponding entry number in the static entry part, the entry in the example in the figure, The information of the number “1001” is hit and the transfer by flooding is executed. That is, the received transfer frame is transferred as it is from all the destination ports “2” to “4” obtained from the hit information.

  Similarly, any of the other core switches CSW2 to CSW4 has a management table, and when the corresponding information has not been learned and is not stored in the dynamic entry portion of the management table, the first Similarly to the core switch CSW1, the received transfer frame is transferred as it is from all the destination ports which are stored in the static entry portion and included in the information of the entry number hit.

  Here, the transfer frame transferred from the destination port “2” of the third core switch CSW3 reaches the third edge switch ESW3, and the transfer frame transferred from the destination port “3” is the second edge switch ESW2. To reach. At this time, as a premise, the transfer frame is unicast, and the transfer frame includes “02: 00: 00: 00: 13 (ESW3)” as the destination switch identifier DSID indicating the third edge switch ESW3. It is included. Accordingly, the third edge switch ESW3 performs an operation in an egress switch described later, and the second edge switch ESW2 receives the destination switch identifier DSID of the received transfer frame that is different from its own switch identifier. The transferred frame is discarded as it is.

  As shown in the figure, the first to fourth core switches CSW1 to CSW4 may be ring-connected, and the transfer frame that reaches the third core switch CSW3 passes through the second core switch CSW2. Some of them pass through the fourth core switch CSW4, and the third core switch CSW3 performs batting. Therefore, in order to prevent this batting, the third core switch CSW3 executes a discarding process for one of the transfer frames according to a preset rule. In the example shown in the figure, the transfer frame passing through the fourth core switch CSW4 is discarded. The fourth core switch CSW4 may discard the transfer frame.

  FIG. 8 is an explanatory diagram showing an operation in the core switch CSW in which information corresponding to the received transfer frame is not learned when a transfer frame by flooding is received.

  As in the case shown in FIG. 7, each core switch CSW executes forwarding by flooding. However, in this case, the operation of the third edge switch ESW3 is different. That is, since the destination switch identifier DSID included in the transfer frame that has reached the third edge switch ESW3 is “UN”, the third edge switch ESW3 extracts the user frame as described later. The transfer data is transmitted from each destination port. Then, by receiving the response information corresponding to the flooding, the corresponding information is learned and stored in the dynamic entry portion of the management table.

B4. Operation in edge switch (Egress edge switch):
The operation of the edge switch ESW3 as the egress edge switch also differs depending on whether or not the information corresponding to the received transfer frame has been learned, as with the edge switch ESW1 and the core switch CSW as the ingress edge switch. Therefore, in the following, the operation of the edge switch ESW3 as the egress edge switch will be described separately depending on whether the information corresponding to the received transfer frame has been learned or not.

(1) If you have already learned:
FIG. 9 is an explanatory diagram showing an operation in the edge switch ESW3 as an egress edge switch having learned information corresponding to the received transfer frame. The edge switch ESW3 also has a management table as shown in the figure. This management table extracts a user frame from a 12-bit VLAN-ID corresponding to a 20-bit VPN-ID and a transfer frame, which are searched using a VPN-ID and a destination MAC address (DA) as a key. The destination port for transmitting the extracted user frame is managed as information related to the VPN-ID and the destination MAC address. However, in the management table, the dynamic entry portion includes information in which the VPN-ID and the destination MAC address are associated with the corresponding VLAN-ID and the destination port based on information received as flooding response information. It is remembered. Also, in the static entry portion, information for performing flooding when information corresponding to the VPN-ID and the destination MAC address included in the received transfer frame is not stored in the dynamic entry portion is already constructed. It is prepared for each VPN.

  If the information corresponding to the received transfer frame has been learned and the learned information is stored in the dynamic entry portion of the management table, the corresponding entry number in the dynamic entry portion is searched when the management table is searched. In this example, the VPN-ID represented by “05” of the upper part VPN-U and “001” of the lower part VPN-D of the VPN-ID is “0x05001”, and the destination MAC address (DA) is “A3”. Therefore, the information of the entry number “1” is hit. At this time, information about the user frame included in the payload of the transfer frame and the VLAN-ID obtained from the management table are used to construct a user frame according to the format shown in FIG. The user frame is transmitted from the destination port “4” obtained from the above to the host A3 corresponding to the destination MAC address “A3”.

  In this way, user frames transmitted from the host A1 to the host A3 are sequentially transferred through the wide area Ethernet network and can be received only by the host A3.

(2) In case of not learning:
FIG. 10 is an explanatory diagram showing an operation in the edge switch ESW3 as an egress edge switch whose information corresponding to the received transfer frame is not learned. In this case, as shown in the figure, the edge switch ESW3 has a management table in which information corresponding to the dynamic entry portion is not learned.

