WO2007010593A1 - Tcp session emulator - Google Patents

Abstract

A TCP session emulator comprising a session search table searched for an identifier for specifying a session of the TCP protocol by using at least the IP (Internet Protocol) acquired from the header of the received packet or the port number as the search key, a session status management memory for acquiring the session status code provided according to the identifier acquired by the search, and a sequencer for determining a pseudo-session operation of the TCP protocol used by one of application protocols according to the session status code acquired from the session status management memory.

Description

 Specification

 TCP session emulation equipment

 Technical field

 The present invention relates to a device for verifying the performance of TCP communication in a communication network system using TCP (Transmission Control Protocol) as a communication protocol, and more particularly, to a device (communication device) connected to an IP (Internet Protocol) network. Or a TCP session emulation device for emulating events that occur in the application software.

 Background art

 [0002] Japanese Patent Application Laid-Open No. 11-27308 (Patent Document 1) discloses a technique for analyzing the state of a communication sequence by emulating the behavior and internal procedures of a TCP protocol and investigating the cause of a decrease in throughput. Is disclosed. With these technologies, actual communication is monitored and the state transition that causes the problem operation is investigated by analyzing the state transition of the TCP protocol.

 [0003] However, in the conventional emulation technology, it is possible to monitor the actual communication between communication systems or communication devices and check the normality of the state transition of the TCP protocol. An abnormal sequence state or high load state occurs, and the correctness of the processing operation of the communication system at that time cannot be confirmed. In addition, by intentionally generating a response delay in the handshake operation between communication systems, it is not possible to confirm the correctness of the operation when the response waiting process times out.

In addition, the configuration shown in FIG. 10 shows an example of the configuration of a conventional test apparatus. In this configuration, the header extraction / protocol identification unit 20 extracts the header of the received packet, identifies the protocol, and is selected. The packet is written to the receive packet buffer 22 by the received packet read Z write (RZW) control unit 21 and the header content is included in the data of the transmit packet buffer 24 specified by the transmit packet read Z write (RZW) control unit 23. It is possible to add a header generated by the cooperation of the setting register 25 and the packet header generation unit 26, generate a transmission packet by the transmission packet generation unit 27, and transmit it to the network. However In this conventional test device, the TCP protocol state transition is not generated in a pseudo manner.

 [Patent Document 1] JP 11 27308 A

 [Patent Document 2] JP 2000-267963 A

 [Patent Document 3] JP 2000-106557 A

 [Patent Document 4] JP-A-2004-140596

 Disclosure of the invention

 Problems to be solved by the invention

[0005] The problem of the present invention is that it is possible to arbitrarily generate an abnormal sequence state or a high load state on the TCP protocol, which is difficult to intentionally occur in an actual network, depending on the setting. It is to provide technology to do.

 Means for solving the problem

[0006] In order to solve the above-described problem, the TCP session emulation apparatus of the present invention uses at least one of an IP (Internet Protocol) address and a port number obtained from the header of a received packet as a search key. A session search table for searching for an identifier that identifies a session of the TCP (Transmission Control Protocol) protocol; and a session status code that is subtracted based on the identifier obtained as a search result of the session search table. A session state management memory for obtaining the session state management memory, and a sequencer for determining a pseudo session operation of the TCP protocol used by one of a plurality of application protocols according to the obtained session status code. With.

 [0007] In a TCP session emulation device employing this configuration, the sequencer is provided for each application protocol including HTTP (Hyper Text Transfer Protocol), FTP (File Transfer Protocol), and SMTP (Simple Mail Transfer Protocol). It is.

[0008] Further, the session status code includes a port number through which the TCP protocol session is communicating, a TCP status code indicating a transition state of the TCP protocol, and an upper status code indicating a transition state of the application protocol. It is configured. [0009] The TCP session emulation apparatus further includes a state setting register that holds a preset setting value for intentionally generating an abnormal processing operation of the TCP protocol session; The operation of the sequencer is determined according to both values of the session status code.

 [0010] Further, the TCP session emulation device uses the TCP protocol sequence number as the header information from the header of the received packet, together with the IP address and the port number.

Extracting means for obtaining a confirmation response number and code bit; generating header information of a transmission packet based on the header information obtained by the extracting means and a header content instruction from the sequencer; And an additional means for transmitting.

