Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-03-13
2004-04-13
Cangialosi, Salvatore (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395610
Reexamination Certificate
active
06721326
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ATM network and in particular multiplexing system for multiplexing cells with small delay.
BACKGROUND OF THE INVENTION
ATM (Asynchronous Transfer Mode) is expected as a communication technology for realizing multimedia services. Equipment using this technology has been developed for high-speed data communication including computer-to-computer communication.
In recent communication market, a network using ATM is desired which can interwork (communicate mutually) with communication protocols such as HDLC and Frame Relay as well as voice signals.
A standard ATM cell is transmitted using a fixed-length cell composed of 53 bytes, including a payload of 48 bytes. However, there is a problem that HDLC terminals connected to low speed lines of, for example, 1,200 bits per second (bps) to 9,600 bps which require short response time may not be handled properly when using the standard ATM cell.
In more detail, an example of delay time is calculated as follows.
When a payload of 48 bytes in a cell is fully packed by assembled data from a terminal having the speed of 2,400 bps,
delay time=48/(1200/8)=0.32 second=320 milliseconds
Therefore, time consumed from the transmission of data at a terminal to the reception of its response will be,
320×2+&agr;=640+&agr;≈700 milliseconds
where, &agr; is processing time consumed in the terminal.
This may exceed an acceptable response time for a HDLC terminal which is generally regarded as 300 milliseconds (ms) to 500 ms.
In order to shorten delay time produced in cell assembling, it may be possible to apply a method in which cell assembling is completed before the payload of 48 bytes is fully packed. According to this method, however, a large amount of dummy data has to be transmitted which results in reduced transmission efficiency.
Small delay transmission may also be attained using AAL
2
which was recently discussed in the ATM Forum. In this method, however, there is also a problem of low transmission efficiency because a header having three bytes is specified in AAL
2
. Furthermore, a short packet used in AAL
2
has variable length. This raises such problems as requiring complicated cell multiplexing process which requires to implement a large amount of mechanism to be implemented in the equipment.
On the other hand, there is a known technology that a plurality of short cells are multiplexed into a standard ATM cell after generating the short cell. In this method there is also a problem that a generation timing of a standard ATM cell may be drifted in case that short cell generation timings are different line by line.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a multiplexing equipment in an ATM network which attains to small delay and high transmission efficiency due to small deviation in the timing duration of standard ATM cell generation.
According to the present invention, a basic concept of multiplexing equipment in an ATM network to solve the aforementioned problems is to adjust a reception completion timing to be determined at the start of receiving processing on a terminal line in order to adjust a short cell generation timing.
Preferably, in the present invention, selection of a reference line to determine a receiving timing is performed in the following way.
When there exists no line which has already been in a receiving state, any line is selected as a reference line, on which receiving operation is performed at a timing predetermined to that line.
On the other hand, when there exists a line (or lines) which has already been in receiving state, it is checked whether a line (or lines) is in receiving operation under the same timing. If there exists a line which is in receiving operation under the same timing, the line is selected as a reference line. On the other hand, if there is no line having the same timing, a line having the latest timing is selected as a reference line.
Also, preferably it is checked with regard to a terminal line whether the amount of data which has already been received from the line is larger than that received from a reference line. If the received data is more than that of the reference line, the data already received is discarded, and interruption caused by data reception on the terminal line is made possible.
Furthermore, preferably the length of multiplexed effective data in a short cell is informed to equipment connected on the opposite side via a route other than that used for transmitting standard ATM cells.
In addition, preferably an effective data length per terminal is specified in advance and stored in ATM switching equipment, and is read out at the time when a line is activated for receiving data.
REFERENCES:
patent: 5742610 (1998-04-01), Natarajan
patent: 5802051 (1998-09-01), Petersen et al.
patent: 5822321 (1998-10-01), Petersen et al.
patent: 5946309 (1999-08-01), Westberg et al.
patent: 6289016 (2001-09-01), Subbiah et al.
patent: 6341131 (2002-01-01), Eneroth et al.
patent: 6434151 (2002-08-01), Caves et al.
patent: 6574223 (2003-06-01), Brueckheimer et al.
patent: 6597697 (2003-07-01), Petersen
patent: 63-197148 (1988-08-01), None
patent: 4-157843 (1992-05-01), None
patent: 5-103016 (1993-04-01), None
patent: 7-162437 (1995-06-01), None
patent: 7-202895 (1995-08-01), None
patent: 7-245628 (1995-09-01), None
patent: 7-336354 (1995-12-01), None
patent: 10-70557 (1998-03-01), None
patent: 10-173673 (1998-06-01), None
patent: 97/33406 (1997-09-01), None
Cangialosi Salvatore
Katten Muchin Zavis & Rosenman
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