KR100440579B1 - Packet Header Conversion Scheme for VC Merger of MPLS System based on ATM - Google Patents

Abstract

The present invention provides a virtual channel capable of supporting efficient use and scalability of channel resources by performing packet header conversion function for VC merging while maintaining an original function as an ATM switch in an MPLS system based on an ATM switch. It relates to a packet processing method in a merging controller, and uses a channel handle value of a received packet as an offset value of a merging table to read and store a transmission channel identification value, a port identification value, a virtual path identification value, and a virtual channel identification value from a merging table. A first step of doing; A second step of identifying a type of the received packet; If the type of the received packet is an extended forwarding control (EFC) packet, reading a transmitter channel identification value contained in the payload portion of the received packet and inserting the transmitter channel identification value into a channel identifier field of the transmission packet; A fourth step of inserting a transmitter channel identification value read and stored from the merging table into a channel identification value field of the transmission packet when the received packet type is a general packet; If the type of the received packet is a pure ATM cell, the port-specific basic transmitter channel identification value (TCID) of the port looked up from the merging table is inserted into the channel identification value field of the transmission packet, read from the merging table, and stored. Inserting the virtual path identification value and the virtual channel identification value into the corresponding fields, respectively; And a sixth step of transmitting the header changed packet.

Description

Packet Processing Method in Virtual Channel Merge Controller of Multiprotocol Label Switching System Based on Asynchronous Transmission Mode {Packet Header Conversion Scheme for VC Merger of MPLS System based on ATM}

The present invention relates to a packet processing method in a virtual channel merging controller of a multi-protocol label switching (MPLS) system based on an Asynchronous Transfer Mode (ATM) exchange. More particularly, the present invention relates to a packet processing method in a virtual channel merging controller capable of providing efficient use and scalability of channel resources by classifying various packets input to the VC merging controller according to types. .

The Multiprotocol Label Switching (MPLS) system is designed to provide the flexibility and scalability of the Internet Protocol (IP) while providing the quality of service of ATM or frame relay. Can provide enhanced IP services, such as "Voice over IP", "Video over IP" and traffic engineering mechanisms for providing virtual private network services or voice or video services. The basic principle of the MPLS system is to combine different control modules and forward them through label swapping.

The Label Switched Path (LSP), which is a connection in the MPLS network, is set by the Label Distribution Protocol (LDP), which is a connection establishment protocol of MPLS, and the packet forwarding in the Label Switched Path (LSP) is short. Since the header is performed using the header, three layers of packets can be transmitted efficiently and quickly. In general, the MPLS network is located at the boundary with the existing network and creates an MPLS packet by labeling an IP packet, enters the MPLS packet into the MPLS network, and terminates the MPLS connection for transmission from the MPLS network to another existing network. It consists of a Label Edge Router (LER) that performs a function of making a label and a Label Switched Router (LSR) that performs a label switching function.

A technique related to a virtual channel (VC) merging module in an ATM-based MPLS network is disclosed in Korean Laid-Open Patent Publication No. 2001-63845 filed by the present applicant.

The prior art relates to a virtual channel merging module that can handle up to 622 Mbps traffic required by an MPLS system to provide IP services in an ATM network. The UTOPIA (Universal Test and Operations PHY) standardized in the ATM Forum of the US Interface for ATM) Receiving cell processor which receives ATM cell and physical link port number from interface and reads transmission / reception channel identification value from receiving control memory using VPI / VCI value and physical link port number and transmits it to receiving cell storage with cell. When the call is set up, the CPU receives the transmission / reception channel identification value allocated by the physical link number and the VPI / VCI from the CPU, stores it in the memory, and deletes it when the call is released. It receives the value and uses it as the address of the memory to read the transmission / reception channel identification value from the memory and deliver it to the receiving cell processor. Receives the cell from the new control memory and the receiving cell processing unit and successively connects cells belonging to the same frame using each receiving channel identification value to store a packet consisting of the transmission channel identification value and the AAL5 frame in the receiving packet memory. When receiving a notification from the transmitter that a frame can be transmitted through the UTOPIA interface, it reads one complete frame from the packet memory and checks whether an error is included in the AAL5 frame. If there is an error, the corresponding packet is discarded. The receiving cell storage unit which transmits the data consisting of the transmission channel identification value and the IP packet to the UTOPIA matching unit, the UTOPIA matching unit which transfers the transmitted data to the packet receiving unit, and stores the data in the memory at the request of the receiving cell storage unit or Receive packet memory and UTOPIA information to read and deliver to receive cell storage. Receives the data including the transmission channel identification value and the IP packet from the receiver, reads the transmission channel expression value from the transmission control memory using the transmission channel identification value, and transfers the IP packet received from the UTOPIA matching unit to the 48-byte ATM cell. The packet receiving unit divides the payload, attaches the transmission channel identification value received from the transmission control memory, and transmits it to the transmission buffer control unit, and receives the transmission channel expression value for each VCC from the CPU at the time of call setup and stores it in the memory. Manages the state of the transmission control memory that deletes these values when canceled and the transmission packet memory for storing packets for each channel. If there is no space for storing the received packets, the received ATM cell is discarded. In this case, the transmission buffer control unit for transmitting the ATM cell to the packet storage unit, the transmission channel identification value, transmission channel expression value, 48 bar from the transmission buffer control unit. AAL5 frame is generated by receiving the IP packet divided by T, and ATM cells are generated using the transmission channel expression value, and ATM cells are stored in the transmission packet memory, and cells are stored for each transmission channel identification value. The location is managed by cell storage information, and cell management information for each transmission channel identification value is transmitted to the cell scheduling function.In addition, when there is a request for transmission of an ATM cell of a specific channel from scheduling, it reads an ATM cell from the transmission packet memory for scheduling. Scheduling for receiving the packet storage unit and the cell storage information provided from the packet storage unit to determine the next cell to be delivered according to the priority information and traffic shaping information determined at call setup and forwarding the packet to the packet storage unit; To store or read a packet in memory at the request of the storage unit, and deliver it to the packet storage unit. Receiving the transmission in the new cell and the packet memory, the scheduling a transmission cell processing section for transmission to the outside through a UTOPIA level 2 interface.

