JPS5834650A - Packet switching system - Google Patents

Abstract

PURPOSE:To realize priority transmission of urgent packet by interrupting transmission of packet under transmission temporarily, and after transmitting packet that needs urgent transmission, transmitting the interrupted packet. CONSTITUTION:During receiving normal packet PKTA1 continuously in succession more than 2 flag sequences F, an output signal SG0 of a gate G0 and an input signal SG1 to gates G1, G2 are at (0) level. Receiving packet PKTA1 is received by a receiving control section RLSI0 by opening G1 and closing G2. After that, when urgent transmitting packet PKTB is received continuously is succession to F of 1, SG0 changes to 0 1 0 level and consequently, SG1 changes to 1 level. By this operation, G1 is closed and G2 is opened, and receiving operation of RLSI0 is stopped. At the same time, PKTB is received by a receiving control section RLSI1. When PKTA2 is received continuously in succession to receiving of F of 1 of PKTB, G1 is opened and G2 is closed, and PKTA2 is received by RLSI0.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a packet switching system in a packet switching network.

In a packet-switched network, data sent from a data communication device and network management data generated by the packet switch itself are both sent and received in packet format using the same transmission path. There are some that require urgent transmission and others that are non-urgent, but if an urgent packet occurs while a non-urgent packet is being transmitted, the transmission of the non-urgent packet will be terminated. It is necessary to wait until the transmission of urgent packets. For this reason, there is a drawback that the transmission delay of the emergency packet becomes large and the urgency cannot be fulfilled.

SUMMARY OF THE INVENTION An object of the present invention is to provide a packet switching system that eliminates the drawbacks of the prior art described above and reduces the transmission delay time of emergency packets.

According to the present invention, when it becomes necessary to transmit an urgent packet while transmitting a non-urgent packet, the transmission of the non-urgent packet that is currently being transmitted is temporarily suspended, the urgent packet is transmitted, and the transmission is interrupted when the transmission is completed. This method realizes efficient optical transmission of emergency packets by restarting the transmission of non-emergency packets.

In a packet switching network as shown in Fig. 1, terminal TA
is to the terminal Tc, and the terminal TB is to the terminal TD, respectively, as shown in the conventional Figure 2 (5 buckets) PKTA and PK.
When transmitting TB, PKTA and PKTB are accumulated in packet switches PEA and PSB, respectively, and then transmitted to packet switch PSc. With this conventional method,!
'Fifth also if KTB needs to be delivered urgently.
As shown in the figure, there is a problem in that the transmission of PKTB must wait until the transmission of PKTA is completed.

In order to eliminate the above-mentioned problems, the present invention provides the fourth
As shown in the figure, while transmitting PAD KPKTA from PSc, if it becomes necessary to transmit PKTB from PSc to PSD, the transmission is temporarily interrupted when part of PKTA is transmitted. Send PKTB, PK
When the transmission of TB is completed, the remaining part of PKTA
The feature is that by transmitting A2, urgent packets are preferentially transferred.

An implementation example of the present invention will be described in detail below.

In packet switching, high-level transmission control procedures (HDLC) are used as transmission control procedures for sending and receiving packets.
). In this HDLC, as shown in Fig. 2, 1
The above flag sequence F is used. In the present invention, two or more Fs are used to separate packets, and as shown in FIG.
B stores one continuous packet PKTA as PKTAl
By displaying that the packet was transmitted by interrupting PKTi, in the form of dividing it into PKTA2,
This is a packet transmission and reception method that achieves priority transmission of emergency transmission packets. FIG. 7 is an example of implementing the above-mentioned priority transmission. When the interrupt display signal Is is at the Iol level as shown in FIG. 6, the gates G11 and G12 are closed and the gates 1 and Go2 are opened to transmit a normal bucket) PKTA from the HDLC transmitter 8ENDo. do. Furthermore, in the case of s-0, two or more Fs are transmitted prior to transmitting a packet, and two or more Fs are similarly transmitted after transmitting a packet. Then the interrupt send bucket) PKI'H
When I8 changes to 11 levels due to the occurrence of , by closing GOl and Go2 and opening 011 and G12, the HDLC transmitter 8END1 to 10F and subsequently PKTB are transmitted, and finally 1 F is transmitted. . During this time, since the transmission clock ST is interrupted by GO1, 811M)o stops at the time when PKTM1, a part of PKTA, is transmitted. After that, after sending PKTB and 1 F, Is returns to 10 lbel, G11 and G
By closing Go I Go 12 and opening Go I Go 2, transmission of the remaining PKTA 2 is resumed from 5ENDo.

Next, an implementation example on the packet receiving side will be described with reference to FIGS. 8 and 9. In Figure 8, after 2 or more F, PK
While receiving TA1, the output signal 8GO of game) Go and game) G1. The input signal SG1 to G2 is at 10 lv;
By opening G2 and closing G2, the reception control unit RI
, 8IO receives the received packet PKTA1. After that, when PKTB is received following 1.10F, SGo changes to IQI-e'1'-e'Q level as shown in FIG. 8, and 8G1 changes to the level state.

This operation closes G1, opens G2, and RL8
In addition to stopping the reception operation of Io, the reception control unit RL
PKTB is received at 811. Furthermore, when PKTB receives F of 1 and then receives MU2, 8Go becomes 'Q'
-e'j changes to '4'0' level, 8 (h is 1
11. Changes to lQI. As a result, G1 is opened and Q is closed, thereby stopping the receiving operation of RL8 I4, and receiving RI, SIo, and M2. By the above operation, the emergency transmission packet pKTB is transferred to the normal bucket)
Priority transmission by interrupting PKTA.

It becomes possible.

The maximum packet length differs depending on the packet network, but CCIIIT Recommendation packet lengths are also considered.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a packet switching network, Fig. 2 is an explanatory diagram of packets of a conventional method, Fig. 3 is an explanatory diagram of a packet transmission/reception method according to a conventional method, and Fig. 4 is an explanation of a transmission/reception method of a packet switching method according to the present invention. Figure 5 is an explanatory diagram of a packet in the method shown in Figure 4. Figure 6 is an illustration of an interrupt control signal in the form of a transmission node in the method shown in Figure 4. FIG. 8 is a diagram illustrating the relationship between transmission packets and gate signals in the method shown in FIG. 4, and FIG. 9 is a circuit diagram of the reception control section in the method shown in FIG. 4. Fig. 6 8: Interrupt control signal Fig. 7 PKT: Transmission packet ST: Transmission clock Gol, Goz, G11. G12: Gate 8 ENDO:
Normal packet transmission control unit 8FJ'JD1: Emergency Fig. 8 SGo, SG1: Gate signal Fig. 9: Transmission clock RO, R1, R2: Shift register DCO, DCl, DC2: TE: 7-fGo, G
1, G2: Gate JKFF: JK flip-flop RL8Io: Normal packet reception control unit RLS11: Emergency PKTc: Received packet processing unit −−−１− °′°−

Claims (1)

[Claims] Occurs during packet transmission in a packet switch.
In order to give priority to packets that need to be sent urgently, K temporarily suspends the sending of the packet that is currently being sent, and after sending the packet that needs to be sent urgently, sends the packet that is currently being sent. Characteristic packet switching method.