ATM cell multiplexing system

Details ATM cell multiplexing system ATM cell multiplexing system

1998-06-05

2001-05-15

Olms, Douglas (Department: 2661)

Multiplex communications

Communication techniques for information carried in plural...

Combining or distributing information via time channels

C370S395430

Reexamination Certificate

active

06233258

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multiplexing method and equipment for the multicast communication (selectively simultaneous communication) in ATM(Asynchronous Transfer Mode) communication.
2. Description of the Prior Art
There is known a multicast connection as one of the techniques supporting the multicast communication in ATM communication. In the point to multi point connection, among them, ATM cells from different transmitting nodes toward one receiving node are multiplexed into one UNI (User Network Interface) when transmitted. In this case, it is necessary that, at the receiving node, the ATM cells with the same VPI/JVCI (Virtual Pass Identity/Virtual Channel Identity) addresses be identified for each receiving node and be re-combined into a packet of (ATM Adaptation Layer).
Hitherto, the above mentioned identification was implemented by by using MID (Multiplexing Identification) field of AAL
3
/
4
, as shown in ITU-T 1.363.
The ATM cell format of AAL
3
/
4
is shown in FIG.
7
. As shown in (a) of
FIG. 7
, the ATM cell of AAL
3
/
4
has
10
bit MID field
71
for multiplexing. When the value of this field is set so as to be different for each receiving node, multiplexed ATM cells can be identified at the receiving node.
As shown in
FIG. 7
, comparing the ATM cell of AAL
3
/
4
with the ATM cell of AAL
5
as recommended by ITU-T, the payload
73
of ATM cell of AAL
5
is 48 octet payload, while that of AAL
3
/
4
is 44 octet and therefore, has greater overhead than AAL
5
. Accordingly, the communication by using the ATM cell of AAL
3
/
4
is less efficient than AAL
5
. Furthermore, the ATM cell of AAL
3
/
4
is costly and complex in management, because AAL
3
/
4
has 5 functional fields including MID field
71
in addition to the cell header.
On the other hand, when more efficient AAL
5
, instead of AAL
3
/
4
, is employed for multiplexing, there is the disadvantage that the multiplexed cells per se can not be distinguished at receiving node, because AAL
5
has not any identification field corresponding to the MID field of AAL
3
/
4
for multiplexing.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to identify cells at receiving node, by using AAL
5
in cell multiplexing for multicast communication, by using AAL
5
.
Another object of the present invention is to improve efficiency and performance of ATM multicast communication, by constructing a multiplexing system, wherein the received cells can be identified at receiving port by using AAL
5
which is more efficient than AAL
3
/
4
.
In accordance with the present invention, there is provided an ATM cell multiplexing system, which comprises ATM cell multiplexing means for inserting the ATM cells that have past record information or route information, as routing cell, when multiplexing said ATM cells inputted at different plural ports, and separation means for receiving said ATM cells, detecting routing cells from said ATM cells, separating said ATM cells on the basis of the information of said routing cells.
Further, in accordance with the present invention, there is provided a method of ATM communication wherein packets are transmitted as cells, which comprises the step of inserting routing cell to identify multiplexed ATM cells in receiving node, when multiplexing said ATM cells inputted at different plural ports.
As a result of inserting RC (Routing Cell), the present invention can improve the efficiency and the performance of ATM multicast communication, by implementing a multiplexing system such that the received cells can be identified at receiving node, by using AAL
5
which is more efficient than usual AAL
3
/
4
.


REFERENCES:
patent: 5974045 (1999-10-01), Ohkura et al.
patent: 6021135 (2000-02-01), Ishihara et al.
patent: 6034954 (2000-03-01), Takase et al.
patent: 1-175431 (1989-07-01), None
patent: 2-67848 (1990-03-01), None
patent: 8-223217 (1996-08-01), None
English translation of Japanese Office Action dated Feb. 8, Hei 11.
“Recommendation I.363,” pp. 1-22, Mar. 1993.

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