JP3530099B2 - Packet transfer device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet transfer device capable of realizing high speed transfer when transferring a packet having a compressed header.

[0002]

2. Description of the Related Art A packet transfer apparatus for transferring a packet whose header is compressed by a header compression method CRTP specified in IETF REC 2508 is provided with an input interface unit, a header decompression unit, an IP route control unit, a header compression unit, and It is composed of an output interface unit.

The input interface unit receives a packet transferred from an external packet transfer device and sends it to the header restoration unit. The header restoration unit restores the header of the packet received from the input interface unit, and transmits the packet with the restored header to the IP route control unit. The IP route control unit has an IP transfer table composed of correspondence data between IP and output links, extracts header information from the packet received from the header restoration unit, and outputs the header information by referring to the IP transfer table. The link is determined and the packet is sent to the header compression unit. The header compression unit compresses the header of the packet received from the IP route control unit and transmits the packet with the compressed header to the output interface unit. The output interface unit transfers the packet received from the header compression unit from the output link to an external packet transfer device.

In a device for transferring a packet whose header is compressed, as described above, when performing the IP route control, the compressed header is restored and returned to the form of the IP packet before the IP route control. Then, the header was compressed again and the transfer process was performed. However, this method has a problem that the processing load and processing delay for header decompression and recompression at the time of packet transfer are large.

Further, in a device for transferring a packet with a header compressed and cellized, conventionally, an IP transfer process is performed after the packet is assembled, and the packet is disassembled into cells before transmission. This method has a problem that the IP transfer process cannot be performed until all cells forming the packet arrive, and the packet assembly delay is large. There is also a problem that a processing load and a processing delay for the packet assembly processing and the packet disassembly processing occur.

Further, in a device for encapsulating a packet in which a header is compressed and cellized and encapsulating the packet in a connectionless transfer protocol, the packet is conventionally assembled (de) encapsulated and then (de) encapsulated. The packet was divided into cells and then sent. In this method, the (de) encapsulation process cannot be performed until all cells forming the packet arrive, and there is a problem that the packet assembly delay is large. There is also a problem that a processing load and a processing delay for the packet assembly processing and the packet disassembly processing occur.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce a transfer processing delay and a transfer processing load when transferring a header-compressed packet, and to transfer a header-compressed packet at high speed. It is to provide a packet transfer device capable of performing the packet transfer.

[0008]

In order to achieve the above object, the packet transfer apparatus of the present invention has a header compression method C.
A CRTP transfer table including correspondence data between the flow identifier CID in RTP and an output link, an input interface unit for receiving a packet transferred from an external packet transfer device and transmitting the packet to a packet transfer processing unit, and an input interface unit A packet transfer processing unit for receiving the packet to be read, reading the CID from the header thereof, searching the CRTP transfer table to specify the output link, and transmitting the packet to the output interface unit; and a packet transfer processing unit And an output interface unit for transferring the packet received from the output link to the external packet transfer device.

According to such a packet transfer apparatus of the present invention, when transferring a packet whose header is compressed, the correspondence data between the CID and the output link is obtained from the information of the flow identifier CID in the compressed header. CR including
By referring to the TP transfer table and specifying the output link, the packet can be transferred without decompressing the compressed header. Therefore, header decompression and recompression processing can be omitted, and processing delay and processing load can be reduced.

Further, in the case of including an IP transfer table containing the correspondence data of the destination IP address and the output link,
When performing the transfer processing of the first packet of the flow, refer to the IP transfer table from the header information of the first packet, and execute C
By generating an entry in the RTP transfer table, it is possible to dynamically set, for each flow, the corresponding data between the CID and the output link, which is different for each flow, so there is no need to set the entry for each flow.

Further, according to the present invention, an apparatus for dividing a packet having a compressed header into cells having a fixed length and transferring the packet is a destination IP using a connection identifier VPI and / or VCI.
I including data corresponding to address and output VPI / VCI
P transfer table, CRTP transfer table containing correspondence data of flow identifier CID and output VPI / VCI in header compression method CRTP, cell exchange table containing correspondence data of input VPI / VCI and output VPI / VCI, external packet transfer An input interface unit for receiving a cellized packet transferred from a device and transmitting it to a cell transfer processing unit, a cell transmitted from the input interface unit, an IP transfer table, CRTP
From the cell transfer processing unit for specifying the output VPI / VCI of the cell by setting and / or referring to the transfer table and the cell exchange table and transmitting the cell to the output interface unit, and the cell transfer processing unit. It is characterized by comprising an output interface unit for receiving the transmitted cell and transferring it to an external packet transfer device.

According to the packet transfer apparatus of the present invention as described above, the IP transfer table, the CRTP transfer table and the cell exchange table are provided, and the respective tables can be linked. In particular, when the first packet first cell, the first packet succeeding cell, the succeeding packet first cell, and the succeeding packet succeeding cell are identified, individual transfer processing can be performed for each of them.

That is, by referring to the IP transfer table from the header information of the head cell of the head packet and generating the entries of the CRTP transfer table and the cell exchange table, the CRTP route control of the subsequent packet and the cell exchange of each cell of the head packet. Processing becomes possible. Further, by referring to the CRTP transfer table from the header information of the succeeding packet head cell and generating the entry of the cell exchanging table, the cell exchanging process of each cell of the succeeding packet becomes possible.

Therefore, header decompression and recompression processing can be omitted, and dynamic CRTP route control for each flow and transfer processing for each cell can be performed. As a result, processing delay and processing load for header decompression and recompression processing can be reduced, and further, packet assembly and disassembly processing can be omitted, and packet assembly delay can be reduced. Processing delay and processing load can be reduced.

