JP4605246B2 - Packet transfer apparatus, packet transfer control method, and packet transfer apparatus setting method - Google Patents

Description

The present invention relates to a packet communication device, and in particular, a virtual private network (VPN: Virtual Pr).
ivate Network).

As one of the means to build an intranet in a company, VLAN (Virtual Lo
cal Area Network). The VLAN system is standardized as IEEE802.1Q by the IEEE802 committee in the United States.

FIG. 2 shows a VLAN packet format according to IEEE802.1Q. In a VLAN based on IEEE802.1Q, an IP (Internet Protocol) packet 500 is an Ethernet (registered trademark) to which tag control information 514 is added.
It is transferred as a frame 510. A 12-bit VLAN ID 514-3 is set in the tag control information 514. The VLAN ID is an identifier of a group constituting the VLAN. The 3-bit user priority 514-1 indicates the priority of the packet.

FIG. 3 shows an example of a VLAN network configuration. In FIG. 3, the network is
It is assumed that the building straddles two locations 6-1 and 6-2, such as the first and second floors of the building. Location 6-1 includes two networks, VLAN #A (7-
1-1) and VLAN #B (7-2-1) exists. There are also two networks, VLAN #A (7-1-2) and VLAN #B (7-2-2), at location 6-2. VLAN #A (7-1-1) and VLAN #B (7-2-1) are multiplexed by the switching hub 2-1. Similarly, VLAN #A (7-1-2
), VLAN #B (7-2-2) is multiplexed by the switching hub 2-2. A unique VLAN ID is assigned to each of VLAN #A and VLAN #B. The switching hubs 2-1 and 2-2 recognize the VLAN to which the packet belongs by looking at the VLAN ID. For example, a packet transmitted from the VLAN # A7-1-1 to the location 6-2 is transmitted by the switching hub 2-2 to the VLAN.
Only forwarded to # A7-1-2.

On the other hand, as a packet transfer technology on the Internet, MPLS (Multip
rotocol Label Switching). In MPLS, a packet transfer apparatus in a network performs packet transfer processing using a fixed-length connection identifier called a label.

FIG. 7 shows an example of an MPLS network configuration. A case where a packet is transferred from the terminal 4-A to the terminal 4-C will be described. A device 3-1 serving as an entrance to the MPLS network
Then, from the destination IP address set in the packet, the output destination of the packet and the value of the label attached to the packet are determined. In the device 3-2 that relays the packet, the output destination of the packet and the value of the label attached to the output packet are determined based on the label attached to the input packet. The device 3-3 serving as the exit of the MPLS network removes the label from the packet and determines the packet transfer destination by looking at the IP header set in the packet. For the MPLS protocol, IETF (Internet Engineering Tas
(k Force), standardization work is underway.

FIG. 4 shows an M using PPP (Point to Point Protocol) as a lower layer.
The packet format of PLS is shown. In MPLS using PPP, PPP
A 4-byte Shim header 522 between the header 521 and the IP header 501
Is inserted. The shim header is a 20-bit label 521-1 and a 3-bit Ex
p field 521-2, 1 bit S bit 521-3, 8 bit TTL (
Has a Time to Live field. In IETF, Exp field 521-2
Is being used as a QoS (Quality of Service) class.

FIG. 5 shows an MPLS packet format using ATM (Asynchronous Transfer Mode) as a lower layer. The IP packet 500 is provided with a padding 535-1 and a trailer 535-2 to become an AAL5 frame 535 (null encapsulation defined by RFC 2684 of IETF). The AAL5 frame 535 is divided into 48 bytes, and a cell header 531 is assigned to each of the AAL5 frames 535 to become ATM cells 530-1 to 530-n.

FIG. 6 shows an ATM cell format. In MPLS using ATM,
Cell header 531 VPI (Virtual Path Identifier) 531-2, VCI (V
irtual Channel Identifier) 531-3 is used as a label. A 1-bit CLP (Cell Loss Priority) bit 531-5 represents the priority of cell discard.

Hereinafter, a shim header or an ATM cell header in which a label value is set is referred to as an MPLS header.

