Connection Management Access Protocol (CMAP) Specification

This document specifies a Connection Management Access Protocol (CMAP) for managing multipoint connectinos in high-speed packet switched networks. We target CMAP to networks employing the Asynchronous Transfer Mode (ATM) communication standard. We define a multipoint connection as a communication channel between two or more clients of the network, where all data sent by one client is received by all other clients who have elected to receive. A point-to-point connection is a special case of a multipoint connection involving only two clients. CMAP specifies the access procedures exercised by clients to create, modify and delete multipoint connections. once a connection is established, clients exchange data using protocols that are specified separately from CMAP. To establish a multipoint connection, a client first creates a call between itself and the network. The client creating a call is designated the owner of the call. Additional endpoints are added either by invitation from the owner, invitation from another client of the network, or by explicitely requesting to be added. These three modes are sufficient for supporting point-to-point communication (for example, a telephone call), many-to-many communication (for example, a conference call or data exchange), one-to-many communication (for example, broadcast video), and many-to0one communication (for example, distributed data collection)

Semantics of optimistic computation

The derivation of a semantically equivalent optimistic computation from a pessimistic computation by application-independent transformations is discussed. Computations are modeled by program dependence graphs (PDGS). The semantics of a computation is defined by a mapping from an initial state to a final state and is realized by a graph rewriting system. Semantics-preserving transformations are applied to PDGS of the pessimistic computation to produce an optimistic version. The transformations result from guessing data values and control flow decisions in the computation. The transformations are used to derive an optimistic version of fault tolerance based on message logging and checkpointing. The transformations yield an optimistic version similar to optimistic fault-tolerance algorithms reported in the literature, although additional application-dependent transformations are necessary to produce a realistic optimistic implementatio

Performance of Optimistic Make

Optimistic make is a version of make that executes the commands necessary to bring targets up-to-date prior to the time the user types a make request. Side effects of these optimistic computations (such as file or screen updates) are concealed until the make request is issued. If the inputs read by the optimistic computations are identical to the inputs the computation would read at the time the make request is issued, the results of the optimistic computations are used immediately, resulting in improved response time. Otherwise, the necessary computations are reexecuted. We have implemented optimistic make in the V-System on a collection of SUN-3 workstations. Statistics collected from this implementation are used to synthesize a workload for a discrete-event simulation and to validate its results. The simulation shows a speedup distribution over pessimistic make with a median of 1.72 and a mean of 8.28. The speedup distribution is strongly dependent on the ratio between the target out-of-date times and the command execution times. In particular, with faster machines the median of the speedup distribution grows to 5.1, and then decreases again. The extra machine resources used by optimistic make are well within the limit of available resources, given the large idle times observed in many workstation environment

A B-ISDN Object-Oriented Call Model

An object-oriented call model for broadband communications is presented. This model brings together and encapsulates call, connection and endpoint attributes in an object containment hierarchy. The object hierarchy helps to identify and clarify control and signalling requirements needed for the support of the services being developed in the ANSI T1S1.5 and the CCITT XI/4-3 broadband working groups. To expedite the development of broadband control/signalling software, this contribution proposes that the ANSI T1S1.5 Broadband Network and Services SWG investigate: 1) the benefits of an object-oriented Control Information Base (CIB) containing a set of call control objects, and 2) the standardization of an object-oriented call model and its associated objects. ****************************************************************************** DATE: May 11--15, 1992 ****************************************************************************** DISTRIBUTION TO: T1S1.5 Technical Subcommittee Wor..

Semantics of Optimistic Computation

We address the issue of deriving a semantically equivalent optimistic computation from a pessimistic computation by application-independent transformations. Computations are modeled by program dependence graphs (pdgs). The semantics of a computation is defined by a mapping from an initial state to a final state, and is realized by a graph rewriting system. Semanticspreserving transformations are applied to the pdgs of the pessimistic computation to produce an optimistic version. The transformations result from guessing data values and control flow decisions in the computation. We use our transformations to derive an optimistic version of fault tolerance based on message logging and checkpointing. The transformations yield an optimistic version similar to optimistic fault tolerance algorithms reported in the literature, although additional application-dependent transformations are necessary to produce a realistic optimistic implementation. 1 Introduction Optimistic computations use gu..

Multipoint Connection Management In High Speed Networks

We describe our Connection Management Access Protocol (CMAP) for managing multipoint connections in highspeed packet switched networks. A multipoint connection is a communication channel between two or more clients of the network, where all data sent by one client is received by all other clients. A point-to-point connection is a special case of a multipoint connection involving only two clients. CMAP specifies the access procedures exercised by clients to create, manipulate, and delete multipoint connections. Once a connection is established, clients exchange data using protocols that are specified separately from CMAP. We target our protocol to Broadband Integrated Services Digital Networks (BISDNs) employing the Asynchronous Transfer Mode (ATM) communication standard. To establish a multipoint connection, a client first creates a call between itself and the network. The client creating a call is designated the owner of the call. Immediately after creation, the owner is the only en..

A Call Model For Multipoint Communication in Switched Networks

We describe a call model for multipoint communication in switched networks. The model provides network clients with dynamic multipoint, multiconnection communication channels, which we term calls. Clients create, manage and manipulate calls using our Connection Management Access Protocol (CMAP). The call model provides basic interconnection services suitable for local and wide area networks, where more sophisticated services can be layered over this substrate. From: ICC `92: Proceedings of the IEEE International Conference on Communications, pages 609-615, June 1992. sent by one client is received by all other clients who have elected to receive on this cell pipe. Cell pipes are implemented in the ATM network by setting up low level connections between each switch traversed by the cell pipe. When a cell arrives at a switch, its VPI/VCI is examined and used to route the cell to the appropriate output link. The VPI/VCI is then updated so as to be meaningful to the next switch on its ro..