 [0011] Further, the TCP session emulation device stores the reception time of the received packet as time stamp information in the session state management memory for each corresponding session; a register for setting a delay time of the response packet A response delay is realized by transmitting the response packet after the set delay time.

 The invention's effect

 [0012] According to the present invention, it is possible to intentionally generate an abnormal sequence, a large amount of traffic, a response delay, and the like by enabling the session operation of the TCP protocol to be executed in a pseudo manner. This is useful for verification of equipment) and application software. This will greatly contribute to improving the quality of IP network-related systems.

[0013] Other objects, features and advantages of the present invention will become apparent upon reading the following described embodiments, when taken in conjunction with the drawings and claims. Brief Description of Drawings

 FIG. 1 is a block diagram showing a configuration of a communication network system to which a TCP session emulation apparatus according to an embodiment of the present invention is applied.

 FIG. 2 is a block diagram showing a configuration of a TCP session emulation apparatus according to an embodiment of the present invention.

 FIG. 3 is a diagram for explaining an operation procedure of the TCP session emulation apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a transmission packet buffer. FIG. 5 is a diagram showing a configuration example of a session search table.

 6] A diagram showing a configuration example of the session state management memory.

 7) A diagram for explaining the operation procedure of the response packet generation sequencer.

 8] A diagram showing a configuration example of a response packet generation sequencer.

 [Figure 9] State transition diagram of TCP protocol.

 [10] Block diagram showing a configuration example of a conventional test apparatus.

 Explanation of symbols

 TSE TCP session emulation equipment

 1 Header extraction, protocol identification part

 2 Session search table

 3 Session state management memory

 4 Receive packet buffer

 5 Transmit packet buffer

 6 Response packet generation sequencer

 7 Status setting register

 8 Packet header generator

 9 Response packet generator

 10 Time stamp generation

 11 Receive packet read Z write (RZw) control unit

 12 Transmit packet read Z write (RZW) controller

 13 Delay setting register

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The drawings show a preferred embodiment of the present invention. However, the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0017] A TCP (Transmission Control Protocol) session in one embodiment of the present invention shown in FIG. The Yon-Emulation device TSE is applied to the communication network system SYS shown in Fig. 1 (A) and (B).

 Referring to FIGS. 1 and 2 and FIG. 3 showing the operation procedure, the communication network system SY S includes at least one network (IP (Internet Protocol) network) NW. This network NW constitutes a computer network such as UNIX (registered trademark) and a wide-area packet switching network. Sano SV and client CL are usually connected to network NW as communication devices each having an IP address. Sano SV and client CL send and receive data (TCP communication) through a communication line (sometimes referred to as a communication path or connection) via network NW.

 [0019] TCP as a communication protocol is a protocol in the fourth layer (transport layer) above the IP (network layer) in the third layer of the OSI (Open Systems Interconnection) reference model. The characteristic of TCP is reliable data transmission (transfer), that is, control of normal transmission of data while maintaining the reliability of the communication channel from the start to the end of communication, and error detection and It is to perform recovery. For this reason, TCP provides a connection 'orientated virtual channel to provide full-duplex' bi-directional stream services to higher-layer users.

 [0020] In the communication network system SYS, in order to perform connection 'orientated data transfer with stream service and maintain reliability, it is indispensable to perform a simulation test of TCP communication performance.

[0021] The TCP session emulation device TSE can be implemented in the pseudo client CL or the pseudo server SV. Here, the pseudo client CL is a pseudo-generation of a state in which a large number of client CLs are accessing the Sano SV, and the pseudo Sano SV is a pseudo-simulation with many actual client CLs. Communication. By introducing the TCP session emulation device TSE as a pseudo client CL or pseudo server SV into the communication network system SYS, it is close to the limit processing performance of the server SV, which is usually difficult. In addition, it is possible to simulate a sequence error that occurs due to packet loss on the network NW. [0022] In the TCP session emulation device TSE, the header extraction 'protocol identification unit 1 extracts the header and identifies the protocol from the packet received by the network NW force (S10, Sl in Fig. 3). Header extraction 'Protocol identification unit 1 extracts the IP address and port number of the target TCP bucket (strictly speaking, TCPZIP packet), and inputs it as a search key in the session search table 2 for searching for TCP sessions. (S1 2 and S13 in Fig. 3). The session search table 2 is composed of a content addressable memory (CAM) including a search engine.

