ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification, ITU, March 1993.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of the data is left to the ATM adaptation layer, which is also responsible for breaking up messages into cell sized chunks at the sending end, and reassembling cells into messages at the receiving end. ATM adaptation layer type 5 (AAL5) was defined to support conventional data transfer over ATM [6]. The functions of AAL5 are illustrated in Figure 2. Given a message up to 64 KBytes in size, AAL5 adds an 8 byte trailer containing a 16 bit length field and a 32 bit CRC, and inserts a 7 pad field before the trailer so that the resulting packet is a multiple of 48 bytes. The packet is then ....

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification, ITU, March 1993.

....multiplexer, which help us to understand the multiplexing effect. For this analysis we used the test case (b) and (c) respectively. 5. 1 CBR Traffic Characteristics The Constant Bit Rate (CBR) services are currently seen as one of the relevant ATM applications which coexists with VBR services [8, 9]. This traffic arises e.g. from CBR video coders or circuit emulation. The generated CBR traffic can sufficiently be characterized by its peak rate. However, the original CBR traffic may get distorted as it is traveling through the network due to the interference by other traffic streams in ATM ....

ITU-T Rec. I.360., B-ISDN ATM Adaptation Layer (AAL) Functional Description,

....multiplexer, which help us to understand the multiplexing effect. For this analysis we used the test case (b) and (c) respectively. 5. 1 CBR Traffic Characteristics The Constant Bit Rate (CBR) services are currently seen as one of the relevant ATM applications which coexists with VBR services [5, 6]. This traffic arises e.g. from CBR video coders or circuit emulation. The generated CBR traffic can sufficiently be characterized by its peak rate. However, the original CBR traffic may get distorted as it is traveling through the network due to the interference by other traffic streams in ATM ....

ITU-T Rec. I.360., B-ISDN ATM Adaptation Layer (AAL) Functional Description,

....and AAL4 have been combined in AAL3 4 and a new AAL5 has been defined. AAL 1 AAL 2 AAL 3 4 AAL 5 Timing Relation Real Time Non Real Time Bit Rate Constant Variable Connection mode Connection Oriented Connectionless and Connected ConnectionOriented Table 2. 1: ATM adaptation layer main attributes [ITU I.363] As the ATM service classes, the AALs are meant to be used for different services having different requirements. AAL1 is meant for synchronous constant rate bit flows like for example circuit emulation. AAL3 4 is meant for connected and connectionless data transfer in telecommunication ....

....emulation. AAL3 4 is meant for connected and connectionless data transfer in telecommunication networks. These two AALs are not considered further. AAL2 has been developed to offer transport service for compressed data and low bit rate ( 64kbps) real time flows to use the bandwidth efficiently [ITU I.363.2] It enables packing several microcells in ATM cells. New compressing speech codecs generate small packets discontinuously, so combining many speech connections in an AAL2 VC connection saves bandwidth. AAL2 will be referred regularly in later chapters and a more specific description of it will ....

[Article contains additional citation context not shown here]

ITU-T Recommendation I.363. B-ISDN ATM adaptation layer (AAL) specification. 1993. In the world wide web: http://www.itu.int/itudoc/itut /rec/i/i363.html

....management) and the control plane. The control plane is concerned with calls and connections, processing all relevant signalling information. Signalling protocols sit within the control plane, on top of the AAL layer. As the AAL layer is service specific, the Signalling ATM Adaptation Layer (SAAL) [6] provides for the adaptation of signalling messages into the cell format required by ATM. The B ISDN protocols of the standards bodies have been developed using extensions to existing narrowband (N ISDN) protocols. In keeping with this, two protocols are defined. The ITU T define its standards as ....

ITU-T Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Geneva, Switzerland, Aug. 1994.

....PDU is found to optimize the network throughput but an additional 8 byte CS PDU trailer has to be inserted every 2 MPEG2 TS packets within the AAL5 PDU to improve the error control capability of the end systems. However, AAL5 does not have facilities for FEC and jitter control and, as defined in [6], seems to be inappropriate for real time video communications. A possible improvement is to introduce new features by means of an Audio Visual Service Specific Convergence Sublayer (AV SSCS) as those proposed in [7] and [8] Some authors have tested the effect of passing corrupted AAL5 PDU to ....

ITU-TS, 'Recommandation I.363 B-ISDN ATM Adaptation Layer (AAL) Specification', Geneva, March 1993, pp.38-57.