However, the above prior art provides only the virtual channel merging function for the AAL5 type IP packet channel in the virtual channel merging module using the cell reassembly and partitioning method. However, packet frames input to the VC merging module in ATM-based MPLS networks provide general AAL-5 data packets for communication between subscribers, message control between MPLS Service Controller (MSC) / forwarding engines, or MSC / subscriber (router). There are Extended Forwarding Control (EFC) packets and pure ATM cells. Therefore, the VC merging module must handle each packet differently according to the type of each packet.

Accordingly, the present invention can support efficient use and scalability of channel resources by performing a packet header conversion function for VC merging while maintaining an original function as an ATM switch in an MPLS system based on an ATM switch. An object of the present invention is to provide a packet processing method in a virtual channel merging controller of an asynchronous transmission mode based multiprotocol switching switching system.

1 is a block diagram of a virtual channel (VC) merging module to which the present invention is applied.

2 is a flowchart illustrating packet processing for virtual channel merging according to the present invention.

3 is a structural diagram of a received packet input to a virtual channel (VC) merging controller.

4 is a structural diagram of a packet converted and transmitted from a virtual channel (VC) merging controller.

5 is a structural diagram of a packet converted and transmitted from a virtual channel (VC) merging controller for a pure ATM cell.

FIG. 6 is a diagram for describing the meaning of each field constituting a merging table according to the type of each packet in a virtual channel (VC) merging controller.

Explanation of symbols on the main parts of the drawings

100: virtual channel (VC) merging module 101: transmitter

101-1: Transmission packet memory 101-2: Transmission division and recombination (SAR) element

102: merging table 103: receiving unit

103-1: Receive memory packet 103-2: Receive split and recombine (SAR) element

104: virtual channel (VC) merging controller 104-1,4: UTOPIA matching unit

104-2: FIFO 104-3: packet processing unit

104-5: Arbit logic and internal registers 105: CPU

In accordance with another aspect of the present invention, there is provided a packet processing method in a virtual channel merging controller of an asynchronous transmission mode based multiprotocol label switching system.

A first step of reading and storing a transmission channel identification value, a port identification value, a virtual path identification value, and a virtual channel identification value from the merging table using the channel handle value of the received packet as an offset value of the merging table;

A second step of identifying a type of the received packet;

If the type of the received packet is an extended forwarding control (EFC) packet, reading a transmitter channel identification value contained in the payload portion of the received packet and inserting the transmitter channel identification value into a channel identifier field of the transmission packet;

A fourth step of inserting a transmitter channel identification value read and stored from the merging table into a channel identification value field of the transmission packet when the received packet type is a general packet;

If the type of the received packet is a pure ATM cell, the port-specific basic transmitter channel identification value (TCID) of the port looked up from the merging table is inserted into the channel identification value field of the transmission packet, read from the merging table, and stored. Inserting the virtual path identification value and the virtual channel identification value into the corresponding fields, respectively; And

And a sixth step of transmitting the header changed packet.