Further, a packet transfer device for transferring a packet from a user network to a packet transfer network according to the present invention comprises an IP transfer table containing correspondence data between a destination IP address and a destination packet transfer device, a flow identifier CID and a destination packet. CRTP transfer table containing correspondence data with transfer device, connectionless transfer protocol transfer table containing correspondence data with destination packet transfer device and output VPI / VCI, input VPI / VCI
Cell exchange table containing correspondence data between output and output VPI / VCI, user network input interface unit for receiving cellized packets transferred from the user network and transmitting them to the encapsulation transfer processing unit, user network input interface To the connectionless transfer protocol of the packet by receiving the cellized packet transmitted from the unit and setting and / or referring to the IP transfer table, the CRTP transfer table, the connectionless transfer protocol transfer table and the cell exchange table. For encapsulating the packet and specifying the output VPI / VCI of the cell obtained by dividing the packet, and transmitting the packetized connectionless transfer protocol packet to the packet transfer network output interface unit. And a packet transfer network output interface unit for receiving a cellized connectionless transfer protocol packet transmitted from the encapsulation transfer processing unit and transferring the packet to a packet relay device. And

According to the packet transfer apparatus of the present invention as described above, the IP transfer table, the connectionless transfer protocol transfer table, the CRTP transfer table and the cell exchange table are provided, and each table can be linked. In particular, when the first packet first cell, the first packet succeeding cell, the succeeding packet first cell, and the succeeding packet succeeding cell are identified, individual transfer processing can be performed for each of them.

That is, the destination packet transfer device is specified by referring to the IP transfer table and the connectionless transfer protocol transfer table from the header information of the head packet start cell, and the entries of the CRTP transfer table and the cell exchange table are generated, and based on this. Create a cell containing the header of the connectionless transfer protocol, add the header cell before the head cell, and encapsulate the head packet in the connectionless transfer protocol, thereby CRTP route control and encapsulation of the subsequent packet. It enables cell exchange processing of each cell of the first packet.

Further, the destination packet transfer device is specified by referring to the CRTP transfer table and the connectionless transfer protocol transfer table from the header information of the succeeding packet head cell, and the entry of the cell exchange table is generated,
Based on that, a cell containing the header of the connectionless transfer protocol is created, and the header cell is added in front of the first cell to encapsulate the subsequent packet in the connectionless transfer protocol, whereby each cell of the encapsulated subsequent packet It enables the cell exchange process.

Therefore, header decompression and recompression processing can be omitted, and dynamic CRTP route control and encapsulation transfer processing for each flow can be performed for each cell. This makes it possible to reduce the processing delay and processing load for header decompression and recompression processing when performing encapsulation transfer.
Further, the packet assembly delay can be reduced, and the packet assembly and disassembly processing delays and processing loads can be reduced.

Further, the packet transfer device for transferring a packet from the packet transfer network of the present invention to the user network includes a destination IP address and an output VPI /
IP transfer table containing correspondence data with VCI, CRTP transfer table containing correspondence data with flow identifier CID and output VPI / VCI, input VPI / VCI and output V
A cell exchange table containing data corresponding to PI / VCI,
Cell transfer transmitted from the packet transfer network input interface unit for receiving the cellized connectionless transfer protocol packet transferred from the packet relay device and transmitting it to the decapsulation transfer processing unit Received connectionless transfer protocol packet,
The packet is decapsulated, an IP forwarding table,
By setting and / or referring to the CRTP transfer table and the cell exchange table, the output VPI / VCI of the cell obtained by dividing the decapsulated packet is specified, and the cellified packet is transmitted to the user network output interface unit. And a user network output interface unit for receiving the cellized packet transmitted from the decapsulation transfer processing unit and transferring it to the user network.

According to the packet transfer apparatus of the present invention as described above, the IP transfer table, the CRTP transfer table and the cell exchange table are provided and the respective tables can be linked. In particular, when the first packet first cell, the first packet succeeding cell, the succeeding packet first cell, and the succeeding packet succeeding cell are identified, individual transfer processing can be performed for each of them.

That is, by referring to the IP transfer table from the header information of the head cell of the head packet and creating the entries of the CRTP transfer table and the cell exchange table, the CRTP route control of the succeeding packet and the cell exchange of each cell of the head packet. Allow processing. Furthermore, the entry of the cell exchange table is generated by referring to the CRTP transfer table from the header information of the succeeding packet head cell,
Thereby, the cell exchange processing of each cell of the subsequent packet is enabled.

Therefore, header decompression and recompression processing can be omitted, and dynamic CRTP route control and decapsulation transfer processing for each flow can be performed for each cell. This makes it possible to reduce processing delay and processing load for header decompression and recompression processing when performing decapsulation transfer, further reduce packet assembly delay, and reduce packet assembly and disassembly processing delay and The processing load can be reduced.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a packet transfer device of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a packet transfer network to which the packet transfer device of the present invention is applied. Packet transfer network 1
Is a packet transfer device 31-36 and a packet relay device 41,
42 shall be configured by linking. The packet transfer devices 31 to 36 are user networks 11 to 19 and 21 to
Accommodating 29, these, user networks 11-19, 21
Packets transferred from ~ 29 are encapsulated in connectionless transfer protocol and transferred. The packet relay devices 41 and 42 transfer using the connectionless transfer protocol.

FIG. 2 is a diagram showing a configuration example of the packet transfer apparatus of the present invention. The packet transfer device 31 includes an IP transfer table (for encapsulation) 111, a CRTP transfer table (for encapsulation) 112, a connectionless transfer protocol transfer table 113, and a cell exchange table (for encapsulation) 11
4, user network input interface section 115,
Encapsulation transfer processing unit 116, packet transfer network output interface unit 117, IP transfer table (for decapsulation) 121, CRTP transfer table (for decapsulation) 122, cell exchange table (for decapsulation) 123,
Packet transfer network input interface unit 12
4, a decapsulation transfer processing unit 125, and a user network output interface unit 126.

IP transfer table (for encapsulation) 111
Contains the correspondence data between the destination IP address and the destination packet transfer device. CRTP transfer table (for encapsulation)
112 includes data corresponding to the CID and the destination packet transfer device. Connectionless transfer protocol transfer table
113 includes the correspondence data between the destination packet transfer device and the output VPI / VCI. The cell exchange table (for encapsulation) 114 has an input VPI / VCI and an output VPI / VCI.
Includes data corresponding to.

The user network input interface section 115 receives cellized packets from the user networks 11 to 13 and sends them to the encapsulation transfer processing section 116. The encapsulation transfer processing unit 116 receives the cellized packet transmitted from the user network input interface unit 115, and the IP transfer table (for encapsulation) 111 and the CRTP transfer table (for encapsulation) 1
12, connectionless transfer protocol transfer table 113
By setting and referring to the cell exchange table (for encapsulation) 114 as necessary, the packet is encapsulated in the connectionless transfer protocol and the output VPI / VCI of the cell into which the packet is divided is specified. ,
Packetized network of connectionless transfer protocol packets is transferred to network output interface section
Send to 117. The packet transfer network output interface unit 117 receives the packet of the cellized connectionless transfer protocol transmitted from the encapsulation transfer processing unit 116, and transfers the packet to the packet relay device 41.

