Method of routing ATM cell in ATM network

Details Method of routing ATM cell in ATM network Method of routing ATM cell in ATM network

1999-09-03

2003-07-15

Kizou, Hassan (Department: 2662)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S389000, C370S386000

Reexamination Certificate

active

06594266

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of routing an ATM cell in an ATM network, and more particularly, to a method of routing an ATM cell and a structure of an ATM adaptation layer in an ATM network in which data based on an AAL-Type2 (ATM Adaptation Layer Type2) and an AAL-Type5 (ATM Adaptation Layer Type5) is transferred to the same destination.
2. Discussion of Related Art
In general, the most basic function in a communication network is to select a desired party among a large number of subscribers, connect circuits and freely exchange necessary information.
The ATM switching system among switching systems develops a packet switching principle and simply processes a packet in the midst of a transmission so as to gain a highly speedy operation similar to that in a circuit switching system. The ATM switching system may exchange various information signals having several kinds of natures freely, efficiently, thus this system is very useful for the next generation communication system based on future multimedia information. This ATM switching system can be applied to a desired wired section between a base station and an exchange station, or between the exchange station and a controller.
A protocol stack of individual network elements constructing the ATM network, for example, a base station, an exchange station, etc., is generally composed of an ATM layer, an ATM adaptation layer positioned over the ATM layer, and a user application layer positioned over the ATM adaptation layer. Among them the ATM adaptation layer is classified into an AAL Type1 through an AAL-Type5 according to an object and a characteristic of a user application and a kind of a service class, wherein the AAL-Type2 through the AAL-Type5 are mainly used in a mobile radio communication system.
In the AAL (ATM Adaptation Layer)-Type2, one ATM cell can be multiplexized, therefore can provide a band for the sake of an efficient transmission of a low-rate, short and variable length packet in the user application sensitive to a delay. That is, the AAL-Type2 requires a real time process and is utilized to process sound or image data based on a small quantity of data.
Meantime, the AAL-Type5 improves a service provided by the ATM layer in order to support a function required by its next higher rank layer. The AAL-Type5 performs a function required by a user and a controlling and managing plane, and supplies a mapping between the ATM layer and its next higher rank layer. Thus the AAL-Type5 is used to process connection oriented/connectionless higher rank application user data, e.g., a packet or an IP service, of non-real time and variable length.
The AAL-Type2 and the AAL-Type5 are described referring to the recommendation, I.363.2 and I.363.5 of Telecommunication Standardization Sector of ITU (ITU-T) provided in International Telecommunication Union, as follows.
FIG. 1
represents a protocol stack for the AAL-Type2 based on the ITU-T recommendation. With reference to
FIG. 1
, the protocol stack of AAL-Type2 based on the ITU-T recommendation is made up of an ATM layer
100
, an ATM adaptation layer
200
formed at a higher rank than the ATM layer
100
and subdivided into a common part sublayer (CPS) and a service specific convergence sublayer (SSCS), and a user application layer
300
positioned at a higher rank than the ATM adaptation layer
200
. Herewith, AAL-Type2 negotiation procedures (ANP) provides a channel identifier (CID) for individual mini cells which construct one ATM cell.
First, described is in the following a case that data is transferred from the user application layer
300
to the ATM layer
100
through the ATM adaptation layer
200
. The data outputted from the user application layer
300
is transferred to the SSCS through an AAL-SAP (Service Access point)
60
. The SSCS performs a call linkage operation to the user application layer
300
, and transfers the received data to the Common Part Sublayer CPS. The CPS turns the data received from the SSCS into a common part sublayer protocol data unit (CPS-PDU) having a
48
octet type according to a service class as shown in
FIG. 1
, and transfers it to the ATM layer
100
through an ATM-SAP
13
. This CPS-PDU is constructed by a start field
20
containing start information of a field every an ATM cell and by numerous mini cells
30
through
50
which are respectively composed of each of mini cell headers
31
,
41
,
51
and each of transmission data
32
,
42
,
52
. Then, each multiplexized mini cell
30
-
50
is transferred to a service terminating point desired by a user through one ATM layer connection having one virtual channel identification/virtual path identification value.
Next, operations on the AAL-Type2 are described for a case that the ATM layer
100
receives data in an ATM cell type, as follows. When the ATM layer
100
receives the ATM cell
10
, it is transferred to the ATM adaptation layer
200
through the ATM-SAP
13
. The CPS analyzes the start field
20
of the received ATM cell
10
and contents of the headers
31
,
41
,
51
of each mini cell
30
-
50
, and transfers it to the SSCS. The SSCS each transfers the respective user data
32
,
42
,
52
to a corresponding user application layer through the AAL-SAP
60
according to the header
31
,
41
,
51
of the mini cell
30
-
50
.
FIG. 2
indicates a protocol stack for the AAL-Type5 based on the ITU-T recommendation. In
FIG. 2
, the protocol stack of AAL-Type5 based on the ITU-T recommendation is made up of the ATM layer
100
, the ATM adaptation layer
200
formed at a higher rank than the ATM layer
100
and subdivided into a convergence sublayer (CS) and a segmentation and reassembly sublayer (SAR), and the user application layer
300
positioned at a higher rank than the ATM adaptation layer
200
.
As shown in
FIG. 2
, one ATM layer is suitable to the structure for servicing one kind of data which mainly means packet data. Therefore, the AAL-Type5 does not have a multiplexing operation for connecting several factors since the mini cells are not used in the inside thereof.
In the following described is a case that data is transferred from the user application layer
300
to the ATM layer
100
through the ATM adaptation layer
200
. The data outputted from the user application layer
300
is provided to the CS through the AAL-SAP
60
. The CS performs a mapping for the data into a conversions sublayer protocol data unit (CS-PDU) of a 48xn octet type as shown in
FIG. 2
, and transfers it to the SAR, wherein n is an integer. The SAR subdivides the received data by the 48 octet type, and transfers the subdivided data to the ATM layer
100
through the ATM-SAP
13
.
Also, operations for the AAL-Type2 are described as follows, in a case that the ATM layer
100
receives the data in an ATM cell type. When the ATM layer
100
receives the ATM cell
10
, the data is transferred to the SAR of the ATM adaptation layer
200
through the ATM-SAP
13
. The SAR re-combines the received data by the octet type of 48xn and provides the combined data to the user application layer
300
through the AAL-SAP
60
, wherein n represents an integer. Herein, a PAD (Packet Assembly and Disassembly) & trailer
40
provides each of a PAD field and a trailer field, the PAD field indicating an octet presented so that an overall payload becomes a multiple of 48xn in an ending part of a payload
30
, the trailer field representing a common part indicator, length and CRC.
However, the ATM adaptation layer of respective elements equipped in such conventional ATM network is provided as only one kind of ATM adaptation layer determined previously in an aspect of a hardware. In other words, each ATM network element is supported in hardware so as to transmit and receive only a characteristic of its own dealing information, an object of a communication, and specific data matched with a service class.
The ATM adaptation layers over two kinds may be, of course, determined in one ATM network element, but in this case, the construction of the ATM network elemen

Affiliated with

Also associated with

Rating

Method of routing ATM cell in ATM network does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of routing ATM cell in ATM network, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of routing ATM cell in ATM network will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3053473