 [0023] The search result of the session search table 2 is used to specify the entry number of the session state management memory 3 as a session identifier (address) indicating each TCP session number (S14 in FIG. 3). . In the session state management memory 3, a connection is established! A code (session status code) indicating the state (state) of each TCP session, and an address (packet storage location) in the received packet buffer 4 ( (Reception buffer address) and time stamp indicating packet reception time, etc., are registered for each entry number (session number) (S15, S16 in Fig. 3).

 The session status code output from the session state management memory 3 is used as a transition condition to the next state of the response bucket generation sequencer 6 (S17 in FIG. 3). Here, the response packet generation sequencer 6 is a hardware sequencer that realizes the state transition of the TCP session. The session status code and the value of the state setting register 7 that is set by the main control unit (CPU) are set. As a result of the transition, the three-way handshake operation on the TCP session is realized for normal operation or abnormal operation (S18 in Fig. 3). The response packet generation sequencer 6 writes a session status code indicating the state after transition to the session state management memory 3 (S19 in FIG. 3).

[0025] After the response operation for the received packet is determined in the response packet generation sequencer 6, the content of the transmission header and the content of the transmission data corresponding to the response operation are controlled by the packet header generation unit 8 and the transmission packet read Z write (RZW) control. Passed to part 12. The packet header generation unit 8 generates a transmission packet header based on the instruction content (transmission header content) from the response packet generation sequencer 6 and outputs it to the response packet generation unit 9. Transmit packet R The ZW control unit 12 outputs the transmission packet read address to the transmission packet buffer 5 based on the instruction content from the response packet generation sequencer 6 (contents of transmission data). The response packet generator 9 adds the transmission packet header from the packet header generator 8 to the transmission packet data from the transmission packet buffer 5, generates a response packet, and returns it to the other party through the network NW connection. (S21 in Figure 3).

 Whether or not the delay time set in the delay setting register 13 has elapsed is determined based on a comparison between the time stamp information read from the session state management memory 3 and the timer value of the time stamp generation unit 10. The transmission packet RZW control unit 12 determines that the transmission packet data is read from the transmission packet buffer 5 and transmitted from the response packet generation unit 9 after the set delay time has elapsed (S20 and S21 in FIG. 3).

 [0027] If there is no matching entry in session search table 2, the IP address and port number of the received packet are registered in session search table 2, and the corresponding session status code is set to the initial value in session state management memory 3. (S14, S22, S23 in FIG. 3).

 [0028] In addition, the header identification 'protocol identification unit 1 further extracts a TCP header sequence number (sequence number) and an acknowledgment number as the header information of the packet to be transmitted, and sends it to the packet header generation unit 8 It is done. These sequence number and confirmation response number are used in response packet generation in the response packet generation unit 9.

[0029] In the TCP session emulation device TSE, the received packet read Z write (R ZW) control unit 11 reads out the packet data stored in the received packet buffer 4 from the CPU, and the transmission packet buffer 5 Packet data can be set by the CPU, and higher-level protocol processing can be processed by the CPU. When the response packet generation sequencer 6 requires protocol processing by the CPU, the response packet generation sequencer 6 sends an interrupt notification to the CPU. Note that when sending a packet (not a response packet but a packet for generating traffic) to the network NW first from the TCP session emulation device TSE, the CPU power is also sent to the transmission packet RZW control unit 12. The packet is transmitted by notifying the control. [0030] In more detail, in the above-described TCP session emulation device TSE, the contents of the transmission packet buffer 5 are as shown in Fig. 4 for each protocol of the application (for example, HTTP (Hyper Text Packet data corresponding to Transfer Protocol (FTP), File Transfer Protocol 1 (FTP), Simple Mail Transfer Protocol (SMTP), etc. is written in advance by the CPU. Therefore, the response packet generation sequencer 6 that has received the session status code from the session state management memory 3 passes the transmission data content indication indicating the address where the corresponding protocol is stored to the transmission packet RZW control unit 12, Address power stored in the transmission packet buffer 5 for the relevant protocol Transmission packet data is read.

 FIG. 5 shows a configuration example of the session search table 2. As shown in this configuration example, the session search table 2 stores a source address and a destination address (both are IP addresses), a protocol code, a source port number, and a destination port number. Each entry in this table 2 corresponds to an individual session (session number) of TCP, and the header information extracted from the received packet, that is, source address, destination address, protocol code, source port number, The TCP session is identified by searching this table 2 based on at least one of the destination port number and the destination port number.