IP transfer table (for decapsulation) 121
Contains the correspondence data between the destination IP address and the output VPI / VCI. CRTP transfer table (for decapsulation)
122 includes the correspondence data between the CID and the output VPI / VCI. The cell exchange table (for decapsulation) 123 includes correspondence data between the input VPI / VCI and the output VPI / VCI.

The packet transfer network input interface section 124 receives the packetized connectionless transfer protocol packet from the packet relay device 41,
It is transmitted to the decapsulation transfer processing unit 125. The decapsulation transfer processing unit 125 receives the packetized connectionless transfer protocol packet transmitted from the packet transfer network input interface unit 124, decapsulates the packet, and transfers the IP transfer table (for decapsulation) 121. , The CRTP transfer table (for decapsulation) 122 and the cell exchange table (for decapsulation) 123 are set and referred to as necessary to specify the output VPI / VCI of the cell into which the decapsulated packet is divided, The packetized cell is transmitted to the user network output interface unit 126. The user network output interface unit 126 receives the cellized packet transmitted from the decapsulation transfer processing unit 125 and transfers it to the user networks 11 to 13.

FIG. 3 is a diagram showing a configuration example of the encapsulation transfer processing unit in the packet transfer apparatus of the present invention. The encapsulation transfer processing unit 116 includes a cell identification unit 161, a head packet head cell encapsulation transfer processing unit 162, a head packet subsequent cell encapsulation transfer processing unit 163, a subsequent packet head cell encapsulation transfer processing unit 164, and a subsequent packet subsequent cell. An encapsulation transfer processing unit 165 is provided.

The cell identification unit 161 receives the cell transmitted from the user network input interface unit 115, determines whether the cell is the cell of the first packet of the flow or the cell of the subsequent packet other than the first packet, and further the first packet. A cell or a subsequent cell other than the head cell is identified, and if the cell is the head cell of the head packet of the flow, it is transmitted to the head packet head cell encapsulation transfer processing unit 162, and the cell is the head packet of the flow. If the cell is a subsequent cell, the first packet is transmitted to the subsequent cell encapsulation transfer processing section 163. If the cell is the first cell of a subsequent packet in the flow, the subsequent packet first cell encapsulation transfer processing section 16 is transmitted.
If the cell is a subsequent cell of a subsequent packet of the flow, the subsequent packet is transmitted to the subsequent cell encapsulation transfer processing unit 165.

The head packet head cell encapsulation transfer processing unit 162 receives the head cell of the head packet transmitted from the cell identification unit 161, performs head packet head cell route control processing and encapsulation processing, and outputs the cell. VPI / VC
I is specified and the cell is transmitted to the packet transfer network output interface unit 117. The head packet succeeding cell encapsulation transfer processing unit 163 receives the succeeding cell of the head packet transmitted from the cell identifying unit 161, performs the head packet succeeding cell route control processing, and outputs the output VPI / V of the cell.
The CI is specified and the cell is transmitted to the packet transfer network output interface unit 117. The subsequent packet first cell encapsulation transfer processing unit 164 receives the first cell of the subsequent packet transmitted from the cell identification unit 161, performs the subsequent packet first cell route control process and the encapsulation process, and outputs the output VPI / VCI of the cell. And transmits the cell to the packet transfer network output interface unit 117. Subsequent packet Subsequent cell encapsulation transfer processing unit 165
Receives the succeeding cell of the succeeding packet transmitted from the cell identifying unit 161, performs the succeeding packet succeeding cell route control process to specify the output VPI / VCI of the cell, and determines the cell as the packet transfer network output interface unit 117. Send to.

FIG. 4 is a diagram showing a configuration example of the head packet head cell encapsulation transfer processing unit according to the present invention. The head packet head cell encapsulation transfer processing unit 162 includes a header information extraction unit 1621, an IP route control unit 1622, and an encapsulation unit.
1623 and a cell exchange section 1624.

The header information extraction unit 1621 is provided in the cell identification unit 16
The first cell of the first packet transmitted from 1 is received, the header information of the cell is extracted, the header information is transmitted to the IP route control unit 1622, and the cell is transmitted to the encapsulation unit 1623. The IP route control unit 1622 includes a header information extraction unit 16
The header information transmitted from 21 is received, the IP packet transfer table (for encapsulation) 111 and the connectionless transfer protocol transfer table 113 are referenced from the header information, the destination packet transfer device is identified, and the CRTP transfer table ( The entries of the encapsulation 112 and the cell exchange table 114 (for encapsulation) are generated. The encapsulation unit 1623 creates a cell including a header of the connectionless transfer protocol based on the obtained destination packet transfer device information, adds the header cell before the head cell received from the header information extraction unit 1621, and adds the header cell. The packet including the first cell is encapsulated in the connectionless transfer protocol, and those cells are transmitted to the cell switching unit 1624. The cell switching unit 1624 identifies the output VPI / VCI of the cell by referring to the cell switching table (for encapsulation) 114 from the input VPI / VCI of the cell received from the encapsulation unit 1623, and determines the cell as a packet transfer network. It is transmitted to the output interface unit 117.

FIG. 5 is a diagram showing a configuration example of a head packet subsequent cell encapsulation transfer processing unit according to the present invention. The head packet subsequent cell encapsulation transfer processing unit 163 includes a cell switching unit 1631. The cell exchange unit 1631 is a cell identification unit 161.
The output VPI / VCI of the cell is specified by referring to the cell exchange table (for encapsulation) 114 from the input VPI / VCI of the cell received from the cell, and the cell is transmitted to the packet transfer network output interface unit 117.

FIG. 6 is a diagram showing a configuration example of a succeeding packet head cell encapsulation transfer processing unit according to the present invention. The subsequent packet head cell encapsulation transfer processing unit 164 includes a header information extraction unit 1641, a CRTP route control unit 1642, an encapsulation unit 1643, and a cell switching unit 1644.