Conventionally, communication between geographically distant bases within the same company is generally performed by a dedicated line. However, in recent years, the virtual private network (V
By building a PN (Virtual Private Network), an increasing number of users connect bases.

When VLANs existing at geographically distant bases are connected by an MPLS network, a device located at the entrance of the MPLS network deletes tag control information. For this reason,
Information indicating which VLAN the packet belongs to (VLAN ID)
Is lost from the packet it forwards. Therefore, there is a problem that a device located at the exit of the MPLS network cannot set a VLAN ID for an output packet.

Also, since tag control information is deleted from the packet, the packet priority information (
User priority) is lost. Therefore, the VL on the packet sending side
There is a problem that the same QoS control as the packet transmission side cannot be performed in the AN and the VLAN on the packet reception side.

In short, mapping of information written in the header of a layer corresponding to layer 2 of the OSI model to the MPLS header has not been studied.

Therefore, an object of the present invention is to enable mapping of information written in a header of a layer corresponding to layer 2 of the OSI model to an MPLS header.

The object of the present invention is to provide VLs that are located in geographically separated locations and belong to the same group.
The AN is to connect the ANs using an MPLS network while maintaining the closed region.

Another object of the present invention is to perform unified end-to-end QoS control even when the VLAN network is interworked by the MPLS network.

In the present invention, a packet header used in a network that does not use the MPLS protocol is provided to a packet transfer apparatus that interworkes an MPLS network and a network that does not use the MPLS protocol.
The header of the layer corresponding to layer 2 of the OSI model different from the MPLS header (hereinafter referred to as “layer 2 header”) provided before the header of the layer corresponding to (hereinafter referred to as “layer 3 header”). ), The layer 3 header information, and the header conversion information indicating the correspondence between the MPLS header information. By using this information, the packet transfer apparatus converts the layer 2 header into an MPLS header.

In addition, header conversion information indicating a correspondence relationship between the set of the MPLS header information, the layer 3 header information, and the layer 2 header information is set in the packet transfer apparatus. The packet transfer apparatus uses this information to convert the MPLS header into the layer 2 header.

In one embodiment of the present invention, a VLAN ID and an MPLS label are associated with each other in a device that interworkes VLAN and MPLS. In an apparatus that interworkes from a VLAN network to an MPLS network, an output MPLS label is determined from a set of VLAN ID and packet header information. The output MPLS label is assigned an independent value for each VLAN. In the device that interworkes from the MPLS network to the VLAN network,
Map the input MPLS label to the VLAN ID.

In another embodiment of the present invention, an apparatus for interworking VLAN and MPLS associates 3 bits of user priority of tag control information with a field for setting a QoS value of an MPLS header. In the case of MPLS by PPP, 3 bits of user priority are mapped to 3 bits of Exp field of the Shim header. In the case of MPLS by ATM, 3 bits of user priority are converted into 1 bit of CLP bits of the cell header.

According to the present invention, information described in a header of a layer corresponding to layer 2 of the OSI model can be mapped to an MPLS header.

Further, according to the present invention, VLAN networks existing at geographically separated positions can be interworked by the MPLS network without impairing their closedness. Also, end-to-end QoS control between VLAN networks can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration example of a network to which the present invention is applied. VLAN
#A is the network 7-1-1, 7-1-2, 7-1-3, 7-1-4 and 7-
1-5. VLAN #B is a network 7-2-1, 7-
It consists of 2-2, 7-2-3, 7-2-4 and 7-2-5. Place 6-1,
6-2, 6-3, 6-4 and 6-5 are mutually connected by the MPLS network 5. The MPLS network 5 includes network interworking apparatuses 1-1, 1-2 and 1
-3 and the packet relay device 3.

In the following, the network interworking apparatus 1 from VLAN # A7-1-1.
-1, 1-2 will be described as an example of packet transfer to VLAN # A7-1-4.

FIG. 8 shows the network interworking apparatus (1-1, 1-2, 1-3) of the present invention.
The example of a structure is shown. Network interworking device is Ethernet
Lower layer processing unit 11, packet layer processing unit 12, MPLS lower layer processing unit 13,
A switch 14 and a controller 15.

