JPH03270440A - Synchronous time setting system for packet multiplexer - Google Patents

Abstract

PURPOSE:To exactly set time for synchronizing another station device by sending a signal for counting propagation delay time and a signal corresponding to the counted delay time to the other station device while adding those signals to a frame (UI frame) for which the arrival of data is not confirmed. CONSTITUTION:The signal for counting the propagation delay time and the signal corresponding to the counted delay time are sent from a line control part 4a in the packet multiplexer of a present station to a line control part 3b in the packet multiplexer of the other station by the frame (UI frame) for which the arrival of data is not confirmed. Therefore, no time for waiting the transmission of a packet remains in order to confirm the arrival of data. Thus, the propagation delay time and the fluctuation of the time can be reduced and the time for synchronization can be exactly set.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a synchronized time setting method for a high-speed packet multiplexing device that packet-multiplexes and communicates multimedia such as audio data and image data. In particular, it is characterized by measuring the propagation delay time of packets with respect to other stations and setting the time for synchronization.
This invention relates to a synchronization time setting method for a packet multiplexer.

[Prior Art] FIG. 2 is a block diagram showing a conventional packet multiplexing apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 176239/1983. In this FIG. 2, (1) is a packet multiplexing device;
(2) is a system management unit that controls the entire packet multiplexing device; (3) is a timer part that is located within this system management unit (2) and measures the propagation delay time of packets to other stations;
(4> is the signal output from this timer part (3),
(5) is a system bus that interconnects the various means in the packet multiplexer (1) , (6) is a line through which signals output from the line control section (4) are propagated.

FIG. 3 is a sequence diagram for explaining the operation of the apparatus shown in FIG. 2. In this Figure 3, (20) is
A signal (delay measurement command) from the packet multiplexer (1a) of the own station to the packet multiplexer (1b) of the other station to notify the start of measurement of the packet propagation delay time.
30) is a signal (delay measurement response) that notifies the packet multiplexer (1a) of the own station that the packet multiplexer (1b) of another station has received the delay measurement command (20>), (40) is the above delay measurement command (2
0) and the delay measurement response (30) in the timer part (3a) of the packet multiplexer f(la) of the own station, and the packet multiplexer of the own station is calculated from the packet multiplexer of the other station. This is a signal (timer set command) that sets the time to synchronize with the device.

FIG. 4 is a time chart diagram for explaining the operation of setting the time of another station device in the conventional example.

The operation of measuring the packet propagation delay time from the packet multiplexing device (1a) of the own station to the packet multiplexing device (1b) of another station will be explained below with reference to FIGS. 2 to 4 as appropriate. do.

First, the timer part (3a) in the system management unit (2a) of the packet multiplexer (la) of the own station holds the current time t1 (step 1), and measures the propagation delay time of the packet. A signal (delay measurement command) (20) informing the start is output from the timer part (3&) to the line control unit (4a) (step 2). This delay measurement command (20>) is sent to the line control unit (Frame (■ frame) in which data delivery is confirmed in 4a>
It is added to the packet multiplexed signal f (lb) of another station and sent out.

When the packet multiplexer W (lb) of another station receives a packet sent from the packet multiplexer (1a) of the local station, a signal indicating this (delay measurement response) (3
0) is output from the timer section (3b) in the system management section (2b) of the packet multiplexer (1b) of the other station to the line control section (4b). This delay measurement response (30) is added to the I frame in the line control unit (4b) and sent to the packet multiplexer ff(la) of the local station.

Delay measurement response (30) was received (step 3)
) The system management unit (2a) of the packet multiplexing unit W(la) of its own station retains the received time t.
p4), this time t, and the delay measurement command described above (2
Time difference (tz t+) from time t when outputting 0)
is calculated (step 5). Furthermore, the outward propagation delay time ts = [(jz t+)/2] is calculated, and the time t calculated from this outward propagation delay time t and the current time t, = [t-(t2-tl) /2] is the timer set command (40>), and the line control unit (40>
In a), it is added to the ■ frame and sent to the packet multiplexer (1b) of another station (step 6
).

The packet multiplexer (1b) of the other station that has received the timer set command (40) t4 sets a time synchronized with the packet multiplexer (la) of its own station according to this timer set command <40) t. Ru.

The line control units (4a) and (4b) transmit data 31! Time td, and tdx respectively for confirmation
Since the transmission of packets is waited for, the round-trip propagation delay time (t2-t+) described above is
d, and td2 included 6 hours 1, and t2
varies depending on how crowded the data is, so the time difference (
t2-t,) is the average value of the values measured several times.

[Problems to be Solved by the Invention] In a conventional packet multiplexing device, a delay measurement command, a delay measurement response, and a timer set command are added to a frame (I frame) in which data delivery is confirmed in a line control unit. Therefore, depending on the data congestion, the waiting time until the packet is sent from the line control unit may be long, and the time may fluctuate widely, so it is important to set the time accurately to synchronize other station equipment. The problem was that it was difficult to do so.