The header information extraction unit 1641 is provided in the cell identification unit 16
The first cell of the subsequent packet transmitted from 1 is received, the header information of the cell is extracted, and the header information is sent to the CRT.
It is transmitted to the P route control unit 1642, and the cell is encapsulated by the encapsulation unit 1643.
Send to. The CRTP route control unit 1642 receives the header information transmitted from the header information extraction unit 1641, and from the header information, the CRTP transfer table (for encapsulation).
112 and connectionless transfer protocol transfer table 1
13, the destination packet transfer device is specified, and the entry of the cell exchange table (for encapsulation) 114 is generated. The encapsulation unit 1643 creates a cell including the header of the connectionless transfer protocol based on the obtained destination packet transfer device information, and the header information extraction unit 1641
A header cell is added before the head cell received from the packet, the packet including the head cell is encapsulated in the connectionless transfer protocol, and those cells are transmitted to the cell switching unit 1644. The cell exchange unit 1644 refers to the cell exchange table (for encapsulation) 114 based on the input VPI / VCI of the cell received from the encapsulation unit 1643 and outputs VPI / VCI of the cell.
The VCI is specified and the cell is transmitted to the packet transfer network output interface unit 117.

FIG. 7 is a diagram showing an example of the configuration of a subsequent packet subsequent cell encapsulation transfer processing unit according to the present invention. The subsequent packet subsequent cell encapsulation transfer processing unit 165 includes a cell switching unit 1651. The cell exchange unit 1651 has a cell identification unit 161.
The output VPI / VCI of the cell is specified by referring to the cell exchange table (for encapsulation) 114 from the input VPI / VCI of the cell received from the cell, and the cell is transmitted to the packet transfer network output interface unit 117.

FIG. 8 is a diagram showing a configuration example of the decapsulation transfer processing unit in the packet transfer apparatus of the present invention. The decapsulation transfer processing unit 125 includes a cell identification unit 251, a head packet head cell decapsulation transfer processing unit 252, a head packet subsequent cell decapsulation transfer processing unit 253, a subsequent packet head cell decapsulation transfer processing unit 254, and a subsequent packet. The packet subsequent cell decapsulation transfer processing unit 255 is provided.

The cell identifying unit 251 receives the cell transmitted from the packet transfer network input interface unit 124, removes the header cell if the cell is a cell including the header of the connectionless transfer protocol, and removes the header cell. If not, the cell is identified as the cell of the first packet of the flow or the cell of the subsequent packet other than the first packet, and further the first cell of the packet or the subsequent cell other than the first cell is identified, and the cell is the first cell of the flow. If it is the first cell of the packet, it is transmitted to the first packet first cell decapsulation transfer processing unit 252, and if the cell is the subsequent cell of the first packet of the flow, it is transmitted to the first packet subsequent cell decapsulation transfer processing unit 253. If the cell is the first cell of the subsequent packet of the flow, the subsequent packet first cell decapsulation transfer processing Transmitted to part 254, if the cell is a subsequent cell of the subsequent packets of the flow is sent to the subsequent packets subsequent cell decapsulation transfer processing unit 255.

The head packet head cell decapsulation transfer processing unit 252 receives the head cell of the head packet transmitted from the cell identification unit 251, performs head packet head cell route control processing, and outputs VPI / VCI of the cell. User cell output interface unit 126
Send to. The head packet subsequent cell decapsulation transfer processing unit 253 receives the subsequent cell of the head packet transmitted from the cell identification unit 251, performs head packet subsequent cell route control processing, and specifies the output VPI / VCI of the cell. , The user network output interface unit 126
Send to. The subsequent packet first cell decapsulation transfer processing unit 254 receives the first cell of the subsequent packet transmitted from the cell identification unit 251 and performs the subsequent packet first cell route control processing to specify the output VPI / VCI of the cell. , The user network output interface unit 126
Send to. The subsequent packet subsequent cell decapsulation transfer processing unit 255 receives the subsequent cell of the subsequent packet transmitted from the cell identification unit 251 and performs the subsequent packet subsequent cell route control processing to specify the output VPI / VCI of the cell. , The user network output interface unit 126
Send to.

FIG. 9 is a diagram showing a configuration example of the head packet head cell decapsulation transfer processing unit according to the present invention. The head packet head cell decapsulation transfer processing unit 252 includes a header information extraction unit 2521, an IP route control unit 2522, and a cell switching unit 2523.

The header information extraction unit 2521 is used by the cell identification unit 25.
The first cell of the first packet transmitted from 1 is received, the header information of the cell is extracted, the header information is transmitted to the IP route control unit 2522, and the cell is transmitted to the cell switching unit 2523. The IP route control unit 2522 has a header information extraction unit 2521.
From the header information transmitted from the IP transfer table (for decapsulation) 121 and the entry of the CRTP transfer table (for decapsulation) 122 and the cell exchange table (for decapsulation) 123. Generate. The cell exchange unit 2523 is a header information extraction unit.
The output VPI / VCI of the cell is specified by referring to the cell exchange table (for decapsulation) 123 from the input VPI / VCI of the cell received from 2521, and the cell is transmitted to the user network output interface unit 126.

FIG. 10 is a diagram showing a configuration example of the head packet subsequent cell decapsulation transfer processing unit according to the present invention.
The head packet subsequent cell decapsulation transfer processing unit 253
The cell exchange unit 2531 is provided. The cell exchange unit 2531 identifies the output VPI / VCI of the cell from the input VPI / VCI of the cell received from the cell identification unit 251 by referring to the cell exchange table (for decapsulation) 123, and sets the cell to the user network. It is transmitted to the output interface unit 126.

FIG. 11 is a diagram showing an example of the configuration of a subsequent packet head cell decapsulation transfer processing unit according to the present invention.
The subsequent packet top cell decapsulation transfer processing unit 254
It comprises a header information extraction unit 2541, a CRTP route control unit 2542 and a cell exchange unit 2543.

