Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1998-02-24
2003-03-25
Marcelo, Melvin (Department: 2663)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S395210, C370S395640, C370S412000
Reexamination Certificate
active
06538992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates in general to a method and system for servicing users' in an Asynchronous Transfer Mode (ATM) environment, and in particular, to a method and system for servicing users' with multilevel Quality of Service (QoS) requirements in a ATM Adaptive Layer 2 (AAL2).
2. Description of Related Art.
ATM has been selected as a world standard for broadband ISDN in network communication systems. ATM systems have been implemented on a global basis and developed in a rapid growth. ATM technology is destined to play a major role in both public and private broadband networks. AAL2 is one of the four types of AAL (ATM Adaptive Layer) protocols which have been recommended by CCITT, namely AAL1, AAL2, AAL3/4 and AAL5. In general, the layer services provided by AAL1 are constant bit rate (CBR) services which require information to be transferred between source and destination at a constant bit rate. AAL1 technology is generally designed to satisfy concurrent or near concurrent transmission, such as related to voice transmission, which requires very high transmission speed. AAL2 offers a transfer of information with a variable bit rate. In addition, timing information is transferred between source and destination. Since the source is generating a variable bit rate (VBR), it is possible that cells are not completely filled and that filling level varies from cell to cell. AAL2 technology is generally designed to satisfy a transmission of packets with variable bit rates, often with low bit rates, such as voice/video type of transmission. AAL3/4 is used for transfer of data which is sensitive to loss, but not sensitive to delay. AAL3/4 protocol may be used for connection oriented as well as for connectionless data communication. AAL3/4 itself does not perform all functions required by a connectionless service, since functions like routing and network addressing are performed on the network layer. AAL5 is designed to offer a service with less overhead and better error detection below the CPCS layer. AAL3/4 and AAL5 are often designed to satisfy a secured transmission of data packets, for example, transactions in the banking industry, or aviation industry.
In a AAL2 protocol, AAL2 Negotiation Procedure (ANP) is a ITU-T recommendation for establishing peer-to-peer AAL2 channels on a single ATM connection, which is introduced in BISDN ATM Adaptation Layer 2 specification—(Annex C Dynamic allocation of AAL type 2 channels) published as a draft new recommendation I.363.2 (Madrid, November 1996) and approved in September 1997 (hereinafter “Recommendation”).
In recent time, the need for supporting low bit rate and delay sensitive applications in a ATM environment has necessitated the ITU-T to propose a new AAL2 whereby packets less than ATM payload size can be packed efficiently and transmitted on a single ATM connection. The new AAL2 is generally targeted towards voice and telephony over ATM, where voice packets from different users can be multiplexed on a single ATM connection. In addition, the same AAL2 can be used to transport data packet (individually or with voice packets). The new AAL2 is designed to improve the efficiency of network resources, such as using less number of queues, and provide a cost-effective solution to customers.
In a traditional ATM network, a single ATM cell carries a packet from a single user. This is designed to provide a necessary QoS guarantee for each user. Further, this traditional one-ATM-cell for one-user at a time type of model is designed to control QoS parameters, such as delay, delay variation, and cell loss, at the ATM cell level. However, the traditional ATM networks and methods are not suitable for providing QoS in a AAL2 environment because a ATM cell carries packets from two or more users on a single ATM connection. A typical AAL2 environment generally provides about 256 channels (248 of which are generally available for the users and 8 of which are provided for system management). Using one level of QoS to serve multilevel users' QoS requirements for transferring different packets would cause some users to experience significant delay and/or other degradation below an acceptable level. With a rapid development of communication systems in a AAL2 environment, providing multilevel QoS to satisfy different users has become a very important issue. Some users may require a faster, less delay service, whereas other users may require a less cost but with moderate delay service. In existing AAL2 systems, even if the users require different QoSs for their transfer of packets, the packets are transferred with a pre-configured QoS without considering different QoS required by the users at a ATM cell level. As a result, various users' multilevel QoS requirements are not met. One solution to the problem is to adding more queues or ATM cells. However, this approach would waste network resources. Further, this approach does not help differentiate the cost to the users who demand a higher QoS from the cost to the users who demand a less QoS. Therefore, in existing systems, it is very difficult to meet QoS guarantee at a ATM cell level when a single ATM cell may contain packets from two or more users with different QoS requirements.
Also, during a network congestion, a ATM cell may be lost or dropped by the network. Since the existing ATM systems cannot differentiate a packet with a higher QoS requirement from a packet with a lower QoS requirement at the ATM cell level, the existing ATM systems cause both types of packets to be lost or dropped.
It can be seen that there is a need for a method and system to service multilevel QoS in a AAL2 network to meet individual QoS guarantee and reduce number of queues or ATM cells needed.
It can also be seen that there is a need for a method and system to service multilevel QoS in a AAL2 network such that different application services/users can specify different QoS requirements, e.g. delay constraints, delay variation constraints, cell loss constraints, or other QoS parameter constraints, which are supported by the AAL2 network in a cost effective manner.
It can further be seen that there is a need a method and system for supporting multilevel QoS in many communication environments, such as mobile, wireline trunking environments, data network environments including internet applications, or traditional telephony environments.
SUMMARY OF THE INVENTION
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and system for servicing users' in an Asynchronous Transfer Mode (ATM) environment, and in particular, to a method and system for servicing users' with multilevel Quality of Service (QoS) requirements in a ATM Adaptive Layer 2 (AAL2).
In general, the present invention solves the above-described problems by obtaining a QoS requirement of each user either from the user or computer based on a call request setup during a AAL2 Negotiation Procedures (ANP). The details on a ANP is described in the related patent application as mentioned above, which is incorporated herewith by reference. The obtained QoS requirements are stored or updated in a ANP memory (or memory table) along with other parameters, such as a Channel Identification (CID), a CID status, etc. After a successful negotiation in the ANP, a packet associated with the call request, such as a voice/data packet, is received by a AAL2 multilevel QoS service module. The packet's identification is checked, and the corresponding QoS requirement is obtained from the ANP memory. Based on the QoS requirement from the ANP memory, the packet is placed into a queue that matches the QoS requirement required by the user or closely matches the QoS requirement required by the user. The queues can be configured by a provisioning procedures based on the network operators pre-defined QoS offerings or adjustable based on the demand by
Dixit Sudhir
Subbiah Baranitharan
Altera Law Group LLC
Hyun Soon-Dong
Marcelo Melvin
Nokia Telecommunications Oy
LandOfFree
Adaptive scheduling method and apparatus to service... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adaptive scheduling method and apparatus to service..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adaptive scheduling method and apparatus to service... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3045301