JP3576701B2 - Packet receiving system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a packet receiving system, and more particularly to a packet receiving system in data communication performed by multiplexing packets.
[0002]
[Prior art]
In general, in a system for performing data communication by multiplexing packets, when a packet transmitted from a terminal is received after a link is established with a plurality of accommodated terminals, the received packet is temporarily stored in a buffer. . Then, an event for activating the protocol processing is issued corresponding to each of the stored received packets, and the event is loaded in the queue. The events loaded in the queue are taken out by the processing unit of the system, and protocol processing is performed on each packet.
[0003]
When a large number of packets are temporarily transmitted from a specific terminal, the processing of the packet on the system side is occupied by the specific terminal, and services to other terminals are restricted. For example, a case in which a large number of packets are transmitted due to a terminal failure or a case in which a user intentionally transmits a large number of packets is considered. In such a case, the service of another user to the terminal is restricted.
[0004]
A system for preventing this service from being restricted is described in JP-A-7-177196. In this conventional receiving system, an upper limit value of the number of events loaded in a queue is set for each link, and an event of a link exceeding the upper limit value is discarded. By performing this discarding process, even if a large number of packets are transmitted temporarily, the service to the terminal of another user is not restricted.
[0005]
[Problems to be solved by the invention]
However, the conventional packet receiving system described above has the following disadvantages.
[0006]
First, an event for a packet received from a certain terminal is extracted from the queue and determined, and during a process until the event is discarded, the queue for another terminal may reach the upper limit. As described above, in the conventional system using the queue, since the abnormal packet is transmitted from one terminal, even the queue of the normal link reaches the upper limit, and only the packet of the abnormal link is used. However, there is a disadvantage that packets of a normal link are discarded.
[0007]
Further, in the conventional system, all the packets are discarded regardless of the type of the packet by discarding the event for starting the protocol processing corresponding to the received packet. Therefore, a response packet from the system to the information packet, which is a packet for transmitting and receiving user data transmitted from the terminal, is not returned to the terminal, and the information packet is retransmitted from the terminal. The disadvantage is that the number of packets sent to the system is not reduced.
[0008]
The present invention has been made in order to solve the above-mentioned drawbacks of the prior art. The purpose of the present invention is to provide a system for transmitting a packet even if a large number of packets are temporarily sent due to an abnormal operation of a certain terminal. An object of the present invention is to provide a packet receiving system capable of performing stable processing for normal packet reception without impairing processing performance.
[0009]
[Means for Solving the Problems]
A packet receiving system according to the present invention is a packet receiving system for receiving a multiplexed packet. The packet receiving system includes a counting means for counting the number of control packets among the received packets, and a new means when the count value reaches a predetermined value. And packet discarding means for discarding the control packet received.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The operation of the present invention is as follows.
[0011]
When a packet received from a certain link is determined to be a control packet, the number of reception control packets on that link is counted up. In this case, counting is performed until the timer started simultaneously with the establishment of the link expires. When the timer expires, the count value is cleared and the timer is restarted. After the time point when the count value exceeds the predetermined value of the corresponding link, all control packets received while the count value exceeds the corresponding predetermined value are discarded. The above processing is performed when the control packet is received.
[0012]
Next, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a block diagram showing a configuration of one embodiment of a packet receiving system according to the present invention. In the figure, a packet receiving system according to one embodiment of the present invention includes a receiving line control unit 2 for receiving a packet from a receiving line, and a receiving control packet monitoring block 1. The packets received by the receiving line control unit 2 include an information packet for transmitting and receiving user data and a control packet for performing communication control predetermined by a communication protocol. The information packet and the control packet can be distinguished by checking the contents of a specific field in the received packet.
[0014]
The reception control packet monitoring block 1 predetermines between a terminal (not shown) and a reception packet type determination unit 3 that determines the type of a received packet, sorts an information packet and a control packet, and extracts a control packet. A default value holding unit 4 for setting and holding a predetermined value, a timer 6 for counting time and clearing the counted value at predetermined time intervals, and count-up information 30 which is a determination result of the received packet type determination unit 3. It is configured to include a reception control packet number counting unit 5 that performs a count-up operation.
[0015]
Also, the reception control packet monitoring block 1 compares the count value of the counter 5 with the default value held in the default value holding unit 4, and controls the reception control packet number determination unit 7. And a reception control packet discarding unit 8 for discarding control packets received after the count value exceeds a predetermined value.
[0016]
The received packet type determining unit 3 determines the type of the packet received by the receiving line control unit 2, and sorts the received packet into an information packet and a control packet. If the packet is determined to be an information packet, normal protocol processing is performed on the packet. On the other hand, when it is determined that the received packet is a control packet, the count-up information 30 is transmitted from the received packet type determining unit 3 to the received control packet number counting unit 5, and the received packet number determining unit 7 performs a comparison determination process.