The header information extraction unit 2541 is provided in the cell identification unit 25.
The first cell of the subsequent packet transmitted from 1 is received, the header information of the cell is extracted, and the header information is sent to the CRT.
It transmits to the P route control unit 2542 and transmits the cell to the cell switching unit 2543. The CRTP route control unit 2542 receives the header information transmitted from the header information extraction unit 2541, and from the header information, the CRTP transfer table (for decapsulation)
122, cell exchange table (for decapsulation) 1
Generate 23 entries. The cell exchange unit 2543 receives the input VPI / V of the cell received from the header information extraction unit 2541.
The CI refers to the cell exchange table (for decapsulation) 123 to specify the output VPI / VCI of the cell, and transmits the cell to the user network output interface unit 126.

FIG. 12 is a diagram showing an example of the configuration of a subsequent packet subsequent cell decapsulation transfer processing unit according to the present invention.
Subsequent packet Subsequent cell decapsulation transfer processing unit 255,
The cell exchange unit 2551 is provided. The cell switching unit 2551 identifies the output VPI / VCI of the cell by referring to the cell switching table (for decapsulation) 123 from the input VPI / VCI of the cell received from the cell identification unit 251, and determines the cell as the user network. It is transmitted to the output interface unit 126.

Next, the operation will be described based on the configuration example of the packet transfer apparatus of the present invention shown in FIGS.
The packet transfer device 31 (FIG. 1) will be described below as an example.

It is assumed that the user network input interface unit 115 of the packet transfer device 31 receives a packet flow whose header is compressed from the user network 11. First, the user network input interface unit 115 receives the head cell of the head packet of the flow. The user network input interface unit 115 transmits the cell to the encapsulation transfer processing unit 116. The cell identification unit 161 of the encapsulation transfer processing unit 116 receives the cell transmitted from the user network input interface unit 115, identifies that the cell is the head cell of the head packet of the flow, and heads the cell. Packet top cell encapsulation transfer processing unit 16
Send to 2.

The header information extraction unit 1621 of the head packet head cell encapsulation transfer processing unit 162 receives the head packet head cell transmitted from the cell identification unit 161, extracts the header information of the cell, and extracts the header information. It transmits to the IP route control unit 1622 and transmits the cell to the encapsulation unit 1623. The IP path control unit 1622 receives the header information transmitted from the header information extraction unit 1621, refers to the IP transfer table (for encapsulation) 111 and the connectionless transfer protocol transfer table 113 from the header information, and refers to the destination packet. The transfer device is specified, and the entries of the CRTP transfer table (for encapsulation) 112 and the cell exchange table (for encapsulation) 114 are generated.

The encapsulation unit 1623 creates a cell including the header of the connectionless transfer protocol based on the obtained destination packet transfer device information, and the header information extraction unit 1623.
A header cell is added in front of the head cell received from 21 to encapsulate a packet including the head cell in a connectionless transfer protocol, and these cells are exchanged with the cell switching unit 1624.
Send to. The cell switching unit 1624 refers to the cell switching table (for encapsulation) 114 based on the input VPI / VCI of the cell received from the encapsulation unit 1623 and outputs the output VPI of the cell.
/ VCI is specified and the cell is transmitted to the packet transfer network output interface unit 117. The packet transfer network output interface unit 117 receives the cellized connectionless transfer protocol packet transmitted from the cell switching unit 1624 of the head packet head cell encapsulation transfer processing unit 162 of the encapsulation transfer processing unit 116, and Transfer to the relay device 41 (FIG. 1).

Next, the user network input interface unit 115 receives the subsequent cell of the first packet of the flow. The user network input interface unit 115 transmits the cell to the encapsulation transfer processing unit 116. Cell identification unit 161 of encapsulation transfer processing unit 116
Is the user network input interface section 11
The cell transmitted from 5 is received, the cell is identified as the subsequent cell of the first packet of the flow, and the cell is transmitted to the first packet subsequent cell encapsulation transfer processing unit 163. First packet Subsequent cell encapsulation transfer processing unit 163
The cell switching unit 1631 identifies the output VPI / VCI of the cell from the input VPI / VCI of the cell received from the cell identification unit 161 by referring to the cell switching table (for encapsulation) 114, and transfers the cell to the packet. It is transmitted to the network output interface unit 117. The packet transfer network output interface unit 117 includes an encapsulation transfer processing unit 1
The first packet 16 of the subsequent cell encapsulation transfer processing unit 163 receives the cellized connectionless transfer protocol packet transmitted from the cell switching unit 1631 and transfers the packet to the packet relay device 41 (FIG. 1). The same applies hereinafter.

[0053]

As described above, according to the packet transfer apparatus of the present invention, when a packet whose header is compressed can be transferred without decompressing the header, the header is further compressed. When packets are transferred in cells, they can be transferred to cell-by-cell without assembling cellized packets, and the packets are assembled even when encapsulating and transferring cellized packets whose headers are compressed. Can be (de) encapsulated and transferred to a cell-by-cell without having to. As a result, the packet with the compressed header can be transferred at high speed. In addition, short packets (eg Voice over
When transferring (IP packet) etc., it is possible to improve the use efficiency of the band and at the same time realize high-speed transfer, thereby making it possible to broaden the band of the packet transfer network. As a result, the cost performance of the packet transfer network is improved and the user cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a packet transfer network to which a packet transfer device of the present invention is applied.

FIG. 2 is a diagram showing a configuration example of a packet transfer device of the present invention.

FIG. 3 is a diagram showing a configuration example of an encapsulation transfer processing unit in the packet transfer device of the present invention.

FIG. 4 is a diagram showing a configuration example of a head packet head cell encapsulation transfer processing unit according to the present invention.

FIG. 5 is a diagram showing a configuration example of a head packet subsequent cell encapsulation transfer processing unit according to the present invention.

FIG. 6 is a diagram showing a configuration example of a succeeding packet head cell encapsulation transfer processing unit according to the present invention.

FIG. 7 is a diagram showing a configuration example of a subsequent packet subsequent cell encapsulation transfer processing unit according to the present invention.

FIG. 8 is a diagram showing a configuration example of a decapsulation transfer processing unit in the packet transfer device of the present invention.

FIG. 9 is a diagram showing a configuration example of a head packet head cell decapsulation transfer processing unit according to the present invention.

FIG. 10 is a diagram showing a configuration example of a head packet subsequent cell decapsulation transfer processing unit according to the present invention.

FIG. 11 is a diagram showing a configuration example of a succeeding packet head cell decapsulation transfer processing unit according to the present invention.