  When the information corresponding to the received transfer frame is not learned and the learned information is not stored in the dynamic entry part of the management table, the corresponding entry number in the static entry part In this example, the information of the entry number “1001” is hit and the user frame is transmitted by flooding. That is, the user frame is transmitted from all the destination ports “2” and “3” obtained from the hit information to the hosts A3 and A4 connected thereto. Then, by receiving a response from each of the hosts A3 and A4, the MAC address of each host is used as the destination MAC address, the VPN-ID corresponding to each VLAN-ID and the destination MAC address are used as keys, and the corresponding VLAN -Information associated with ID and destination port is learned and stored in the dynamic entry portion of the management table.

  Here, the destination MAC address of the user frame transmitted from “2” and “3” of the destination port of the third edge switch ESW is “A3”. Therefore, the user frame transmitted from the destination port “2” and reaching the host A3 is taken into the host A3. On the other hand, the user frame transmitted from the destination port “3” and reaching the host A4 is not taken into the host A4 but discarded. As a result, the user frames transmitted from the host A1 to the host A3 are sequentially transferred through the wide area Ethernet network and can be received only by the host A3.

  In the above description, the case where the VLAN-ID is obtained from the VPN-ID included in the received transfer frame using the management table has been described as an example, but the intermediate identifier is temporarily determined from the VPN-ID. The VLAN-ID may be obtained from an intermediate identifier.

C. effect:
As can be seen by comparing the structure of the user frame shown in FIG. 3 with the structure of the transfer frame shown in FIG. 4, the structure of the appearance of the transfer frame is the same as the user frame. Therefore, it is possible to construct a wide area Ethernet network using a conventional switch that supports user frame transfer.

  Further, as shown in FIG. 4, the transfer frame has a structure in which the user frame is encapsulated using the destination PMAC address and the source PMAC address corresponding to the destination MAC address and the source MAC address. In the case of a frame encapsulated in this way, a dedicated MAC address that is used only within the wide area Ethernet network can be used as the destination PMAC address and the source PMAC address. Since it is not necessary to manage all the MAC addresses included in the user frame to be transmitted, the amount of information to be managed can be reduced.

  The transfer frame has a VPN-ID for identifying the VPN of 20 bits, of which the 12-bit lower part VPN-D corresponds to the VLAN-ID field of the user frame, and the upper 8 bits (1 byte). The partial VPN-U is inserted into the 6-byte destination PMAC address and the 6-byte source MAC address in the lower 1 byte. However, the switch identifier used as the destination switch identifier DSID and the source switch identifier SSID inserted into the 6-byte destination PMAC address and the 6-byte source PMAC address is 5 bytes.

  As can be seen from the above description, in the above embodiment, in the wide area Ethernet network, by applying a new transfer frame having the same appearance as a conventional user frame that can only support a VPN of 12 bits or less, It is possible to provide a VPN. Further, unlike the case of providing more than 4096 VPNs using the VLAN stacking technology described in the prior art, it is not necessary to use a switch corresponding to this, and it is possible to provide a wide area Ethernet network at a low cost.

D. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the scope of the invention.

  In the above description, the VPN-ID has been described as 20 bits, but the present invention is not limited to this. The sum of the number of bits of the switch identifier and the number of bits of the upper part VPN-U of the VPN-ID may be 48 bits (6 bytes), and the switch identifier bits in consideration of the number of switches constituting the wide area Ethernet network. By determining the number and number of bits in the upper part of the VPN-ID, it is possible to provide various numbers of VPNs exceeding 4096.

  In the above description, the wide-area Ethernet network is taken as an example, but the present invention can be applied to other network configurations having similar functions.

It is explanatory drawing which shows the network with which the data communication system of this invention is applied. It is a block diagram which shows the structure of the switch which can be used as an edge switch or a core switch. It is explanatory drawing which shows the format of a user frame. It is explanatory drawing which shows the format of a transfer frame. It is explanatory drawing shown about operation | movement in edge switch ESW1 as an ingress edge switch. It is explanatory drawing which shows the operation | movement in the core switch CSW in which the information corresponding to the received transfer frame was learned. It is explanatory drawing which shows the operation | movement in the core switch CSW in which the information corresponding to the received transfer frame is not learned when the transfer frame by unicast is received. It is explanatory drawing which shows the operation | movement in the core switch CSW in which the information corresponding to the received transfer frame is not learned when the transfer frame by flooding is received. It is explanatory drawing which shows operation | movement in edge switch ESW3 as an egress edge switch by which the information corresponding to the received transfer frame was learned. It is explanatory drawing which shows the operation | movement in edge switch ESW3 as an egress edge switch in which the information corresponding to the received transfer frame is unlearned.