....Part ATS for other test purposes which are not included in this ATS, but identified in the test purpose document [8] will be developed in future. This ATS is based on the ATM Forum ATM User Network Interface (UNI) Specification, version 3.0 and 3.1 [1] 2] and the ITU T draft Recommendation I. 363 [3]. The Protocol Implementation eXtra Information for Testing (PIXIT) proforma for the test cases that are described in this document is provided in Annex A. The PIXIT questionnaire needs to be completed for a particular Implementation Under Test (IUT) prior to conformance testing. 2. Methodology ....

ITU-T Draft Recommendation I.363, Section 6 : 1993, B-ISDN ATM Adaptation Layer (AAL) Type 5.

....such as multicast or multipeer requirements [75] A.2.2 Key Issues in an ATM Signaling Scenario Signaling Protocol Architecture A necessary prerequisite for transferring signaling messages is a reliable network service. Therefore, a SAAL (Signaling ATM Adaptation Layer) based on AAL type 5 [76] has been defined in the Recommendations Q.2100 [77] Q.2110 [78] Q,2120 [79] and Q.2130 [80] e.g. Q.2931 [57] runs on top of SAAL, which in turn runs on top of the ATM layer. Different types of AAL may be used as well, e.g. SPANS [64] runs on 23 top of either AAL type 3 or type 5. Moreover, ....

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) specification. Geneva, Switzerland, 4. August 1994.

....is that ATM sends data in tiny cells with a fixed size of only 53 bytes instead of in variable size frames. While this difference is important at the lowest protocol layers, higher layers typically use larger units which are then transformed from to cells by a so called ATM adaption layer (AAL, [3]) Figure 1 shows the structure of an ATM network. The network itself consists of interconnected 1 switches. Two types of networks are distinguished: private networks are typically company or campus networks, and public networks correspond to what is offered by telephone carriers. The ....

ITU-T Recommendation I.363. B-ISDN ATM adaptation layer (AAL) specification, ITU, March 1993.

....is that ATM sends data in tiny cells with a fixed size of only 53 bytes instead of in variable size frames. While this difference is important at the lowest protocol layers, higher layers typically use larger units which are then transformed from to cells by a so called ATM adaption layer (AAL, [7]) Figure 1 shows the structure of an ATM network. The network itself consists of interconnected switches. Two types of networks are distinguished: private networks are typically company or campus networks, and public networks correspond to what is offered by telephone carriers. The ....

ITU-T Recommendation I.363. B-ISDN ATM adaptation layer (AAL) specification, ITU, 1993.

....such as multicast or multipeer requirements [22] 2.2 Key Issues in an ATM Signaling Scenario Signaling Protocol Architecture A necessary prerequisite for transferring signaling messages is a reliable network service. Therefore, a SAAL (Signaling ATM Adaptation Layer) based on AAL type 5 [23] has been defined in the Recommendations Q.2100 [24] Q.2110 [25] Q,2120 [26] and Q.2130 [27] e.g. Q.2931 [4] runs on top of SAAL, which in turn runs on top of the ATM layer. Different types of AAL may be used as well, e.g. SPANS [11] runs on top of either AAL type 3 or type 5. Moreover, the ....

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) specification. Geneva, Switzerland, 4. August 1994.

....a sender than as a receiver. There are 15 test purposes for AAL 3 4 sublayers as senders and only 6 as receivers. So, the initial motivation of our work was to analyse why such a difference in the number of test purposes. Using the service definition and the protocol specification of AAL 3 4 layer [10], we have described a new set of test purposes : 24 test purposes for AAL 3 4 sublayers as senders and 24 as receivers. This result allows us to say that the difference in the number of test purposes is not due to different complexities of the sender and receiver function definitions. The second ....

....in Appendix 2) is not supported by the conformance transverse test method. The SAR sublayer sends an Abort SAR PDU (see note 1.2, page 16) if it receives from the CPCS sublayer a SAR U Abort invoke( primitive. But the CPCS sublayer primitive CPCS U Abort invoke( is used in streaming mode only [10] (page 22) and the specification does not describe procedures of the CPCS sublayer in this mode [10] page 33) So, there is no possibility to make this sequence of pritimives AAL U Abort request( CPCS U Abort invoke( SAR U Abort request( to happen [2] 3.5 Implementation of the ....

[Article contains additional citation context not shown here]

ITU-T. B-ISDN ATM Adaptation Layer (AAL) Specification. Technical specification, ITU-T, March 1993. I.363 Recommendation.