FIG. 12 is a diagram showing a configuration example of a succeeding packet subsequent cell decapsulation transfer processing unit according to the present invention.

[Explanation of symbols]

1 packet transfer network 31-36 packet transfer device 41, 42 packet relay device 11-19, 21-29 user network 111 IP transfer table (for encapsulation) 112 CRTP transfer table (for encapsulation) 113 connectionless transfer protocol transfer table 114 cell exchange table (for encapsulation) 115 user network input interface unit 116 encapsulation transfer processing unit 117 packet transfer network output interface unit 121 IP transfer table (for decapsulation) 122 CRTP transfer table (for decapsulation) 123 cell exchange table (For decapsulation) 124 Packet transfer network input interface section 125 Decapsulation transfer processing section 126 User network output interface Interface unit 161, 251 cell identification unit 162 head packet head cell encapsulation transfer processing unit 163 head packet subsequent cell encapsulation transfer processing unit 164 subsequent packet head cell encapsulation transfer processing unit 165 subsequent packet subsequent cell encapsulation transfer processing unit 252 head Packet head cell decapsulation transfer processing unit 253 Head packet subsequent cell decapsulation transfer processing unit 254 Subsequent packet head cell decapsulation transfer processing unit 255 Subsequent packet subsequent cell decapsulation transfer processing unit 1621, 1641, 2521, 2541 Header Information extraction units 1622, 2522 IP route control units 1623, 1643 Encapsulation units 1624, 1631, 1644, 1651, 2523,
2531, 2543, 2551 Cell switching unit 1642, 2542 CRTP route control unit

Continuation of front page (56) Reference JP-A-7-321794 (JP, A) JP-A-10-257070 (JP, A) JP-A-2001-251360 (JP, A) Special Table 2003-511981 (JP, A) ) Special Table 2003-502948 (JP, A) S.I. Casner et. al. , C compressing IP / UDP / RTP Headers for Low-Speed Serial Links, RFC 2508, USA, IETF, February 1999 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/56 H04L 12 / 28 H04L 12/46 H04L 12/66

Claims (20)