Explanation of symbols

ESW: Edge switch ESW1-ESW3: Edge switch CSW: Core switch CSW1-ESW4: Core switch A1-A5 ... Host B1, B2 ... Host 100 ... Switch 110 ... Control unit 112 ... CPU
114 ... Memory 120 ... Communication unit 122 ... Network interface

Claims (7)

A data transmission system for transmitting data from a source host included in a first user network to a destination host included in a second user network via a virtual private line provided in a wide area network,
The wide area network is:
A source edge switch to which the source host is connected;
A destination edge switch to which the destination host is connected;
A core network configured by one or more core switches and connecting between the source edge switch and the destination edge switch;
With
The source edge switch generates a transfer frame from the user frame when a user frame including the data arrives from the source host, transfers the generated transfer frame to the core network,
When the transfer frame arrives, the core switch in the core network transfers the transfer frame as it is,
The destination edge switch generates the user frame from the transfer frame when the transfer frame arrives, transmits the generated user frame to the destination host,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. an n-bit (n is an integer) virtual network identifier in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The data transmission system, wherein the virtual private line identifier is defined corresponding to the virtual network identifier. The data transmission system according to claim 1, wherein
The source edge switch is for the destination edge switch composed of the destination edge switch identifier and the second partial identifier based on the destination MAC address and the virtual network identifier included in the user frame. A data transmission system comprising a table for obtaining a MAC address, the first partial identifier, and a destination port for transferring the transfer frame. A data transmission system according to claim 2, wherein
The core switch includes a table for obtaining a destination port for forwarding the forwarding frame based on the destination edge switch identifier constituting the destination edge switch MAC address included in the forwarding frame. Characteristic data transmission system. The data transmission system according to claim 3, wherein
The transmission destination edge switch includes the first partial identifier included in the transfer frame, and the second partial identifier configuring the transmission destination edge switch MAC address and the transmission source edge switch MAC address. Based on the virtual private line identifier represented and the destination MAC address included in the transfer frame, a virtual network identifier corresponding to the destination host and a destination port for transmitting the user frame are obtained. A data transmission system comprising a table. The transmission source host of a data transmission system for transmitting data from a transmission source host included in the first user network to a transmission destination host included in the second user network via a virtual private line provided in the wide area network A source edge switch to which the destination host is connected, a destination edge switch to which the destination host is connected, and one or more core switches, and connects between the source edge switch and the destination edge switch A transmission frame generated from the user frame in the source edge switch for transmitting a user frame including the data in a wide area network comprising a core network,
The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. an n-bit (n is an integer) virtual network identifier in the header, the data in the payload,
The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits ( m is from n) identifying the virtual private line. A first integer identifier of n bits of a virtual private line identifier of a large integer ) in a header, and the user frame excluding the virtual network identifier is included in a payload,
The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
The transfer frame according to claim 1, wherein the virtual private line identifier is defined corresponding to the virtual network identifier.   In a data transmission system for transmitting data from a transmission source host included in a first user network to a transmission destination host included in a second user network via a virtual private line provided in a wide area network, the transmission destination host A source edge switch connected to a destination edge switch to which the source host is connected via a core network composed of one or more core switches, to which the source host is connected,
  When a user frame including the data arrives from the source host, a transfer frame is generated from the user frame, and the generated transfer frame is transferred to the transfer destination edge switch via the core switch in the core network,
  The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. n bits (n is an integer virtual network identifier) in the header, the data in the payload,
  The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
  The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
  The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
  The virtual private line identifier is defined corresponding to the virtual network identifier.
  A source edge switch characterized by that.   In the data transmission system for transmitting data from a transmission source host included in the first user network to a transmission destination host included in the second user network via a virtual private line provided in the wide area network, the transmission source host Is connected to a source edge switch to which is connected via a core network composed of one or more core switches, and is a destination edge switch to which the destination host is connected,
  When a forward frame transferred from the source edge switch via the core switch in the core network arrives, a user frame including the data transmitted from the source frame to the source edge switch is generated from the forward frame. And transmitting the generated user frame to the destination host,
  The user frame identifies a source MAC address indicating the source host and a destination MAC address indicating the destination host, and a virtual network provided in the first user network and the second user network. n bits (n is an integer virtual network identifier) in the header, the data in the payload,
  The forwarding frame includes a MAC address for a source edge switch indicating the source edge switch, a MAC address for a destination edge switch indicating the destination edge switch, and m bits for identifying the virtual private line (m is from n) A first integer identifier of n bits of a virtual private line identifier of a large integer) in a header, and the user frame excluding the virtual network identifier is included in a payload,
  The source edge switch MAC address includes a dedicated source edge switch identifier used only in the wide area network, and a second partial identifier of (mn) bits of the virtual private line identifier. And
  The destination edge switch MAC address includes a dedicated destination edge switch identifier used only in the wide area network, and the second partial identifier,
  The virtual private line identifier is defined corresponding to the virtual network identifier.
  A destination edge switch characterized by that.

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