In addition, the present invention, in a computer,

A first function of reading a transmission channel identification value, a port identification value, a virtual path identification value, and a virtual channel identification value from the merging table by using the channel handle value of the received packet as an offset value of the merging table;

A second function of ascertaining a type of the received packet;

A third function of reading a transmitter channel identification value contained in a payload portion of a received packet and inserting the transmitter channel identification value into a channel identifier field of a transmission packet when the type of the received packet is an extended forwarding control (EFC) packet;

A fourth function of inserting a transmitter channel identification value read and stored from the merging table into a channel identification value field of the transmission packet when the received packet type is a general packet;

If the type of the received packet is a pure ATM cell, the port-specific basic transmitter channel identification value (TCID) of the port looked up from the merging table is inserted into the channel identification value field of the transmission packet, read from the merging table, and stored. A fifth function of inserting the virtual path identification value and the virtual channel identification value into the corresponding fields, respectively; And

A computer readable recording medium having recorded thereon a program for executing the sixth function of transmitting the header changed packet is provided.

The present invention processes a packet input from a VC merging receiver composed of a segment and reassembly (SAR) element in an ATM based MPLS system, and inputs the packet to a VC merging transmitter composed of another SAR element, thereby providing a general AAL. -5 processes data packets, extended forwarding control (EFC) packets, and pure ATM cells. By dividing the input packets and processing them in different ways according to the packets, all packets in the VC merging module can be processed, and the input data can be processed in a pipelined manner to process the transmission line speed.

A general AAL-5 data packet identifies the sender channel from which the packet should be sent from the merging table using the channel handle value used for processing the packet in the high performance SAR device as the offset address value of the merging table. A value (TCID: TxSAR Channel Identifier) is found and the transmitter channel identification value is input to the VC merging transmitter in the overhead so that the packet can be processed in the SAR element of the VC merging transmitter.

In the case of a forwarding engine control packet, a specific value ('FFFF') is set in advance in the transmitter channel identification value field of the merging table when the channel is set, and when this value is read, the forwarding engine control packet is recognized and the payload ( By substituting with the merging transmitter channel identification value indicated in the payload, the general AAL-5 data packet and the forwarding control packet can be distinguished and processed.

In case of pure ATM cell, port identification value (PID), virtual path identification value (VPI: Virtual Path Identifier) and virtual channel identification value (VCI: Virtual Cicuit Identifier) are recorded in merging table when channel is set up. If the packet type field is read among the overhead of the received packet, and if it is a pure ATM cell, it is set as the channel identification value of the transmitting unit with the representative identification value of the preset port, and the VPI / packet is entered in the Packet Tag 2 field of the transmission overhead. By creating VCI values, the transmitting SAR device can recognize the VPI / VCI values of pure ATM cells. By doing this, all kinds of packets input to the VC merging controller can be processed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a VC merging module to which the present invention is applied.

As shown in FIG. 1, the virtual channel merging module 100 includes a receiving unit 103 composed of a receiving packet memory 103-1, a receiving division and recombination (SAR) element 103-2, and a virtual channel merging function. VC merging controller 104, a merging table 102, a transmission packet memory 101-1, and a transmission unit 101 composed of transmission division and recombination (SAR) elements 101-2.

The cells transmitted from the ATM matching module (not shown) are assembled into packets by the receiving SAR element 103-2 and provided to the VC merging controller 104. The VC merging controller 104 uses the information stored in the merging table 102 to determine the cell packets having the same forwarding group according to the identification value included in the header of the packet transmitted from the receiving SAR element 103-2. Performs virtual channel (VC) merging function to convert into identification value. The header converted packet by the VC merging controller 104 is broken down into an ATM cell by the transmitting SAR element 101-2 and delivered to a physical layer processing module (not shown).

The VC merging controller 104 performs UTOPIA matching units 104-1 and 104-4 for matching between the transmitting SAR element 101-2 and the receiving SAR element 103-2, and performs header conversion of the received packet. Arbit logic for interfacing with a packet processing unit 104-3 having a pipe structure, a FIFO 104-2 for temporarily storing header-transformed transmission packets, and an interface with the CPU 105 and the merging table 102. It consists of an internal register 104-5.

2 is a flowchart illustrating a packet processing procedure in a VC merging controller according to the present invention, which will be described with reference to FIGS. 3 to 6.

When the VC merging controller 104 receives a packet of the type shown in FIG. 3 from the receiving SAR element 103-2 through the UTOPIA matching unit 200, the channel handle of the packet shown in FIG. The value is read from the merging table 102 using the channel handle value of the field 300 as the offset value of the merging table 102 (201).

Here, the VC merging controller assumes the types of each packet and transmit channel identification value indicated by the TCID field 600 shown in FIG. 6 for the case of a normal packet which is an AAL-5 data packet from each field of the merging table. Port identification value (PID) field 602, virtual path identification value (VPI) field 603, and virtual channel identification value (VCI) field 604 shown in FIG. The port identification value, VPI, and VCI values are determined and stored in the internal register 104-5 of the VC merging controller (202).