 FIG. 6 shows a configuration example of the session state management memory 3. Each entry in the session state management memory 3 corresponds to each entry in the session search table 2. The session state management memory 3 stores a session status code indicating the session state, a reception buffer address indicating the storage position of the received packet, and a time stamp indicating the time when the packet is received. Here, the session status code consists of the port number with which the TCP session is communicating, the TCP status code indicating the TCP transition status, and the upper status code indicating the transition status of the upper protocol (application protocol)! Speak. For the state transition of the higher-level protocol, the force performed by either hardware or software. When the state transition is performed by software, the state transition of the next state is detected by an interrupt notified from the response packet generation sequencer 6. Occurs.

FIG. 7 shows an operation procedure example of the response packet generation sequencer 6. This operation procedure (S71 to S78) enables the TCP protocol state transition to be realized. When it is set to ABLISHED, upper protocol communication is performed. For the state transition of the upper protocol, pass the upper status code indicating the current status to the upper protocol processing sequencer (protocol sequencer) (Fig. 8) in the response packet generation sequencer 6 configured by hardware or software. Is done.

When an abnormal sequence is generated, the TCP protocol state transition is changed to a state different from the normal state according to the setting contents of the state setting register 7. It should be noted that the TCP protocol state transitions shown in this operation procedure can be generated in hardware, so that a large amount of traffic generation states can be generated.

 FIG. 8 shows a configuration example of the response packet generation sequencer 6. As in this configuration example, the response packet generation sequencer 6 is ESTABL ISHED in the TCP protocol state transition shown in FIG. 6 Hierarchical configuration is adopted so that the internal high-level protocol processing sequencer operates. For the upper protocol processing sequencer, the sequence operation is completed when the TCP protocol state transition force CLOSE state is entered by sending and receiving FINs.

 [0036] As a specific example of the occurrence of an abnormal condition, if an ACK response packet to a TCP protocol SYN packet reception is not returned normally, the abnormal condition occurrence is set in the status setting register 7 to generate a response packet. When the TCP sequencer inside the sequencer 6 is in the SYN-RCVD state, and normally sends a send instruction to the send packet RZW control unit 12 and the packet header generation unit 8 to return an ACK packet to the sender of the SYN packet. Without this operation, the ACK packet is not transmitted and the operation stays in SYN-RCVD.

 [0037] Also, when an abnormality of the confirmation response number in the packet header is generated, an abnormal state occurrence is set in the status setting register 7, and the response packet generation sequencer 6 is used to indicate the content of the transmission packet header. An abnormality generation instruction signal is transmitted, and the packet header generation unit 8 generates a packet header storing an acknowledgment number that is different from the normal one, and a packet having this abnormality header is transmitted to the communication destination. Will be.

[0038] Figure 9 shows the state transition of the TCP protocol specified in RFC793. Accordingly, the operation of the response packet generation sequencer 6 is determined. In the TCP protocol, a connection identified by the source port number and destination port number in the TCP header and the IP address in the IP header is established. This connection is established in three TCP segments: a 3-way handshake, namely SYN (synchronization), ACK (acknowledgement), and SYN + ACK (acknowledgement). For data transfer, the sequence number and confirmation response number in the TCP header are used. When the data transfer is completed, the connection is released by exchanging two TCP segments, FIN (end) and ACK (acknowledge), between the communication devices or communication systems.

 [0039] The TCP header includes fields such as a source port number, a destination port number, a sequence number, an acknowledgment number, a code bit (control bit), a window size, a checksum, and an emergency pointer.

 [0040] The 6-bit code bit field of the TCP header has 6 flag bits: URG, ACK, PSH, RST, SYN, and FIN. The meaning of each code bit is as follows.

(1) URG: The urgent pointer is valid.

 (2) ACK: Acknowledgment number is valid.

 (3) PSH: The receiver (receiver) must pass the data to the application as soon as possible.

 (4) RST: Reset the connection.

 (5) SYN: Synchronizes sequence numbers to initialize the connection.

 (6) FIN: The sending side (sender) has finished sending data.

 [0041] Only one of these code bits can be turned on, and a plurality of code bits can be turned on simultaneously. A TCP segment whose code bit is on is called as follows.

 (1) SYN segment: Only the SYN bit is on (ACK bit is off).

 (2) SYN + ACK segment: Only SYN bit and ACK bit are on.