[0017]
The timer 6 sets a monitoring time for the number of control packets received by the system for each link. A timer for timing is provided for each link, and is activated when each link transits to an established state to perform timing.
[0018]
The reception control packet number counting unit 5 counts the number of control packets received during the activation period of the timer 6 for each reception link. It is assumed that a counter is provided for each link.
[0019]
The default value holding unit 4 sets an upper limit value of control packets received within the activation period of the timer 6 for each link. The default value holding unit 4 has means for storing a default value corresponding to each link. When this storage means is realized by hardware, for example, a memory for a default value is provided in advance, and the default value is stored in this memory. It is clear that this storage means can be realized by hardware other than a memory, and can be realized by software (firmware).
[0020]
The number-of-reception-control-packets determination unit 7 compares the default value held in the default value holding unit 4 with the count value of the counting unit 5, and sends a control packet to the control packet discarding unit 8 according to the comparison result. is there. When the reception control packet number determination unit 7 is realized by hardware, for example, a comparator that compares a predetermined value with a count value, and a selector that determines a destination of a control packet according to the output of the comparison unit What is necessary is just to comprise using. It is obvious that the determination unit 7 can be realized by hardware other than the comparator and the selector, and can be realized by software (firmware).
[0021]
The reception control packet discarding unit 8 discards the reception control packet when the determination unit 7 determines that the count value exceeds the predetermined value.
[0022]
The operation of the receiving system having such a configuration will be described with reference to the sequence diagram of FIG.
[0023]
In this system, when a link with a terminal to be accommodated is established, a timer corresponding to the link is started (reference numeral 9 in FIG. 2). During the activation period of the timer (reference numeral 11 in FIG. 2), when the reception line control unit 2 receives a packet from the link, the reception packet type determination unit 3 separates an information packet and a control packet according to the packet type. Distribute. When an information packet is received, normal protocol processing is performed.
[0024]
When a control packet is received, the control packet number counting section 5 counts up a counter corresponding to the link (reference numeral 10 in FIG. 2), and the reception control packet number determination section 7 performs comparison processing with a default value. Do. The reception control packet number determination unit 7 refers to the default value in the default value holding unit 4 for the link, and compares it with the count value of the counting unit 5.
[0025]
As a result of this comparison, when it is determined that the value counted by the counting unit 5 exceeds the predetermined value (reference numeral 12 in FIG. 2), the control packet is discarded (reference numeral 13 in FIG. 2). ). On the other hand, when the count value is equal to or smaller than the predetermined value, the normal protocol processing is performed on the control packet, and a response packet corresponding to the received control packet is returned to the line (reference numeral 10 in FIG. 2). ).
[0026]
In this system, the above processing is performed for each link from the start of activation of the timer 6 (reference numeral 9 in FIG. 2) to expiration of the timing (reference numeral 14 in FIG. 2) (reference numeral 11 in FIG. 2). When the timer 6 expires, the value of the corresponding link counted by the counting unit 5 is cleared. When the timer 6 is restarted after the clear, the reception of the control packet is restarted.
[0027]
Further, an operation when SSCOP (Service Specific Connection-oriented Protocol; ITU-T Recommendation Q.2110) is applied to the receiving system of FIG. 1 will be described with reference to a sequence diagram of FIG.
[0028]
In this case, a POLL-PDU (Poll-Protocol Data Unit; hereinafter, referred to as POLL) corresponds to the above-described control packet (reference numeral 15 in FIG. 3). The default value of the timer POLL (TimerPOLL) that determines the POLL transmission interval is defined as 750 [ms] (reference numeral 17 in FIG. 3).
[0029]
As an example, for a certain link in the present system, the number of POLLs received in each POLL monitoring period (reference numeral 19 in FIG. 3) by a timer (reference numeral 18 in FIG. 3) started from the time of link establishment is “10”. Stipulate. That is, the above-mentioned default value = 10.
[0030]
This default value is stored in the default value memory of the corresponding link provided in the default value holding unit 4 in advance.
[0031]
One cycle time of the timer for monitoring the corresponding link is 750 [ms] × 10 = 7.5 [sec] from the above-described default value and the number of receptions (reference numeral 19 in FIG. 3).
[0032]
The reception control packet number counting unit 5 for counting the number of received POLLs includes a counter provided for each link and a memory for holding the count value of each counter. This memory is assumed to be cleared when the link is established.
[0033]
When the system receives POLL, the count value of the counter of the corresponding link is incremented by "1". Then, the reception control packet number determination unit 7 reads the default value of the link from the memory in the default value holding unit 4 and compares it with the count value (reference numeral 20 in FIG. 3). As a result of the comparison, if the counter value is equal to or smaller than the predetermined value, a STAT-PDU (Solicited Status-Protocol Data Unit; hereinafter, referred to as STAT) is returned to the line side as normal protocol processing (reference numeral 16 in FIG. 3).