On the other hand, when the received packet is an Extended Forwarding Control (EFC) packet for message control between an MSC (MPLS Service Controller) / forwarding engine or an MSC / subscriber (router), as shown in FIG. Similarly, a specific value "FFFF" is set in the transmission channel identification value (TCID) field in advance to distinguish EFC packets, and it is checked whether the received packet is an EFC packet (203).

As a result of the check, when the packet type is an extended forwarding control (EFC) packet, the transmitter channel identification value TCID carried in the payload portion of the received packet is read, and the channel identifier of the packet shown in FIG. It is inserted into the (Channel ID) field (208). That is, if the input packet is an EFC packet, the value of the MSC_CHID field 302 contained in the payload portion of the received packet as shown in Fig. 3 is read, and the channel identification value of the transmission packet as shown in Fig. 4 is read. Substitute the insertion into the (Channel ID) field 400 (208).

If the type of the received packet is not an EFC packet (203), the packet type (PKT) field 301 of the received packet as shown in Fig. 3 is read to determine whether the received packet is a normal packet or a pure ATM cell. Confirm (204). In general, in case of a pure ATM cell, a value of "001" is set in a packet type (PKT) field.

As a result of the check, when the packet type is a general packet having an AAL-5 data packet, the transmitter channel identification value read from the merging table and stored in the channel ID field 400 of the transmission packet as shown in FIG. (TCID) Substitute insert (207).

As a result of the check, when the packet type is a pure ATM cell, the default transmitter channel identification value (TCID) of each port of the port looked up from the merging table in the channel ID field 500 of the transmission packet as shown in FIG. Is inserted into the value (205). Then, the virtual path identification value and the virtual channel identification value (VPI / VCI) stored in the merging table and stored are stored in the VPI field 501 of Packet Tag 2, which is the transmission packet overhead shown in FIG. Substitute inserts into VCI field 502 (206).

The header-converted packet is transmitted to the packet transmitter 101 comprising the transmission packet memory 101-1 and the transmission SAR element 101-2 through the UTOPIA packet mode interface (209).

As described above, the present invention can perform VC merging while maintaining the original ATM switch function in an MPLS network based on an ATM switch, thereby providing efficient use and scalability of channel resources, and providing EFC packets. Is processed by the VC merging controller, the MSC can transmit / receive protocol-related data with routers connected through the subscriber interface.

Claims (4)

A packet processing method in a virtual channel merging controller of an asynchronous transmission mode based multiprotocol switching switching system, A first step of reading and storing a transmission channel identification value, a port identification value, a virtual path identification value, and a virtual channel identification value from the merging table using the channel handle value of the received packet as an offset value of the merging table; A second step of identifying a type of the received packet; If the type of the received packet is an extended forwarding control (EFC) packet, reading a transmitter channel identification value contained in the payload portion of the received packet and inserting the transmitter channel identification value into a channel identifier field of the transmission packet; A fourth step of inserting a transmitter channel identification value read and stored from the merging table into a channel identification value field of the transmission packet when the received packet type is a general packet; If the type of the received packet is a pure ATM cell, the port-specific basic transmitter channel identification value (TCID) of the port looked up from the merging table is inserted into the channel identification value field of the transmission packet, read from the merging table, and stored. Inserting the virtual path identification value and the virtual channel identification value into the corresponding fields, respectively; And And a sixth step of transmitting the header changed packet. The method of claim 1, In the second step, the extended forwarding control (EFC) packet is inputted by setting a specific value in a transmitter channel identification value field in advance, and confirming the type of the received packet using the information in the transmitter channel identification value field. Packet processing method in a virtual channel merging controller. The method of claim 2, In the second step, the pure ATM cell and the normal packet are distinguished through a value set in a packet type (PKT) field of the received packet. On the computer, A first function of reading a transmission channel identification value, a port identification value, a virtual path identification value, and a virtual channel identification value from the merging table by using the channel handle value of the received packet as an offset value of the merging table; A second function of ascertaining a type of the received packet; A third function of reading a transmitter channel identification value contained in a payload portion of a received packet and inserting the transmitter channel identification value into a channel identifier field of a transmission packet when the type of the received packet is an extended forwarding control (EFC) packet; A fourth function of inserting a transmitter channel identification value read and stored from the merging table into a channel identification value field of the transmission packet when the received packet type is a general packet; If the type of the received packet is a pure ATM cell, the port-specific basic transmitter channel identification value (TCID) of the port looked up from the merging table is inserted into the channel identification value field of the transmission packet, read from the merging table, and stored. A fifth function of inserting the virtual path identification value and the virtual channel identification value into the corresponding fields, respectively; And And a computer-readable recording medium having recorded thereon a program for executing the sixth function of transmitting the header changed packet.