(57) [Claims] 1. A device for transferring a packet, the header of which is compressed by a header compression method CRTP specified in REC 2508 of IETF, which is a flow identifier CID in the header compression method CRTP.
And a CRTP transfer table containing correspondence data between output links, an input interface unit for receiving a packet transferred from an external packet transfer device and transmitting it to a packet transfer processing unit, and a packet transmitted from an input interface unit Then, the CID is read from the header, and the CRTP
A packet transfer processing unit for searching the transfer table to specify the output link and transmitting the packet to the output interface unit, and transferring a packet received from the packet transfer processing unit from the output link to an external packet transfer device A packet transfer apparatus comprising an output interface section for performing the operation. 2. The apparatus further comprises an IP transfer table including correspondence data of a destination IP address and an output link, wherein the packet transfer processing unit receives a packet transmitted from the input interface unit, and the packet is transmitted to the REC 2508. The header packet of the specified header compression method CRTP is identified as the first packet or the subsequent packet of the flow, and if the packet is the first packet of the flow, it is transmitted to the first packet transfer processing unit, and the packet is the subsequent packet of the flow. In the case of receiving the packet identification unit for transmission to the subsequent packet transfer processing unit and the first packet transmitted from the packet identification unit,
A head packet transfer processing unit for identifying an output link by referring to the IP transfer table from the header information of the packet, generating an entry of the CRTP transfer table, and transmitting the packet to the output interface unit, and a packet identification unit Received subsequent packets sent from
The packet according to claim 1, further comprising a subsequent packet transfer processing unit for identifying an output link by referring to a CRTP transfer table from the header information of the packet and transmitting the packet to the output interface unit. Transfer device. 3. An apparatus for dividing a packet, the header of which is compressed by the header compression method CRTP specified in REC 2508 of IETF, into fixed-length cells and transferring the cells. An IP transfer table containing the correspondence data between the destination IP address using the connection identifier VPI and / or VCI defined in 150 and the output VPI / VCI, and the flow identifier CID in the header compression method CRTP.
CRTP transfer table containing correspondence data between input VPI / VCI and output VPI / VCI, cell exchange table containing correspondence data between input VPI / VCI and output VPI / VCI, receiving cellized packets transferred from an external packet transfer device Then, the input interface unit for transmitting to the cell transfer processing unit and the cell transmitted from the input interface unit are received,
A cell transfer processing unit for specifying the output VPI / VCI of the cell by setting and / or referring to the IP transfer table, the CRTP transfer table and the cell exchange table, and transmitting the cell to the output interface unit, and A packet transfer apparatus comprising an output interface section for receiving a cell transmitted from a cell transfer processing section and transferring it to an external packet transfer apparatus. 4. The cell transfer processing unit receives a cell transmitted from an input interface unit,
It identifies whether the cell is the cell of the first packet of the flow or the cell of the subsequent packet, and the first cell of the packet or the subsequent cell, and if the cell is the first cell of the first packet of the flow, the first cell of the first packet Send to the transfer processing unit, and if the cell is the subsequent cell of the first packet of the flow, the first packet subsequent cell. Send to the transfer processing unit, and if the cell is the first cell of the subsequent packet of the flow, the subsequent packet first cell. If the cell is a subsequent cell of a subsequent packet of the flow, the cell identification unit for transmitting to the subsequent packet subsequent cell transfer processing unit, the first cell of the first packet transmitted from the cell identification unit To receive, perform head packet top cell route control processing, specify the output VPI / VCI of the cell, and transmit the cell to the output interface unit Of the first packet of the first packet, the subsequent cell of the first packet transmitted from the cell identification section is received, the first packet subsequent cell route control processing is performed to specify the output VPI / VCI of the cell, and the cell is output. Head packet for transmission to interface section Subsequent cell transfer processing section, Receives the head cell of the subsequent packet transmitted from the cell identification section, performs subsequent packet head cell route control processing, and specifies the output VPI / VCI of the cell Then, the subsequent packet first cell transfer processing unit for transmitting the cell to the output interface unit and the subsequent cell of the subsequent packet transmitted from the cell identification unit are received, and the subsequent packet subsequent cell route control process is performed to Subsequent packet subsequent cell transfer processing for specifying the output VPI / VCI of the cell and transmitting the cell to the output interface unit The packet transfer apparatus according to claim 3, characterized in that it comprises a part. 5. The head packet head cell transfer processing unit receives the head packet head cell transmitted from the cell identification unit, extracts header information of the cell, and transmits the header information to the IP routing controller. , A header information extraction unit for transmitting the cell to the cell switching unit, receiving header information transmitted from the header information extraction unit, and referring to the IP transfer table from the header information, C
Input VPI / V of the cell received from the IP route control unit for generating the entries of the RTP transfer table and the cell exchange table, and the header information extraction unit
From CI, refer to the cell exchange table and output V of the cell
The packet transfer device according to claim 4, further comprising a cell switching unit for specifying the PI / VCI and transmitting the cell to the output interface unit. 6. The head packet succeeding cell transfer processing unit refers to a cell exchange table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VCI of the cell.
The packet transfer device according to claim 4, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the output interface unit. 7. The succeeding packet leading cell transfer processing unit receives the succeeding packet leading cell transmitted from the cell identifying unit, extracts header information of the cell, and sends the header information to a CRTP route control unit. , A header information extraction unit for transmitting the cell to the cell exchange unit, receiving header information transmitted from the header information extraction unit, and referring to the CRTP transfer table from the header information to generate an entry of the cell exchange table CR for
Input VPI / V of the cell received from the TP route control unit and the header information extraction unit
From CI, refer to the cell exchange table and output V of the cell
The packet transfer device according to claim 4, further comprising a cell switching unit for specifying the PI / VCI and transmitting the cell to the output interface unit. 8. The subsequent packet subsequent cell transfer processing unit refers to a cell exchange table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VCI of the cell.
The packet transfer device according to claim 4, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the output interface unit. 9. A connectionless transfer protocol for accommodating a user network, specifying a route of a packet transferred from the user network, the packet being header-compressed by the header compression method CRTP and transferred from the user network, by the connectionless transfer protocol. A packet transfer device that performs transfer by encapsulating in a packet, and a packet relay device that transfers using the connectionless transfer protocol,
A device for transferring a packet from a user network to a packet transfer network in a packet transfer network connected in a network by a communication link, and an IP transfer table including a correspondence data between a destination IP address and a destination packet transfer device, and a flow. A CRTP transfer table containing the correspondence data between the identifier CID and the destination packet transfer device, a connectionless transfer protocol transfer table containing the correspondence data between the destination packet transfer device and the output VPI / VCI, an input VPI / VCI and an output VPI / VCI Cell exchange table containing corresponding data, user network input interface section for receiving cellized packet transferred from user network and sending to encapsulation transfer processing section, user network input interface Receives the packet cell assembling sent from over the face portion, IP forwarding table, CRTP forwarding table, set the connectionless transport protocol forwarding table and cell exchange table and /
Alternatively, by referring to the packet, the packet is encapsulated in a connectionless transfer protocol and the output VPI / VCI of the cell into which the packet is divided is specified, and the packetized connectionless transfer protocol packet is output to the packet transfer network output interface. And a packet transfer network output interface for receiving a cellized connectionless transfer protocol packet sent from the encapsulation transfer processing unit and transferring it to a packet relay device. A packet transfer device comprising a unit. 10. The encapsulation transfer processing unit receives a cell transmitted from a user network input interface unit, and the cell is a cell of a first packet of a flow or a cell of a subsequent packet, and a first cell of the packet. Or the subsequent cell, if the cell is the first cell of the first packet of the flow, it is transmitted to the first packet first cell encapsulation transfer processing unit, and if the cell is the succeeding cell of the first packet of the flow, Head packet Subsequent cell Send to encapsulation transfer processing unit, and if the cell is the head cell of subsequent packet of flow, send it to subsequent packet head cell encapsulation transfer processing unit, and that cell is subsequent cell of flow subsequent packet If it is, the subsequent packet is transmitted from the cell identification unit for transmitting to the subsequent cell encapsulation transfer processing unit, and the cell identification unit. Head packet head cell for receiving the head cell of the head packet, performing head packet head cell routing control and encapsulation processing to specify the output VPI / VCI of the cell, and transmitting the cell to the packet transfer network output interface unit The cell encapsulation transfer processing unit receives the subsequent cell of the head