 (3) ACK segment: No user data in the data field Only the ACK bit is on

(4) DT segment: Regardless of whether the URG bit or RST bit is on or off, there is user data and only the ACK bit is valid. (5) FIN segment: FIN bit is on (ACK bit is often on!).

 (6) RST segment: RST bit is on (ACK bit is often on!).

 [0042] Events (events) for the TCP protocol include transmission events (transmitted TCP segments) and reception events (received TCP segments). Typical examples and their meanings are as follows.

 (1) SYNsent: SYN segment sent.

 (2) S YN + ACKsent: SYN + ACK segment sent.

 (3) ACKsent: The transmitted ACK segment.

 (4) DT / ACKsent: Transmitted DT segment or ACK segment.

 (5) FINsent: FIN segment sent.

 (6) SYNrecv: Received SYN segment.

 (7) SYN + ACKrecv: Received SYN + ACK segment.

 (8) ACKrecv: Received ACK segment.

 (9) DTZ ACKrecv: Received DT segment or ACK segment.

 (10) FINrecv: Received FIN segment.

 [0043] The states in the TCP protocol are as follows, as shown in Figure 9. It can take the values WAIT, LAST ACK, and TIME WAIT. The meaning of these values is as follows.

 (1) CLOSED: No connection.

 (2) LISTEN: Waiting state.

 (3) SYN—SENT: A state in which connection is being established by sending a SYN segment.

(4) SYN — RCVD: A state in which a SYN segment is received and connection establishment is in progress.

(5) ESTABLISHED: A state where data can be transferred in both directions.

 (6) FIN—WAIT— 1: Data transmission end request status.

 (7) FIN—WAIT— 2: Data transmission complete.

 (8) CLOSING: Data transmission / reception simultaneous termination status.

(9) TIME—WAIT: Connection information retention status when connection release is completed. (10) CLOSE—WAIT: Waiting for connection release.

 (11) LAST—ACK: Waiting to receive the last ACK.

 [0044] As described above, when the TCP session emulation device TSE recognizes that the received packet having the communication line power of the network NW is a TCP packet, the session search table 2 is searched and the session state is determined. The initial state and the operating state of the response packet generation sequencer 6 are determined by the storage information in the management memory 3 and the setting value in the state setting register 7. The time when the packet is received is stored in the session state management memory 3 as a time stamp and used to determine the packet transmission timing.

 [0045] [Modification]

 The processing in the above-described embodiment is provided as a computer-executable program, and can be provided via a recording medium such as a CD-ROM or a flexible disk, and further via a communication line.

 [0046] In addition, each process in the above-described embodiment may be performed by selecting and combining any or all of the processes.

Claims

The scope of the claims  [1] A session search table for searching for an identifier that identifies a session of the TCP (Transmission Control Protocol) protocol using at least one of the IP (Internet Protocol) address and port number obtained from the header of the received packet as a search key. ;  A session state management memory for obtaining a session status code drawn based on the identifier obtained as a search result of the session search table; and a plurality of sessions according to the session status code obtained from the session state management memory A sequencer that determines the simulated session behavior of the TCP protocol used by any of the application protocols;  TCP session emulation device with [2] The sequencer is provided for each application protocol including HTTP (Hyper Text Transfer Protocol), FTP (File Transfer Protocol), and SMTP (Simple Mail Transfer Protocol).  The TCP session emulation device according to claim 1. [3] The session status code is composed of a port number through which the TCP protocol session is communicating, a TCP status code indicating the transition state of the TCP protocol, and a higher level code indicating the transition state of the abrasion protocol. The TCP session emulation device according to claim 1. [4] A status setting register that holds a preset value for intentionally generating an abnormal processing operation of the TCP protocol session;  The operation of the sequencer is determined according to both the setting value and the value of the session status code.  The TCP session emulation device according to claim 1. [5] Extraction means for obtaining a TCP protocol sequence number, an acknowledgment number and a code bit as the header information of the received packet together with the IP address and the port number; Based on the header information obtained by the extracting means and the header content instruction from the sequencer, the header information of the transmission packet is generated and added as the header of the response packet. And means for transmitting;  The TCP session emulation device according to claim 1, further comprising:  Means for storing the reception time of the received packet as time stamp information in the session state management memory for each corresponding session;  A register for setting a delay time of the response packet;  The TCP session emulation device according to claim 1, wherein the response packet is transmitted after the set delay time to realize a response delay.