JPS5932934B2 - Packet switching network abnormal congestion prevention method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention prevents new congestion from occurring due to detour packets caused by congestion in network components, and improves communication between the source exchange and destination exchange of discarded packets. The present invention relates to a method for preventing abnormal congestion in a packet switching network, which prevents an increase in the number of invalid and discarded packets by stopping the packet switching network for a certain period of time.

Conventionally, when relaying packets in a packet switching network, packets that encountered congestion in a network element were detoured to a non-congested network element, and the detour was continued until the detour destination became congested.

Also, when detouring became impossible, the packet was simply discarded. However, in such a method, a detour packet generated due to the congestion of one network component causes a chain reaction of congestion in the network component at the detour destination, causing packet detours at the detour destination as well. Furthermore, it was difficult to prevent the inflow of subsequent packets from the switching center that sent the discarded packet.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, to efficiently relay packets in a packet network, and to prevent abnormal congestion in one network component from spreading to other network components. The object of the present invention is to provide an economical method for preventing abnormal congestion that does not require special equipment.

That is, the present invention sets a network component congestion encounter indication to a packet that encounters congestion in a network component (transmission line, switch, etc.) at the relay destination when relaying a packet within the network.
The packet is detoured to the network element registered as the next detour destination, and the relay of the packet with the network element congestion encounter indication is limited to when the usage rate of the relay destination network element is below a certain value. If it is determined that the packet cannot be detoured or is unlikely to reach the destination exchange due to the detour, the packet is discarded, and a relay failure notification packet is sent to the source exchange and destination exchange of the discarded packet. By doing so, communication is stopped for a predetermined period of time, and detour packets caused by congestion in one network component (transmission line, switch, etc.) can cause a chain reaction of congestion in the detour destination network component. This is to prevent

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a packet switching network. As shown in FIG. 1, the packet switching network 10 includes a plurality of exchanges such as packet exchanges 11, 12, 13, 14, .
It consists of each exchange 11, 12, 13,
14..., 1n have data terminals 31, 32, 33, 3
4,...,3n are accommodated. Each exchange also has a relay exchange determination table 40 for controlling packet relay processing shown in FIG. 2, a table 45 for indicating queue length values for sending packets in the inter-office route, and a table 45 for controlling packet transmission queue lengths shown in FIG. 3. A relay failure notification packet sent registration table 50 that displays the source exchange and destination exchange, a specific exchange restriction registration table 60 that displays that communication with a specific exchange shown in FIG. 4 is stopped, and a network configuration shown in FIG. 5. It has an element congestion determination value table 71 and a network component detour determination value table 72 to perform bucket relay processing. Note that FIG. 6 shows the format of a data communication packet, and FIG. 7 shows the format of a packet for relay failure notification. Part 1 below
Taking the configuration shown in the figure as an example, switch 1 is configured such that switch 1n is the packet source switch and switch 11 is the destination switch.
I will explain how the four trees are relayed. Here, γ- shown in FIG. 1 represents an interoffice route number. First, the relay exchange determination table 40 shown in FIG. In order to grasp the usage status of the elements, the setting is such that +1 is added each time a packet transmission request is made for the interoffice route (γ), and the amount of completed transmission is subtracted when transmission to the adjacent exchange is completed.

The exchange 14 transfers the packet 80 shown in FIG. 6 to the exchange 1n.
When the packet is received from the destination exchange, in order to check whether the packet has its own exchange as the destination exchange, the relay exchange determination table 40 shown in FIG. 2 is indexed by the destination exchange number (DNOC) 82 of the packet shown in FIG. , check the value of switch decision indicator (PI) 41. When the packet received from the exchange 1n does not have the exchange 14 as the destination exchange, the relay exchange number counter (HOP) 8 shown in FIG.
It is checked whether the value of 1 is within the allowable value determined by the packet network, and if it is within the allowable value, the value of the packet relay switch number counter 81 is set in order to relay the packet to the next switch 13. After +1, packet 80 shown in FIG.
Check the network component Convergence Encounter Display (R) 87.
If the convergence encounter display (R) 87 is set, the first inter-office route number (RN1) 42 shown in FIG. , long value (Q46 is indexed, and the queue waiting for packet transmission is the long value (Q)
is less than the value α of the network component detour judgment value table 72 shown in FIG. +1 and the corresponding inter-office relay line (for example, 25 in Figure 1)
). In addition, when the value is equal to or greater than the value α in the network component detour judgment value table 72, the next inter-office route number registered in the relay switch determination table 40 is selected and the packet is relayed, so the second inter-office route is selected. Number (RN2) 43
Repeat the same process as above using . Furthermore, if the congestion encounter display is not set in the network element congestion display (R) 87 of the packet shown in FIG. The packet transmission waiting queue length value (Q) is indexed, and the packet transmission waiting queue length value (Q is the value β(
If β≧α) or less, add 1 to the inter-office route packet transmission waiting queue length value (Q) corresponding to the first inter-office route number (RNl) and send the packet to the corresponding inter-office trunk line. , when the network component congestion encounter display (G87) of the packet 80 shown in FIG. A selection process is performed.In the above packet relay process, the value of the packet relay exchange number counter (HOP) 81 shown in FIG. If it cannot be determined, the exchange 14 discards the packet, and at the same time checks the relay failure notification no-market sent registration table 50 shown in FIG.
), if the destination exchange number (DNOC) pair is unregistered, the seventh
The relay failure notification packet 90 shown in the figure is edited and sent to the source exchange 1n1 and destination exchange 11 of each packet.