When the Ethernet lower layer processing unit 11 receives the Ethernet frame, the Ethernet lower layer processing unit 11 performs termination processing on the physical layer and the data link layer of the frame, and passes the IP packet and tag control information to the packet layer processing unit 12. E
The lower Ethernet layer processing unit 11 assigns the destination MAC address and tag control information determined by the packet layer processing unit 12 to the IP packet, converts the IP packet into an Ethernet frame, and transmits the packet to the VLAN network.

When the MPLS lower layer processing unit 13 receives the MPLS packet, the MPLS lower layer processing unit 13 performs termination processing of the physical layer of the packet and the MPLS header.
The PLS header information is passed to the packet layer processing unit 12. Further, the MPLS header information determined by the packet layer processing unit 12 is attached to the IP packet, and the IP packet is converted into an MPLS packet and transmitted to the MPLS network.

The packet layer processing unit 12 determines the packet transfer destination based on the IP header information and tag control information or MPLS header information of the input packet.

The switch 14 determines the packet sent from the packet layer processing unit 12 by another packet layer processing unit 1 that is determined by the packet layer processing unit 12 and corresponds to the transfer destination.
2 to send.

The control unit 15 is connected to the management device and controls each processing unit of the network interworking device 1.

FIG. 9 shows the configuration of the Ethernet lower layer processing unit 11 located on the VLAN side line.

The physical layer reception processing unit 111 performs physical layer processing of the received Ethernet frame. The Ethernet reception processing unit 112 performs termination processing for the received Ethernet. That is, a process of discarding frames other than the self-addressed frame from the destination MAC address of the received frame and extracting tag control information of the received frame addressed to the self-frame is performed. The packet layer processing unit interfaces 113 and 114 are interfaces with the packet layer processing unit 12. Ethernet transmission processing unit 11
5 is an IP packet such as MAC address and tag control information.
Perform processing to frame. The physical layer transmission processing unit 116 performs processing for transmitting an Ethernet frame from the physical line. The control unit interface 117 is an interface with the control unit 15 and is connected to each component of the lower layer processing unit 11.

FIG. 10 shows the configuration of the packet layer processing unit 12. The lower layer processing unit interfaces 121 and 126 are interfaces with the Ethernet lower layer processing unit 11 or the MPLS lower layer processing unit. The table search processing unit 122 searches the search table 123 and performs processing for acquiring an output physical port and a VLAN ID or MPLS label to be given to the output packet. The switch interfaces 124 and 125 are interfaces with the switch 14. The control unit interface 127 is an interface with the control unit 15 and is connected to each component of the packet processing unit 12.

FIG. 12 shows a configuration example of the search table 123. The search table 123 is VL
AN ID search table 123-1, MPLS output route search table 123-
2, MPLS label search table 123-3, VLAN output route search table 123-4, MPLS output QoS conversion table 123-5, VLAN output Q
It has an oS conversion table 123-6. These search tables are built on a memory. It is not necessary for all search tables to be built on the same memory.

The VLAN ID search table 123-1 is a table for determining a VLAN to which a VLAN ID is a search key and belonging. The MPLS output route search table 123-2 is a table for determining an output label at the entrance from the VLAN network to the MPLS network. The MPLS label search table 123-3 is a table for determining which VLAN the MPLS label belongs to as a search key. The VLAN output route search table 123-4 is a table for determining an output VLAN ID at the exit from the MPLS network to the VLAN network. The MPLS output QoS conversion table 123-5 is a table for converting the QoS value (user priority) of the VLAN network into the QoS value of the MPLS network. The VLAN output QoS conversion table 123-6 is a table for converting the QoS value of the MPLS network into the QoS value (user priority) of the VLAN network.

