JP3643094B2 - Packet transfer processing method, packet transfer processing device, and network - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IP packet (hereinafter simply referred to as a packet) transfer processing method, and relates to a technique for suppressing an increase in unnecessary traffic when a path loop occurs due to an illegal transfer table or the like.
[0002]
[Prior art]
Conventional packet transfer processing will be described with reference to FIGS. FIG. 9 is a diagram for explaining a conventional packet transfer process. FIG. 10 is a diagram for explaining the TTL process. FIG. 11 is a flowchart showing a conventional packet transfer processing procedure.
[0003]
As shown in FIG. 9, in the packet transfer process, the router refers to the IP header and (1) determines the next hop by performing a transfer table search based on the destination (DA). (2) TTL (Time to live) Check and subtract processing, (3) Header checksum check and recalculation are performed. The abbreviations in the figure are SA (Source address), DA (Destination address), SP (Source port number), and DP (Destination port number), respectively.
[0004]
In the process (2), the TTL value is decremented by 1 each time a packet advances by one hop as shown in FIG. 10. When a packet with a TTL value of 0 is received, This is a process that does not transfer any more. As a result, it is possible to prevent the packets from being continuously transferred even when the forwarding table of each router is inconsistent and a path loop occurs.
[0005]
FIG. 11 is a flowchart of the processing of (1), (2), and (3). This flowchart is executed every time one packet is received, and it is determined whether the received packet is transferred to the next hop or discarded. To do. That is, a packet is received (step 1), it is determined whether TTL is not 0 (step 2), if it is 0, it is discarded (step 10), if not 0, the TTL value is subtracted (step 3), The TTL value is mounted on the IP header (step 4). In parallel with this processing, a transfer table search is performed to determine a transfer destination (step 6). In parallel, it is determined whether or not the header checksum is correct (step 7). If it is not correct, the header checksum is discarded (step 10). If it is correct, the header checksum is recalculated (step 8). (Step 9). In this way, the packet whose TTL is not 0, the forwarding destination is determined, the Header checksum is correct, and the Header checksum is recalculated is forwarded to the next hop (step 5).
[0006]
[Problems to be solved by the invention]
In this way, in the packet transfer process, it is determined whether or not to continue transferring the packet to the subsequent stage based on the TTL value. FIG. 12 is a diagram for explaining a loop problem caused by an illegal forwarding table. As shown in FIG. 12, when each router in the network has an inconsistent illegal forwarding table, a packet is displayed. A transfer path loop occurs. When the TTL value is t when the packet arrives at the node A, assuming that one round of the loop of the transfer path is n hops (n = 3 in the example of FIG. 12), the packet is floor ((t -1) / n-1) loops, and the traffic between the nodes A and B is subjected to floor ((t-1) / n-1) times as much traffic. Here, floor (x) represents the maximum integer not exceeding x. That is, when the TTL value is large and the number of hops of the loop is small, it means that a lot of unnecessary traffic is applied.
[0007]
In recent high-speed routers that perform transfer processing with hardware, the increased unnecessary traffic suddenly occurs, and the transmission path bandwidth is immediately compressed, so the influence becomes enormous. Furthermore, if the transmission path bandwidth is overstressed, routing protocol and signaling protocol packets will not be transferred, leading to a malfunction of the entire network.
[0008]
The present invention is based on such a background. When a node in the network uses an inconsistent invalid forwarding table, a packet is generated when a forwarding route loop occurs. It is an object of the present invention to provide a packet transfer processing method, a packet transfer processing device, a network, a protocol, and a recording medium that can suppress the number of times that the transfer path is circulated and can suppress an increase in unnecessary traffic.
[0009]
[Means for Solving the Problems]
The main feature of the present invention is that the entry in the forwarding table relating to a packet discarded with a TTL value of 0 is marked as a suspicious entry causing a loop. Then, the loop is canceled by discarding the packet that has arrived at the suspect entry. Alternatively, it is characterized in that the loop is canceled by marking the packet that has arrived at the suspicious entry and discarding it when it returns in a loop. Alternatively, the bandwidth may be narrowed so as not to compress other traffic by lowering the transfer priority even if the packet arriving at the suspicious entry is not discarded.