This invention was made in order to solve the problem as described in -h-, and the delay measurement command, delay measurement response, and timer set command are sent to a line control unit for a frame (for which data delivery is not confirmed). U
By adding it to an I frame and transmitting it, it eliminates the packet transmission waiting time spent for confirmation, reduces the propagation delay time and its fluctuation, and makes the time setting for synchronizing other station devices more accurate. The purpose of this invention is to obtain a synchronized time setting method for a packet multiplexer that can perform the following steps.

[Means for Solving the Problems] A synchronization time setting method for a packet multiplexing device according to the present invention includes: measuring a propagation delay time of a packet with respect to another station device; and measuring the propagation delay time. The present invention is characterized in that a signal corresponding to the signal and the measured propagation delay time is added to a frame (UI frame) in which delivery of data is not confirmed and is transmitted toward another station device.

[Operation] In the present invention, a signal for measuring propagation delay time and a signal corresponding to the measured propagation delay time are sent to another station device in a frame (UI frame) in which data delivery is not confirmed. Therefore, there is no time to wait for the transmission of packets to be acknowledged for data delivery, the propagation delay time and its fluctuations can be reduced, and the time for synchronization can be set accurately.

[Embodiment] FIG. 1 is a sequence diagram for explaining the operation of setting the time of another station device in an embodiment of the present invention. Incidentally, in the embodiment of the present invention, t of the packet multiplexing device
The M precept itself is the same as that of the conventional example described above.

Hereinafter, based on the sequence diagram shown in FIG. 1 and the block diagram shown in FIG. The operation will be explained.

First, a timer part (3a) in the system management section (2a) of the packet multiplexing device (1m) of the local station holds the current time t1, and a signal (delay The delay measurement command (20) is output from the timer part (3a) to the line control part (4a) (step a).
> is added to a frame (UI frame) for which packet delivery is not confirmed in the line control unit (4a), and is sent out to the packet multiplexing bag W (Ib) of another station (step b).

When the packet multiplexer (lb) of another station receives the delay measurement command (20) sent from the packet multiplexer 11E (Ia) of its own station, a signal (delay measurement response> (30)) notifying the same is sent. , this delay measurement response is output (step c) from the timer part (3b) in the system management unit (2b) of the packet multiplexing bag f (lb) of the other station to the line control unit (4b). (3
0) is added to the UI frame in the line control unit (4b) and sent to the packet multiplexer 1Ff<la) of the local station (step d).

When the packet multiplexing device (la) of the own station receives the delay measurement response (30) (step e), the timer part (of the packet multiplexing bag ff(la) of the own station) is
3a>, the time 1 when the packet was sent. The time difference (t, z tl) is calculated from the received time t,
Furthermore, the outward propagation delay time ts = [(t2-t,)
/21 is calculated (step f), and the time t4- calculated from this outward propagation delay time t and the current time t.
ft-(tz-t,)/2] is input to the line control unit (4a) as a timer set command (40), where it is added to the UI frame and then sent to the other station's packet multiplexing bag W (Ib). (stepg).

Packet multiplexing bag of another station that received the timer set command (40)! (lb), the time synchronized with the packet multiplexing bag W(la) of the local station is set according to the timer set command (40) t4 written -h (st
ep h).

By using the UI frame in this way, the forward propagation delay time t is reduced by the line controller (4m).

It is reduced by the transmission waiting time in (4b).

Note that the UI frame may be discarded within the network, so if the delay measurement response (30) is not returned within a certain period of time, it is necessary to send the delay measurement command (20) again.

[Effects of the Invention] As explained above, according to the present invention, a signal for measuring propagation delay time and a signal corresponding to the measured delay time are sent to a frame (U
1 frame) and is sent to the other station, there is no time to wait for the packet to be sent for confirmation, and it is possible to reduce the propagation delay time and its fluctuations. This has the effect of making it possible to accurately set the time for synchronizing the devices.

[Brief explanation of drawings]

FIG. 1 is a sequence diagram for explaining the operation of setting the time of another station device in an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional packet multiplexing device, and FIG. In the example, FIG. 4 is a sequence diagram for explaining the operation of setting the time of the other station apparatus, and FIG. 4 is a time chart diagram for explaining the operation of setting the time of the other station apparatus in the conventional example. In the figure, (1> is the packet multiplexing device, (2> is the system management section, (3> is the timer part, (4) is the line control section, (5> is the system bus, (6> is the line, Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] A terminal line support unit that accommodates a data terminal, an audio terminal, and an image terminal; A relay line support unit that transmits or receives packets from the terminal line support unit via a relay line; and A synchronization time setting method for a packet multiplexing device, comprising: a system management unit that controls and manages each of the above corresponding units; and: measuring a propagation delay time of a packet to another station device; and Packet multiplexing characterized by: adding a signal for measuring time and a signal corresponding to the measured propagation delay time to a UI frame in which delivery of data is not confirmed and transmitting the same to the other station device; A synchronized time setting method for devices.