FIG. 11 shows the configuration of the MPLS lower layer processing unit 13. The physical layer reception processing unit 131 performs physical layer processing on the received packet. The MPLS reception processing unit 132 performs processing for extracting the termination of the data link layer and the MPLS header. The packet layer processing unit interfaces 133 and 134 are interfaces with the packet layer processing unit 12. The MPLS transmission processing unit 135 performs processing for adding the termination of the data link layer and the MPLS header to the IP packet.
The physical layer transmission processing unit 136 transmits the packet with the MPLS label from the physical line. The control unit interface 137 is an interface with the control unit 15 and is connected to each component of the lower layer processing unit 13.

A processing procedure for the network interworking apparatus 1 to associate the VLAN ID with the MPLS label will be described.

A processing procedure in which the network interworking apparatus 1-1 in FIG. 1 acquires an output label from an input VLAN ID will be described.

In the network interworking apparatus 1-1, the table search processing unit 122 searches the search table 123.

FIG. 19 shows the concept of the search procedure of the table search processing unit 122 in the network interworking apparatus 1-1. The table search processing unit 122 first searches the VLAN ID search table 123-1, and then searches the MPLS output route search table 123-2.

FIG. 13 shows a configuration example of the VLAN ID search table. VLAN I
In the D search table 123-1, the input VLAN ID 123-1 is used as a search key.
-1 and the VLAN name 123-1- corresponding to the VLAN ID as a search result
2 is set. In the example of FIG. 13, when the VLAN ID search table 123-1 is searched with the input VLAN ID value 10, the result is VLAN #A. It is also possible to use a combination of the input VLAN ID and the input physical port of the packet as a search key. When a combination of the input VLAN ID and the input physical port of the packet is used as a search key, in a configuration where a plurality of physical ports exist in the lower layer processing unit 11 shown in FIG. The same VLA
The value of N ID can be used.

FIG. 14 shows a configuration example of an MPLS output route search table. MPL
In the S output route search table 123-2, the destination IP address 1 is used as a search key.
23-2-1, an output label 123-2-2 and an output physical port 123-2-3 are set as search results. In the MPLS output route search table 123-2, entries are divided for each VLAN. In the example shown in FIG.
The S output route search table 123-2 is an entry 123-for VLAN #A.
It is divided into an entry 123-2-b for 2-a and VLAN #B.

When the search result of the VLAN ID search table 123-1 is VLAN #A, the entry 123-2-a portion of the MPLS output route search table 123-2 is searched. In the example shown in FIG. 14, the destination IP address 192.169.10.0
When the entry 123-2-a is retrieved, the result is the output label value 100 and the output physical port 3.

Next, a processing procedure in which the network interworking apparatus 1-2 in FIG. 1 acquires the output VLAN ID from the input label will be described.

In the network interworking apparatus 1-2, the table search processing unit 122 searches the search table 123.

FIG. 20 shows the concept of the search procedure of the table search processing unit 122 in the network interworking apparatus 1-2. The table search processing unit 122 first searches the MPLS label search table 123-1, and then searches the VLAN output route search table 123-2.

FIG. 15 shows a configuration example of the MPLS label search table 123-3. MPLS
The label search table 123-3 includes an input label 123-3-1 as a search key.
However, the VLAN name corresponding to the input label is set as the search result. In the example shown in FIG. 15, the MPLS label search table 123 uses the input label value 101.
When -1 is searched, the result is VLAN #A. As a search key, a combination of an input label and an input physical port of a packet can be used. When a combination of an input label and an input physical port of a packet is used as a search key, in a configuration in which a plurality of physical ports exist in the lower layer processing unit 13 illustrated in FIG. It is possible to use the same label value.

FIG. 16 shows a configuration example of the VLAN output route search table 123-4.

The MPLS label search table 123-4 includes a destination IP address 123-4-1 as a search key, a destination MAC address 123-4-2 as a search result, and an output V.
A LAN ID 123-4-3 and an output physical port 123-4-4 are set.
The search table 123-4 is divided into entries for each VLAN. In FIG. 16, the VLAN output route search table 123-4 is divided into an entry 123-4-4-a for VLAN #A and an entry 123-4-4-b for VLAN #B.