[0010]
As a result, the number of times that a packet circulates in the transfer path can be suppressed even when a loop of the transfer path occurs due to a node in the network using an inconsistent invalid transfer table, etc. An increase in unnecessary traffic can be suppressed. In a network that performs packet transfer at high speed with hardware, the loop of the transfer path fills up the transmission path bandwidth in an instant, causing fatal damage such as a stop of the network function, but this is avoided by the present invention. can do.
[0011]
That is, a first aspect of the present invention is a packet transfer processing method that searches a transfer table according to a destination address of an arriving packet and determines a next hop destination based on a corresponding entry of the searched transfer table.
[0012]
Here, a feature of the present invention is that a corresponding entry in the forwarding table relating to a packet discarded because the TTL value is 0 is marked as a suspicious entry.
[0013]
In other words, it is unlikely that the TTL value of a packet that has arrived at the network for the first time is 0 from the beginning, and that a packet is discarded with a TTL value of 0 means that a loop has occurred and the packet has circulated on the loop. This means that there is a high possibility that the TTL value has become 0 in the meantime. Therefore, by marking the corresponding entry in the forwarding table for such a packet as a suspicious entry that causes a loop, it is possible to make a countermeasure for solving the loop.
[0014]
Specifically, when a packet corresponding to the suspicious entry arrives, it is desirable to discard the packet regardless of the TTL value.
[0015]
At this time, it is desirable to release the suspicion of the suspicious entry when a certain period of time has elapsed since the mark as the suspect entry.
[0016]
In other words, if a suspicious entry remains even after the loop has been resolved, unnecessary packet discard may continue, so when a certain period of time has passed since the mark was marked as a suspicious entry, The suspicion of the entry should be lifted once. Of course, if a packet that is discarded with a TTL value of 0 arrives again after a certain period of time has passed since the mark as a suspicious entry, the mark added to the suspicious entry is continued. The certain time may be set as appropriate according to the network environment.
[0017]
Alternatively, when a packet corresponding to the suspected entry arrives and the TTL value is larger than 0, a TTL Marker bit is set in the IP header of the packet and then transferred to the next hop, and a packet with the TTL Marker bit set arrives However, when the packet is a packet corresponding to the suspect entry, the packet can be discarded regardless of the TTL value.
[0018]
That is, the TTL value of a packet that first arrives at the suspicious entry is greater than zero. However, since there is a high possibility that the packet will circulate on the loop in the future, unnecessary traffic due to the loop can be suppressed to a minimum by setting the TTL Marker bit and quickly discarding it after one lap.
[0019]
Further, in the forwarding table of the node where the packet first arrives, for example, even if the destination address is z, in the forwarding table of the next hop node, z is further branched and z and z. 1, the packet of the destination z goes around the loop, but the destination z. One packet may be unrelated to the loop. In such a case, if a packet that arrives uniformly at the first node is discarded, the destination z. Since even one packet is discarded together, it is possible to avoid such an inconvenience by once assigning a TTL Marker and transferring it to the next hop.
[0020]
At this time, when a packet with the TTLMarker bit set for a certain period of time has not been transferred to the corresponding entry after marking as the suspected entry, it is desirable to release the suspected entry.
[0021]
In other words, if the suspicious entry remains even after the loop is resolved, unnecessary processing such as setting the TTL Marker bit is performed on the arriving packet, so the packet with the TTL Marker bit set for a certain time or more If it is not transferred to, the suspicion of the suspicious entry should be released immediately. The predetermined time may be set appropriately according to the network environment.
[0022]
Alternatively, when a packet corresponding to the suspected entry arrives and its TTL value is larger than 0, the TTL value subtracted by 1 is compared with a predetermined value, and the smaller one is mounted as an TTL value in the IP header. It can also be forwarded to the next hop.
[0023]
That is, a predetermined number of laps is allowed for a packet that may circulate in the loop. Thereby, when the loop is quickly eliminated, the packet can arrive at the destination without being discarded. As described above, in the forwarding table of the node where the packet first arrives, for example, the destination address z is z, but in the forwarding table of the next hop node, z is further branched and z and z. 1, the packet of the destination z goes around the loop, but the destination z. One packet may be unrelated to the loop. In such a case, if a packet that arrives uniformly at the first node is discarded, the destination z. Since even one packet is discarded together, such inconvenience can be avoided by allowing a predetermined number of rounds. This allowable number of times is preferably set as appropriate according to the network environment.