....So, the transport of real time multimedia data has to be reliable and timely. ATM networks fulfill both conditions but, in some cases, they may fail to guarantee loss ratios. 2. 2 Current AAL Mechanisms Nowadays, two AALs are available for the transport of multimedia data: AAL1 and AAL5 [9]. AAL1 was basically designed to cover circuit emulation services. It therefore offers Constant Bit Rate (CBR) services to the applications. This may be a limitation if constant quality encoding or Variable Bit Rate (VBR) in general is used. The advantages of AAL1 are that it provides a cell level ....

ITU-T, editor, Recommendation I.363 B-ISDN ATM Adaptation Layer (AAL) Specification, ITU-T, Geneva, Mar. 1993.

....in the ATM cell header. The fixed 53 byte cell is the basic data unit processed at the ATM layer and consists of 5byte header and 48 byte payload for the user information. The ATM layer provides services necessary for cell transmission with agreed QoS guarantees. The ATM Adaptation Layer (AAL [5]) provides an interface for higher layers to access the ATM services. The AAL layer is subdivided into the Convergence Sublayer (CS) and Segmentation and Reassembly Sublayer (SAR) The AAL handles Protocol Data Units (PDUs) that could be either variable or fixed in length (different from the ....

....received MAC PDUs and passes them (i.e. SAR PDUs) up to the SAR Gamma 8 The CS sublayer for AAL3 4 and AAL5 is further divided into Common Part CS and Service Specific CS which, however, are ignored here for simplicity. 9 The maximum length of CS PDUs for AAL3 4 and AAL5 is 65,535 bytes [5]. sublayer. Note that the SAR PDUs are not reassembled into CS PDUs at the SAR Gamma sublayer to avoid the overhead introduced by segmentation reassembly segmentation upon the same CS PDU. Instead, the SAR Gamma sublayer directly forms SAR PDUs with the payload of the received SAR ....

ITU-T, Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification, 03/93.

....representing the basic transfer technology of BISDN (Broadband Integrated Services Digital Network) offers four service classes to support different types of traffic, such as voice, video, and data. There are four ATM Adaptation Layer Protocols (AAL) corresponding to these four service classes [11]. For GCP, AAL5 is appropriate to transmit control data for the group and QoS management. It is defined for connection oriented transmission with variable bit rate whereby the sender and the receiver have no time relation. Unfortunately, for multicast communication AAL5 only provides an unassured ....

....AAL5 is appropriate to transmit control data for the group and QoS management. It is defined for connection oriented transmission with variable bit rate whereby the sender and the receiver have no time relation. Unfortunately, for multicast communication AAL5 only provides an unassured service [11]. In an ATM network, the loss of ATM cells due to congestion inside the switches is a real problem. Therefore, the protocol above ATM has to care for reliable delivery, and for atomicity and ordering as well. In GCSVA, AAL5 is used both for group communication and for the transmission of ....

ITU-T Recommendation I.363: B-ISDN ATM Adaptation Layer (AAL) specification. Geneva, 1993

....employed in the WAND Demonstrator In this Figure, A PHY is used to designate the ATM Physical Layer (see also [2] The Magic WAND Deliverable 4D2: Requirements of Control Plane modules AC085 ASC DS P 052 1. 0 7 ATM for ATM Layer (see also [3] AAL for ATM Adaptation Layer (see also [4]) Appli. for any User Applications; R PHY for Radio Physical Layer; MAC for Radio Medium Access Control Layer; WDLC for Wireless Data Link Control Layer; SAAL for Signalling AAL (see also [5] SIG M for ATM signalling with mobility enhancement. The specification of the relevant reference ....

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification

....messages although very few of them. 3. 2 ATM NETWORKEMULATION In order to measure the performance experienced by a workstation cluster over an ATM network, we have considered an ATM environment consisting of five workstations connected to an ATM LAN by using the adaptation layer AAL5, defined in [13], in a native fashion, so that the protocol structure keeps as light as possible. The ATM network is implemented as an event driven simulator, and is executed on one host, while real distributed algorithms are executed on separate processes in a different host, in particular in an ALPHA based ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification (Helsinki, 1993).

....the Adaptation Layer (AAL) is concerned, two sublayers are considered, as shown in Figure 1: a service specific sublayer and a common part sublayer. The latter manages some functions required by several types of applications. The ITU T has issued several definitions for the common part sublayer [8]: AAL1 for applications exchanging data with constant bit rate and with a strict time relation; AAL2 for real time, low rate communications using variable bit rate; and AAL5 for variable bit rate data transmission without time requirements. ITU T has still another definition, the AAL3 4, intended ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Helsinki, March 1993.