When the search result of the MPLS label search table 123-3 is VLAN #A, the table search processing unit 122 searches the entry 123-4-4-part.
If the destination IP address is 192.169.10.0 and the entry 123-4-a is searched, the result is the output MAC address value aa.bb.cc.dd.ee.ff, output VLAN ID.
Value 10 and output physical port 8.

  Next, a processing procedure for realizing end-to-end QoS control will be described.

FIG. 17 shows a configuration example of an MPLS output QoS conversion table 123-10 for mapping the user priority defined by the VLAN to the QoS information in the MPLS header in the network interworking apparatus 1-1.

The MPLS output QoS conversion table 123-10 includes TCP as a search key.
/ IP header information 123-10-1 and user priority 123-10-2
However, the QoS value 123-10-3 of the output MPLS header is set as the search result.

The table search processing unit 122 searches the MPLS output QoS conversion table 123-10 using the TCP / IP header information and user priority given to the input packet as search keys, and, as a result, the Q to be set in the output MPLS header.
Get the oS value. As the TCP / IP header information 123-10, a destination IP address, a TOS (Type of Service) value of the IP header, a destination port number of the TCP header, and the like can be used. In the example shown in FIG. 17, the destination IP address is used as the TCP / IP header information 123-10. MPLS header Qo
The S information can be associated with the Exp field in MPLS using PPP and the CLP bit of the cell header in MPLS using ATM.

FIG. 18 shows the Q of the MPLS header in the network interworking apparatus 1-2.
The structural example of the QoS conversion table 123-11 for VLAN output for performing mapping from OS information to user priority is shown.

In the MPLS output table 123-11, the TCP / IP header information 1233-1-1 and the input MPLS QoS value 1233-11-2 are set as search keys, and the user priority 123-11-3 is set as a search result.

The table search processing unit 122 searches the VLAN output QoS conversion table 123-11 using the TCP / IP header information given to the input packet and the output MPLS QoS value as search keys, and acquires the output user priority value as a result. To do. For the TCP / IP header information 123-11, the destination IP address, the TOS value of the IP header, and the like can be used. In the example shown in FIG.
A destination IP address is used as the IP header information 123-11. MPLS
The QoS information of the header includes an Exp field in MPLS using PPP, and A
In MPLS using TM, it can be associated with the CLP field of the cell header.

Searching the MPLS output QoS conversion table 123-10 in the network interworking apparatus 1-1 and the VL in the network interworking apparatus 1-2
By combining the search of the AN output QoS conversion table 123-11, it is possible to store the QoS value of the VLAN even in a network in which VLAN networks belonging to the same group interwork by the MPLS network.

Since both the user priority of the VLAN tag control information and the Exp bit of the shim header are 3 bits, it is possible to use the same QoS value in the VLAN network and the MPLS network. For this reason, when the lower layer in the MPLS network is PPP, it is not always necessary to set the TCP / IP header in the search key.

Setting of the search table 123 includes a method in which the administrator of the network interworking apparatus 1 manually performs, or a method in which the apparatuses in the network automatically exchange information by autonomously exchanging information.

An example in which the administrator of the network interworking apparatus 1 manually sets the search table 123 will be described.

When the administrator of the network interworking apparatus 1 manually sets the search table 123, the administrator determines the setting value for the search table 123 based on the network operation policy after grasping the network configuration. At this time, the VLAN network operator notifies the manager of the network interworking apparatus 1 of information necessary for connecting the VLAN networks existing at geographically distant locations. An example of the information is IP address information of a connected device. The administrator of the network interworking apparatus 1 sets the search table 123 by inputting a command from the management apparatus connected to the control unit 15 of the network interworking apparatus 1.

As an example of automatically setting the MPLS output route search table 123-2, there is a method of using a signaling protocol for label distribution. For the label distribution protocol, the LD defined in draft-ietf-mpls-ldp-06.txt of IETF
P (Label Distribution Protocol). When using LDP, M
The devices 1-1, 1-2 and 3 constituting the PLS network 5 exchange messages with each other, whereby a label used in the MPLS path is autonomously assigned to each device.