[0024]
At this time, it is desirable to cancel the suspicion of the suspicious entry when a packet discarded with TTL = 0 for a predetermined time or more after being marked as the suspicious entry is not transferred to the corresponding entry.
[0025]
In other words, if the suspicious entry remains even after the loop is resolved, the TTL value of the arrived packet is decremented by 1 and the predetermined value is compared, and the smaller one is mounted as the TTL value in the IP header. Therefore, when a packet discarded with TTL = 0 for a certain time or longer is not transferred to the corresponding entry, it is preferable to quickly cancel the suspicious entry. The certain time may be appropriately set according to the network environment.
[0026]
Alternatively, when a packet corresponding to the suspect entry arrives and its TTL value is greater than 0, the transfer priority of the packet can be lowered before transferring to the next hop.
[0027]
That is, lowering the transfer priority means narrowing the bandwidth compared to other traffic. As a result, the packet is allowed to circulate around the loop in a narrow band that does not compress other traffic. In the meantime, if the loop recovers, the packet is transferred to a normal destination, so that a more flexible packet transfer process can be performed than when it is immediately discarded.
[0028]
Further, a plurality of classes relating to packet transfer priority are provided, and when a packet corresponding to the suspected entry arrives and its TTL value is greater than 0, the packet transfer priority is lowered to a class one rank lower. Can be forwarded from one to the next hop.
[0029]
According to this, the transfer priority can be divided more finely than the former, and the transfer priority can be gradually lowered according to the number of laps. In this case, when it falls to the lowest class, it may be discarded next time. In the former case, there is a possibility that the loop will continue to circulate with a low priority, but in the latter case, the band may be gradually narrowed according to the number of laps and eventually discarded. .
[0030]
In this case, it is desirable to release the suspicion of the suspicious entry when a packet having a transfer priority lower than the threshold value is not transferred for a certain time or more after the suspicious entry is marked.
[0031]
In other words, if the suspicious entry remains even after the loop is resolved, unnecessary processing such as lowering the transfer priority of the arriving packet is performed, so a packet whose transfer priority is lower than the threshold for a certain period of time or more. If the entry is not transferred to the corresponding entry, the suspicion of the suspicious entry should be immediately released. The predetermined time and the threshold value are preferably set as appropriate according to the network environment.
[0032]
According to a second aspect of the present invention, the forwarding table in which the next hop destination corresponding to the destination address is recorded, and the forwarding table is searched according to the destination address of the arrived packet, and the corresponding entry in the searched forwarding table And a means for determining the next hop destination based on the packet transfer processing device.
[0033]
Here, a feature of the present invention lies in that there is provided means for marking a corresponding entry in the forwarding table relating to a packet discarded because the TTL value is 0 as a suspicious entry.
[0034]
Furthermore, it is desirable to provide means for discarding the packet regardless of the TTL value when the packet corresponding to the suspected entry arrives.
[0035]
At this time, it is desirable to provide means for releasing the mark of the suspected entry when a certain period of time has elapsed since the mark as the suspected entry.
[0036]
Alternatively, when a packet corresponding to the suspicious entry arrives and the TTL value is larger than 0, means for setting the TTL Marker bit in the IP header of the packet and then transferring to the next hop, and the packet with the TTL Marker bit set And a means for discarding the packet regardless of the TTL value when the packet is a packet corresponding to the suspected entry.
[0037]
At this time, it is desirable to provide means for canceling the mark of the suspicious entry when a packet with the TTLMarker bit set for a certain period of time has not been transferred to the corresponding entry after marking the suspicious entry.
[0038]
Alternatively, when a packet corresponding to the suspected entry arrives and its TTL value is larger than 0, the TTL value subtracted by 1 is compared with a predetermined value, and the smaller one is mounted as an TTL value in the IP header. It is also possible to provide means for transferring to the next hop.
[0039]
At this time, it is desirable to provide means for releasing the mark of the suspected entry when a packet discarded with TTL = 0 for a certain period of time after being marked as the suspected entry is not transferred to the corresponding entry.
[0040]
Alternatively, when a packet corresponding to the suspect entry arrives and its TTL value is larger than 0, it is possible to provide means for lowering the transfer priority of the packet and transferring it to the next hop.
[0041]
Alternatively, when a plurality of classes related to the packet transfer priority are provided and a packet corresponding to the suspected entry arrives and the TTL value is greater than 0, the packet transfer priority is lowered to a class one rank lower. It is also possible to provide means for transferring from one to the next hop.
[0042]
At this time, it is preferable to provide means for canceling the suspicion of the suspicious entry when a packet having a transfer priority lower than a threshold value is not transferred for a certain period of time after the suspicious entry is marked.
[0043]
A third aspect of the present invention is a network comprising the packet transfer processing device of the present invention.
[0044]
According to a fourth aspect of the present invention, when the information processing apparatus is installed in the information processing apparatus, the packet transfer processing method of the present invention is executed by the information processing apparatus or installed in the information processing apparatus. Further, a program for realizing a function corresponding to the packet transfer processing apparatus of the present invention.
[0045]
A fifth aspect of the present invention is the information processing apparatus-readable recording medium on which the program of the present invention is recorded. By recording the program of the present invention on the recording medium of the present invention, the information processing apparatus can install the program of the present invention using this recording medium. Alternatively, the program of the present invention can be directly installed in the information processing apparatus via a network from a server holding the program of the present invention.
[0046]
As a result, when an information processing device such as a computer device is used and a transfer route loop occurs due to a node in the network using an inconsistent transfer table, etc., the packet passes through the transfer route. It is possible to realize a packet transfer processing method, a packet transfer processing device, and a network that can suppress the number of times of circulation and suppress an increase in unnecessary traffic.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
(First Example)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram for explaining the first embodiment. FIG. 2 is a block diagram of the packet transfer processing apparatus according to this embodiment. As shown in FIG. 2, the first embodiment searches the forwarding table 1 according to the destination address of the arriving packet, and determines the next hop destination based on the corresponding entry of the retrieved forwarding table 1. 2 is a packet transfer processing apparatus including a unit 2. Each of the packet transfer processing devices may be provided in each node, or one or a plurality of packet transfer processing devices may be arranged in the network to control the packet transfer processing of each node.
[0048]
Here, the feature of this embodiment is that the TTL monitoring unit 3 marks a corresponding entry in the forwarding table 1 regarding a packet discarded because the TTL value is 0 as a suspicious entry. The header information of the packet is read by the header reading unit 5 and distributed to the next hop determination unit 2, the TTL monitoring unit 3, and the Header checksum monitoring unit 4, respectively. In addition, the transfer processing unit 6 transfers or discards the packet in accordance with instructions from the next hop determination unit 2, the TTL monitoring unit 3, and the Header checksum monitoring unit 4.
[0049]
In the TTL monitoring unit 3 of the first embodiment, when a packet corresponding to the suspected entry arrives, the packet is discarded regardless of the TTL value. Further, when a certain period of time has passed since the mark as the suspect entry, the suspect entry is released.
[0050]
That is, when a packet arrives at the node A shown in FIG. 1, if the TTL value is 0 and is discarded, the corresponding forwarding table entry is set as a suspect entry. Thereafter, when the packet corresponding to the suspicious entry is received, the node A discards all the packets regardless of the TTL value. This prevents the packet from entering the loop of the transfer path.
[0051]
(Second embodiment)
A second embodiment will be described with reference to FIGS. 1, 2, 4, 5, and 6. FIG. FIG. 4 is a flowchart showing the packet transfer processing procedure of the second embodiment. FIG. 5 is a diagram showing the TOS octet of the IP header. FIG. 6 is a diagram showing TTLMarker coding using the TOS of the second embodiment.
[0052]
When the packet corresponding to the suspicious entry arrives and the TTL value is larger than 0 according to the monitoring result of the TTL monitoring unit 3 shown in FIG. After setting the TTL Marker bit in the IP header of the packet, the packet is transferred to the next hop. Further, the next hop determination unit 2 discards the packet regardless of the TTL value when a packet with the TTL Marker bit set arrives and the packet is a packet corresponding to the suspect entry.
[0053]
The TTL monitoring unit 3 releases the suspicion of the suspicious entry when a packet having the TTL Marker bit set for a certain period of time has not been transferred to the corresponding entry after marking the suspicious entry.
[0054]
As shown in FIG. 1, in the forwarding table of the node A where the packet first arrives, even though the destination address is z, in the forwarding table of the next hop node B, z is further branched and z and z. It is divided into 1. Here, the packet of the destination z goes around the loop, but the destination z. One packet is independent of the loop. In such a case, as in the first embodiment, if the packets arriving uniformly at the first node A are discarded, the destination z. Since even one packet is discarded, in the second embodiment, a TTL Marker is once assigned and the packet is transferred to the next hop.
[0055]
That is, when a packet corresponding to the suspected entry arrives at node A after the suspected entry is marked, if the TTL value is greater than 0, the TTL Marker bit of the header is set and forwarded to node B . Here, it is assumed that the TTL Marker bit is not set when the node A arrives.
[0056]
Next, when the node B receives the packet, it determines the next hop according to the forwarding table. In the transfer table search, the longest match search is performed. That is, the destination z and z. When a destination of 1 exists, the search result is the entry with the longest portion that matches the destination address of the IP header. In this example, the packet destination is z. If it is 1, the next hop is D, otherwise the next hop is C. If the next hop is D, it is transferred to the destination safely, but if it is C, it goes around the loop. That is, since node C has an invalid forwarding table that is inconsistent with nodes A and B, when forwarded to node C, the packet is forwarded to node A.
[0057]
Here, the suspicious entry is marked in the node A, and the packet transferred from the node C is discarded because the TTL Marker bit is set. As a result, it is possible to prevent the transfer path from entering the loop again.
[0058]
In this example, the TTL Marker bit is set, but this bit can be realized by using, for example, a TOS (Type of service) octet. FIG. 5 shows the IP header, and FIG. 6 shows the TOS octet. Some of the Experimental Uses can be used as TTL Markers.
[0059]
The packet transfer processing procedure of the second embodiment is shown in FIG. When the packet is received (step 1), the TTL monitoring unit 3 determines whether TTL is not 0 (step 2). If it is 0, the pseudo entry in the forwarding table 1 is marked (step 5). The TTL value is subtracted (step 3), and the TTL value is mounted on the IP header (step 4). In parallel with this processing, the next hop determination unit 2 searches the transfer table 1 to determine the transfer destination (step 6). It is determined whether the entry in the forwarding table 1 is a suspicious entry. If it is a suspicious entry (step 7), it is determined whether there is a TTL Marker (step 8). If there is no TTL Marker, it is assigned (step 9). Also, if there is a TTL Makerker, it is discarded (step 14). In parallel, the header checksum monitoring unit 4 determines whether the header checksum is correct (step 11), discards the header checksum if it is not correct (step 14), recalculates the header checksum if it is correct (step 12), and the IP header. Is loaded with the recalculated Header checksum (step 13). In this way, the TTL is not 0, the forwarding destination is determined, the TTL Marker is not present, or the TTL Marker is added for the first time, the header checksum is correct, and the header checksum is recalculated as a next hop. Transferred (step 10).
[0060]
(Third embodiment)
A third embodiment will be described with reference to FIGS. FIG. 3 is a conceptual diagram for explaining the third embodiment. When the packet corresponding to the suspected entry arrives and the TTL monitoring unit 3 shown in FIG. 2 subtracts 1 from the TTL value when the TTL value shown in FIG. Are compared with a predetermined value and the smaller one is loaded as the TTL value in the IP header and then transferred to the next hop.
[0061]
Further, the TTL monitoring unit 3 removes the mark of the suspicious entry when a packet discarded with TTL = 0 for a predetermined time or more has not been transferred to the corresponding entry after marking the suspicious entry.
[0062]
In other words, in the second embodiment, the TTL Marker bit is newly defined, but a similar effect can be achieved with only the TTL value. The concept is shown in FIG. An upper limit of how many hops the packet corresponding to the suspicious entry is transferred in the subsequent stage is determined, and it is set as H. When a packet corresponding to the suspicious entry arrives, H is compared with the value obtained by subtracting TTL by 1, and the smaller one is transferred as a new TTL value. Thereby, it is possible to suppress the frequency | count which circulates a loop.
[0063]
(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. FIG. 7 is a flowchart showing the packet transfer processing procedure of the fourth embodiment. When the packet corresponding to the suspicious entry arrives and the TTL value is larger than 0, the next hop determination unit 2 shown in FIG. 2 lowers the transfer priority of the packet. Forward to the next hop.
[0064]
That is, lowering the transfer priority means narrowing the band compared to other traffic. As a result, the packet is allowed to circulate around the loop in a narrow band that does not compress other traffic. In the meantime, if the loop recovers, the packet is transferred to a normal destination, so that a more flexible packet transfer process can be performed than when it is immediately discarded.
[0065]
Further, the next hop determination unit 2 releases the suspicion of the suspicious entry when a packet having a transfer priority lower than the threshold value is not transferred for a predetermined time or more after marking the suspicious entry. Here, the threshold is the transfer priority of normal packets arriving at entries other than the suspicious entry.
[0066]
The packet transfer processing procedure of the fourth embodiment is shown in FIG. When the packet is received (step 1), the TTL monitoring unit 3 determines whether the TTL is not 0 (step 2). If it is 0, the pseudo entry in the forwarding table 1 is marked (step 5). For example, the TTL value is subtracted (step 3), and the TTL value is mounted on the IP header (step 4). In parallel with this processing, the next hop determination unit 2 searches the transfer table 1 to determine the transfer destination (step 6). It is determined whether or not the entry in the forwarding table 1 is a suspicious entry. If it is a suspicious entry (step 7), it is determined whether or not the forwarding priority is lower than that of a normal packet (step 8). If the degree is not lower than that of a normal packet, the priority is lowered (step 9). If the transfer priority is lower than that of a normal packet, the packet is transferred as it is (step 10). In parallel, the header checksum monitoring unit 4 determines whether the header checksum is correct (step 11), discards the header checksum if it is not correct (step 14), recalculates the header checksum if it is correct (step 12), and the IP header. Is loaded with the recalculated Header checksum (step 13). In this way, the packet whose TTL is not 0, the transfer destination is determined, the Header checksum is correct, and the Header checksum is recalculated is transferred to the next hop (step 10).
[0067]
(Fifth embodiment)
A fifth embodiment will be described with reference to FIGS. FIG. 8 is a flowchart showing the packet transfer processing procedure of the fifth embodiment. The packet transfer processing device of the fifth embodiment is provided with a plurality of classes related to packet transfer priorities, and when the packet corresponding to the suspicious entry arrives and its TTL value is greater than 0, the next hop determination shown in FIG. The unit 2 lowers the transfer priority of the packet to a class one rank lower and transfers it to the next hop.
[0068]
That is, the fifth embodiment divides the transfer priority more finely than the fourth embodiment and gradually lowers the transfer priority according to the number of laps. In the fifth embodiment, when the class is lowered to the lowest class, it is discarded next time. In the case of the fourth embodiment, there is a possibility that the loop will continue to circulate with a low priority, but in the case of the fifth embodiment, the band gradually narrows according to the number of laps and is eventually discarded. Like that.
[0069]
Further, the next hop determination unit 2 releases the suspicion of the suspicious entry when a packet having a transfer priority lower than the threshold value is not transferred for a predetermined time or more after marking the suspicious entry. Here, the threshold is the transfer priority of normal packets arriving at entries other than the suspicious entry.
[0070]
The packet transfer processing procedure of the fifth embodiment is shown in FIG. When the packet is received (step 1), the TTL monitoring unit 3 determines whether the TTL is not 0 (step 2). If it is 0, the pseudo entry in the forwarding table 1 is marked (step 5). For example, the TTL value is subtracted (step 3), and the TTL value is mounted on the IP header (step 4). In parallel with this processing, the next hop determination unit 2 searches the transfer table 1 to determine the transfer destination (step 6). It is determined whether or not the entry in the forwarding table 1 is a suspect entry, and if it is a suspect entry (step 7), it is determined whether or not the transfer priority class is the lowest (step 8) and must be the lowest. For example, the priority is lowered by one rank (step 9), and if it is the lowest, it is discarded (step 14). In parallel, the header checksum monitoring unit 4 determines whether the header checksum is correct (step 11), discards the header checksum if it is not correct (step 14), recalculates the header checksum if it is correct (step 12), and the IP header. Is loaded with the recalculated Header checksum (step 13). In this way, a packet in which the TTL is not 0, the forwarding destination is determined, the priority is not the lowest, the Header checksum is correct, and the Header checksum is recalculated is forwarded to the next hop (step 10). ).
[0071]
(Sixth embodiment)
The packet transfer processing apparatus according to the present embodiment can be realized using a computer apparatus that is an information processing apparatus. That is, by installing in the computer apparatus, the computer apparatus is caused to execute the packet transfer processing method of the present embodiment. By installing a program for realizing the function corresponding to the above in the computer apparatus, the computer apparatus can be made an apparatus corresponding to the packet transfer processing apparatus of this embodiment.
[0072]
Further, the program of this embodiment is recorded on the recording medium of this embodiment, so that the computer apparatus can install the program of this embodiment using this recording medium. Alternatively, the program of this embodiment can be directly installed on the computer device from the server holding the program of this embodiment via the network.
[0073]
As a result, the number of times that a packet circulates in the transfer path is suppressed when a loop of the transfer path occurs due to, for example, a node in the network using an inconsistent and invalid transfer table using a computer device. Therefore, it is possible to realize a packet transfer processing method, a packet transfer processing device, and a network that can suppress an increase in unnecessary traffic.
[0074]
【The invention's effect】
As described above, according to the present invention, when a node in a network uses an inconsistent and invalid forwarding table, a packet circulates around the forwarding route when a forwarding route loop occurs. The number of times can be suppressed, and an increase in unnecessary traffic can be suppressed.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for explaining first and second embodiments.
FIG. 2 is a block configuration diagram of the packet transfer processing apparatus according to the embodiment.
FIG. 3 is a conceptual diagram for explaining a third embodiment.
FIG. 4 is a flowchart showing a packet transfer processing procedure according to the second embodiment.
FIG. 5 is a diagram showing a TOS octet of an IP header.
FIG. 6 is a diagram showing TTL Marker coding using the TOS of the second embodiment.
FIG. 7 is a flowchart showing a packet transfer processing procedure according to the fourth embodiment.
FIG. 8 is a flowchart showing a packet transfer processing procedure according to the fifth embodiment.
FIG. 9 is a diagram for explaining conventional packet transfer processing;
FIG. 10 is a diagram for explaining TTL processing;
FIG. 11 is a flowchart showing a conventional packet transfer processing procedure.
FIG. 12 is a diagram for explaining a loop problem due to an illegal forwarding table;
[Explanation of symbols]
A to C nodes
1 Transfer table
Secondary hop determination unit
3 TTL monitoring unit
4 Header checksum monitoring part
5 Header reader
6 Transfer processing part

Claims (23)

In a packet transfer processing method for searching a forwarding table according to a destination address of an arriving packet and determining a next hop destination based on a corresponding entry of the searched forwarding table,
A packet transfer processing method, wherein a corresponding entry in the transfer table relating to a packet discarded because a TTL (Time to live) value is 0 is marked as a suspicious entry. 2. The packet transfer processing method according to claim 1, wherein when a packet corresponding to the suspected entry arrives, the packet is discarded regardless of the TTL value. The packet transfer processing method according to claim 1 or 2, wherein when a certain period of time has passed since the mark as the suspect entry, the suspect of the suspect entry is canceled. When a packet corresponding to the suspected entry arrives and its TTL value is greater than 0, a TTL Marker bit is set in the IP header of the packet and then transferred to the next hop,
2. The packet transfer processing method according to claim 1, wherein when a packet having a TTL Marker bit arrives and the packet is a packet corresponding to the suspicious entry, the packet is discarded regardless of the TTL value. 5. The packet transfer processing method according to claim 4, wherein when a packet with a TTL Marker bit set for a certain period of time has not been transferred to the corresponding entry after marking the suspicious entry, the suspicion of the suspicious entry is canceled. When a packet corresponding to the suspicious entry arrives and the TTL value is larger than 0, the TTL value subtracted by 1 is compared with a predetermined value, and the smaller one is mounted as an TTL value in the IP header. The packet transfer processing method according to claim 1, wherein the packet is transferred to the next hop. 7. The packet transfer processing method according to claim 6, wherein when a packet discarded with TTL = 0 for a predetermined time or more after marking as the suspicious entry is not transferred to the corresponding entry, the suspicion of the suspicious entry is canceled. The packet transfer processing method according to claim 1, wherein when a packet corresponding to the suspicious entry arrives and the TTL value is larger than 0, the packet is transferred to the next hop after the transfer priority of the packet is lowered. There are several classes related to packet transfer priority,
2. The packet transfer processing method according to claim 1, wherein when a packet corresponding to the suspected entry arrives and the TTL value is larger than 0, the transfer priority of the packet is lowered to a class one rank lower and then transferred to the next hop. . 10. The packet transfer processing method according to claim 8 or 9, wherein when a packet having a transfer priority lower than a threshold value is not transferred for a certain period of time after marking as the suspect entry, the suspected entry is canceled. A forwarding table in which a next hop destination corresponding to a destination address is recorded, and a means for searching the forwarding table according to a destination address of an arriving packet and determining a next hop destination based on a corresponding entry of the retrieved forwarding table In a packet transfer processing device comprising:
A packet forwarding processing apparatus comprising means for marking a corresponding entry in the forwarding table relating to a packet discarded due to a TTL value of 0 as a suspicious entry. 12. The packet transfer processing device according to claim 11, further comprising means for discarding the packet regardless of the TTL value when a packet corresponding to the suspicious entry arrives. 13. The packet transfer processing device according to claim 11 or 12, further comprising means for canceling the mark of the suspected entry when a certain period of time has elapsed since the mark as the suspected entry. A packet corresponding to the suspected entry arrives, and when the TTL value is larger than 0, means for setting a TTL Marker bit in the IP header of the packet and then transferring to the next hop;
12. The packet transfer processing device according to claim 11, further comprising means for discarding the packet regardless of the TTL value when a packet with the TTL Marker bit set arrives and the packet is a packet corresponding to the suspicious entry. 15. The packet transfer process according to claim 14, further comprising means for canceling the mark of the suspicious entry when a packet with the TTL Marker bit set for a predetermined time or more has not been transferred to the corresponding entry after marking as the suspicious entry. apparatus. When a packet corresponding to the suspicious entry arrives and the TTL value is larger than 0, the TTL value subtracted by 1 is compared with a predetermined value, and the smaller one is mounted as an TTL value in the IP header. 12. The packet transfer processing device according to claim 11, further comprising means for transferring to the next hop. 17. The packet transfer according to claim 16, further comprising means for releasing the mark of the suspicious entry when a packet discarded with TTL = 0 for a predetermined time or more after being marked as the suspicious entry is not transferred to the corresponding entry. Processing equipment. 12. The packet transfer processing device according to claim 11, further comprising means for lowering the transfer priority of the packet and transferring it to the next hop when a packet corresponding to the suspected entry arrives and the TTL value is larger than zero. There are several classes related to packet transfer priority,
12. The device according to claim 11, further comprising means for lowering the transfer priority of the packet to a class one rank lower and transferring it to the next hop when a packet corresponding to the suspected entry arrives and the TTL value is greater than zero. Packet transfer processing device. 20. The packet transfer according to claim 18 or 19, further comprising means for canceling the suspicion of the suspicious entry when a packet having a transfer priority lower than a threshold value is not transferred for a predetermined time or more after the suspicious entry is marked. Processing equipment. A network comprising the packet transfer processing device according to any one of claims 11 to 20. The information processing apparatus causes the information processing apparatus to execute the packet transfer processing method according to any one of claims 1 to 10, or the information processing apparatus installs the information processing apparatus to install the information processing apparatus. A program for realizing a function corresponding to the packet transfer processing device according to any one of claims 11 to 20. 23. A recording medium readable by the information processing apparatus on which the program according to claim 22 is recorded.

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