[0034]
When the POLL of the corresponding link is received several times and the counter value of the link exceeds the predetermined value corresponding to the link (reference numeral 21 in FIG. 3), the POLL is discarded by the reception control packet discarding unit 8. (Reference numeral 22 in FIG. 3). Even if the POLL of the corresponding link is received after this point, while the count value of the counter exceeds the predetermined value, the POLL is similarly discarded by the discarding unit 8 (reference numeral 22 in FIG. 3).
[0035]
When 7.5 [sec], which is one cycle time of the timer, has elapsed since the establishment of this link, the counter value of the counter corresponding to the link is cleared, and the timer is restarted (see FIG. 3). 23).
[0036]
After this point, if POLL of the link is received, STAT is returned to the line side as a normal protocol process until the counter value of the counter exceeds a predetermined value corresponding to the link (see FIG. 3). 24).
[0037]
If the count value of the counter corresponding to the link is cleared before exceeding the predetermined value corresponding to the link, the POLL is not discarded (reference numeral 24 in FIG. 3).
[0038]
In the present system, an error between the timer on the terminal side and the timer on the system side, a variation in a control packet reception interval on the system side due to the traffic condition of the line, and the like are also considered. In order to realize a system that takes these factors into consideration, the default value (“10” in the above-described example) held in the default value holding unit 4 may be set to a value having a margin.
[0039]
As described above, even when a large number of control packets are temporarily transmitted due to an abnormal operation of a certain terminal, the determination is made every time a control packet is received, and the control packet of the link is immediately transmitted when the control value exceeds a predetermined value. By discarding, it is possible to reliably control only abnormal links without affecting other links.
[0040]
Further, since the discarding process is performed only for the control packet, the processing performance of the system for receiving the packet can be reduced without reducing the processing capability of the system for the control packet and the information packet due to the retransmission of the information packet.
[0041]
The present invention may take the following aspects in connection with the description of the claims.
[0042]
(9) The packet reception system according to any one of claims 2 to 8, wherein the extraction unit extracts the control packet by determining a type of the received packet.
[0043]
(10) The packet receiving system according to any one of claims 1 to 9, wherein the control packet is a POLL-PDU (Poll-Protocol Data Unit) in an SSCOP (Service Specific Connection-oriented Protocol).
[0044]
【The invention's effect】
As described above, the present invention counts the number of control packets extracted from received packets for each link, and immediately discards control packets received after this count value reaches a predetermined value, Even if a large number of packets are sent temporarily due to abnormal operation of a certain terminal, the processing performance of the system is not impaired by these packets, and stable processing can be performed for normal packet reception. There is an effect that can be. In addition, since the discard processing is performed only for the control packet among the received packets, the retransmission of the information packet does not cause a decrease in the processing capacity of the system for the control packet and the information packet, and the processing for the system packet reception is reduced. There is an effect that can be.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a packet receiving system according to an embodiment of the present invention.
FIG. 2 is a sequence diagram showing an operation of the packet receiving system of FIG.
FIG. 3 is a sequence diagram showing an operation when SSCOP is applied to the packet receiving system of FIG. 1;
[Explanation of symbols]
Reference Signs List 1 reception control packet monitoring block 2 reception line control unit 3 reception packet type determination unit 4 default value holding unit 5 reception control packet number counting unit 6 timer 7 reception control packet number determination unit 8 reception control packet discard unit

Claims (9)

A packet receiving system for receiving a multiplexed packet, wherein the counting means counts the number of control packets among the received packets, and discards newly received control packets after the count value reaches a predetermined value. A packet receiving system comprising: packet discarding means. 2. The packet receiving system according to claim 1, wherein said counting means includes an extracting means for extracting a control packet from a received packet, and a means for counting the number of the extracted control packets. 3. The packet receiving system according to claim 1, wherein said counting means counts the number of said control packets for each link. 4. The packet receiving system according to claim 1, wherein said counting means counts the number of control packets received within a predetermined time. The packet receiving system according to claim 1, wherein the predetermined value is predetermined for each link. The packet according to any one of claims 1 to 5, wherein the packet discarding unit includes a comparing unit that compares the count value with the predetermined value, and discards a control packet according to a result of the comparison. Receiving system. 2. The system according to claim 1, further comprising a timer for starting counting of said predetermined time in response to establishment of each link, wherein said counting means counts the number of control packets received within said counted time. 7. The packet receiving system according to any one of claims 1 to 6. The packet receiving system according to claim 7, wherein the timer counts time for each of the links. 9. The packet receiving system according to claim 1, wherein said counting means includes storage means for storing said count value, and said packet discarding means includes storage means for storing said predetermined value. .

Images