As an example of automatically setting the VLAN output search table 123-4, there is a method using a routing protocol. The routing protocol operates between the devices constituting the network interworking device 1-2 and the VLAN networks 7-1-3 and 7-1-4. Examples of routing protocols include the IETF RFC
OSPF (Open Shortest Path First) defined as 2178. By using the routing protocol, the network interworking apparatus 1-2 has a destination IP address 123-4-1 and an output physical port 123-4-4.
And the IP address of the transfer destination can be grasped. In addition, IE
By using the ARP (Address Resolution Protocol) defined by TF RFC826, the network interworking apparatus 1-2 can grasp the correspondence between the IP address of the transfer destination and the MAC address 123-4-2.

It is a figure which shows the structural example of the network comprised using the network interworking apparatus of this invention. It is a figure which shows the packet format of VLAN by IEEE802.1Q. It is a figure which shows the structural example of a VLAN network. It is a figure which shows the frame format of MPLS which uses PPP. It is a figure which shows the frame format of MPLS which uses ATM. It is a figure which shows the cell format of ATM. It is a figure which shows the structural example of an MPLS network. It is a figure which shows the structural example of the network interworking apparatus of this invention. It is a figure which shows the structural example of the lower layer process part of the network interworking apparatus of this invention. It is a figure which shows the structural example of the packet layer process part of the network interworking apparatus of this invention. It is a figure which shows the structural example of the lower layer process part of the network interworking apparatus of this invention. It is a figure which shows the structural example of the search table provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the VLAN ID search table provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the route search table for MPLS output provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the MPLS label search table provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the route search table for VLAN output provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the QoS conversion table for MPLS output provided in the network interworking apparatus of this invention. It is a figure which shows the structural example of the QoS conversion table for VLAN output provided in the network interworking apparatus of this invention. It is a figure which shows the concept of the search procedure of the table search process part provided in the network interworking apparatus of this invention. It is a figure which shows the concept of the search procedure of the table search process part provided in the network interworking apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Network interwork apparatus, 11 Ethernet lower layer process part, 12 Packet layer process part, 13 MPLS lower layer process part, 14 Switch, 15 Control part, 500 IP packet, 510 VLAN frame, 52
0 MPLS frame with PPP, 530 ATM cells.

Claims (15)