packet transmitted from the cell identification unit, performs the head packet subsequent cell route control processing to specify the output VPI / VCI of the cell, and determines the cell as a packet transfer network. Head packet for transmission to the output interface unit Subsequent cell encapsulation transfer processing unit, Receives the head cell of the subsequent packet transmitted from the cell identification unit, performs subsequent packet head cell route control and encapsulation processing, and The output VPI / VCI is specified and the cell is output to the packet transfer network. Subsequent packet head cell encapsulation transfer processing unit for transmission to the interface unit, and the subsequent cell of the subsequent packet transmitted from the cell identification unit, receives the subsequent packet subsequent cell route control process, and outputs the cell. 10. The packet transfer device according to claim 9, further comprising a subsequent packet subsequent cell encapsulation transfer processing unit for specifying the VPI / VCI and transmitting the cell to the packet transfer network output interface unit. 11. The head packet head cell encapsulation transfer processing unit receives the head packet head cell transmitted from the cell identification unit, extracts header information of the cell, and sends the header information to an IP routing controller. A header information extraction unit for transmitting and transmitting the cell to the encapsulation unit, receiving header information transmitted from the header information extraction unit, and referring to the IP transfer table and the connectionless transfer protocol transfer table from the header information An IP path control unit for identifying the destination packet transfer device and generating entries in the CRTP transfer table and the cell exchange table, and a cell including a header of the connectionless transfer protocol based on the obtained destination packet transfer device information. Create and add a header cell before the first cell received from the header information extractor. As a result, the packet including the first cell is encapsulated in the connectionless transfer protocol, and the encapsulation unit for transmitting those cells to the cell switching unit, and the input VPI / VCI of the cell received from the encapsulation unit , VPI / output of the cell by referring to the cell exchange table
The packet transfer device according to claim 10, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the packet transfer network output interface unit. 12. The head packet succeeding cell encapsulation transfer processing unit refers to a cell exchange table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VCI of the cell.
The packet transfer device according to claim 10, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the packet transfer network output interface unit. 13. The subsequent packet leading cell encapsulation transfer processing unit receives the succeeding packet leading cell transmitted from the cell identification unit, extracts header information of the cell, and sends the header information to a CRTP route control unit. Header information extraction unit for transmitting and transmitting the cell to the encapsulation unit, receiving header information transmitted from the header information extraction unit, and referring to the CRTP transfer table and connectionless transfer protocol transfer table from the header information hand,
A CRTP route control unit for identifying the destination packet transfer device and generating an entry in the cell exchange table, creating a cell including a header of the connectionless transfer protocol based on the obtained destination packet transfer device information, and extracting header information By adding a header cell before the head cell received from the unit, a packet including the head cell is encapsulated in a connectionless transfer protocol, and an encapsulation unit for transmitting those cells to the cell switching unit, and From the input VPI / VCI of the cell received from the encapsulation unit, refer to the cell exchange table and output VPI / VPI of the cell
The packet transfer device according to claim 10, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the packet transfer network output interface unit. 14. The subsequent packet subsequent cell encapsulation transfer processing unit refers to a cell switching table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VCI of the cell.
The packet transfer device according to claim 10, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the packet transfer network output interface unit. 15. A connectionless transfer protocol for accommodating a user network, specifying a route of a packet transferred from the user network by compressing a header by the header compression method CRTP and transferring the packet by the IP route control function. A packet transfer network in which a packet transfer device that encapsulates and transfers data in a packet and a packet relay device that transfers using the connectionless transfer protocol are connected in a network by a communication link. A device for transferring a packet, which is an IP transfer table including correspondence data between a destination IP address and an output VPI / VCI, a CRTP transfer table including correspondence data between a flow identifier CID and an output VPI / VCI, and an input VP A cell exchange table containing correspondence data between I / VCI and output VPI / VCI, a packet for receiving a cellized connectionless transfer protocol packet transferred from a packet relay device, and transmitting the packet to a decapsulation transfer processing unit. The packet of the connectionless connection transfer protocol that is transmitted from the transfer network input interface unit and the packet transfer network input interface unit is received, the packet is decapsulated, and the IP transfer table, CRTP transfer table and cell exchange table are created. Output VPI of cell into which decapsulated packet is divided by setting and / or referring
/ VCI, decapsulation transfer processing unit for transmitting the cellized packet to the user network output interface unit, and reception of the cellized packet transmitted from the decapsulation transfer processing unit, A packet transfer device comprising a user network output interface unit for transferring to a network. 16. The decapsulation transfer processing unit receives a cell transmitted from a packet transfer network input interface unit, and when the cell is a header cell including a header of a connectionless transfer protocol, removes the header cell. , If it's not a header cell,
It is identified whether the cell is the cell of the first packet of the flow or the cell of the subsequent packet, and the first cell of the packet or the subsequent cell, and if the cell is the first cell of the first packet of the flow, the first packet first cell Send to the encapsulation transfer processing unit, and if the cell is a subsequent cell of the first packet of the flow, the first packet succeeds the cell, and transmits to the decapsulation transfer processing unit, if the cell is the first cell of a subsequent packet of the flow. To the subsequent cell decapsulation transfer processing unit of the subsequent packet, and if the cell is a subsequent cell of the subsequent packet of the flow, the subsequent packet subsequent cell decapsulation transfer processing unit to transmit to the decapsulation transfer processing unit, cell identification The head cell of the head packet transmitted from the unit is received, the head packet head cell route control processing is performed to specify the output VPI / VCI of the cell, Head packet head cell decapsulation transfer processing unit for transmitting the cell to the user network output interface unit, the succeeding cell of the head packet transmitted from the cell identification unit is received, and the head packet succeeding cell route control process is performed. The output VPI / VCI of the cell is specified, the head packet for transmitting the cell to the user network output interface section, the subsequent cell decapsulation transfer processing section, and the head cell of the subsequent packet transmitted from the cell identification section are received. , A succeeding packet leading cell decapsulation transfer processing unit for performing a succeeding packet leading cell route control process to specify an output VPI / VCI of the cell, and transmitting the cell to the user network output interface unit, and a cell identification The subsequent cell of the subsequent packet sent from the A subsequent packet subsequent cell decapsulation transfer processing unit for performing a subsequent cell route control process to specify an output VPI / VCI of the cell and transmitting the cell to the user network output interface unit. The packet transfer device according to claim 15. 17. The head packet head cell decapsulation transfer processing unit receives the head packet head cell transmitted from the cell identification unit, extracts header information of the cell, and extracts the header information from the IP route control unit. A header information extraction unit for transmitting the cell to the cell switching unit, receiving the header information transmitted from the header information extraction unit, referring to the IP transfer table from the header information,
Input VPI / V of the cell received from the IP route control unit for generating the entries of the CRTP transfer table and the cell exchange table, and the header information extraction unit
From CI, refer to the cell exchange table and output V of the cell
17. The packet transfer apparatus according to claim 16, further comprising a cell switching unit for specifying the PI / VCI and transmitting the cell to the user network output interface unit. 18. The head packet succeeding cell decapsulation transfer processing unit refers to a cell exchange table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VPI of the cell.
The packet transfer device according to claim 16, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the user network output interface unit. 19. The subsequent packet start cell decapsulation transfer processing unit receives the subsequent packet start cell transmitted from the cell identification unit, extracts header information of the cell, and extracts the header information from the CRTP route control unit. Header information extraction unit for transmitting the cell to the cell exchange unit, and receiving the header information transmitted from the header information extraction unit, referring to the CRTP transfer table from the header information, and referring to the cell exchange table. C to create an entry
Input VPI / V of the cell received from the RTP route control unit and the header information extraction unit
From CI, refer to the cell exchange table and output V of the cell
17. The packet transfer apparatus according to claim 16, further comprising a cell switching unit for specifying the PI / VCI and transmitting the cell to the user network output interface unit. 20. The subsequent packet subsequent cell decapsulation transfer processing unit refers to a cell exchange table from the input VPI / VCI of the cell received from the cell identification unit, and outputs VPI / VCI of the cell.
The packet transfer device according to claim 16, further comprising a cell switching unit for specifying the VCI and transmitting the cell to the user network output interface unit.