....lost cells, in contrast, are discarded but not computed. Nevertheless, we have considered the delay introduced by protocol processing in order to emulate a more complex protocol structure. In all cases, the access to the ATM network is done through the adaptation layer AAL5, defined in [18], so that the protocol structure keeps as light as possible. This adaptation layer introduces little overhead, and so it is becoming widely used by the data communications community. The protocol architecture that has been considered is similar to the ATM API based configuration studied in [2] ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Helsinki, March 1993.

....which allocates resources at a per cell block basis [10] ffl The adaptation layer protocol type. An adaptation layer protocol provides additional functionality to ATM and serves to smooth the transition from the applications to ATM. Up to now, the ITU T has defined four adaptation layers types [13]: AAL1 for CBR traffic with tight time interactions, AAL2 for VBR traffic also with tight time interactions, and both AAL3 4 and AAL5 for data transfers without time relations. Users can add a specific sublayer protocol over the defined protocol types, or even define an entire adaptation layer ....

....of redundancy, where the information is partially replicated so that the receiver be able to reconstruct the data. Retransmission mechanisms are implemented by usual transport protocols, while the addition of redundancy is suggested for the FEC (Forward Error Correction) mechanisms in the AAL1 [13] and some proposals in the ATM Forum like the all purpose FEC specification in [5] In order to minimize the impact of loss recovery mechanisms on the performance of HPDC environments, the convergence layer can make use of both flow control functions and routing functions. Flow control mechanisms ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Helsinki, March 1993.

....AAL2 for VBR traffic also with tight time interactions, and both AAL3 4 and AAL5 for data transfers without time relations. Users can add a specific sublayer protocol over the defined protocol types, or even define an entire adaptation layer protocol by keeping an empty AAL as indicated in [12]. ffl The VC VP connectivity . ATM allows for a two level connection hierarchy, virtual paths and virtual channels. This feature enables the establishment of virtual networks and redundant paths. The CBR and rt VBR service categories and AAL1 and AAL2 are intended for real time applications, such ....

....of encapsulating one single HPDC PDU into each cell. Since there will be a number of unused bytes, these can be dedicated to other functions such as reliability providing via redundancy, etc. We have considered this mechanisms to run directly over ATM, without any standard AAL, as indicated in [12]. Although it could have been possible to implement the mechanism over AAL5, we envision that the simplicity of our proposal will enable efficient implementations in hardware where a standard AAL would introduce redundant overhead. The highest efficiency of our mechanism will be possible with ....

ITU-T, Recommendation I.362. B-ISDN ATM Adaptation Layer (AAL) Functional Description. Helsinki, March 1993.

....designed to support connectionless applications. As shown in Figure 1, the AAL3 4 SAR PDU contains a multiplexing identification (MID) and some other fields. These fields provide the multiplexing capability which permits several applications to share a common ATM connection. As shown in Figure 2 [6], the AAL3 4 Service Access Point (SAP) is provided at the AAL interface for the AAL3 4 service access. Each AAL3 4 SAP has its own MID value assigned by the AAL layer. The data from different AAL3 4 SAPs may be interleaved to a common ATM connection at the sender side which will be demultiplexed ....

....of an ATM cell [1] Therefore, 1] suggested to multiplex the information from different mobiles into an ATM cell. B.1 Multiplexing structure A simple way to do share an ATM cell is to divide the payload of an ATM cell into multiple equal length segments. The existing format of the AAL3 4 SAR PDU [6] can be used directly for such multiplexing without modification. As shown in Figure 1, the ST of SAR PDU identifies four types of segments for connectionless messages: BOM, COM, EOM and SSM. The first three segment types along with the SN are used for transmission of long messages which have to ....

ITU-T, Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification

....sequence numbering field of SSCOP can be insufficient. In addition, due to the short length of messages, the 32 bit CRC field of AAL5 is adequate for multiple cell CPCS PDUs [17] but one cell CPCS PDUs do not require such a powerful CRC, so a CRC similar to the 10 bit CRC per AAL3 4 SAR PDU [18] should be sufficient. Figure 2 shows the format of an SD frame. The message tag field corresponds to the tag of a library PDU 2 . The offset field indicates the position of a particular HPDC PDU in the library PDU corresponding to the message tag. The STAT frames can also be adapted to this ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Helsinki, March 1993.

....which allocates resources at a per cell block basis [10] ffl The adaptation layer protocol type. An adaptation layer protocol provides additional functionality to ATM and serves to smooth the transition from the applications to ATM. Up to now, the ITU T has defined four adaptation layers types [13]: AAL1 for CBR traffic with tight time interactions, AAL2 for VBR traffic also with tight time interactions, and both AAL3 4 and AAL5 for data transfers without time relations. Users can add a specific sublayer protocol over the defined protocol types, or even define an entire adaptation layer ....