(Note that the transmitting exchange center number (SNOC) 9 of the relay failure notification packet 90 sent to the destination exchange 11 of the discarded packet is
3 is the sending exchange number (SN
OC) 83 and the destination exchange number (DNOC) 9 of the relay failure notification packet 90 sent to the source exchange 1n.
2 is the destination exchange number (DN) of the packet 80 shown in FIG.
OC) 82) The exchange 14 that discarded the packet sends out a relay failure notification no-market 90, and at the same time
Relay failure notification packet sent registration table 50 shown in the figure
The relay packet is registered as having been transmitted, and the registration is canceled after the time specified by the communication restriction release timing value (TC) 53.

Furthermore, when discarding a packet in the exchange 14, the relay failure notification packet transmitted table 50 shown in FIG.
Checks whether the same pair of destination exchange number (DNOC) 51 and source exchange number (SNOC) 52 of the discarded packet is registered in This prevents many relay failure notification packets 90 from being sent in between. on the other hand,
If there is no registration, set the destination exchange (DNOC) 51, source exchange number (SNOC) 52, and relay failure notification registration display (D54).Next, relay failure notification at the source exchange and destination exchange of the discarded packet is set. Processing after receiving a packet will be explained.

In the exchange 11 of FIG. 1, which is the destination exchange of the discarded packet, and the exchange 1n of FIG. 1, which is the packet source exchange,
Upon receiving the relay failure notification packet 90 shown in FIG.
After that, in order to stop communication between the exchanges indicated by the relay failure notification packet 90 for a certain period of time, the communication partner exchange number (DNOC) 61 and the number determined by the packet network are entered in the specified station regulation registration table 60 shown in FIG. A specific exchange restriction release timing value (TC) 62 is set at the specified exchange restriction release timing value (TC) 62, and a specific exchange restriction release timing start registration display (P) is placed at the relative address (4) to activate the specific exchange restriction timing.
Set 63.

In the exchange 11 and the exchange 1n, in response to a communication request from a data terminal that matches the communication partner exchange number (DNOC) 61 registered in the specific exchange restriction registration table 60 shown in FIG. 4, the data terminal is accommodated. In the exchange 11 or 1n, the specific exchange regulation registration table 60 shown in FIG. 4 is checked, and in the case of a communication ring establishment request packet, CCITT recommendation X. 25 communication link instruction instruction packet is returned.

Also, when the request packet is a data packet, a CCITT recommended RNR packet is returned. Other packets are simply discarded. As described above, according to the present invention, packets that have been detoured due to a convergence encounter between network components;
By setting a difference in the network element usage rate standard value under the detour conditions for packets that have not encountered congestion, new congestion is prevented from occurring due to detour packets caused by congestion of network elements. However, since communication between the source exchange and the target exchange of discarded packets can be stopped for a certain period of time, there is an advantage that the increase in packets that are invalidly discarded due to congestion of network components can be reduced.

Further, according to the present invention, it is possible to realize this without installing any additional hardware by providing a network element congestion encounter indication in a data communication packet and setting a relay failure notification packet, etc., which is very simple and economical. There is also the advantage of having one.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the configuration of a packet switching network, Fig. 2 a is a relay switch determination table that controls packet relay processing, and b is a table showing the queue length of packets waiting to be sent in the interoffice route. 3 is a diagram showing an example of the configuration of a relay failure notification packet sent registration table that displays the source exchange and destination exchange for discarded packets, and FIG. FIG. 5 is a diagram showing an example of the configuration of a restricted registration table that displays outage, and FIG. FIG. 6 is a diagram showing the format of a data communication packet, and FIG. 7 is a diagram showing the format of a packet for relay failure notification. 10: Packet switching network, 11 to 1n: Packet switching network,
21 to 27: interoffice relay line, 31 to 3n: data terminal,
40: Trunk exchange determination table, 41: Exchange determination display (PI), 42: First interoffice route number (RNl), 43:
2nd inter-station route number (RN2), 45: Inter-office route packet transmission waiting queue length table, 46: Queue length value (Ql5O
: Relay failure notification packet sent registration table, 51, 6
1, 82, 92: Destination exchange number (DNOC), 52,
83,93: Source exchange number (SNOC), 53,6
2: Timing value for restriction release (TC), 54, 63: Registration display (P), 60: Specific exchange restriction registration table,
71: Congestion judgment value table, 72: Detour judgment value table, 80: Data communication packet, 81, 91: Intermediate switch number counter (HOP), 86, 94: Packet type information (TYP) 87, 95: Radio harp Encounter display (R), 90:
Relay failure notification packet.

Claims (1)

[Claims] 1 In the packet relay method of a packet switching network, when relaying a packet within the network, a network element congestion encounter indicator is set for a packet that encounters congestion in the relay destination network element (transmission line, switch, etc.), and the next The detour is made to a network element registered in advance as a detour destination, and the detour destination exchange detours the packet with the congestion encounter indication by limiting the usage rate of the relay destination network element to a certain value or less. , when it is determined that the utilization rates of all the network elements registered in advance as packet detour destinations are above a certain value and the packet cannot be detoured, or that there is a low possibility that the packet will reach the destination exchange due to detouring. discards the packet, sends a relay failure notification packet to the source exchange of the discarded packet and the destination exchange, and stops communication between the source exchange of the discarded packet and the destination exchange for a predetermined period of time. A method for preventing abnormal congestion in a packet-switched network.