A first network that transfers a packet by a label in an MPLS header given before a header of a layer corresponding to layer 3 of an OSI (Open System Interconnection) model (hereinafter referred to as “layer 3 header”) And a second network that forwards the packet using a layer header (hereinafter referred to as “layer 2 header”) that corresponds to layer 2 of the OSI model different from the MPLS header, which is provided before the layer 3 header. And a packet transfer control method in a packet transfer device connected to
  In the second network, a plurality of logical networks identified by the identifier of the layer 2 header are configured,
  The packet transfer control method includes:
  Receiving a packet from a second network;
  The first information indicating the correspondence between the priority information of the packet in the layer 2 header, the information in the layer 3 header or the information in the layer 4 header, and the priority information in the MPLS header Converting priority information in the layer 2 header of the received packet into priority information in the corresponding MPLS header based on the correspondence relationship;
  Converting a layer 2 header of the received packet into an MPLS header;
  A packet transfer control method comprising: transmitting a packet obtained by converting the header to a first network.   The layer 2 header included in the received packet is based on a second correspondence relationship indicating a correspondence between the information of the layer 2 header, the information of the layer 3 header, and the information of the MPLS header. The packet transfer control method according to claim 1, further comprising a step of converting into the MPLS header corresponding to the MPLS header.   Receiving a packet from the first network;
  3. The method according to claim 2, further comprising: converting the MPLS header included in the packet received from the first network into the layer 2 header corresponding thereto based on the second correspondence relationship. Packet transfer control method.   Receiving a packet from the first network;
  The method according to claim 1, further comprising: converting priority information in the MPLS header included in a packet received from a first network into priority information in the corresponding layer 2 header based on the first correspondence relationship. The packet transfer control method described in 1. The packet transfer control method according to claim 1,
The layer 2 header is a VLAN packet header defined by IEEE802.1Q.
The packet transfer control method, wherein the layer 3 header is an internet protocol (IP) header. The packet transfer control method according to claim 1,
The layer 2 header is a VLAN packet header defined by IEEE802.1Q.
The priority information in the layer 2 header is a value set in the user priority field,
The MPLS header is a shim header;
The put transfer control method, wherein the priority information in the MPLS header is a value of a 3-bit Exp field. The packet transfer control method according to claim 1,
The layer 2 header is a VLAN packet header defined by IEEE802.1Q.
The priority information in the layer 2 header is a value set in the user priority field,
The MPLS header is an ATM cell header;
The packet transfer control method, wherein the priority information in the MPLS header is a value of a cell discard priority bit (CLP) field. A first network that transfers a packet by a label in an MPLS header given before a header of a layer corresponding to layer 3 of an OSI (Open System Interconnection) model (hereinafter referred to as “layer 3 header”) And a second network that forwards the packet using a layer header (hereinafter referred to as “layer 2 header”) that corresponds to layer 2 of the OSI model different from the MPLS header, which is provided before the layer 3 header. A network system including the first network and a packet transfer device connected to the second network,
  In the second network, a plurality of logical networks identified by the identifier of the layer 2 header are configured,
  The packet transfer device includes:
A receiving unit for receiving packets from the second network;
Based on the correspondence between the priority information of the packet in the layer 2 header, the information in the layer 3 header or the information in the layer 4 header, and the priority information in the MPLS header, A processing unit that converts priority information in the layer 2 header of the received packet into priority information in the corresponding MPLS header, and further converts a layer 2 header of the received packet into an MPLS header;
And a transmission unit that transmits the packet obtained by converting the header to the first network. The network system according to claim 8, wherein
The processor is
The layer 2 header included in the received packet is based on a second correspondence relationship indicating a correspondence between the information of the layer 2 header, the information of the layer 3 header, and the information of the MPLS header. A network system characterized by converting to the MPLS header corresponding thereto.   The network system according to claim 8.
  The receiving unit receives a packet from the first network;
  The processing system converts the MPLS header included in a packet received from the first network into the corresponding layer 2 header based on the second correspondence relationship.   The network system according to claim 8, wherein
  The receiving unit receives a packet from the first network;
  The processing unit converts the priority information in the MPLS header included in the packet received from the first network into the priority information in the corresponding layer 2 header based on the first correspondence relationship. system. A first network that transfers a packet by a label in an MPLS header given before a header of a layer corresponding to layer 3 of an OSI (Open System Interconnection) model (hereinafter referred to as “layer 3 header”) And a second network that forwards the packet using a layer header (hereinafter referred to as “layer 2 header”) that corresponds to layer 2 of the OSI model different from the MPLS header, which is provided before the layer 3 header. And a packet transfer device connected to
  In the second network, a plurality of logical networks identified by the identifier of the layer 2 header are configured,
A receiving unit for receiving packets from the second network;
Based on the correspondence between the priority information of the packet in the layer 2 header, the information in the layer 3 header or the information in the layer 4 header, and the priority information in the MPLS header, A processing unit that converts priority information in the layer 2 header of the received packet into priority information in the corresponding MPLS header, and further converts a layer 2 header of the received packet into an MPLS header;
A packet transfer apparatus comprising: a transmission unit configured to transmit the packet obtained by converting the header to the first network. The packet transfer apparatus according to claim 12, wherein
The processor is
The layer 2 header included in the received packet is based on a second correspondence relationship indicating a correspondence between the information of the layer 2 header, the information of the layer 3 header, and the information of the MPLS header. A packet transfer apparatus that converts the MPLS header corresponding to the MPLS header.   The packet transfer apparatus according to claim 12,
  The receiving unit receives a packet from the first network;
  The processing unit converts the MPLS header included in a packet received from the first network into the corresponding layer 2 header based on the second correspondence relationship.   The packet transfer apparatus according to claim 12, wherein
  The receiving unit receives a packet from the first network;
  The processing unit converts, based on the first correspondence relationship, priority information in the MPLS header included in a packet received from the first network into priority information in the corresponding layer 2 header. Transfer device.

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