....of redundancy, where the information is partially replicated so that the receiver be able to reconstruct the data. Retransmission mechanisms are implemented by usual transport protocols, while the addition of redundancy is suggested for the FEC (Forward Error Correction) mechanisms in the AAL1 [13] and some proposals in the ATM Forum like the all purpose FEC specification in [5] In order to minimize the impact of loss recovery mechanisms on the performance of HPDC environments, the convergence layer can make use of both flow control functions and routing functions. Flow control mechanisms ....

ITU-T, Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification. Helsinki, March 1993.

....AAL2 for VBR traffic also with tight time interactions, and both AAL3 4 and AAL5 for data transfers without time relations. Users can add a specific sublayer protocol over the defined protocol types, or even define an entire adaptation layer protocolby keeping an empty AAL as indicated in [12]. ffl The VC VP connectivity. ATM allows for a two level connection hierarchy, virtual paths and virtual channels. This feature enables the establishment of virtual networks and redundant paths. The CBR and rt VBR service categories and AAL1 and AAL2 are intended for real time applications, ....

....of encapsulating one single HPDC PDU into each cell. Since there will be a number of unused bytes, these can be dedicated to other functions such as reliabilityproviding via redundancy, etc. We have considered this mechanisms to run directly over ATM, without any standard AAL, as indicated in [12]. Although it could have been possible to implement the mechanism over AAL5, we envision that the simplicity of our proposal will enable efficient implementations in hardware where a standard AAL would introduce redundant overhead. The highest efficiency of our mechanism will be possible with the ....

ITU-T, Recommendation I.362. B-ISDN ATM Adaptation Layer (AAL) Functional Description. Helsinki, March 1993.

....relation between source and destination (e.g: connection oriented data transfer) ffl Class D: Variable bit rate connectionless services with no timing relation between source and destination (e. g: LAN data traffic) Correspondingly, five types of the ATM Adaptation Layer functions are defined [24]: ffl AAL type 1: for supporting Class A, ffl AAL type 2: for supporting Class B, ffl AAL type 3: for supporting Class C, ffl AAL type 4: for supporting Class D, ffl AAL type 5: for supporting Class D 2 . The integration of various telecommunication services and the goal to use resources of ....

ITU-T Recommendation I.363. B-ISDN ATM Adaptation Layer (AAL) Specification, 1992. Geneve, Switzerland.

....into ATM cells. Cells received by the AAL functions from the ATM Layer are reassembled to form the information [36] 5 ITU T has classified four B ISDN service classes provided by AAL functions and five AAL types. The B ISDN services can belong to one of the four service classes as follows [23]: ffl Class A: Constant bit rate connection oriented services with a timing relation between source and destination. The two typical services of this class are 64 Kbps voice and constant bit rate video. ffl Class B: Variable bit rate connection oriented services with a timing relation between ....

ITU-T Recommendation I.362. B-ISDN ATM Adaptation Layer (AAL) Functional Description, 1992. Geneve, Switzerland.

....Layer (SAAL) 4] comes from all of the actions at each sublayer. Consequently, the delay caused by each sublayer will be examined more closely. The Signaling ATM Adaptation Layer (SAAL) consists of two groupings, the Service Specific Convergence Sublayer (SSCS) and the Common Part (CP) AAL [5]. Each of these two groupings is further subdivided. The SSCS consists of the Service Specific Coordination Function (SSCF) and the Service Specific Connection Oriented Protocol (SSCOP) The CP AAL consists of a Segmentation And Reassembly (SAR) and Convergence Sublayer (CS) sublayer. The detailed ....

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification Section 6, 1993.

No context found.

ITU-T, B-ISDN ATM Adaptation Layer (AAL) Specification

No context found.

ITU-T I.363.56, B-ISDN ATM Adaptation Layer (AAL) Specification, Type 5

No context found.

ITU-T I.363 (1993) B-ISDN ATM Adaptation Layer (AAL) Specification

No context found.

ITU-T I.362 (1993) B-ISDN ATM Adaptation Layer (AAL) Functional Description

No context found.

ITU-T Recommendation I.363, B-ISDN ATM Adaptation Layer (AAL) Specification, Section 6 (AAL5).

No context found.

ITU-T I.363 B-ISDN ATM Adaptation Layer(AAL) Specification, Section 6 (AAL5).

No context found.

ITU-T I.363 B-ISDN ATM Adaptation Layer(AAL) Specification, Section 6 (AAL5).

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC